Subjects -> MINES AND MINING INDUSTRY (Total: 82 journals)
Showing 1 - 42 of 42 Journals sorted alphabetically
Applied Earth Science : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Archives of Mining Sciences     Open Access   (Followers: 2)
BHM Berg- und Hüttenmännische Monatshefte     Hybrid Journal   (Followers: 2)
Canadian Mineralogist     Full-text available via subscription   (Followers: 6)
CIM Journal     Hybrid Journal  
Clay Minerals     Hybrid Journal   (Followers: 9)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 12)
Environmental Geochemistry and Health     Hybrid Journal   (Followers: 2)
European Journal of Mineralogy     Hybrid Journal   (Followers: 12)
Extractive Industries and Society     Hybrid Journal   (Followers: 2)
Gems & Gemology     Full-text available via subscription   (Followers: 1)
Geology of Ore Deposits     Hybrid Journal   (Followers: 3)
Geomaterials     Open Access   (Followers: 2)
Geotechnical and Geological Engineering     Hybrid Journal   (Followers: 8)
Ghana Mining Journal     Full-text available via subscription   (Followers: 3)
Gold Bulletin     Hybrid Journal  
International Journal of Coal Geology     Hybrid Journal   (Followers: 4)
International Journal of Coal Preparation and Utilization     Hybrid Journal   (Followers: 2)
International Journal of Coal Science & Technology     Open Access   (Followers: 3)
International Journal of Hospitality & Tourism Administration     Hybrid Journal   (Followers: 14)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 9)
International Journal of Mining and Geo-Engineering     Open Access  
International Journal of Mining and Mineral Engineering     Hybrid Journal   (Followers: 5)
International Journal of Mining Engineering and Mineral Processing     Open Access   (Followers: 5)
International Journal of Mining Science and Technology     Open Access   (Followers: 4)
International Journal of Mining, Reclamation and Environment     Hybrid Journal   (Followers: 4)
International Journal of Rock Mechanics and Mining Sciences     Hybrid Journal   (Followers: 6)
Journal of Analytical and Numerical Methods in Mining Engineering     Open Access   (Followers: 1)
Journal of Applied Geophysics     Hybrid Journal   (Followers: 15)
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of China Coal Society     Open Access  
Journal of Convention & Event Tourism     Hybrid Journal   (Followers: 4)
Journal of Geology and Mining Research     Open Access   (Followers: 11)
Journal of Human Resources in Hospitality & Tourism     Hybrid Journal   (Followers: 8)
Journal of Materials Research and Technology     Open Access   (Followers: 2)
Journal of Metamorphic Geology     Hybrid Journal   (Followers: 15)
Journal of Mining Institute     Open Access  
Journal of Mining Science     Hybrid Journal   (Followers: 2)
Journal of Quality Assurance in Hospitality & Tourism     Hybrid Journal   (Followers: 5)
Journal of Sustainable Mining     Open Access   (Followers: 3)
Journal of the Southern African Institute of Mining and Metallurgy     Open Access   (Followers: 5)
Lithology and Mineral Resources     Hybrid Journal   (Followers: 3)
Lithos     Hybrid Journal   (Followers: 9)
Mine Water and the Environment     Hybrid Journal   (Followers: 5)
Mineral Economics     Hybrid Journal  
Mineral Processing and Extractive Metallurgy : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 11)
Mineral Processing and Extractive Metallurgy Review     Hybrid Journal   (Followers: 4)
Mineralium Deposita     Hybrid Journal   (Followers: 4)
Mineralogia     Open Access   (Followers: 2)
Mineralogical Magazine     Hybrid Journal   (Followers: 1)
Mineralogy and Petrology     Hybrid Journal   (Followers: 2)
Minerals     Open Access  
Minerals & Energy - Raw Materials Report     Hybrid Journal  
Minerals Engineering     Hybrid Journal   (Followers: 9)
Mining Engineering     Full-text available via subscription   (Followers: 5)
Mining Journal     Full-text available via subscription   (Followers: 3)
Mining Report     Hybrid Journal   (Followers: 2)
Mining Technology : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 2)
Mining, Metallurgy & Exploration     Hybrid Journal  
Natural Resources & Engineering     Hybrid Journal  
Natural Resources Research     Hybrid Journal   (Followers: 8)
Neues Jahrbuch für Mineralogie - Abhandlungen     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Minerals     Hybrid Journal   (Followers: 4)
Podzemni Radovi     Open Access  
Rangeland Journal     Hybrid Journal   (Followers: 1)
Réalités industrielles     Full-text available via subscription  
Resources Policy     Hybrid Journal   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 4)
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access   (Followers: 1)
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 7)
Rocks & Minerals     Hybrid Journal   (Followers: 3)
Rudarsko-geološko-naftni Zbornik     Open Access  
Stainless Steel World     Full-text available via subscription   (Followers: 17)
Transactions of Nonferrous Metals Society of China     Hybrid Journal   (Followers: 10)
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  This is an Open Access Journal Open Access journal
ISSN (Online) 2075-163X
Published by MDPI Homepage  [84 journals]
  • Minerals, Vol. 12, Pages 784: Application of Dual Silane Coupling
           Agent-Assisted Surface-Modified Quartz Powder in Epoxy Matrix for
           Performance Enhancement

    • Authors: Peiyue Li, Liyun Ma, Zijie Ren, Enjun Xie, Zengzi Wang, Liusha Xie, Huimin Gao, Xinjun Zhou, Jianxin Wu
      First page: 784
      Abstract: Quartz powder (QP) is an inorganic filler that is expected to significantly enhance the dielectric and mechanical properties of epoxy (EP)-based composites applied in copper clad laminates and epoxy molding compounds for 5G applications. As is well-known, the performance of the QP–EP composites is directly correlated with the dispersion effect and the compatibility of QP with an EP matrix. Herein, we propose the surface modification method of QP by mixing SCAs of different alkyl chain lengths that contain amino and carbonyl groups. Different characterization methods (FTIR, TGA, XPS, SEM, contact angle measurement, viscosity, and mechanical properties) and molecular dynamics simulation were adopted to study its effect and mechanism. Through dual SCA modification, the viscosity of QP–EP composites was reduced by 11.70%, and the flexural and tensile strengths increased by 16.89% and 30.01%, respectively. In addition, it was revealed that the superiority of dual SCAs originated from the synergistic effect between APTES and SPIS, it was the electrostatic repulsion force between the amino groups of the two SCAs that caused a steric hindrance that activated the steric stabilization effect of SPIS, thus resulting in better dispersion and excellent compatibility. Meanwhile, the amino and carbonyl groups of the SCA interacted with the EP matrix via chemical bonds and hydrogen bonds, thus strengthening the interfacial adhesion between the QP and EP matrix and improving the mechanical performance of QP–EP composites. These results are evidence of the potential of the proposed approach, which is based on the synergistic compounding of SCA with different molecular structures, in powder industrial applications.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070784
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 785: Mineral Chemistry of Pyrochlore Supergroup
           Minerals from the Boziguoer Nb-Ta-Zr-Rb-REE Deposit, NW China:
           Implications for Nb Enrichment by Alkaline Magma Differentiation

    • Authors: Zhenghao Sun, Kezhang Qin, Yajing Mao, Dongmei Tang, Fangyue Wang, Noreen J. Evans, Qifeng Zhou
      First page: 785
      Abstract: Alkaline rocks are generally enriched in rare metals (e.g., Nb, Ta, and Zr) and rare earth elements (REE), but the key factors controlling Nb-Ta-REE enrichment remain unclear. The Boziguoer Nb (Ta-Zr-Rb-REE) deposit in Southwest Tianshan (northern margin of Tarim Basin) is China’s largest, with reserves of 0.32 Mt Nb2O5 and 0.02 Mt Ta2O5. It is an alkaline felsic complex 4.45 km in length and 0.5–1.3 km in width, composed of alkalic granite and syenite, which can be subdivided into syenite I and syenite II. The main minerals in each lithofacies are the same (albite, K-feldspar, quartz, arfvedsonite and aegirine). The Nb in the deposit is mainly hosted in pyrochlore supergroup minerals, ubiquitous in alkalic granite and syenite of the Boziguoer deposit. The wide variation in cations (Ca, Na, REE, U, Th) in the A-site further classifies the Boziguoer pyrochlore supergroup minerals as fluornatropyrochlore, fluorcalciopyrochlore and fluorkenopyrochlore. All Boziguoer pyrochlore supergroup minerals are Nb-rich and Ta-poor at the B-site and dominated by F at the Y-site. These cation occurrence illustrate a new mechanism of substitution in the Boziguoer pyrochlore supergroup minerals (2Ca2+ +Ti4+ +4Ta5+ = REE3+ +A-V + 5Nb5+, where A-V is the A-site vacancy). This substitution mechanism is different from that in the pyrochlore supergroup minerals from other rocks such as carbonatite and nepheline syenite, which are dominated by the replacement of Ba (Rb, Sr) with Ca+ Na + A-V. In addition, the substitution of REE (mainly La, Ce) for Ca in the Boziguoer pyrochlore supergroup minerals is likely a result of either REE enrichment or a change in the REE partition coefficient during the evolution of the alkaline magma. Both the pyrochlore supergroup minerals and their host rocks display negative large ion lithophile element (LILE; K, Rb, Sr, and Ba) anomalies, positive high-field-strength element (HFSE) anomalies and light rare earth element (LREE) enrichment with negative Eu anomalies. This is consistent with the crystallization of the pyrochlore supergroup minerals from the magma rather than from hydrothermal fluids, suggesting a magmatic origin. These findings indicate that the mechanisms of pyrochlore supergroup minerals crystallization in alkaline magma may be significantly different from those in carbonatite and nepheline syenite, and that magmatic differentiation processes may have played a role in the enrichment of the Boziguoer deposit by Nb.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070785
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 786: Source Characteristics of the Carboniferous
           Ortokarnash Manganese Deposit in the Western Kunlun Mountains

    • Authors: Bang-Lu Zhang, Zhi-Cheng Lv, Zhi-Guo Dong, Xin Zhang, Xiao-Fei Yu, Yong-Sheng Li, Shi-Min Zhen, Chang-Le Wang
      First page: 786
      Abstract: The specific source of ancient sedimentary manganese (Mn) deposits is commonly complex. Here we use systematic major and trace element data with strontium (Sr) and neodymium (Nd) isotopic analyses of the Ortokarnash Mn(II) carbonate ores and associated carbonate rocks from the Upper Carboniferous Kalaatehe Formation (ca. 320 Ma) in order to constrain the Mn source. This formation consists of three members: the first member is a volcanic breccia limestone, the second member is a sandy limestone, and the third member is a black marlstone with the Mn(II) carbonate interlayers. Petrographic observations in combination with low Al2O3 (<3.0 wt%) and Hf (<0.40 ppm) contents and the lack of correlations between the Al2O3 and 87Sr/86Sr ratios as well as εNd(t) values demonstrate a negligible influence of terrigenous detrital contamination on both Sr and Nd isotopic compositions of the Mn(II) carbonate ores. The Sr isotopes of Mn(II) carbonate ores are most likely affected by post-depositional alteration, while Nd isotopes remain unaltered. The initial 87Sr/86Sr ratios in the associated carbonate rocks are likely the result of a mixture of the chemical components (i.e., seawater) and the Al-rich components (e.g., volcanoclastic material), while the detrital effects on Nd isotopes are negligible. In addition, both Sr and Nd isotopes in these non-mineralized wall rocks remained unchanged during post-depositional processes. The relatively low Th/Sc ratios and positive εNd(t) values suggest that the aluminosilicate fraction in the calcarenite and sandy limestone was mainly derived from the weathering of a depleted mafic source, representing the riverine input into the seawater. Given that the Mn(II) carbonate ores are characterized by negative εNd(t) values, these suggest that seafloor-vented hydrothermal fluids derived from interaction with the underlying old continental crust mainly contribute to the source of the Mn(II) carbonates.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070786
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 787: Hydrodynamic Simulation of the Influence of
           Injection Flowrate Regulation on In-Situ Leaching Range

    • Authors: Chong Zhang, Tingting Xie, Kaixuan Tan, Yixuan Yao, Yaan Wang, Chunguang Li, Yongmei Li, Ying Zhang, Hui Wang
      First page: 787
      Abstract: Reasonable control of the leaching range is one of the critical indicators of the in-situ leaching uranium mining process. However, there is currently no mature control technology. To verify and improve the current control technology of the leaching range in the industry, this work proposes an injection control mode for a small flow around the well-site and establishes a hydrodynamic model of the leaching range under eight different pumping and injection conditions by using the groundwater modeling system (GMS). The model calculation, range prediction, comparative analysis, and on-site SO42− and S isotope verification tests were carried out. Results show that with the change of liquid injection ratio, the area ratios of fixed pumping injection ratio (total pumping flowrate is greater than 0.3% of the total injection flowrate) and model leaching range under four pumping injection equilibrium conditions were 99.10%, 99.99%, 98.30%, and 97.95%, respectively. The farthest migration distance ratios of the leaching solution were 99.37%, 100%, 98.02%, and 97.58%, respectively. It is considered that the operation mode with a fixed pumping injection ratio has no noticeable control effect on the leaching range; selecting a reasonable proportion to regulate the flowrate of injection wells at different positions can effectively reduce the area of the groundwater flow field and realize the effective control of the leaching range. The research results are conducive to saving a lot of evaporation pool construction, land acquisition, human and material resource investment, and environmental policy pressure.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070787
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 788: Parameter Optimization and Fragmentation
           Prediction of Fan-Shaped Deep Hole Blasting in Sanxin Gold and Copper Mine

    • Authors: Bo Ke, Ruohan Pan, Jian Zhang, Wei Wang, Yong Hu, Gao Lei, Xiuwen Chi, Gaofeng Ren, Yuhao You
      First page: 788
      Abstract: For San-Xin gold and copper mine, deep blasting large block rate is high resulting in difficulty in transporting the ore out; secondary blasting not only increases blasting costs but is more likely to cause the top and bottom plate of the underground to become loose causing safety hazards. Based on the research background of Sanxin gold and copper mine, deep hole blasting parameters were determined by single-hole, variable-hole pitch, and oblique hole blasting tests, further using the inversion method to determine the optimal deep hole blasting parameters. Meanwhile, the PSO-BP neural network method was used to predict the block rate in deep hole blasting. The results of the study showed that the optimal minimum resistance line was 1.24–1.44 m, which was lower than 1.6–1.8 m in the original blasting design, which was one of the reasons for the higher blasting block rate. In addition, the PSO-BP deep hole blasting fragmentation prediction model predicts the block rate of the optimized blasting parameters and predicted a block rate of 6.83% after the optimization of hole network parameters. Its prediction accuracy is high, and the blasting parameter optimization can effectively reduce the block rate. It can reasonably reduce the rate of large pieces produced by blasting, improve blasting efficiency, and save blasting costs for enterprises. The result has wide applicability and can provide solutions for underground mines that also have problems with blasting large block rate.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070788
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 789: Comprehensive Physical Properties and
           Exploration Potential of the Permian Igneous Rocks in the Southwestern
           Sichuan Basin

    • Authors: Kui Xiang, Liangjun Yan, Zhigang Wang, Yao Lu
      First page: 789
      Abstract: The Permian igneous rocks in the Sichuan Basin represent a major breakthrough, opening up a new prospect for oil and gas exploration, and igneous reservoirs have become a new field of oil and gas exploration. Gravity-magnetic-electric exploration is an effective means of identifying igneous rocks and helps in reducing the multiplicity of the prediction results. However, the lithology of igneous rocks is quite different, and the exploration theory and evaluation techniques need urgently to be improved. In order to deeply study the response characteristics of the gravity-magnetic-electric and physical properties of the Permian igneous rocks in the Sichuan Basin and their relationships with the reservoir parameters, physical property testing was carried out on outcrop samples of the Permian igneous rocks in southwestern Sichuan. The comprehensive physical properties of the samples with different lithologies, including basalt, tuff, and volcanic breccia, were analyzed and studied. Based on the geological characteristics of the igneous rocks, such as the mineral composition, microstructure, and reservoir properties, a multi-parameter intersection relationship model for the resistivity, polarizability, density, magnetic susceptibility, and their relationships with the reservoir parameters was established, and effective parameters favorable for igneous rock identification and reservoir evaluation were identified. The results of this study provide a physical basis and technical support for non-seismic exploration of igneous oil and gas reservoirs in the Sichuan Basin.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070789
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 790: Sulfide and Fluoride Mineralization of the
           NNE Region of Achemmach (Central Morocco): Paragenetic Sequences and
           Pyrrhotite-Sphalerite Geothermometry Constraints

    • Authors: Hafid Mezougane, Mohamed Aissa, Souiri Muhammad, Azizi Moussaid, Abdelaziz El Basbas, Mourad Essalhi, Abdel-ali Kharis, Mohammed El Azmi, Ahmed Touil, Essaid Bilal
      First page: 790
      Abstract: Sulfide and fluoride mineralization in the NNE Achemmach (NNE-A) area is located in the NE of Central Hercynian Morocco. In veins or when disseminated, it is hosted either in Visean sedimentary formations or in the magmatic bodies, described for the first time in this article and corresponding to pillow-lavas, dolerites and olivine-bearing gabbros. The mineralization is multiphase and results from the succession of the following three events: (i) an early high-temperature hydrothermal event (T ≈ 350–420 °C) associated with a simple primary sulfide paragenesis composed of pyrrhotite, pyrite, chalcopyrite, sphalerite and galena with gangue of quartz.(ii) The second event corresponds witha low temperature fluorite hydrothermal one (T ≈ 120–160 °C), whereas the (iii) third is marked by, the deposition of a late sulfide paragenesis in a carbonate gangue within a moderate temperature (T ≈ 200–250 °C). The temperatures of the paragenetic stages (350–400 °C) are estimated on the basis of the geothermometry constraints of the mineralogical assemblages, particularly the pyrrhotite-sphalerite equilibrium, in which the FeO content varies from 9.23 to 14.42 Wt%, and in the full study of their corresponding fluid phases. They are in perfect agreement with the fluid inclusion data of the first event.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070790
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 791: Geochronology and Tectonic Implications of
           the Nianzigou Granites and Associated Mo Deposit, Inner Mongolia

    • Authors: Yang Li, Yongqiang Yang, Lei Hua, Yaxing Leng, Jiang Xin
      First page: 791
      Abstract: Multiple stages of igneous rocks occur in the recently discovered Nianzigou Mo deposit in Chifeng, Inner Mongolia, which can provide insights into the late Mesozoic geodynamic evolution of the southern Da Hinggan Range. The mineralization age is similar to the age of local granites, but there are few detailed studies of the tectonic setting during Cu-Mo mineralization in this area. The Nianzigou Mo deposit is located close to the northern margin of the North China Craton and in the eastern Central Asian Orogenic Belt and is a typical quartz-vein-type Mo deposit in the Xilamulun Mo ore belt. The granite in this deposit has high SiO2, Al2O3, K2O, and Na2O contents, and low MgO, CaO, and Fe2O3t contents. The granite is characterized by enrichments in large-ion lithophile elements and depletions in high-field-strength elements and, in particular, Sr, Ti, and P. The granite has high contents of rare-earth elements, is enriched in light rare-earth elements, and has marked negative Eu anomalies. The granite is an alkaline and calc-alkaline and metaluminous A-type granite. The zircon U-Pb ages of the monzogranite and granite porphyry are 157.2 ± 0.3 and 154.4 ± 0.4 Ma. The model age obtained by Re-Os isotopic dating is 154.3 ± 1.7 Ma, indicating that molybdenite mineralization also occurred during the Late Jurassic period. Given that the molybdenite Re contents are 7.8–24.9 ppm (average = 16.8 ppm), the ore-forming materials of the Nianzigou Mo deposit had a mixed crust–mantle source, but were mainly derived from the lower crust. Based on the geology and geochemistry, we propose that the Nianzigou Mo deposit formed in a postorogenic extensional tectonic setting associated with the southward subduction of the Mongol–Okhotsk oceanic plate.
      Citation: Minerals
      PubDate: 2022-06-21
      DOI: 10.3390/min12070791
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 792: Geochronology and Zircon Hf Isotope of the
           Paleoproterozoic Gaixian Formation in the Southeastern Liaodong Peninsula:
           Implication for the Tectonic Evolution of the Jiao-Liao-Ji Belt

    • Authors: Hongchao Yu, Jin Liu, Zhonghua He, Zhenghong Liu, Changquan Cheng, Yujie Hao, Chen Zhao, Hongxiang Zhang, Yachao Dong
      First page: 792
      Abstract: The Jiao-Liao-Ji belt (JLJB), in the Eastern Block of the North China Craton, is a major Paleoproterozoic orogen and underwent a complicated tectonic evolution during 2.2–1.8 Ga. The Liaohe Group, an important stratigraphic unit in the JLJB, is key to understanding the complex evolution of this belt. In this paper, we present new detrital zircon U–Pb ages and Hf isotope data for meta-sedimentary rocks from the Gaixian Formation in different areas of the JLJB, in addition to compiled data for other formations of the Liaohe Group, to establish the depositional age and source of detrital materials of the group. U–Pb age results show that the age ranges of zircons from the different samples are broadly similar. The youngest zircon group is ca. 2.06 Ga, and the youngest single-grain age is ca. 2.0 Ga, constraining the depositional age of the Gaixian Formation to between 2.0 Ga and the metamorphic age of ca. 1.9 Ga. The zircon age data indicate that the provenance was primarily Archaean basement of the Nangrim Block and Paleoproterozoic volcanic rocks of the Li’eryu Formation. On the basis of the new geochronological data and results from previous studies, it is inferred that the JLJB underwent a successive process of rifting–subduction–collision, with the different formations of the Liaohe Group being deposited in different stages from rift to passive continental margin and then to active continental margin. Zircon Hf isotope data from the JLJB and adjoining Longgang and Nangrim blocks indicate that a major crustal growth event occurred at 2.9–2.5 Ga, followed by crustal growth and intense recycling of ancient crust at ca. 2.2 Ga.
      Citation: Minerals
      PubDate: 2022-06-22
      DOI: 10.3390/min12070792
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 793: Insights into the Ore Genesis of the Harla
           Gold Deposit in Eastern Tianshan, NW China: Evidence from Geology, Fluid
           Inclusions, and H-O-C-S-Pb Isotopes

    • Authors: Chuan Chen, Shunda Li, Fang Xia, Lingling Gao, Xuebing Zhang
      First page: 793
      Abstract: The Harla gold deposit is located on the eastern segment of the Kanggur-Huangshan ductile shear belt in Eastern Tianshan, on the southern margin of the Central Asian Orogenic Belt. The orebodies show close spatial association with NEE-trending faults and are hosted in volcanic rocks of the Lower Carboniferous Xiaorequanzi Formation. Three mineralization stages were recognized: an early stage characterized by specularite–pyrite–quartz mineralization, an intermediate stage with pyrite–chalcopyrite–gold–quartz genesis, and a late stage defined by sulfide-poor calcite and quartz veins. Three types of fluid inclusions (FIs) were recognized: daughter mineral-bearing triphase FIs (S-type), liquid-dominated biphase FIs (LV-type), and liquid-only monophase FIs (L-type). S- and LV-type FIs entrapped in the early stage show similar homogenization temperatures (Th) at 216–229 °C and 199–222 °C. However, they display contrasting salinities of 32.2–33.4 and 6.7–8.9 wt.% NaCl eqv., respectively. LV-type FIs entrapped in the intermediate stage display Th of 163–191 °C, with salinities of 5.6–7.4 wt.% NaCl eqv. LV-type FIs occur in the late stage display Th of 135–258 °C and salinities of 3.7–5.6 wt.% NaCl eqv. Insights from hydrogen, oxygen, and carbon isotope analyses (δ18OH2O = −10.7 to 3.3‰, δDH2O = −88.1 to −61.4‰, δ13CH2O = −8.9 to −6.2‰), combined with FI characteristics, indicate that the ore-forming fluids were derived from a hybrid source of magmatic and meteoric water, with the latter becoming dominant in the later stage. Sulfide and lead isotopic compositions (δ34Spyrite = 0.2 to 2.5‰, 206Pb/204Pb = 17.709–18.273, 207Pb/204Pb = 15.483–15.569, 208Pb/204Pb = 37.533–37.754) suggest that ore-forming materials were mainly derived from wall rocks (Xiaorequanzi Formation rocks and plagiogranite). By integrating geological background work and fluid inclusion analyses, as well as isotope data, we conclude that the Harla gold deposit is an epithermal-type deposit.
      Citation: Minerals
      PubDate: 2022-06-22
      DOI: 10.3390/min12070793
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 794: Petrography and Provenance of the
           Sub-Himalayan Kuldana Formation: Implications for Tectonic Setting and
           Palaeoclimatic Conditions

    • Authors: Ahmer Bilal, Muhammad Saleem Mughal, Hammad Tariq Janjuhah, Johar Ali, Abrar Niaz, George Kontakiotis, Assimina Antonarakou, Muhammad Usman, Syed Asim Hussain, Renchao Yang
      First page: 794
      Abstract: In this paper, the depositional environment, age, and tectonic context of the Sub-Himalayan Kuldana Formation are discussed in detail. To determine the Kuldana Formation’s depositional environment, age, and tectonic setting, sedimentological, palaeontological, and petrographic investigations have been conducted accordingly. The Kuldana Formation lithologically consists of both siliciclastic and carbonate rocks. Petrographically, the Kuldana Formation’s sandstone is divided into litharenite and feldspathic litharenite petrofacies. The sandstone plots on the QtFL and QmFLt suggest that the sandstone of the Kuldana Formation derived from a recycled orogen provenance field that developed during the collision of the Indian and Eurasian plates in the Lesser and Higher Himalayas. The plots in the diamond diagram further demonstrate that the detritus of the Kuldana Formation was derived from low and middle-to-upper rank metamorphic rocks of the Himalayas. Throughout the deposition of sandstone, paleo-climate conditions were semi-humid to semiarid. Dolostone and limestone are the two main types of carbonate rocks found in the Kuldana Formation. According to Dunham’s Classification, the Kuldana Formation limestone is classified as mudstone, wackstone, and packstone. These petrofacies suggest that the limestone was deposited in an inner-outer ramp setting. The bioclasts include bivalves, brachiopods, crinoid, gastropods, Globigerinoides spp, Lockhartia pustulosa, miliolids, Nummulites atacicus, Nummulites discorbina, Nummulites mamillatus, Nummulites djodjokartae, Nummulites vascus, and ostracods suggesting that the age of Kuldana Formation is Middle Eocene- early Oligocene. The Kuldana Formation was deposited during the initial stages of the Himalayan Orogeny as a result of the Ceno-Tethys Ocean’s regression and transgression, as revealed by a succession of siliciclastic and non-clastic rocks.
      Citation: Minerals
      PubDate: 2022-06-22
      DOI: 10.3390/min12070794
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 795: Study on a High-Efficiency Mining Technology
           System for Gas Outburst in Coal Seams—Example of an H Coal Mine

    • Authors: Chuming Pang, Yongkui Shi, Xin Wang, Benzheng Li, Hengjie Luan
      First page: 795
      Abstract: Coal will continue to play an important role in China’s economic development and social development in the coming decades. However, due to the complex distribution conditions of coal resources, the mining of coal resources is subject to various restrictions. Coal and gas outburst is an important issue in coal mining, and the threat to the mining of coal resources caused by high gas outburst activity has been receiving more attention. In order to solve the problems related to safe and efficient mining under coal seams with gas outburst, such as mining difficulties, large amounts of work, resource waste, no guaranteed gas treatment time, and low economic efficiency, it is necessary to innovate mining technology and methods for managing gas outburst in coal seams to improve the efficiency of coal mines and to solve the above problems. This study proposes a green mining technical method system known as the “L-H method”, which is applicable to the safe and efficient mining of coal seams with gas outburst based on combined theoretical analysis and numerical simulation. The following research results are achieved: (1) The “L-H method” is proposed, and a mining area model of coal seams with gas outburst is established. The specific details of the method and the implementation process are introduced. (2) Examples of H coal mine applications are presented, and the effects of the implementation of the “L-H method” are analyzed and summarized through mine pressure observations from roadways, and it is concluded that the implementation of top-cutting and pressure-relief technology has a good control effect on the roadway-surrounding rock and that gas extraction reaches the national standard of less than 8 m3/t for protrusion prevention; this ensures safety and also achieves efficient mining. This study will provide a good reference for the implementation of green mining methods to similar coal and gas outburst mines.
      Citation: Minerals
      PubDate: 2022-06-22
      DOI: 10.3390/min12070795
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 796: Characterization Analysis of Airborne
           Particulates from Australian Underground Coal Mines Using the Mineral
           Liberation Analyser

    • Authors: Nikky LaBranche, Kellie Teale, Elaine Wightman, Kelly Johnstone, David Cliff
      First page: 796
      Abstract: Exposure monitoring and health surveillance of coal mine workers has been improved in Australia since coal workers’ pneumoconiosis was reidentified in 2015 in Queensland. Regional variations in the prevalence of mine dust lung disease have been observed, prompting a more detailed look into the size, shape, and mineralogical classes of the dust that workers are being exposed to. This study collected respirable samples of ambient air from three operating coal mines in Queensland and New South Wales for characterization analysis using the Mineral Liberation Analyser (MLA), a type of scanning electron microscope (SEM) that uses a combination of the backscattered electron (BSE) image and characteristic X-rays for mineral identification. This research identified 25 different minerals present in the coal samples with varying particle size distributions for the overall samples and the individual mineralogies. While Mine 8 was very consistent in mineralogy with a high carbon content, Mine 6 and 7 were found to differ more significantly by location within the mine.
      Citation: Minerals
      PubDate: 2022-06-22
      DOI: 10.3390/min12070796
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 797: Weathered Cortex of Eluvial–Deluvial
           Jadeite Jade from Myanmar: Its Features, Formation Mechanism, and

    • Authors: Xiangyu Zhang, Guanghai Shi, Guowu Li, Xin Li
      First page: 797
      Abstract: Myanmar is the principal provider country of high-quality jadeite jade in the world, including so-called primary and secondary stones. The secondary stones occur as rounded pebbles, boulders, and blocks in eluvium–alluvium and often hold varying degrees of weathering. Unlike common rocks, such as granite, gabbro, schist, gneiss, and amphibolite, secondary jadeite stones frequently have weathered cortexes that vary in appearance, depth, texture, and mineral components compared with those of inner primary bodies. In this study, representative samples of secondary eluvial–deluvial jadeite stones with varying weathered cortexes were selected, and their appearances, textures, mineral components, and chemical composition features were analyzed. Their weathered cortexes were red, yellow, white, or black, and were 0.01–1.80 cm thick. The cortexes were opaque, often with soil luster and a fansha phenomenon. The body of the jade was usually translucent, and green and white in color. Along the border between the weathered cortex and the body of a certain jade stone, the textures were the same for the successive grain sizes. The only difference was that there were more cracks, cleavage planes, and fissures in the cortex. Jadeite was the main mineral component of both; however, minor late-stage supergene minerals (such as gibbsite, kaolinite, and halloysite) and Fe-bearing colloidal minerals were identified along the grain boundaries in the cortex. Studies of the textures and mineral components of weathered cortexes have gemmological applications including the identification and grading raw jadeite, as well as its design and carving. Moreover, such studies might provide information for improving our understanding of the unique weathering processes of monomineralic aggregates relative to multiple-mineral rocks, as well as gambling jadeite jade pieces through analyzing their cortex.
      Citation: Minerals
      PubDate: 2022-06-22
      DOI: 10.3390/min12070797
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 798: Adsorption and Mechanism of Glycine on the
           Anatase with Exposed (001) and (101) Facets

    • Authors: Zeling Liu, Xiaomei Zhong, Yifan Liu, Hanyun Rao, Hongfu Wei, Wenyuan Hu, Xiaoqin Nie, Mingxue Liu
      First page: 798
      Abstract: As a widely existing mineral types on Earth, semiconductor minerals play an important role in the origin of life and the material geochemical cycle. The first step of peptide formation is amino acid adsorption on the mineral surface, but the role and mechanism of different crystal facets of semiconductor minerals are not well understood. Anatase (TiO2) with exposed (001) facets was synthesized by a hydrothermal method, and then analyzed and compared with the purchased ordinary anatase (TiO2) for the adsorption of glycine, the simplest amino acid. XRD, SEM and TEM results show that the hydrothermally synthesized anatase (TiO2) has a good anatase crystal form, which is micro-nano-scale flake particles and mainly composed of (001) facets. The results of HPLC used in the adsorption experiment showed that under optimal conditions (pH 5 to 6, an adsorption time of 24 h, and an initial concentration of 0.09 mol/L), the adsorption quantity of glycine on anatase (TiO2) with exposed (001) facets may reach 10 mg/m2, which is larger than that for ordinary anatase (TiO2) with exposed (101) facets. Based on a combination of various characterizations and simulation calculations, the results proved that anatase can activate thermodynamically stable γ-glycine to β-glycine. The adsorption of glycine on anatase (TiO2) has two forms, one is the zwitterionic form in which the carboxyl group forms a bridge structure with two Ti atoms connected by surface bridging oxygen, and the dissociated form is in which the amino group forms a bond with the surface Ti atom. Among these, glycine is mainly adsorbed to anatase by dissociative molecules on the anatase (TiO2) with exposed (001) facets and by zwitterion adsorption on the anatase (TiO2) with exposed (101) facets. This research elucidates the conditions and mechanism of amino acid adsorption by semiconductor minerals in weak acidic environment, which is similar to the environmental pH that was beneficial to the formation of life on the early Earth. Therefore, these can provide a reference for the further study of the role of semiconductor minerals in the adsorption and polymerization of small biomolecules in the origin of life.
      Citation: Minerals
      PubDate: 2022-06-22
      DOI: 10.3390/min12070798
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 799: Ore Genesis of the Changkeng–Fuwan
           Au-Ag Deposit in Central Guangdong, South China: Evidence from Fluid
           Inclusions and C-H-O-S-Pb-He-Ar Isotopes

    • Authors: Guangyao Shi, Jianling Xue, Xiaoqiang Zhu, Zhenshan Pang, Xueqiu Wang, Fan Yang, Gilby Jepson, Wen Tao, Shimin Zhen
      First page: 799
      Abstract: The Changkeng–Fuwan Au-Ag deposit is representative in South China, which is located in the southwest of the Qin–Hang metallogenic belt (QHMB). The Au and Ag orebodies are located in the same altered fracture zone, forming independent gold and silver orebodies respectively, with the characteristics of “upper gold and lower silver” in space. Three metallogenic stages have been identified: the pyrite–quartz–sericite stage, the polymetallic sulfide stage, and the quartz–calcite stage. The fluid inclusions (FIs) from the deposit are the two-phase liquid-rich (type I) and the pure liquid FIs (type II). The microthermometric measurements of type I FIs are characterized by temperatures of 158–282 °C and 146–289 °C and salinities of 0.35–9.88 wt.% NaCl equiv. and 0.18–11.70 wt.% NaCl equiv. The H, O, He, and Ar isotopic data show that the ore-forming fluids of the deposit were derived from a mixture of magmatic and meteoric fluids. The C and O isotopic data suggest that the carbon of the fluid may derive from a magmatic source. The S and Pb isotopic data indicate that the primary source of the metals in the Changkeng–Fuwan deposit may be a magma source. Based on the geological characteristics, FI microthermometry, and isotope data (C, H, O, He, Ar, S, and Pb), we propose that the Changkeng–Fuwan deposit should be classified as a far-source low-temperature magmatic–hydrothermal deposit.
      Citation: Minerals
      PubDate: 2022-06-23
      DOI: 10.3390/min12070799
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 800: Unravelling the Deformation of
           Paleoproterozoic Marbles and Zn-Pb Ore Bodies by Combining 3D-Photogeology
           and Hyperspectral Data (Black Angel Mine, Central West Greenland)

    • Authors: Pierpaolo Guarnieri, Sam T. Thiele, Nigel Baker, Erik V. Sørensen, Moritz Kirsch, Sandra Lorenz, Diogo Rosa, Gabriel Unger, Robert Zimmermann
      First page: 800
      Abstract: The Black Angel Zn-Pb ore deposit is hosted in folded Paleoproterozoic marbles of the Mârmorilik Formation. It is exposed in the southern part of the steep and inaccessible alpine terrain of the Rinkian Orogen, in central West Greenland. Drill-core data integrated with 3D-photogeology and hyperspectral imagery of the rock face allow us to identify stratigraphic units and extract structural information that contains the geological setting of this important deposit. The integrated stratigraphy distinguishes chemical/mineralogical contrast within lithologies dominated by minerals that are difficult to distinguish with the naked eye, with a similar color of dolomitic and scapolite-rich marbles and calcitic, graphite-rich marbles. These results strengthen our understanding of the deformation style in the marbles and allow a subdivision between evaporite-carbonate platform facies and carbonate slope facies. Ore formation appears to have been mainly controlled by stratigraphy, with mineralizing fluids accumulating within permeable carbonate platform facies underneath carbonate slope facies and shales as cap rock. Later, folding and shearing were responsible for the remobilization and improvement of ore grades along the axial planes of shear folds. The contact between dolomitic scapolite-rich and calcitic graphite-rich marbles probably represents a direct stratigraphic marker, recognizable in the drill-cores, to be addressed for further 3D-modeling and exploration in this area.
      Citation: Minerals
      PubDate: 2022-06-23
      DOI: 10.3390/min12070800
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 801: Adsorption and Desorption of Coal Gangue
           toward Available Phosphorus through Calcium-Modification with Different pH

    • Authors: Tiantian Ye, Xiangyu Min, Xuzi Jiang, Mingyue Sun, Xinju Li
      First page: 801
      Abstract: The chemical reaction between calcium ions (Ca2+) and phosphate in the soil is the main way to maintain the availability of soil phosphorus. Thus, we believe stimulating coal gangue with Ca2+ solution would be an effective way to improve its adsorption and desorption capacity toward phosphate. In order to explore the effects of different pH of Ca2+ solution on the modified effect of coal gangue, we conducted mechanical grinding (<1 mm), high temperature calcination (800 °C), and the stimulation of Ca2+ solution with different pH (2, 7, 13), to prepare acidic calcium-modified coal gangue (Ac-CG) (Ac-CG, acidic calcium-modified coal gangue; Ne-CG, neutral calcium-modified coal gangue; Al-CG, alkali calcium-modified coal gangue; RCG, raw coal gangue), neutral calcium-modified coal gangue (Ne-CG), and alkali calcium-modified coal gangue (Al-CG); raw coal gangue (RCG) was regarded as the control. The results indicated that Al-CG had better phosphate adsorption (3.599 mg g−1); this favorable adsorption performance of Al-CG was related to the formation of hydrated calcium silicate gel and ettringite, which provided more Ca2+, Al3+, and hydroxyl groups, and a larger specific surface area (9.497 m2 g−1). Moreover, Al-CG not only held more phosphate but also maintained its availability longer for plants. It is suggested that stimulating coal gangue with Ca2+ solution under alkaline conditions is a perfect way to enhance its adsorption and desorption capacity toward phosphate; the Al-CG we prepared could be used as filling material and soil conditioner in the reclamation area.
      Citation: Minerals
      PubDate: 2022-06-24
      DOI: 10.3390/min12070801
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 802: Investigation on Oil Physical States of
           Hybrid Shale Oil System: A Case Study on Cretaceous Second White Speckled
           Shale Formation from Highwood River Outcrop, Southern Alberta

    • Authors: Hong Zhang, Haiping Huang, Mengsha Yin
      First page: 802
      Abstract: Nine samples collected from the Upper Cretaceous Second White Speckled Shale Formation at the Highwood River outcrop in southern Alberta were geochemically characterized for their oil contents, physical states, and chemical compositions. Cold extraction was performed on 8–10 mm and 2–5 mm chips sequentially to obtain the first and second extractable organic matter (EOM-1 and EOM-2), while Soxhlet extraction was performed on powder from previously extracted chips to obtain the third extract (EOM-3). EOM-1 can be roughly regarded as free oil and EOM-2 is weakly adsorbed on mineral surfaces, while EOM-3 may represent the oil strongly adsorbed on kerogen. While both extraction yields and Rock-Eval pyrolysates differed from their original values due to the evaporative loss during outcropping, there was a generally positive correlation between the total EOM and total oil derived from Rock-Eval pyrolysis. EOM-1 was linearly correlated with Rock-Eval S1, while the extractable S2 content was well correlated with the loss of TOC, suggesting that TOC content was the main constraint for adsorbed oils. A bulk composition analysis illustrated that EOM-1 contained more saturated hydrocarbons, while EOM-3 was enriched in resins and asphaltenes. More detailed fractionation between the free and adsorbed oils was demonstrated by molecular compositions of each extract using quantitative GC-MS analysis. Lower-molecular-weight n-alkanes and smaller-ring-number aromatic compounds were preferentially concentrated in EOM-1 as compared to their higher-molecular or greater-ring-number counterparts and vice versa for EOM-3. Fractionation between isoprenoids and adjacent eluted n-alkanes, isomers of steranes, hopanes, alkylnaphthalenes, alkylphenanthrenes and alkyldibenzothiophenes was insignificant, suggesting no allogenic charge from deep strata. Strong chemical fractionation between saturated and aromatic hydrocarbon fractions was observed with EOM-1 apparently enriched in n-alkanes, while EOM-3 retained more aromatic hydrocarbons. However, the difference between free and adsorbed state oils was less dramatic than the variation from shales and siltstones. Lithological heterogeneities controlled both the amount and composition of retained fluids. Oil that resided in shales (source rock) behaved more similar to the EOM-3, with diffusive expulsion leading to the release of discrete molecules from a more adsorbed or occluded phase to a more free phase in siltstones with more connected pores and/or fractures (reservoir). Under current technical conditions, only the free oil can flow and will be the recoverable resource. Therefore, the highest potential can be expected from intervals adjacent to organic-rich beds. The compositional variations due to expulsion and primary migration from source rocks to reservoirs illustrated in the present study will contribute to a better understanding of the distribution of hydrocarbons generated and stored within the shale plays.
      Citation: Minerals
      PubDate: 2022-06-24
      DOI: 10.3390/min12070802
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 803: Joint Inversion with Borehole and
           Semi-Airborne TEM Data Based on Equivalent Filament Approximation

    • Authors: Junjie Wu, Qingquan Zhi, Xiaohong Deng, Xingchun Wang, Yi Yang
      First page: 803
      Abstract: The borehole transient electromagnetic (TEM) method can be useful in deep mineral exploration to detect blind ore bodies beside or below the borehole, and is especially adapted to finding small-scale, deep, rich ore bodies. In this method a transmitting loop is deployed on the top surface of the Earth, while a receiving coil is moved down the borehole. As the borehole TEM method is limited by the borehole’s location and depth, so its exploration scope is limited. The surface to airborne TEM method is a semi-airborne TEM configuration that transmits on the surface and receives TEM response in air. The two systems are combined into one system in this study, sharing the transmission loop deployed on the surface. With this combined system, the TEM response in the borehole and in the air can be observed at the same time. This paper employs a joint interpretation method based on the equivalent filament, which is introduced to obtain more reliable geometric information for the target with both borehole and aerial TEM data. The eddy currents induced in a thin confined conductor can be represented by equivalent current filaments, and the distribution of filaments can reflect the position and geometry of the conductor. Therefore, geometric parameters of targets can be obtained by filament inversion, and the joint inversion can be more accurate with both borehole and aerial response. Numerical modeling results show that the joint inversion based on the equivalent filament results can reliably obtain the geometric parameters of the thin conductive plate embedded in half space.
      Citation: Minerals
      PubDate: 2022-06-24
      DOI: 10.3390/min12070803
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 804: Mill Feed Control System and Algorithm Based
           on Python

    • Authors: Wenkang Zhang, Dan Liu, Yu Du, Ruitao Liu, Daqian Wang, Longzhou Yu, Shuming Wen
      First page: 804
      Abstract: Grinding is an important link in the process of mineral processing. It plays a vital role in mineral processing by optimizing the grinding process, improving the quality of grinding products and ensuring the follow-up operation indicators. In this paper, the Python language, intelligent theoretical control technology and mineral processing were combined to solve the problem of ore feeding control in mineral processing. Using error factor analysis, an extended control algorithm was designed. The NumPy library and data collected from the Yuan YangMou concentrator in China were used to quantitatively analyze the factors affecting the error of electronic belt scales. This paper introduces the use of Kalman filtering for electronic belt scale weight data to reduce the effect of noise and hence reduce errors. The factors affecting the process of mill feeding are also analyzed. The core ideas and methods of fuzzy control theory are summarized, and a Python-based fuzzy controller suitable for the mill feeding process that improves the overall robustness and accuracy of feeding system is implemented.
      Citation: Minerals
      PubDate: 2022-06-24
      DOI: 10.3390/min12070804
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 805: Cryogenic Soil—Product of Mineral
           Weathering Processes

    • Authors: Ze Zhang, Jinbang Zhai, Andrey Melnikov, Shengrong Zhang, Xianglong Li
      First page: 805
      Abstract: Since the Quaternary, the alternate climate of dry and wet, cold and warm, and the emergence of glacial and interglacial periods have led to great changes in the global environment and climate. As an event closely related to cold climate, cryogenic soil has important reference significance for the study of climate change in a certain region and time period. The research on cryogenic soils mainly focuses on the following three aspects: particle size composition, surface morphology and mineral composition. Through the study of the relevant literature, we find that the correlation coefficient of particle size composition before and after freeze-thaw is used to determine the cause of cryogenic weathering. Due to the singleness of judgment conditions, the result is difficult to be convincing; It is difficult to prove the microscopic morphology of the cause of cryogenic weathering from a single mineral of quartz. Therefore, it is necessary to start with more types of primary minerals, and analyze the differences in the particle shape and microscopic surface morphology of different types of primary minerals during the cryogenic weathering process. And on this basis, the typical mineral morphology of the cause of cryogenic weathering is comprehensively judged; Freeze-thaw has little effect on the mineral composition of the soil, but has a greater impact on the size of the mineral particles, and this size change corresponds to the phenomenon of particles silt-fication. The mineral composition also controls the geochemical composition, and the insignificance of the mineral-chemical composition in the process of cryogenic silt-fication increases the difficulty of judging the cause of cryogenic weathering.
      Citation: Minerals
      PubDate: 2022-06-24
      DOI: 10.3390/min12070805
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 806: Genesis of the Tangshang Au Deposit in
           Southeast Yunnan Province, China: Constraints from In Situ Chemical and
           S-Sr Isotope Analyses

    • Authors: Weifang Song, Pan Wu, Jianzhong Liu, Junhai Li, Zepeng Wang, Qinping Tan, Zhuojun Xie, Lulin Zheng
      First page: 806
      Abstract: The Yunnan–Guizhou–Guangxi district (also known as the Dian–Qian–Gui “Golden Triangle”) in southwestern China contains numerous Carlin-type Au deposits (CTGDs). However, the sources of Au and Au-bearing fluids in these deposits remain controversial. The Tangshang Au deposit is a middle-sized CTGD in southeastern Yunnan Province. This study involved in situ chemical and S isotope analyses of sulfides and in situ trace elemental and Sr isotope analyses of ore-related calcite; these data were used to trace the sources of fluids and Au, as well as the genesis of this deposit. Four pyrite types (Py1, Py2, Py3, and Py4) and two arsenopyrite types (Apy1 and Apy2) were identified based on their textural characteristics. It was found that Py1 contains relatively lower Au, Sb, Cu, and Tl contents than those of Py2, Py3, and Py4. Py1 is wrapped by rim-Py2 and Py3, which indicates an early-ore-stage genesis. The Carlin-type mineralization elements are elevated in the pyrites (Au = 3.04–38.1 ppm; As = 40,932–65,833 ppm; Tl = 0 to 3.3 ppm; Sb = 1.2 to 343 ppm; and Cu = 10 to 102 ppm), and the average Co/Ni ratio is 0.54. Additionally, Au has a positive correlation with Tl and Cu. The high concentrations of As and Au in all types of pyrite indicate that the ore-forming fluids are rich in both elements. The sulfides in the ores were shown to produce similar S isotope ratios, which are obviously higher than the S isotope value of sulfide (~0‰) in Emeishan basalt; therefore, the integration of these and elemental composition data indicated that all pyrites (Py1, Py2, Py3, and Py4) form during the ore stage. These results also demonstrate that the δ34S values of the Au-bearing fluids are higher than those of basalt wall rocks. The flat chondrite-normalized REEs pattern and positive Eu anomaly of the calcite were similar to those obtained from Emeishan basalt, which suggests a reducing characteristic of hydrothermal fluids. The 87Sr/86Sr ratios (0.70557–0.70622) of calcite were also comparable to the range obtained from Emeishan basalt. Some slightly higher 87Sr/86Sr ratios, which ranged between those obtained from Emeishan basalt and limestone from the Maokou Formation, indicated that the Sr isotope ratios of the Au-bearing fluids are higher than those of Emeishan basalt. Based on data generated in the present study and the regional geology of this area, a genetic model involving a metamorphic fluid system was proposed for the Tangshang gold deposit, and a gold mineralization event related to metamorphic fluid in the south of the Dian–Qian–Gui “Golden Triangle” was indicated.
      Citation: Minerals
      PubDate: 2022-06-24
      DOI: 10.3390/min12070806
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 807: Constant Wear Criterion for Optimization of
           the Crushing Chamber of Cone Crushers

    • Authors: Zhang, Ren, Cheng
      First page: 807
      Abstract: The crushing chamber is the core component of a cone crusher, consisting of mantle and concave parts. Reducing the impact of crushing chamber wear on the performance of cone crushers and the quality of crushed products while extending the service life of the mantle and concave has become a significant research challenge. The impact of the compression ratio and particle size distribution coefficient on the particle crushing pressure is investigated here in order to establish the particle pressure model. The effect of the normal and tangential components of particle crushing pressure on the wear of the mantle and concave is discussed, and the wear with the increase in crushed products and accumulation of operating time is explored in order to develop a wear model of the crushing chamber. By evaluating the compensation of the worn crushing chamber according to the adjustment mechanism of the mantle, a constant wear criterion for the crushing chamber of the cone crusher is proposed. Through analysis of industrial experimental data on an experimental prototype of a ZS200MF cone crusher with an optimized mantle and concave, the capacity was found to fluctuate at 83.45 t/h with no apparent downward trend, the calibration size production was reduced by 6.2%, and the wear similarity coefficient was 8.82%. This indicates that replacing the optimized mantle and concave based on the constant wear criterion maintains the performance of the cone crusher, delays the decline in the quality of the crushed products, and ensures similarity between the adjusted worn crushing chamber and the initial crushing chamber, which verifies the feasibility and effectiveness of the constant wear criterion for the optimization of crushing chamber. Based on the constant wear criterion, cone crushers can be optimized to obtain a crushing chamber with constant wear characteristics, which provides theoretical support for the development of new high-efficiency cone crushers as well as the optimization of existing equipment.
      Citation: Minerals
      PubDate: 2022-06-24
      DOI: 10.3390/min12070807
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 808: Stability Evaluation and Structural
           Parameters Optimization of Stope Based on Area Bearing Theory

    • Authors: Hao-Yu Qiu, Ming-Qing Huang, Ya-Jie Weng
      First page: 808
      Abstract: A reasonable and stable stope structure is the premise of realizing safe mining of underground metal ore. To safely mine the gently inclined medium-thick ore body, stope stability in Bainiuchang Mine was analyzed based on the pillar area bearing theory, and stope stability with regard to nine groups of structural parameters was numerically simulated. The results show that the existing stope structural parameters failed to maintain stability requirements and tended to be exposed to the risk of stope collapse. The middle section of the pillar as well as stope roofs and floors are vulnerable due to tensile stress when mining by open stoping, and the compressive stress concentration is prone to occur at the junction of the pillars, stope side walls, roofs and floors. Shear stress contributes little to pillar failure. The reasonable stope structural parameters of open stoping for the gently inclined medium-thick ore body in Bainiuchang mine are optimized using ANSYS numerical simulation: stope height 4.5 m, pillar diameter 4 m, pillar spacing 7 m and pillar row spacing 8 m. The onsite trial shows that the ore recovery rate reaches 82% under these parameters, which also realizes the equilibrium of safety and economy.
      Citation: Minerals
      PubDate: 2022-06-25
      DOI: 10.3390/min12070808
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 809: Sustainable Production of Rare Earth
           Elements from Mine Waste and Geoethics

    • Authors: Marouen Jouini, Alexandre Royer-Lavallée, Thomas Pabst, Eunhyea Chung, Rina Kim, Young-Wook Cheong, Carmen Mihaela Neculita
      First page: 809
      Abstract: The vulnerability of the rare earth element (REE) supply in a global context of increasing demands entails important economic and political issues, and has encouraged several countries to develop their own REE production projects. This study comparatively evaluated the production of REEs from primary and secondary resources in terms of their sustainability and contribution to the achievement of the Geoethics concept as responsibility towards oneself, colleagues, society, and the Earth system. Twelve categories of potential environmental and social impacts were selected: human health toxicity, global warming or climate change, terrestrial and aquatic eutrophication, acidification potential, particulate matter, resource depletion, water consumption, fresh water ecotoxicity, ionizing radiation, fossil fuel consumption, and ozone depletion. The results showed that the environmental impact of REE production from secondary sources is much lower relative to primary sources. A comparison of conventional and non-conventional REE resources showed that significant impact categories were related to particulate matter formation, abiotic resource depletion, and fossil fuel depletion, which could result from avoiding the tailings disposal before reuse. Based on these findings, governments and stakeholders should be encouraged to increase the recycling of secondary REE sources with Geoethics in mind, in order to balance the high demand of REEs while minimizing the overexploitation of non-renewable resources.
      Citation: Minerals
      PubDate: 2022-06-25
      DOI: 10.3390/min12070809
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 810: Effects of Accumulated Damage on the Dynamic
           Properties of Coal Measures Sandstone

    • Authors: Ziheng Sha, Hai Pu, Junce Xu, Hongyang Ni, Shiru Guo
      First page: 810
      Abstract: The coupling effect of accumulated damage and impact load substantially affects the integrity of the surrounding rock structure in deep coal mining engineering, which has inhibited safe and effective coal mining. Therefore, dynamic compression tests were performed on coal measures sandstone specimens with accumulated damage using the SHPB device. The effects of a high strain rate and accumulated damage on the sandstone’s mechanical behavior and damage evolution were investigated. The results reveal that accumulated damage has a considerable impact on specimen stress–strain curves and lowers dynamic compressive strength and deformation modulus substantially. The sandstone failure mode looks to be shear failure from a macroscopic perspective, while it appears to be intergranular fracture between the mineral particles from a microscopic perspective. The macroscopic and microscopic failure mechanisms of the sandstone specimens likewise conformed to the energy absorption law. The accumulated damage factor and the accumulated damage correction coefficient were presented in order to construct a statistical damage constitutive model of rocks based on the Weibull distribution. This model provides a decent description of the effects of accumulated damage and the strain rate on sandstone’s mechanical behavior, with parameters that are all of evident physical significance.
      Citation: Minerals
      PubDate: 2022-06-25
      DOI: 10.3390/min12070810
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 811: Prospective Evaluation of Geothermal
           Resources in the Shangqiu Uplift of the Southern North China Basin with
           Magnetotelluric Detection

    • Authors: Bowen Xu, Huailiang Zhu, Zhilong Liu, Bingsong Shao, Gaofeng Ye
      First page: 811
      Abstract: The magnetotelluric sounding (MT) method is used to detect and study the deep stratigraphic structure and hidden faults in the Shangqiu Uplift. A total of 4 MT profiles are arranged, and 97 stations are collected. The nonlinear conjugate gradient (NLCG) two-dimensional inversion method is used to jointly invert data from both the TE and TM modes after a dimensionality analysis and impedance tensor decomposition; reliable two-dimensional resistivity models are produced since the data quality is excellent. Three-dimensional inversion is carried out to full impedance tensor as well to produce a three-dimensional resistivity model of the study area, which shows good consistency with the two-dimensional models. The results show that the electrical structure of the Shangqiu Uplift has typical layered characteristics, which can be divided into three layers from top to bottom, namely low-, medium-to-high-, and high-resistivity layers. According to the resistivity models and in combination with the gravity, aeromagnetic, seismic, and regional geological data of the study area, a geological map of the basement rock of the Shangqiu Uplift is produced. Two prospective geothermal anomaly areas are proposed according to the distribution of the high-resistivity anomaly formed by the basement uplift, which has a good corresponding relationship with the high-value area of the regional geothermal field. A geothermal exploration well (SR-1) is constructed in one of the inferred prospective geothermal anomaly areas. The well is 1702 m deep, with a water output of 1500 m3/day and a wellhead water temperature of 51.5 °C. This is the geothermal well with the largest water yield in the Shangqiu area at present, which provides a new basis for future geothermal exploration, development, and utilization.
      Citation: Minerals
      PubDate: 2022-06-25
      DOI: 10.3390/min12070811
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 812: Bioavailability of Colloidal Iron to
           Heterotrophic Bacteria in Sediments, and Effects on the Mobility of
           Colloid-Associated Metal(loid)s

    • Authors: Malgorzata Grybos, Delphine Masson, Pauline Gorgeon, Patrice Fondanèche, Nicolas Martin, Fabrice Dupuy, Emmanuel Joussein, Valentin Robin
      First page: 812
      Abstract: The submicrometric fraction of surface sediments that accumulate in the bottom of dam reservoirs represent important sources of nutrients and contaminants in freshwater systems. However, assessing their stability in the presence of sediment bacteria as well as their bioavailability in the sediment remains poorly understood. We hypothesized that sediment’s bacteria are able to extract nutrients from sedimentary colloids (<1 µm fraction) and thus contribute to the release of other colloid-associated elements to water. Experiments were performed under laboratory conditions, using the submicrometric fractions of sediments recovered from two dam reservoirs (in calcareous and crystalline granitic contexts) and two heterotrophic bacteria (Gram-negative Pseudomonas sp. and Gram-positive Mycolicibacterium sp.). The results demonstrated that bacteria were able to maintain their metabolic activity (the acidification of the growth medium and the production of organic ligands) in the presence of colloids as the sole source of iron (Fe) and regardless of their chemical composition. This demonstrates that bioavailable Fe, aside from ionic forms, can also occur in colloidal forms. However, the bacteria also catalyzed the release of potentially toxic metallic elements (such as Pb) associated with colloids. These results help improve our understanding of the processes that influence contaminants’ mobility in the ecosystems as well as provide an important insight into current research evaluating the bioavailability of different forms of nutrients.
      Citation: Minerals
      PubDate: 2022-06-25
      DOI: 10.3390/min12070812
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 813: Quantification of Small-Scale Heterogeneity
           at the Core–Mantle Boundary Using Sample Entropy of SKS and SPdKS
           Synthetic Waveforms

    • Authors: Surya Pachhai, Michael S. Thorne, Tarje Nissen-Meyer
      First page: 813
      Abstract: Qualitative and quantitative analysis of seismic waveforms sensitive to the core–mantle boundary (CMB) region reveal the presence of ultralow-velocity zones (ULVZs) that have a strong decrease in compressional (P) and shear (S) wave velocity, and an increase in density within thin structures. However, understanding their physical origin and relation to the other large-scale structures in the lowermost mantle are limited due to an incomplete mapping of ULVZs at the CMB. The SKS and SPdKS seismic waveforms is routinely used to infer ULVZ presence, but has thus far only been used in a limited epicentral distance range. As the SKS/SPdKS wavefield interacts with a ULVZ it generates additional seismic arrivals, thus increasing the complexity of the recorded wavefield. Here, we explore utilization of the multi-scale sample entropy method to search for ULVZ structures. We investigate the feasibility of this approach through analysis of synthetic seismograms computed for PREM, 1-, 2.5-, and 3-D ULVZs as well as heterogeneous structures with a strong increase in velocity in the lowermost mantle in 1- and 2.5-D. We find that the sample entropy technique may be useful across a wide range of epicentral distances from 100° to 130°. Such an analysis, when applied to real waveforms, could provide coverage of roughly 85% by surface area of the CMB.
      Citation: Minerals
      PubDate: 2022-06-26
      DOI: 10.3390/min12070813
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 814: Trace Element Concentrations and Mineralogy
           of Quartz Vein Deposits from Southeastern Hubei Province, China

    • Authors: Jiuyi Wang, Zefeng Xie, Chunlian Wang, Yufei Hu
      First page: 814
      Abstract: Hydrothermal quartz samples collected from the Fujiashan and Yipanqiu quartz deposits in southeastern Hubei Province, China have been investigated by analytical combination of optical microscopy, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy, in conjunction with conventional beneficiation processing to evaluate their potential as sources of high purity quartz (HPQ) from a commercial perspective. Microscopy efforts reveal that major mineral impurities associated with quartz are K-feldspar, muscovite, iron oxides, rutile with accessory kaolinite. Bulk trace element concentrations of the processed quartz products demonstrate that the Fujiashan-II quartz vein with cumulative impurities of less than 50 μg g−1 with <30 μg g−1 Al and <10 μg g−1 Ti fits with the lattice-bound criteria for HPQ, meeting the requirement by a HPQ deposit. However, the Yipanqiu quartz deposits are not promising for HPQ production due to high fluid inclusion contents, intimate intergrowth texture with highly variable crystal size, and probably high lattice-bound element contents. The early Neoproterozoic Fujiashan quartz deposits have likely been experienced long-term retrograde metamorphism-related recrystallisation which might contribute to high-purity quartz formation. Due to a much younger crystallization age compared to the Fujiashan deposits, quartz grains in the middle Cretaceous Yipanqiu quartz vein retain high trace elements, leading to exclusion of being a HPQ deposit.
      Citation: Minerals
      PubDate: 2022-06-26
      DOI: 10.3390/min12070814
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 815: Magmatic Process Associated with the Baogutu
           Reduced Cu Porphyry-Type Deposit (West Junggar, Northwest China): Evidence
           from Multiple Enclaves

    • Authors: Chu Wu, Tao Hong, Xing-Wang Xu, Xiao Zheng, Cheng-Xi Wang, Wan-Juan Liang, Ke-Feng Sun, Hui-Jun Zhang, Bin Wang, Lian-Hui Dong
      First page: 815
      Abstract: Enclaves constitute a key tracer guide to assess the magmatic source and evolutionary processes of Cu–Mo–Au porphyry-type deposits. In this study, four types of enclaves were identified in the Baogutu reduced Cu porphyry-type deposit, West Junggar, Northwest China: gabbroic enclaves (Type 1) and schist enclaves (Type 2) are proposed to be restites and immiscible enclaves, respectively, which confirm the contributions of mantle components and sediments in the reduced Cu porphyry-type deposit. Fine-grained dioritic enclaves (Type 3) have a similar mineral composition and texture to the dioritic host rocks, which are probably autoliths derived from inhomogeneous fractional crystallization. Tuffaceous siltstone enclaves (Type 4) with a zircon U-Pb age of 339.2 ± 7.5 Ma (MSWD = 0.55), the formation age of which is in agreement with the host early Carboniferous rock unit, indicate that these tuffaceous siltstone enclaves might have formed in a contamination process. Moreover, the schist enclaves, together with the newly discovered 2691.3 ± 12.3 Ma inherited zircon in tuffaceous siltstone enclaves, further indicate that the Baogutu arc could be a continental arc.
      Citation: Minerals
      PubDate: 2022-06-26
      DOI: 10.3390/min12070815
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 816: Natural Magnetite Minerals Enhance
           1,2-Dichloroethane Reductive Dechlorination

    • Authors: Patrícia Leitão, Matteo Tucci, Carolina Cruz Cruz Viggi, Henri Nouws, Anthony S. Danko, Federico Aulenta
      First page: 816
      Abstract: Contamination of soil and groundwater by chlorinated solvents is an environmental issue of primary concern. Recently, electrically conductive iron particles have been proposed as a novel approach to accelerate anaerobic bioremediation processes. In fact, it was demonstrated that conductive particles facilitate the exchange of electrons between microorganisms via Direct Interspecies Electron Transfer (DIET) processes, thus enhancing the pollutant-degrading potential of the microbial community. However, the use of natural minerals in this context has not been reported so far. In this study, we applied, for the first time, natural magnetite and hematite to accelerate the reductive dechlorination of 1,2-dichloroethane by an enrichment culture in lab-scale anaerobic microcosms. After four feeding cycles, low magnetite-amended microcosms (13 mg/L) yielded the highest rate of 1,2-DCA reductive dechlorination and reduced methanogenic activity. By contrast, hematite did not display any apparent stimulatory effect. Surprisingly, in the presence of higher amounts of iron oxides, a weaker effect was obtained, probably because iron(III) present in the minerals competed for the electrons necessary for reductive dechlorination. For all microcosms, the concentration of the toxic byproduct vinyl chloride was negligible throughout the whole study. The SEM/EDS analysis confirmed the close interaction between the conductive iron oxide particles and the dechlorinating bacteria. This work opens the possibility of using natural conductive minerals for bioremediation applications as well as shedding light on the previously unrecognized role of such minerals in contaminated ecosystems.
      Citation: Minerals
      PubDate: 2022-06-26
      DOI: 10.3390/min12070816
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 817: Behavior and Mechanism of a Novel
           Hydrophobic Collector in the Flotation of Bastnaesite

    • Authors: Xiang Yao, Xinyang Yu, Yuhui Zeng, Linghan Mao, Honghui Xie, Shanming Liu, Guichun He, Zhiqiang Huang, Haolin Wang, Zhilin Liu
      First page: 817
      Abstract: In order to improve the recovery of rare earth elements, finding a collector with a strong selectivity ability had become the focus of research. In this paper, phenylpropyl hydroxamic acid (PHA) was used as a new hydrophobic surfactant collector for the separation of bastnaesite from calcite, and salicylic hydroxamic acid (SHA) was used as a reference collector. The results of a single mineral flotation test with SHA show that the reagent has good collection performance and selectivity. In addition, Zeta potential measurements and FTIR analysis show that PHA is adsorbed on the surface of bastnaesite by chemical adsorption, and the surface state of bastnaesite changes after PHA treatment. By XPS analysis, PHA interacts with Ce, and forms a Ce–O bond with Ce. It is speculated that the hydroxamic acid forms a five-element-chelated hydroxamic group with Ce on bastnaesite surface, so as to improve the hydrophobicity of bastnaesite, and make bastnaesite float more easily out of the pulp. According to DFT calculation, PHA has better adsorption capacity and stronger hydrophobicity than SHA, and shows superior electronic group capacity and chemical reactions that promote its flotation performance.
      Citation: Minerals
      PubDate: 2022-06-26
      DOI: 10.3390/min12070817
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 818: Revisiting Glauconite Geochronology: Lessons
           Learned from In Situ Radiometric Dating of a Glauconite-Rich Cretaceous
           Shelfal Sequence

    • Authors: Esther Scheiblhofer, Ulrike Moser, Stefan Lӧhr, Markus Wilmsen, Juraj Farkaš, Daniela Gallhofer, Alice Matsdotter Bäckström, Thomas Zack, Andre Baldermann
      First page: 818
      Abstract: The scarcity of well-preserved and directly dateable sedimentary sequences is a major impediment to inferring the Earth’s paleo-environmental evolution. The authigenic mineral glauconite can potentially provide absolute stratigraphic ages for sedimentary sequences and constraints on paleo-depositional conditions. This requires improved approaches for measuring and interpreting glauconite formation ages. Here, glauconite from a Cretaceous shelfal sequence (Langenstein, northern Germany) was characterized using petrographical, geochemical (EMP), andmineralogical (XRD) screening methods before in situ Rb-Sr dating via LA-ICP-MS/MS. The obtained glauconite ages (~101 to 97 Ma) partly overlap with the depositional age of the Langenstein sequence (±3 Ma), but without the expected stratigraphic age progression, which we attribute to detrital and diagenetic illitic phase impurities inside the glauconites. Using a novel age deconvolution approach, which combines the new Rb-Sr dataset with published K-Ar ages, we recalculate the glauconite bulk ages to obtain stratigraphically significant ‘pure’ glauconite ages (~100 to 96 Ma). Thus, our results show that pristine ages can be preserved in mineralogically complex glauconite grains even under burial diagenetic conditions (T < 65 °C; <1500 m depth), confirming that glauconite could be a suitable archive for paleo-environmental reconstructions and direct sediment dating.
      Citation: Minerals
      PubDate: 2022-06-27
      DOI: 10.3390/min12070818
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 819: CO2-Degassing Carbonate Conduits in Early

    • Authors: Angela Baldanza, Roberto Bizzarri, Chiara Boschi, Federico Famiani, Francesco Frondini, Marco Lezzerini, Steven Rowland, Paul A. Sutton
      First page: 819
      Abstract: Early Pleistocene marine deposits in southwestern Umbria (Orvieto–Allerona area, Italy) recently revealed the presence of more than forty carbonate conduits distributed over 2 km along the Paglia riverbed. In order to investigate their origins, analyses of their mineralogy, δ18O and δ13C stable isotopes, and organic geochemistry were conducted. All the carbonate conduits are made of euhedral microcrystals of dolomite with subordinate quartz, plagioclases, and micas. The stable carbon and oxygen isotope values of the bulk concretionary carbonates range from −0.57 to +4.79‰ (δ13C) and from +1.58 to +4.07‰ (δ18O), respectively. The lack of organic geochemical biomarkers of anaerobic methane oxidation (AOM) and the very low values of extractable organic matter suggest a non-biological origin for the dolomite precipitation. The latter is probably related to the rise of volcanic carbon dioxide due to the incipient Vulsini magmatism recorded in Early Pleistocene marine deposits all around the study site. The spatial distribution of the structures indicates that the upward migration of the CO2 was controlled by the fault system, while the vertical development of the conduits suggests that carbon dioxide degassing occurred, with multiple events. Carbon dioxide was probably stored in pockets within the clayey sediments until the pressure exceeded the eruptive threshold. These structures represent the first documentation of a volcanic carbon dioxide marine seepage event in the Umbria region.
      Citation: Minerals
      PubDate: 2022-06-27
      DOI: 10.3390/min12070819
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 820: A New Approach Determining a Phase
           Transition Boundary Strictly Following a Definition of Phase Equilibrium:
           An Example of the Post-Spinel Transition in Mg2SiO4 System

    • Authors: Takayuki Ishii, Artem Chanyshev, Tomoo Katsura
      First page: 820
      Abstract: The Clapeyron slope is the slope of a phase boundary in P–T space and is essential for understanding mantle dynamics and evolution. The phase boundary is delineating instead of balancing a phase transition’s normal and reverse reactions. Many previous high pressure–temperature experiments determining the phase boundaries of major mantle minerals experienced severe problems due to instantaneous pressure increase by thermal pressure, pressure drop during heating, and sluggish transition kinetics. These complex pressure changes underestimate the transition pressure, while the sluggish kinetics require excess pressures to initiate or proceed with the transition, misinterpreting the phase stability and preventing tight bracketing of the phase boundary. Our recent study developed a novel approach to strictly determine phase stability based on the phase equilibrium definition. Here, we explain the details of this technique, using the post-spinel transition in Mg2SiO4 determined by our recent work as an example. An essential technique is to observe the change in X-ray diffraction intensity between ringwoodite and bridgmanite + periclase during the spontaneous pressure drop at a constant temperature and press load with the coexistence of both phases. This observation removes the complicated pressure change upon heating and kinetic problem, providing an accurate and precise phase boundary.
      Citation: Minerals
      PubDate: 2022-06-28
      DOI: 10.3390/min12070820
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 821: Fast-Curing Geopolymer Foams with an
           Enhanced Pore Homogeneity Derived by Hydrogen Peroxide and Sodium Dodecyl
           Sulfate Surfactant

    • Authors: Kyung Won Kim, Hyung Mi Lim, Seog-Young Yoon, Hyunseok Ko
      First page: 821
      Abstract: The properties of porous and lightweight ceramic foam that can be cured at room temperature using metakaolin-based geopolymers were studied. A geopolymer slurry was prepared using metakaolin and a potassium-based alkaline medium at room temperature, and the obtained viscous paste was expanded via gaseous methods, by means of the decomposition of peroxide at room temperature. Therefore, geopolymer (GP) foam developed in this study through multivariate geopolymer, foaming agents, and surfactants can be cured at room temperature (within 5 days) without a separate heat treatment process. The homogeneous micropores were obtained through the stabilization of the interface between geopolymer slurry and oxygen gas bubbles generated through the base-catalyzed decomposition of hydrogen peroxide. The porosity was confirmed to be 29% and 54% before and after using sodium dodecyl sulfate (SDS). The compressive strengths and densities were 1.57 MPa and 0.75 g/cm3 for GP foam without SDS, and 3.63 MPa and 0.48 g/cm3 for GP foam with SDS. Through the mercury intrusion porosimetry analysis, the pores were further refined from 100 µm to 30 µm when SDS was used, and at the same time, the variation of pore size was minimized, so that a relatively uniform pore size was maintained. In addition, the thermal conductivity is 0.0803 W/m·K and the pore size is 33.2 μm, which is smaller in pore diameter than the geopolymer containing only hydrogen peroxide. As a result, although the hydrogen peroxide alone sample has excellent thermal conductivity, the use of a surfactant is recommended for fine micropore size control. While reducing the non-uniform distribution of pores and the size of micropores generated through the direct foaming method as an inorganic binder, the possibility of an insulation finish was also confirmed by reducing the weight.
      Citation: Minerals
      PubDate: 2022-06-28
      DOI: 10.3390/min12070821
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 822: Mineralogy, Geochemistry, and Stable
           Isotopes (C, O, S) of Hot Spring Waters and Associated Travertines near
           Tamiahua Lagoon, Veracruz, Gulf of Mexico (Mexico)

    • Authors: Israel Porras-Toribio, Teresa Pi-Puig, Ruth Esther Villanueva-Estrada, Marco Antonio Rubio-Ramos, Jesús Solé
      First page: 822
      Abstract: Laminated travertine forms in and around an active hot spring on the west coast of Tamiahua Lagoon, north of the state of Veracruz, Mexico. Fluid chemistry is characterized by discharging slightly acidic pH hot water and gas at a constant flow rate. Moreover, finely interbedded mineralogical products from discharging waters at 70 °C host scattered hydrocarbons. The mineralogy and geochemistry of the travertine formations were characterized to determine their origin. Rock samples were collected and further studied by transmitted light petrography, X-ray diffraction, and EDS-coupled scanning electron microprobe. Identified mineralogy from outcrop samples includes aragonite, gypsum, anhydrite, and elemental sulfur as essential minerals, with calcite, celestine, barite, jarosite, opal, and fluorite as accessory minerals. Isotopic analyses for C and O were determined in carbonates, S isotope ratios on both elemental sulfur and sulfates, whereas measurements for trace elements and lanthanides were performed on carbonates. A suit of brines and condensates from gas samples was collected for H and O isotopic analyses and concentration determinations of the main ions and major and trace elements. Isotopic values of 𝜹13C and 𝜹18O of aragonite are in the range of +1.75‰ to +2.37‰ and −1.70‰ to −0.78‰, respectively. The 𝜹34S isotopic values of native sulfur and sulfates ranged from −4.0‰ to +1.2‰. The isotopic values of 𝜹2H (−5.50‰) and 𝜹18O (+7.77‰) of hot water samples collected in terraces where aragonite precipitates suggest a mixture between meteoric water and the Gulf of Mexico oil-field related waters. It was concluded that the aragonitic formations near Tamiahua Lagoon are hypogenic and were generated by CO2 and H2S emanations of deep origin and by oxidation-reduction reactions that can be linked to surficial bacterial activity.
      Citation: Minerals
      PubDate: 2022-06-28
      DOI: 10.3390/min12070822
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 823: Integration of Lineal Geostatistical
           Analysis and Computational Intelligence to Evaluate the Batch Grinding

    • Authors: Freddy A. Lucay, José Delgado, Felipe D. Sepúlveda
      First page: 823
      Abstract: The kinetic characterization of the grinding process has always faced a special challenge due to the constant fluctuations of its parameters. The weight percentage of each size (WPES) should be mentioned. There are particular considerations for WPESs, because their tendencies are not monotonic. The objective of this work is to provide a methodology and model that will allow us to better understand the kinetics of grinding through the analysis of the Response Surface (RS), using geostatistical (data reconstruction) and computational intelligence (meta-model) techniques. Six experimental cases were studied and trends were evaluated/adjusted with multiple parameters, including an identity plot adjusted to 0.75–0.90, a standardized error histogram with a mean of −0.01 to −0.05 and a standard deviation of 0.63–1.2, a standardized error based on an estimated value of −0.09 to −0.02, a meta-model adjusted to between 92 and 99%, and finally, using the coefficient of variation, which classifies the information (stable/unstable). In conclusion, it was feasible to obtain the results of the WPES from RS, and it was possible to visualize the areas of greatest fluctuation, trend changes, error adjustments, and data scarcity without the need for specific experimental techniques, a coefficient analysis of the fracturing or the use of differential equation systems.
      Citation: Minerals
      PubDate: 2022-06-28
      DOI: 10.3390/min12070823
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 824: Sedimentation of Fine Arsenopyrite with PEI
           and the Flotation Significance

    • Authors: Pingtian Ming, Dan Zou, Fei Li, Qingqing Xing, Zhen Wang
      First page: 824
      Abstract: The flotation of fine mineral particles is always a difficult problem. The flotation of fine arsenopyrite particles (−20 μm) in a sodium butyl xanthate (SBX) system was studied by using polyethyleneimine (PEI) as a flocculant. The flocculation properties of PEI on fine arsenopyrite were studied using sedimentation tests. The results showed that the optimum pH for the sedimentation of PEI was approximately 7.5; the higher the molecular weight (M.W.) of the flocculant, the better the sedimentation effect. In the flotation experiments, it was found that the flotation recovery of PEI-3 with high M.W. as flocculant was only 57%, while the flotation recovery of PEI-2 with medium M.W. was 90% under respective optimum conditions. The contact angle tests showed that the natural contact angle of arsenopyrite was 37°; the addition of moderate PEI-2 had a slightly negative influence on the hydrophobicity of arsenopyrite in the SBX system. From the size analysis results, the maximum particle size (D100) and median size (D50) of the arsenopyrite increased from 20 and 11 μm to 48 and 28 μm after treatment with 40 mg/L PEI-2, a size more conducive to bubble capture. From the combination of these results, it can be concluded that PEI-2 improved the flotation of fine arsenopyrite mainly by increasing the particle size to a suitable range through flocculation. The XPS results indicated that the adsorption of PEI-2 on the arsenopyrite surface was due to the chemisorption between the imino group and the active Fe/As sites. Applying PEI-2 to a fine disseminated arsenopyrite-type gold ore, a concentrate containing 36 g/t Au with a Au recovery of 88% can be obtained.
      Citation: Minerals
      PubDate: 2022-06-28
      DOI: 10.3390/min12070824
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 825: Metallic-Mineral Prospecting Using
           Integrated Geophysical and Geochemical Techniques: A Case Study from the
           Bela Ophiolitic Complex, Baluchistan, Pakistan

    • Authors: Mehboob Ur Rashid, Waqas Ahmed, Muhammad Waseem, Bakht Zamin, Mahmood Ahmad, Mohanad Muayad Sabri Sabri
      First page: 825
      Abstract: An integrated geophysical and geochemical investigation was conducted to investigate the metallic minerals hosted in the mafic and ultramafic rocks in the Bela Ophiolitic Complex. Two thousand magnetic observations were made along with six vertical electrical soundings, with Induced Polarization (IP) targeting the anomalous magnetic zones. The magnetic raw field data were interpreted qualitatively and quantitatively, and two anomalous zones (A1 and A2) were identified on the magnetic maps. The residual magnetic values in the high-magnetic-anomalous zone (A2) ranged from 310 nT to 550 nT, while the magnetic signatures in the low-magnetic zone (A1) ranged from –190 nT to 50 nT. The high-anomalous zone (A2) was distinguished by a high IP value ranging from 3.5 mV/V to 15.1 mV/V and a low apparent and true resistivity signature of 50 ohm·m. Whereas, the low-anomalous zone (A1) was distinguished by very low IP values ranging from 0.78 mV/V to 4.1 mV/V and a very high apparent and true resistivity of 100 ohm·m. The Euler deconvolution was used to determine the depth of the promising zone, which for A1 and A2 was in the 100 m range. The statistical analysis was carried out using hierarchical classification to distinguish between background and anomalous data. The high-magnetic anomalous signature of probable mineralization was in the range of 46,181 nT–46,628 nT, with a total intensity range of 783 nT–1166 nT. The major and trace-element analysis of the 22 rock and stream sediments collected from the high-magnetic-anomalous zone confirmed the mineralization type. The geomagnetic and geophysical cross sections revealed that anomalous mineralization was concentrated with the anticlinal Bela Ophiolitic Complex. The generated results also aided in the identification of rock boundaries, depth, and hidden faults in the area. The findings revealed that the study area has excellent mineralization associated with the ultramafic-rock sequence.
      Citation: Minerals
      PubDate: 2022-06-28
      DOI: 10.3390/min12070825
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 826: New Evidence of Submarine Exhalative
           Sedimentation in the Uranium-Polymetallic Phosphorite Deposit in Baizhuyu,
           Hunan, China

    • Authors: Zhixing Li, Mingkuan Qin, Yuqi Cai, Longsheng Yi, Wenquan Wang, Jian Wang, Longlong Li
      First page: 826
      Abstract: There are as many as 25 kinds of minerals (including non-ferrous metals, ferrous metals, rare and dispersed elements, precious metals, non-metallic and energy minerals) enriched in uranium-polymetallic fertile beds in black rock series, which is therefore widely attracting scholars all over the world. However, there is still great controversy in terms of the metallogenic mechanism in such beds. The black rock series have been systematically sampled from the Baizhuyu deposit in northwestern Hunan Province, China based on field geological and radioactivity surveys. Major and trace elements as well as rare earth elements (REE) of uranium-polymetallic phosphorite and its wall rocks were analyzed. Furthermore, carbon and oxygen isotopes, Sm-Nd isotopes, and mineralogy of the Baizhuyu deposit were studied. The results show that dolomite is a normal marine sediment, while and uranium-polymetallic elements were pre-enriched in phosphorites and black carbonaceous argillaceous shales and slates that formed from marine sedimentation and submarine exhalative sedimentation. Hydrothermal reworking to uranium-polymetallic phosphorites is significant as a result of submarine exhalative sedimentation. The research results of this paper can support a better understanding of metallogenesis and the future exploration of uranium-polymetallic phosphorite in the Lower Cambrian Niutitang Formation in the study area.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070826
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 827: Micro and Nanoscale Structures and Corrosion
           Patterns in Brass: The Case Study of Ancient Roman Orichalcum Coins

    • Authors: Melania Di Fazio, Anna Candida Felici, Fiorenzo Catalli, Laura Medeghini, Caterina De Vito
      First page: 827
      Abstract: This study investigated the micro and nanoscale structure in Cu-Zn alloy, as well as its corrosion patterns. To achieve this goal, a set of Roman orichalcum coins were analysed using Scanning Electron Microscopy (SEM-EDS), X-ray maps, high resolution field emission scanning electron microscopy (HR-FESEM-EDS) and electron microprobe analyser (EMPA) techniques. The samples showed a high degree of corrosion on their external surfaces, which evolved in depth up to ~1 mm. Micro and sub-micro imaging of the inner metal highlighted the presence of “stressed areas” caused by mechanical processing work, representing the trigger zone of corrosion and causing the loss of material. These images also permitted us to follow the grain-grain interface and selective Zn-dealloying in the examined samples. X-ray maps of Cu and Zn helped us to understand the evolution of the dezincification process, from rim to core. HR-FESEM-EDS imaging investigation highlighted a heterogeneous composition within the strain line structures, confirming that the mechanically stressed areas were active zones for corrosion processes. Cracks and voids also characterised the patina. Conversely, the uncorroded cores of the samples were not affected by dealloying.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070827
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 828: Unusual Luminescence of Quartz from La
           Sassa, Tuscany: Insights on the Crystal and Defect Nanostructure of Quartz
           Further Developments

    • Authors: Andrea Maurizio Monti, Giulia Ricci, Marco Martini, Anna Galli, Federico Lugli, Maria Chiara Dalconi, Gilberto Artioli
      First page: 828
      Abstract: Quartz luminescence finds applications on many fields, but much work still needs to be done to precisely characterize it. In this work, we made further developments on the study of luminescence of quartz from La Sassa, Tuscany: a sample with unique properties in this regard. Photoluminescence (PL) measurements allowed study of the excitation profile of the previously reported luminescence, showing an excitation maximum at around 4.3 eV, among other minor ones. This kind of luminescence has also been studied as a function of X-ray irradiation, showing that ionizing radiation desensitizes the photoluminescence emissions. New radioluminescence (RL) measurements have been done to study the effect of thermal annealing at 1000 °C, showing a more complex emission picture in the red region (1.8–2.0 eV), with multiple emissions. The data presented here allow more precise assumptions regarding the assignment of the centers responsible for each emission. The assignment has been confirmed by chemical profiles measured by laser-ablation inductively coupled plasma (ICP) mass spectrometry. The previously tentative assignment of non-bridging oxygen hole centers (NBOHCs) has been disproved for the PL and LIF emissions and confirmed for the RL ones.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070828
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 829: Sodium N-Lauroylsarcosinate (SNLS) as a
           Selective Collector for Calcareous Phosphate Beneficiation

    • Authors: Mohamed M. Abdel-Halim, Mohamed A. Abdel Khalek, Renji Zheng, Zhiyong Gao
      First page: 829
      Abstract: Sodium N-lauroylsarcosinate (SNLS) was employed as a selective flotation collector for dolomite–apatite separation. The influence of pH, condition time, and collector dose on the flotation performance of both apatite and dolomite minerals was investigated using single mineral and binary mixed mineral flotation experiments. The performance of SNLS was compared to sodium oleate (NaOL), as a standard collector. In this study, the adsorption mechanism of SNLS on both minerals was studied using zeta-potential and FT-IR measurements. The results showed that SNLS prefers to adsorb on the dolomite mineral. The maximum difference in floatability was 83% for single dolomite and apatite minerals at pH 10 in the presence of 0.05 mmol/L SNLS. Binary mixtures of dolomite and apatite minerals of different ratios were applied, to evaluate their separation efficiency. The SNLS could separate dolomite from its mixtures with apatite minerals. Using 0.2 mmol/L of SNLS at pH 10, a concentrate of 30.9% P2O5 and 0.79% MgO was obtained from a natural phosphate ore having 25.8% P2O5 and 5.16% MgO.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070829
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 830: Pyrite Characteristics and Its Environmental
           Significance in Marine Shale: A Case Study from the Upper Ordovician
           Wufeng–Lower Silurian Longmaxi Formation in the Southeast Sichuan
           Basin, SW China

    • Authors: Lei Chen, Xin Chen, Xiucheng Tan, Xuetao Hu, Gaoxiang Wang
      First page: 830
      Abstract: Pyrite, as a characteristic mineral in organic-rich marine shale, is a significant index for the interpretation of paleoredox conditions. In this study, based on drilling cores and focused ion beam-scanning electron microscopy (FIB-SEM), the occurrence, diameter and particle size distribution of pyrites from 32 samples obtained from the Wufeng–Longmaxi Formation in the southeast Sichuan Basin were analyzed. The results show that pyrite displays various occurrences at the macro-scale and micro-scale. At the macro-scale (mm–cm), pyrite laminations, nodular pyrites and lenticular pyrites can be found from drilling cores. At the micro-scale (nm–µm), the common occurrences of pyrite are pyrite framboids, euhedral pyrites and infilled pyrite framboids. According to the formation mechanism of pyrites, pyrites can be divided into syngenetic pyrites and diagenetic pyrites. The infilled pyrite framboids are categorized as diagenetic pyrites. The mean pyrite framboid diameters (Mean, D) range from 2.94 µm to 5.33 µm (average of 4.26 µm), with most samples showing pyrite framboid diameters from 3.5 μm to 4.8 μm. Most of the diameters of the framboid microcrystals (Mean, d) are less than 0.4 µm. Therefore, according to the (Mean, D) and the (Mean, d), the pyrite framboids can be divided into three sizes: syngenetic framboids (SF, D < 4.8 µm, d ≤ 0.4 µm), early diagenetic framboids (EDF, D > 4.8 µm, d > 0.4 µm) and late diagenetic framboids (LDF, D < 4.8 µm, d > 0.4 µm). Additionally, box-and-whisker charts of the diameter, standard deviation/skewness value of the mean diameter of pyrite framboids (Mean, D) and the ratio of trace elements indicate that the sedimentary water body was a euxinic–dysoxic environment. Euxinic conditions dominated the Wufeng Formation to the lower part of the Long11-3 section, which is beneficial for the preservation of organic matter. However, the middle-upper part of the Long13-Long12 sub-member is a dysoxic sedimentary environment.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070830
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 831: Age of Gold Mineralizations of Dongping and
           Xiaoyingpan Gold Deposits in North China Craton: Constraints from the
           Zircon U–Pb Dating and Fission-Track Analysis

    • Authors: Yunlei Feng, Hao Wei, Dong Li, Wenbiao Du
      First page: 831
      Abstract: Northwest Hebei province is one of the gold-producing areas in China. Based on a geochronological analysis of the Zhangjiakou-Xuanhua area, zircon U–Pb with an age of 2487–142 Ma and zircon fission-track (ZFT) with a cooling age of 155–66 Ma were obtained. Zircon U–Pb dating of the Xiaoyingpan deposit revealed two ages of 2487 ± 92 Ma and 1745 ± 89 Ma, representing the Archaean and Early Proterozoic metamorphism of the Sanggan Group. The ZFT cooling age of 155 ± 10 Ma represents the deposit’s lower limit metallogenic age. The Shuiquangou (SQG) alkaline complex emplaced at 388.9 ± 3.0 Ma and experienced magmatic activities until the Late Devonian (ca 377 Ma), considering the response to the collision between the Siberian plate and the North China Craton. The emplacement age of Shangshuiquan (SSQ) granite is 142.3 ± 1.1 Ma and is coeval with the thinning of the North China Craton during the Late Jurassic–Early Cretaceous. The intrusion of SSQ might partially reheat the SQG complex, resulting in the Yanshanian gold mineralization in Dongping. The SQG complex and SSQ granite underwent a relatively consistent rapid cooling process in the Cretaceous based on the ZFT ages.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070831
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 832: Genesis of Color Zonation and Chemical
           Composition of Penglai Sapphire in Hainan Province, China

    • Authors: Guang-Ya Wang, Xiao-Yan Yu, Fei Liu
      First page: 832
      Abstract: The Penglai sapphires are mainly hosted in alkaline basalts and derived in alluvial sediments. Previous studies have investigated the formation of the Penglai sapphires; however, the genesis of color zoning remains ambiguous. In this paper, we report spectral and chemical composition data of sapphires using ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), and laser-ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS). The results show that the Penglai sapphire has a magmatic origin, mostly showing various shapes of incomplete girdles, barrels, and flakes. The content of Ti in rims is higher than in cores of color-banded sapphire, which results from ubiquitous Ti-bearing inclusions within grown bands. The main chromophore of the deep-blue core is Fe2+-Ti4+, which pairs with Fe3+-Fe3+, Cr3+, and V3+ in the core, likely producing purple-hued blue in an oxidizing environment. The yellowish-brown rim is due to Fe3+ and Cr3+ in a reduced environment. Compared with the basaltic sapphires worldwide, the Fe content is moderately higher than those of most Asian sapphires but obviously lower than those of Changle sapphires in Shandong, China, and overlaps with those of African sapphires.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070832
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 833: Mathematical Model of Ilmenite Separation
           Efficiency Using a High Gradient Plate Magnetic Separator

    • Authors: Fangping Ye, Weijie Jiang, Xiangjun Ren, Jinyue Xu, Zhiqiang Guo, Chenyu Li
      First page: 833
      Abstract: High gradient magnetic separation is widely used in magnetic minerals upgrading, and its separation performance is significant depending on the parameters. In this investigation, the Mathematical model of the plate high gradient magnetic separator is established, the magnetic induction and the flow field distribution are investigated based on the COMSOL multi-physical simulation, and then the separation efficiency and TiO2 grade are analyzed using the plate high gradient magnetic separator. Additionally, the key factors affecting the efficiency of mineral separation are detailed in the experimental separation, the separation efficiency is demonstrated and its feasibility is verified by experiments. It is founded that the mathematical model and simulation results are basically validated by the experimental separation process, and the TiO2 grade can be effectively upgraded from 5.2% to 11.5% with the rinsing water consumption 9.5 L/min and the belt rotating speed 2 r/min. It is thus concluded that plate high gradient magnetic separator has provided an effective way in upgrading ilmenite quality.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070833
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 834: Research on Leaching of V and Ni in Spent
           FCC Catalyst Using Oxalic Acid/H2O2 under Microwave-Assisted Conditions

    • Authors: Dalong Zheng, Yimin Zhang, Tao Liu, Jing Huang, Zhenlei Cai, Ruobing Zhang
      First page: 834
      Abstract: In this work, we propose a rapid and facile method (oxalic acid leaching under microwave-assisted conditions) to study the simultaneous recovery of vanadium (V) and nickel (Ni) from spent fluid catalytic cracking (SFCC) catalysts. The central issue in all of these studies is to test the modeling and experimental results of excellent fitting effects of leaching parameters. In order to maximize the recovery of V and Ni, leaching parameters were investigated. Furthermore, response surface methodology (RSM) was applied to optimize the leaching parameters. The optimum conditions obtained were as follows: oxalic acid concentration of 1.8 mol/L; leaching time of 91 min; microwave-assisted power of 500 W; H2O2 concentration of 1.1 mol/L. The maximum leaching rates of V and Ni reached the values of 91.36% and 46.35%, respectively. The results showed that microwave energy was very helpful in improving the efficiency of the leaching process and shortening the leaching time by 75%. According to the shrinking core model, test results showed that a surface chemical reaction was the controlling step of the overall reaction kinetics. The activation energy of V and Ni during the leaching reaction was calculated to be 3.28 and 34.41 kJ/mol, respectively.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070834
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 835: Geochemical Fractal Characteristics of
           Deep-Sea REE-Rich Sediments in the Western Pacific

    • Authors: Yan Zhang, Gaowen He, Fenlian Wang, Yong Yang, Yonggang Liu, Li Zhang, Yongzhang Zhou
      First page: 835
      Abstract: At present, the challenge for geochemical prospecting of deep-sea, rare, earth-rich sediments is the selection of exploration sites. Because of the unpredictability of offshore operations, the distribution and selection of survey line stations face great challenges. In this paper, we study the fact that the concentration distribution of geochemistry in space may be a part of a special complex process, which is called the multifractal. It requires a large number of indexes to characterize its scale characteristics. Based on the multifractal spectrum, 38 geochemical indices in the Pigafetta Basin region of the western Pacific Ocean are divided into three categories. The three indexes are distinguished by the multifractal parameters. The results of multifractals are in good agreement with those of the cluster analysis and principal component analysis. In addition, on the basis of principal component analysis, we further used the multifractal filtering method to extract element anomalies and delineate element enrichment regions. The first principal component clearly represents the potential element enrichment area. The spatial analysis technique and multifractal method proposed in the paper provide a new idea for geochemical prospecting of deep-sea, rare, earth-rich sediments.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070835
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 836: Seismic Response Models and the AVO
           Simulation of Coal-Bearing Reservoirs

    • Authors: Yijun Xi, Xingyao Yin
      First page: 836
      Abstract: The presence of coal in complex structures featuring sandstone reservoirs seriously hinders reservoir characterization and the identification of fluids in subsurface formations. Coal can strongly obscure the reflections from sandstone, easily leading to false bright spots during exploration; thus, reservoirs and their boundaries cannot be accurately described. Furthermore, sandstone layers intercalated with thin coal seams form complex composite reflections. Therefore, considering the complexity of coal-bearing reservoirs together with the geological evolution of coal and actual logging data, this study systematically analyses the seismic reflections of coal-bearing reservoirs. First, the seismic responses of various coal-bearing reservoir models are established by evaluating multiple well logs of the target layer. Then, by forward-simulating theoretical seismic data, seismic response models comprising different lithological combinations are established. Finally, seismic attributes (such as the amplitude, frequency and phase) of coal-bearing and non-coal-bearing strata are compared, and the seismic responses of typical lithological combinations of coal-bearing reservoirs are summarized. A single-well model test and a comparison between synthetic and seismic data confirm that numerical simulations can be used to forward model the seismic response characteristics of different sand–coal models, thereby eliminating the influences of coal and accurately characterizing sandstone reservoirs.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070836
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 837: Separation Analysis of New Magnetic
           Separator for Pre-Concentration of Ilmenite Particles

    • Authors: Liren Han, Zhiyong Cheng, Dongfang Lu
      First page: 837
      Abstract: To achieve the utilization of fine ilmenite (especially −0.075 mm) produced in the titanium-magnetite processing plant in Panzhihua, a radial turbulent outer-cylinder magnetic separator (RTOCMS), was developed in this study. After optimizing the conditions of rotation speed and water flow, an RTOCMS concentrate with TiO2 grade of 22.84% and TiO2 recovery of 66.93% was obtained through one-stage roughing pre-concentration flowsheet. Magnetic force and competing forces were calculated and analyzed to illustrate the pre-concentration mechanism, and the results revealed that the combination of high water flow and high rotation speed resulted in the most effective for pre-concentration of the fine ilmenite in the RTOCMS process. In addition, particle size analysis of the concentrate product indicated that the RTOCMS was effective for the recovery of medium particle sizes (−0.075+0.038 mm), with a continued enhancement for the recovery of fine-grained products (−0.038 mm). Hence, the RTOCMS provides an effective way to pre-concentrate fine ilmenite ore.
      Citation: Minerals
      PubDate: 2022-06-29
      DOI: 10.3390/min12070837
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 838: Protected Areas vs. Highway
           Construction—Problem of Environmental Pollution

    • Authors: Anna Turek, Kinga Wieczorek, Małgorzata Szczesio, Jakub Kubicki
      First page: 838
      Abstract: Landscape parks are protected areas, attractive to live close to and relax in. In parks, economic and agricultural activities are allowed to a limited extent. The high interest in these areas is the cause of unfavorable changes, including environmental contamination. This paper presents the results of soil quality research in Wzniesienia Łódzkie Landscape Park (Poland). The analyses were performed in 2008, before the construction of the highway in the park began, and after its completion in 2016. The contents of Zn, Cu, Pb, Cd and Ni were determined by flame atomic absorption spectrometry (FAAS). The descriptive statistics, principal component analysis (PCA), cluster analysis (CA), and geographic information system (GIS) were used to assess the impact of different sources on the content of metal in the soil. Over the period of 8 years, there has been an increase in pH and the level of metals, especially nickel. The changes in the metal content result from the different land use, especially abandonment of agricultural activity and emissions related to the construction of the A1 highway.
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070838
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 839: Green Mining Takes Place at the Power Plant

    • Authors: Zhiyi Zhang, Hao Liu, Hui Su, Qiang Zeng
      First page: 839
      Abstract: The number of large coal power plants, characterized by pithead plants, is increasing rapidly in major coal mining countries around the world. Overburden movement caused by coal mining and greenhouse gas emissions caused by coal thermal power generation are intertwined, and have become important challenges for mine ecological environment protection at present and in the future. In order to provide more options for green mining in large coal power plants, a large coal power base in northwest China was taken as the researching background in this paper, and a green mining model considering the above two aspects of ecological environment damages was proposed; that is, the carbon dioxide greenhouse gas produced by coal-fired power plants can be geologically trapped in goaf, whose overburden stability is controlled by backfill strips made of solid mine waste. In order to explore the feasibility of this model, the bearing strength of the filled gray brick consisting mainly of aeolian sand and fly ash under different curing methods was firstly studied, and it was discovered that the strength of the gray brick significantly improved after carbonization curing. After that, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to compare the mineral composition and its spatial morphology in gray brick before and after carbonization, and it is believed that the formation of dense acicular calcium carbonate after carbonization curing was the fundamental reason for the improvement of its bearing strength. Finally, a series of stope numerical models were established with UDEC software to analyze the surface settlement, crack propagation height and air tightness of the overlying strata, respectively, when goaf was supported by the backfilling strips with carbonized gray brick. The research results of this paper showed that the stability of overlying strata in goaf can be effectively controlled by adjusting the curing methods, width and spacing of the filled gray brick, so as to facilitate the following geological sequestration of carbon dioxide greenhouse gas in goaf. Consequently, the ecological environment damages caused by coal mining and utilization in a large coal power base can be resolved as a whole, and the purpose of green mining can be achieved as desired.
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070839
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 840: Editorial for Special Issue “Exploring

    • Authors: Javier Fernández-Lozano
      First page: 840
      Abstract: The first mining compendium, edited by Georg Bauer, also known as G. Agricola, was published in 1556, providing the basis of mining and metallurgical processing methods for almost two centuries [...]
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070840
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 841: The Li-Bearing Pegmatites from the Pampean
           Pegmatite Province, Argentina: Metallogenesis and Resources

    • Authors: Miguel Ángel Galliski, María Florencia Márquez-Zavalía, Encarnación Roda-Robles, Albrecht von Quadt
      First page: 841
      Abstract: The Li-bearing pegmatites of the Pampean Pegmatite Province (PPP) occur in a rare-element pegmatite belt developed mainly in the Lower Paleozoic age on the southwestern margin of Gondwana. The pegmatites show Li, Rb, Nb ≤ Ta, Be, P, B, Bi enrichment, and belong to the Li-Cs-Ta (LCT) petrogenetic family, Rare-Element-Li (REL-Li) subclass; most of them are of complex type and spodumene subtype, some are of albite-spodumene type, and a few of petalite subtype. The origin of the pegmatites is attributed predominantly to fractionation of fertile S-type granitic melts produced by either fluid-absent or fluid-assisted anatexis of a thick pile of Gondwana-derived turbiditic sediments. Most of the pegmatites are orogenic (530–440 Ma) and developed during two overlapped collisional orogenies (Pampean and Famatinian); a few are postorogenic (~370 Ma), related to crustal contaminated A-type granites. The pegmatites were likely intruded in the hinterland, preferably in medium-grade metamorphic rocks with PT conditions ~200–500 MPa and 400–650 °C, where they are concentrated in districts and groups. Known combined resources add up 200,000 t of spodumene, with variable grades between 5 and 8 wt.% Li2O. The potential for future findings and enlargement of the resources is high, since no systematic exploration program has yet been developed.
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070841
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 842: Revealing the Softening-Melting Behaviors
           and Slag Characteristics of Vanadium-Titanium Magnetite Burden with
           Various MgO Addition

    • Authors: Bin Wang, Wei Zhao, Xinghua Zhang, Shaoyan Hu, Hongwei Guo, Mansheng Chu
      First page: 842
      Abstract: MgO addition plays an essential role in the blast furnace smelting process, including softening-melting characteristics and metallurgical properties of slag. In the present study, the effect of MgO distribution on the softening-melting characteristics and slag system of vanadium-titanium magnetite burden were explored by simulating BF conditions. The results show that the MgO flux addition significantly affects the crystallization temperature of slag-phase, the precipitated phase components, and slag viscosity. This indicates that appropriate MgO addition can improve the metallurgical properties of blast furnace slag effectively, thereby improving the softening-melting-dripping performance of the mixed burden. The V-Ti pellets with a MgO content higher than 2.40 wt% exhibit optimum metallurgical properties. With a constant MgO content in mixed burden, the softening-melting properties of composite burden could be improved effectively as the MgO partitioning scheme includes 1.90 wt% MgO in sinter and 3.02 wt% MgO in pellet.
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070842
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 843: Caledonian Tin Mineralization in the
           Jiuwandashan Area, Northern Guangxi, South China

    • Authors: Zhi-Heng Yue, Ling-An Bai, Rong-Guo Hu, Jie Wu, Yu Dai, Shou-Yu Zhou, Zuo-Hai Feng, Cheng Xu, Zeng-Xia Zhao, Xi-Jun Liu
      First page: 843
      Abstract: The Jiangnan orogenic belt is located between the Yangtze and Cathaysia blocks in South China and is one of the largest W–Sn–Nb–Ta ore belts worldwide. Mineralization occurred from the Proterozoic to Mesozoic, but Caledonian Sn mineralization has rarely been reported. The Jialong cassiterite–sulfide deposit is located in the western Jiangnan orogenic belt. It is hosted by the Sibao Group and in contact with the northeastern part of the Yuanbaoshan granite. The deposit was overprinted by the Sirong ductile shear zone. Here, we present cassiterite U–Pb and mylonitic granite muscovite 40Ar/39Ar ages for this deposit. The cassiterite and muscovite yielded concordant U–Pb and 40Ar/39Ar ages of 422–420 Ma, indicating that Sn mineralization occurred during the early Paleozoic and was spatially and temporally related to the ductile shear zone. The cassiterite is depleted in Nb (0.51–5.46 ppm), Ta (0.01–1.09 ppm), Ti (32.84–423.15 ppm), Sc (0.02–1.45 ppm), Hf (0–1.11 ppm), and other high-field-strength elements. Elements, such as Pb (0.01–8.11 ppm) and Sb (9.92–56.45 ppm), are relatively enriched in the cassiterite, which indicate the Jialong deposit was not directly related to magmatism. Shearing along the Sirong ductile shear zone occurred at 419.6 ± 3.8 Ma, concurrent with the formation of the Jialong Sn–Cu deposit. Moreover, cassiterite in the deposit exhibits obvious shear and brittle deformation, and dissolution and regrowth, suggesting that Sn mineralization was closely related to ductile shearing. The Sirong ductile shear zone and secondary shear structures had a key role in controlling the Sn orebody. The heat generated during tectonic deformation in the ductile shear zone may have produced the ore-forming hydrothermal fluids, and NW–SE-trending fractures in the strata provided the space for mineralization. Metamorphic hydrothermal fluids generated by Caledonian shear deformation extracted Sn from Sn-rich strata, which then migrated along interlayer fractures produced by shearing. A decrease in pressure and water–rock reactions led to the mineralization of Sn and other elements. This deposit is the first example of Caledonian and shear zone-related Sn mineralization identified in the Jiuwandashan area of northern Guangxi.
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070843
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 844: Electron Probe Microanalysis and Microscopy
           of Polishing-Exposed Solid-Phase Mineral Inclusions in Fuxian Kimberlite

    • Authors: Donggao Zhao
      First page: 844
      Abstract: Solid-phase mineral inclusions in diamond (1–3 mm in diameter) from the No. 50 kimberlite diatreme of Liaoning Province, China, were exposed by polishing. A variety of silicate, carbonate and sulfide inclusions were recovered in the diamond. The common solid-phase inclusions are olivine, chromite, garnet and orthopyroxene; the rare phases include Ca carbonate, magnesite, dolomite, norsethite, pyrrhotite, pentlandite, troilite, a member of the linnaeite group, an unknown hydrous magnesium silicate and an Fe-rich phase. Abundance and composition of the solid-phase inclusions in diamond indicate that they belong to the peridotitic suite and are mainly harzburgitic. No eclogitic mineral inclusions were found in the diamond. The slightly lower Mg # of the olivine inclusions (peak at 93) than that of harzburgitic olivine inclusions worldwide (Mg # peak at 94), the higher Ni content (0.25–0.45 wt. %) of the olivine inclusions than those of olivine inclusions worldwide (0.30–0.40 wt. %), the higher Ti contents (up to 0.79 wt. %) in some chromite inclusions in diamond than those in chromite inclusions worldwide, the existence of carbonate inclusions in diamond, and the possible presence of hydrous silicate phases in diamond all indicate a metasomatic enrichment event in the source region of diamond beneath the North China craton, suggesting that the diamond probably formed by solid-state growth under metasomatic conditions with the presence of a fluid. Solid-state growth of diamond is also supported by abundant graphite inclusions in the diamond. Sulfide inclusions in diamond often coexist with chromite and olivine or are rich in Ni content, indicating that the sulfide inclusions belong to the peridotitic suite. From the chemical compositions, most sulfide inclusions in diamond from the No. 50 kimberlite were probably trapped as monosulfide crystals, although some may have been entrapped as melts.
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070844
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 845: Anatomy of Garnet from the Nanminghe Skarn
           Iron Deposit, China: Implications for Ore Genesis

    • Authors: Chen-Tao Ruan, Xiao-Yan Yu, Shang-Guo Su, M. Santosh, Li-Jie Qin
      First page: 845
      Abstract: Garnet is a common constituent of skarn type iron deposits and can be used to derive potential information on the genesis of skarn type deposits. Here, we investigate the petrologic, spectroscopic, and geochemical characteristics of garnet from the Nanminghe skarn iron deposit in China to elucidate the formation process, growth environment, and genesis. We employ a combination of multiple techniques including petrography, Infrared spectroscopy (IR), X-ray powder diffraction (XRD), Raman spectrum, electron microprobe, and LA-ICP-MS. The primary mineral assemblage in the skarn is garnet–diopside–magnetite–quartz–calcite–pyrite. The garnet occurs as granular aggregates or veins, and generally shows a combination form bounded by dodecahedral faces {110} and trapezohedron faces {211}. Oscillatory zoning and abnormal extinction of garnet are also noted. We identify at least three stages of garnet growth, with a gradual decrease in the iron content from early to late stage, accompanied by the precipitation of magnetite. Regarding the rare earth distribution model, the Nanminghe garnet is generally in the right-dipping mode enriched in LREE and depleted in HREE, which may be mainly controlled by adsorption. Major and trace elements of different generations of garnet suggest that the garnet in the iron skarn crystallized under high oxygen fugacity and is of hydrothermal origin.
      Citation: Minerals
      PubDate: 2022-06-30
      DOI: 10.3390/min12070845
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 846: Investigation of the Attenuation and Release
           of Cu2+ Ions by Polymer-Treated Tailings

    • Authors: Mohammad Boshrouyeh Ghandashtani, Mansour Edraki, Thomas Baumgartl, Allan Costine, Samar Amari
      First page: 846
      Abstract: This study investigated the attenuation and release behaviour of copper ions using a standard kaolin-silt slurry as the synthetic tailings in a high solids/high salinity application before and after inline flocculation. A homogenous, synthetic tailings slurry was prepared in a 0.6 M NaCl solution and treated in a low-shear mixer by adding Magnafloc® 336 flocculant. Following the evaluation of morphological properties of both the untreated (UT) and polymer-treated tailings (PT), identical equilibrium tests were performed via the bottle-point method constant concentration technique. The maximum copper ions uptake capacity of polymer-treated tailings was 25% more than the untreated slurry at the equilibrium state in a chemisorption process in which the ions had the capability of binding onto one location on the sorbent, which could be influencing other binding sites on the same sorbent. Polymer treatment resulted in a highly porous structure that exhibited an increased capacity to adsorb and retain copper ions compared to the UT materials. This behaviour indicates the strong binding between the copper ions and active site of the treated tailings particles with greater capability of this material for preserving heavy metal ions within their structure across a wide pH range (2–10) compared to the UT materials. The results advance the fundamental understanding of how inline flocculation can considerably improve the sorption capacity of high solids/high salinity tailings favouring potential long-term rehabilitation purposes at mine closure and the role of sorption and desorption of heavy metal ions’ behaviour play to achieve this goal.
      Citation: Minerals
      PubDate: 2022-07-01
      DOI: 10.3390/min12070846
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 847: Effect of Particle Size of Fly Ash
           Microspheres (FAMs) on the Selected Properties of Concrete

    • Authors: Elżbieta Haustein, Aleksandra Kuryłowicz-Cudowska
      First page: 847
      Abstract: This paper presents the investigations of selected properties of concrete containing two fractions of fly ash microspheres (FAMs) with grain size up to 200 µm and up to 500 µm. Concrete mixtures with ordinary Portland cement and three substitution rates of cement by FAMs, 1.3%, 2.0%, and 2.6%, were investigated. For all concrete mixes, the constant water–binder ratio (w/b) equal to 0.50 was used. The research program included the determination of chemical composition, particle size distribution, and pozzolanic activity of FAMs. The analysis showed that the microspheres consist of three main elements: silicon, aluminum, and iron, whose oxides constitute about 89% of the material. The total content of air pores, measured in concrete at 28 days, ranges from 1.3 to 3.1% for the grain sizes below 200 µm and from 1.4% to 3.9% for the grain sizes up to 500 µm. The FAMs with a particle diameter < 200 µm have a relatively high level of activity pozzolanic at 28 days. The SEM analysis proved that the use of microspheres reduces gaps and increases the CSH phase. The compression test showed that the addition of fly ash microspheres with grain size below 200 µm increases long-term concrete strength.
      Citation: Minerals
      PubDate: 2022-07-01
      DOI: 10.3390/min12070847
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 848: Evolution of Sulfidic Legacy Mine Tailings:
           A Review of the Wheal Maid Site, UK

    • Authors: Verity Fitch, Anita Parbhakar-Fox, Richard Crane, Laura Newsome
      First page: 848
      Abstract: Historic tailings dams and their associated mine waste can pose a significant risk to human and environmental health. The Wheal Maid mine site, Cornwall, UK, serves as an example of the temporal evolution of a tailings storage facility after mining has ceased and the acid-generating waste subjected to surficial processes. This paper discusses its designation as a contaminated land site and reviews our current understanding of the geochemistry, mineralogy, and microbiology of the Wheal Maid tailings, from both peer-reviewed journal articles and unpublished literature. We also present new data on waste characterisation and detailed mineral chemistry and data from laboratory oxidation experiments. Particularly of interest at Wheal Maid is the presence of pyrite-bearing “Grey Tailings”, which, under typical environmental conditions at the Earth’s surface, would be expected to have undergone oxidation and subsequently formed acidic and metalliferous mine drainage (AMD). The results identified a number of mechanisms that could explain the lack of pyrite oxidation in the Grey Tailings, including a lack of nutrients inhibiting microbial Fe(II) oxidation, passivation of pyrite mineral surfaces with tailings processing chemicals, and an abundance of euhedral pyrite grains. Such research areas need further scrutiny in order to inform the design of future tailings facilities and associated AMD management protocols.
      Citation: Minerals
      PubDate: 2022-07-01
      DOI: 10.3390/min12070848
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 849: Chromian Spinels from Kazanian-Stage Placers
           in the Southern Pre-Urals, Bashkiria, Russia: Morphological and Chemical
           Features and Evidence for Provenance

    • Authors: Ildar R. Rakhimov, Dmitri E. Saveliev, Mikhail A. Rassomakhin, Aidar A. Samigullin
      First page: 849
      Abstract: Six minor alluvial chromite placers (Kolkhoznyi Prud, Verkhne-Yaushevo, Sukhoy Izyak, Bazilevo, Novomikhaylovka, Kiryushkino) and one major littoral placer (Sabantuy) were found in sandy sediments of the Kazanian stage of the Permian System (Late Roadian and Wordian Stages) in the Southern Pre-Urals. It is shown that the morphological features of chromian spinels are diverse, which is not evidence of the heterogeneity of the source. The bulk chemical composition of chromian spinels from all placers is similar and generally correlates with compositions of chromian spinels from the Kraka ophiolitic complex in the Southern Urals. The morphological diversity of grains, varied chemical composition and presence of melt inclusions in Ti-high octahedral grains of chromian spinels comply with the ophiolitic nature of the source. Thus, there is no need to refer to other sources for chromite ores but ophiolitic. The new placers expand the dissemination area of chromite-bearing deposits on the east edge of the East-European Platform and offer a prospect to discover new placers.
      Citation: Minerals
      PubDate: 2022-07-01
      DOI: 10.3390/min12070849
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 850: A Natural Vanadate–Arsenate
           Isomorphous Series with Jeffbenite-Type Structure: New Fumarolic Minerals
           Udinaite, NaMg4(VO4)3, and Arsenudinaite, NaMg4(AsO4)3

    • Authors: Igor V. Pekov, Natalia N. Koshlyakova, Natalia V. Zubkova, Dmitry I. Belakovskiy, Marina F. Vigasina, Atali A. Agakhanov, Dmitry A. Ksenofontov, Anna G. Turchkova, Sergey N. Britvin, Evgeny G. Sidorov, Dmitry Yu. Pushcharovsky
      First page: 850
      Abstract: Two new isostructural minerals udinaite and arsenudinaite with the end-member formulae NaMg4(VO4)3 and NaMg4(AsO4)3, respectively, are found in the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. They are associated with one another and anhydrite, diopside, hematite, schäferite, berzeliite, svabite, calciojohillerite, tilasite, reznitskyite, ludwigite, rhabdoborite-group borates, forsterite, magnesioferrite, fluorapatite, pliniusite, and powellite. Both minerals occur as equant tetragonal prismatic–dipyramidal crystals up to 0.15 mm, aggregates up to 1 cm and interrupted crusts up to 2 × 2 cm2. Udinaite and arsenudinaite, visually indistinguishable from one another, are transparent, beige or brownish-yellowish, with vitreous lustre. Both minerals are optically uniaxial (–); ω = 1.785/1.777 and ε = 1.830/1.820, Dcalc. = 3.613/3.816 g·cm−3 (udinaite/arsenudinaite). The empirical formulae are: udinaite: (Na0.55Ca0.16)Σ0.71(Mg4.04Mn0.02Fe0.01)Σ4.07(V1.63As1.05P0.28Si0.03S0.01)Σ3.00O12; arsenudinaite: (Na0.57Ca0.13)Σ0.70(Mg4.01Mn0.01Fe0.01)Σ4.03(As2.07V0.84P0.10Si0.01S0.01)Σ3.03O12. Both minerals are tetragonal, I-42d, Z = 4, a = 6.8011(2)/6.8022(1), c = 19.1839(12)/19.1843(6) Å, and V = 887.35(7)/887.66(4) Å3, R1 = 0.0287/0.0119 (udinaite/arsenudinaite). Their crystal structure consists of the helical chains of edge-sharing MgO6 octahedra and isolated TO4 tetrahedra, forming a heteropolyhedral pseudo-framework with Na cations located in cavities. Both minerals are isostructural to jeffbenite. Udinaite and arsenudinaite form an isomorphous series in which the contents of T constituents vary within (in apfu): V1.6–0.1As2.8–1.0P0.4–0.0.
      Citation: Minerals
      PubDate: 2022-07-01
      DOI: 10.3390/min12070850
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 851: A Dynamic Coupled Elastoplastic Damage Model
           for Rock-like Materials Considering Tension-Compression Damage and
           Pressure-Dependent Behavior

    • Authors: Hu, Zhang, Xu, Tu, Yin, Zhang
      First page: 851
      Abstract: A dynamic coupled elastoplastic damage model for rock-like materials is proposed. The model takes unified strength theory as the strength criterion. To characterize the different damage between compression and tension, two damage variables both in compression and in tension are introduced into the model. The former is represented by the generalized shear plastic strain and volumetric plastic strain and the latter is expressed with the generalized shear plastic strain. Furthermore, the model takes the strain rate effect into account to reflect the strength enhancement under dynamic loading. Because of the difference in plastic hardening between compression and tension, a modified hardening function is adopted. At the same time, the volume strain from HJC model is modified to be consistent with one of continuum mechanics. The developed model is numerically implemented into LS-DYNA with a semi-implicit algorithm through a user-defined material interface (UMAT). The reliability and accuracy of the developed model are verified by the simulation of four basic experiments with different loading conditions. The proposed model was found to be applicable to different mechanical behaviors of rock-like materials under static and dynamic loading conditions.
      Citation: Minerals
      PubDate: 2022-07-02
      DOI: 10.3390/min12070851
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 852: Experimental Test and Field Observations of
           an Electric Potential Monitoring Device for Dynamic Hazards during Mining

    • Authors: Yue Niu, Enyuan Wang, Zhonghui Li, Tiancheng Shan, Mingfu Wang, Jiali Wang, Honghao Wang, Hongchang Liu, Junhai Ding, Jingkun Wang, Feiyang Luo, Wei Shi
      First page: 852
      Abstract: The EP (electric potential) signals can be generated during the deformation and fracture process of coal and rock mass. Meanwhile, the EP response is closely related to its stress state and damage evolution, which is expected to be used in monitoring and coal and rock dynamic disaster hazards. Based on this, this paper developed an EP monitoring device for mining to continuously monitor the temporal response characteristics and spatial distribution of coal seam internal EP signals in real time. Further, the experimental tests were carried out, whose results showed that the device has high monitoring sensitivity and little error for the EP signals and can reveal the loading state and damage degree of the coal and rock specimens during the deformation and fracture process. Moreover, the tests and application of EP monitoring were carried out during mining activities in the field. The results showed that the EP signals fluctuate during the coal mining stage and remain relatively stable during the maintenance stage. When the abnormal mining stress or the coal cannon phenomenon occurs, the intensity of EP signals increases rapidly and fluctuates violently, which has precursory response information for the hazards of dynamic disasters. Considering the advantages of sensitive response and nearly non-destructive monitoring, the study results can provide key monitoring equipment and research basis for field testing the EP signals during the mining process, to monitor and forecast the hazards of coal and rock dynamic disasters.
      Citation: Minerals
      PubDate: 2022-07-03
      DOI: 10.3390/min12070852
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 853: Microstructure and Mechanical Properties of
           Fly Ash-Based Geopolymer Cementitious Composites

    • Authors: Guanglong Yu, Yanmin Jia
      First page: 853
      Abstract: In this paper, the microstructure, mechanical properties, and preparation of geopolymer were investigated. The effects of the proportion of slag and fly ash, the modulus of water glass, and the water–binder ratio on the microstructure, mechanical properties, and preparation of geopolymer were analyzed. The research content of this paper is as follows: Taking the 7-day and 28-day compressive strength and flexural strength of the geopolymer specimens as the evaluation criteria, considering the proportion of slag and fly ash, the modulus of water glass, and the water–binder ratio, the three factors and five levels are respectively considered for a total of 25 sets of orthogonal experiments. Through the range analysis and variance analysis, the influence of each factor on the mechanical properties was analyzed, and the best mix ratio was obtained. Using scanning electron microscope and X-ray diffraction analysis and other testing methods, the mechanical properties, microstructure, and phase composition of geopolymers under the influence of various factors were studied and analyzed.
      Citation: Minerals
      PubDate: 2022-07-04
      DOI: 10.3390/min12070853
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 854: Integrated Collaborative Control of
           “Shielding-Filling-Grouting” of 1 km Deep Large-Section
           Roadways: A Case Study

    • Authors: Wei Zhang, Yandong Zhang, Yanchao Zhu, Jiajia Tang, Longtao Cheng, Zhiliang Suo
      First page: 854
      Abstract: Effective control of deformation failure of surrounding rock in deep roadway has become an important prerequisite for the safe and efficient development of deep coal resources. In this study, the field measurement of the study area’s in-situ stress was carried out for the specific engineering geological conditions of the KCM −967 m level west-wing main track roadway. The west-wing main track roadway’s full-section deformation failure features were summarized and analyzed, and the main roadway’s surrounding rock nonlinear deformation failure mechanism was revealed from the perspective of elastoplastic mechanics. Based on that, a set of highly targeted integrated collaborative control technology of “shielding-filling-grouting” system was proposed. The industrial field test revealed that, after the above integrated collaborative control scheme was adopted, there was no strong deformation failure on the surface of the main roadway surrounding rock and deep rock mass, which played the role of active and passive support collaborative control, reduced the subsequent repeated repair and maintenance workload of the roadway, and satisfied the needs of long-term safe and efficient production of the mine. The results obtained provide a reference for the control of surrounding rock of deep and large-section roadways in other mining areas.
      Citation: Minerals
      PubDate: 2022-07-04
      DOI: 10.3390/min12070854
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 855: Selective Separation of Fluorite from
           Scheelite Using N-Decanoylsarcosine Sodium as a Novel Collector

    • Authors: Zekun Miao, Liming Tao, Jianjun Wang, Zheyi Jiang, Tao Peng, Wei Sun, Zhiyong Gao
      First page: 855
      Abstract: Fluorite and scheelite, which are strategic calcium-bearing minerals, have similar active sites (Ca2+); as a result, the efficient separation of the two minerals is still one of the world’s most difficult problems in the field of flotation. In this work, N-decanoylsarcosine sodium (SDAA), a non-toxic and low-cost amino acid surfactant, was applied in the flotation separation of fluorite from scheelite for the first time. In the test, single mineral, binary mixed minerals, and actual ore experiments showed that the pre-removal of fluorite from scheelite by reverse flotation can be achieved. The results of adsorption capacity detections, zeta potential tests, and FTIR analysis showed that the negatively charged SDAA prefers to adsorb onto the positively charged fluorite surface due to the electrostatic interaction. The results of crystal chemistry and DFT calculations showed that SDAA has a stronger chemical interaction and more electron transfer numbers to the Ca atom on the fluorite surface and forms a Ca-SDAA complex. Therefore, the significant difference in the adsorption behavior of SDAA on the surfaces of two minerals provided a new insight into the separation efficiency of amino acids and possesses a great potential for industrial application in scheelite flotation.
      Citation: Minerals
      PubDate: 2022-07-04
      DOI: 10.3390/min12070855
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 856: Porphyry Copper: Revisiting Mineral Resource
           Assessment Predictions for the Andes

    • Authors: Jane Marie Hammarstrom
      First page: 856
      Abstract: A mineral resource assessment of porphyry copper deposits in the Andes Mountains of South America was done in 2005 in cooperation with geological surveys in South America. The study identified 590 million metric tons (Mt) of copper in identified resources. Continued exploration and development in the region over a 15-year period provide an opportunity to compare the predicted assessment results with new discoveries and resource growth in previously known deposits. The 2005 assessment estimated that 145 undiscovered deposits could contain a mean of 750 Mt of copper. The actual number of deposits increased (2005 to 2020) from 69 to 120 and the amount of identified copper resources increased from 590 Mt to 1600 Mt. Although most of the new deposits and copper resources are concentrated in Miocene-Pliocene and Eocene-Oligocene mineral belts, new deposits have been discovered in Jurassic and Cretaceous mineral belts. Resource growth in porphyry copper deposits known in the Andes in 2005 (1100 Mt copper) exceeds copper resources in new discoveries since 2005 (490 Mt copper) by a factor of 2.
      Citation: Minerals
      PubDate: 2022-07-04
      DOI: 10.3390/min12070856
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 857: Hybrid Serving of DOE and RNN-Based Methods
           to Optimize and Simulate a Copper Flotation Circuit

    • Authors: Alireza Gholami, Meysam Movahedifar, Hamid Khoshdast, Ahmad Hassanzadeh
      First page: 857
      Abstract: Prediction of metallurgical responses during the flotation process is extremely vital to increase the process efficiency using a proper modeling approach. In this study, two new variants of the recurrent neural network (RNN) method were used to predict the copper ore flotation indices, i.e., grade and recovery within different operating conditions. The model input parameters including pulp pH and solid content as well as frother and collector dosages were first analysed and then optimized using a two-step factorial approach. The statistical analysis showed a reliable correlation between operating parameters and copper grade and recovery with coefficients of 99.86% and 94.50%, respectively. The main effect plots indicated that pulp pH and solid content positively affect copper grade while increasing the frother and collector dosages negatively influenced the quality of the final concentrate. Despite the same effect from pulp pH, reverse effects from other variables were observed for copper recovery. Process optimization revealed that maximum copper recovery of 44.39% with a grade of 11.48% could be achieved under the optimal condition as pulp pH of 10, solid content of 20%, and frother and collector concentrations of 25 g/t and 9.9 g/t, respectively. Then, the predictive efficiency of long short-term memory (LSTM) and gated recurrent unit (GRU) networks with proper structure were evaluated using mean square error (MSE), root mean square error (RMSE), mean absolute percentage error (MAPE), and correlation coefficient (R2). The simulation results showed that the LSTM network with higher R2 of 0.963 and 0.934 for copper grade and recovery, respectively, was more effective than the GRU algorithm with the corresponding values of 0.956 and 0.919, respectively. The results show that the LSTM model could be useful in predicting the copper flotation behaviour in response to changes in the operating parameters.
      Citation: Minerals
      PubDate: 2022-07-05
      DOI: 10.3390/min12070857
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 858: Removal of Fluoride from Phosphogypsum
           Leaching Solution with Phosphate Tailing Based Layered Double Hydroxides:
           Kinetics and Equilibrium Isotherms

    • Authors: Yanming Liu, Han Zhang, Dunquan Xiao, Hanjun Wu, Zhenyue Zhang, Lulu Xu, Qingrong Cheng, Hong Zhou, Junxia Yu, Zhiquan Pan, Dongsheng Wang
      First page: 858
      Abstract: In this work, ternary and quaternary layered double oxides (PTB-LDO3 and PTB-LDO4) based on phosphate tailings were synthesized by the coprecipitation method. The as-prepared samples were characterized and applied to remove fluorine ions from a phosphogypsum leaching solution. The results indicated that both the precursor of PTB-LDO3 and PTB-LDO4 showed a layered structure with characteristic diffraction peaks of hydrotalcite. Compared with PTB-LDO4, PTB-LDO3 exhibited better adsorption performance at pH 5–6 and a dosage of 0.04 mg L−1. The adsorption kinetics results revealed that the adsorption of fluorine by PTB-LDO3 and PTB-LDO4 reached the adsorption equilibrium in about 3 h, and followed the pseudo-second-order model. The adsorption data could be fitted better with the Langmuir isotherm with the maximum adsorption amounts of 26.03 mg g−1 and 15.66 mg g−1 for PTB-LDO3 and PTB-LDO4, respectively. The adsorption of fluorine by PTB-LDO3 and PTB-LDO4 were both spontaneous and exothermic, and exhibited excellent reusability and stability. This study provides a possibility for the combined treatment of phosphorus chemical solid waste (phosphorus tailings) and phosphorus chemical wastewater (phosphogypsum leaching liquid).
      Citation: Minerals
      PubDate: 2022-07-05
      DOI: 10.3390/min12070858
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 859: Application of Chemical Sequence
           Stratigraphy to the Prediction of Shale Gas Sweet Spots in the Wufeng and
           Lower Longmaxi Formations within the Upper Yangtze Region

    • Authors: Qian Wang, Yongjian Huang, Zhifeng Zhang, Changhong Wang, Xiang Li
      First page: 859
      Abstract: Effective shale gas exploration is hindered by the need for obtaining high-resolution correlations between shale strata and the need for classifying shale facies. To address these issues, chemostratigraphy, sequence stratigraphy, and shale gas geology methods were integrated to develop a new method known as “chemical sequence stratigraphy,” which was successfully applied to the Wufeng–Lower Longmaxi Formations in the upper Yangtze region. Well Huadi 1 was used as a case study, and detailed data were acquired. Multivariate statistical analyses were applied to three defined indices having different genetic significance, namely: terrigenous input intensity (TII), authigenic precipitation intensity (API), and organic matter adsorption and reduction intensity (OARI). By analyzing the trends of these three indices, the Wufeng–Lower Longmaxi Formations were divided into five fourth-order chemical sequences (from bottom to top): LCW, MCL1-1, MCL1-2, MCL1-3, and MCL1-4. The geochemical facies were named and classified using the chemical sequence stratigraphic framework. The enrichment factor (EF) transformation of elements was conducted to determine whether an element is rich or deficient. The results showed that the favorable geochemical facies in the well were EF-Al deficient, EF-Ca rich, and EF-V rich. The organic matter content and rock brittle strength were then used as chemical parameters, and it was predicted that the LCW and MCL1-1 chemical sequences most likely comprised shale gas sweet spots. This conclusion is consistent with the drilling results and indicates that our proposed method is effective and reliable. This method is further applied to the Changning Shuanghe section, the Shizhu Liutang section, and sections in the Xindi 1 well in the upper Yangtze region. The comparative study of these four sections showed that LCW and MCL1-1 are the key chemical sequences for shale gas exploration and development in the Wufeng–Lower Longmaxi Formations within the Upper Yangtze region.
      Citation: Minerals
      PubDate: 2022-07-05
      DOI: 10.3390/min12070859
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 860: Titaniferous-Vanadiferous,
           Magnetite-Ilmenite Mineralization in a Mafic Suite within the Chhotanagpur
           Gneissic Complex, Bihar, India

    • Authors: Ashmeer Mohammad, Anup K. Prasad, Kehe-u Wetsah, Mohammad Azad, Vivek Aryan, Hesham El-Askary
      First page: 860
      Abstract: Titanium or vanadium metals or their alloys are important industrial metals/alloys. Because these resources are in short supply, the investigation of potential titaniferous-vanadiferous deposits needs special attention to bridge the supply-demand gap. The study integrates geological, geochemical, remote sensing, and geophysical data for assessing the potentiality of titaniferous-vanadiferous, magnetite-ilmenite mineralization in and around the Sudamakund and Paharpur areas, Gaya and Jehanabad districts, Bihar, India, and delineation of specific targets for detailed exploration. Field visits for large scale mapping on (1:12,500 scale) were used to conduct a reconnaissance survey for magnetite-ilmenite mineralization in parts of toposheet number 72G/04 in the Gaya and Jehanabad districts of Bihar, as well as the collection of bedrock samples (BRS), pit/trench samples (PTS), petrographic samples (PS), and petrochemical samples (PCS), followed by petrographic and ore microscopic study, and interpretation of chemical results. Signatures of oxidized iron-bearing sulphides (iron-oxides ratio) and other ferrous-iron-bearing minerals surrounded by altered rocks (clay bearing minerals) are visible in remote sensing images. The geological work was followed by ground geophysical gravity and magnetic surveys in selected blocks by the Geophysics Division, eastern region (ER) on a 1:12,500 scale. The magnetite ore is hard, compact, crystalline, and at some places, granular in nature. The analytical value of these magnetite ore bodies indicates average Fe content at 49.53% (range 25.85–60.78%), with a considerable amount of TiO2 (average 15.85%, range 1.47–26.77%), and V (average 144.79 ppm, range 30.00–256.00 ppm, from PTS). The trends of these magnetite ore deposits correspond to the major lineaments (NE-SW and NW-SE). The superimposition of gravity and magnetic contour maps with the geological map (1:12,500 scale) helps explain the observed geophysical anomalies, and the possible subsurface (horizontal and vertical) expansion of magnetite ore deposits in alluvium cover regions warrants further investigation.
      Citation: Minerals
      PubDate: 2022-07-05
      DOI: 10.3390/min12070860
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 861: Elemental Associations in Stream and
           Alluvial Sediments of the Savinja and Voglajna Rivers (Slovenia, EU) as a
           Result of Natural Processes and Anthropogenic Activities

    • Authors: Gorazd Žibret
      First page: 861
      Abstract: Stream and alluvial sediments of the Savinja and Voglajna rivers were sampled, and sediment fractions <0.063 and 0.063–0.125 mm were analyzed on the content of 60 of the main and trace elements. The objective was to determine elemental associations and identify possible sources of these associations. Differences of Al/Ti oxides ratio (9.7–26) can be attributed to the variations in the source rocks, while the K/Al oxides ratio indicates erosional or depositional river regime and variation in source rocks. One anthropogenic and three natural associations of elements were identified. The anthropogenic association (Ag, In, Sb, Cu, As, Zn, Pb, Cd, Bi, Mo and Sn) is linked to historic Zn smelting in the Celje area, and the subsequent erosion of the material from inadequately managed pyrometallurgical waste deposit. The second association (Li, Sc, Al, V, Cs and Ga) is linked to clay minerals, the third one (Mg, Ca and Te) to carbonate rocks, and the fourth one (Hf, Zr) to the heavy mineral fraction.
      Citation: Minerals
      PubDate: 2022-07-05
      DOI: 10.3390/min12070861
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 862: Adsorption of Cs(I) and Sr(II) on Bentonites
           with Different Compositions at Different pH

    • Authors: Yulia Izosimova, Irina Gurova, Inna Tolpeshta, Michail Karpukhin, Sergey Zakusin, Olga Zakusina, Alexey Samburskiy, Victoria Krupskaya
      First page: 862
      Abstract: This paper deals with adsorption regularities and mechanisms of nonradioactive Cs(I) and Sr(II) analogs on bentonites of different chemical and mineral composition from solutions of Cs and Sr nitrates with pH 3, 7, and 10 units at constant ionic strength. The bentonites were taken from the deposits Taganskoe (T), Dash-Salakhlinskoe (DS), Zyryanskoe (Z), and 10th Khutor (10H). The pH of bentonite aqueous suspensions, T and DS, exceeded 9 units. A less alkaline reaction was observed in bentonite suspensions Z and T with pH 8.94 and 7.70, respectively. Bentonites T and DS contained significant amounts of nonsilicate iron compounds, 1.0 and 0.5%, respectively. The recovery rate of the studied clays from aqueous solutions of Cs(I) and Sr(II) ions in concentrations from 0.25 to 5 mmol/L varied from 50% to 90% and decreased in the following order: “Ta-ganskoe” > “Dash-Salakhlinskoe” > “Zyryanskoe” > “10th Khutor” in the studied pH range. The main mechanism of Cs(I) and Sr(II) sorption in the studied pH range was cation fixation in the form of outer-sphere complexes on planar surfaces resulting from ion exchange. Increasing pH (pH > 6) enhanced pH-dependent positions, which allowed Cs(I) and especially Sr(II) ions to fix on them more firmly as inner-sphere complexes. At pH 9–10, Sr(II) could precipitate in the form of carbonates. The sorption of Cs(I) + and Sr(II) was accompanied by competitive interactions with proton at pH < 6 and Na+, Ca2+, Mg2+, and K+ cations at higher pH values. This competition was more apparent at concentrations of Cs(I)and Sr(II) in initial solutions < 0.5 mmol/L. The ability of bentonite T to sorb Cs(I) and Sr(II) in large amounts compared to the other bentonites was determined by high CEC values and charge of smectite T.
      Citation: Minerals
      PubDate: 2022-07-07
      DOI: 10.3390/min12070862
      Issue No: Vol. 12, No. 7 (2022)
  • Minerals, Vol. 12, Pages 763: Expansion Properties of Cemented Foam
           Backfill Utilizing Coal Gangue and Fly Ash

    • Authors: Xiao Wang, Jixiong Zhang, Meng Li, Feng Gao, Abbas Taheri, Binbin Huo, Ling Jin
      First page: 763
      Abstract: The cemented backfill (CB) utilizing coal gangue (CG) and fly ash (FA) is widely applied in coal mines. However, the bleeding and shrinkage of CB leads to insufficient contact with surrounding rock, which is not beneficial for controlling roof subsidence and even stope stability. Herein, a cemented foam backfill (CFB) formulation is demonstrated, employing hydrogen dioxide (H2O2) as a chemical foaming agent. The cement and FA show noticeable inhibiting effects on volume expansion due to the network formed by their hydrates. Moderately lower cement, FA, and solid concentration are beneficial to improve volume increment and prolong expanding duration. A foaming coefficient (k) is proposed in theory to evaluate the foaming efficiency. The kem values, determined by volume evolution experiments of CFB slurries, provide a calculation basis for the needed dosage of H2O2 solution targeting specific volume increment. CFB specimens with expanding ratios of 21%~103% and densities of 994~592 kg/cm3 were prepared, with an actual foaming coefficient of 52.40 cm3/g and uniaxial compressive strength (UCS) of 0.32~0.55 MPa. The mass of H2O2 solution was 1.9%~11.3% of cement and 0.29%~1.67% of total solid materials by weight. The UCS decline compared to CB was attributed to rich pores observed by CT and carbonation indicated by X-ray diffraction (XRD).
      Citation: Minerals
      PubDate: 2022-06-15
      DOI: 10.3390/min12060763
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 764: Structural and Surface Modification of
           Oxalic-Acid-Activated Bentonites in Various Acid Concentrations for
           Bleaching Earth Synthesis—A Comparative Study

    • Authors: Danai Tsakiri, Iliana Douni, Maria Taxiarchou
      First page: 764
      Abstract: The aim of this study is to investigate the oxalic acid activation of bentonites containing different types of smectites, analyse their surface modification as a function of acid concentration and create good quality bleaching earths. In particular, two different bentonite samples (one containing aluminum and one containing ferruginous smectite), after being characterized through XRD, XRF and FT-IR analysis, are treated with oxalic acid at a concentration of 0.5, 0.7 and 1 M. Their structural modifications after treatment are observed through FT-IR spectra and surface area and porosity measurement (using the BET equation and the BJH method, respectively) combined with the determination of the main structural metals’ extraction from them (using an atomic adsorption spectrometer). The results showed that the ferruginous smectite is more susceptible to oxalic acid activation compared to the aluminum smectite, and all the final products have developed extra porosity in their structure while retaining the structure of smectite (even at 0.5 M acid concentration). The activated samples were used as bleaching earths in soybean oil, and the results proved that Lovibond yellow and red colours as well as the chlorophyll of oil (measured spectrophotometrically) were reduced to the values set by the specifications.
      Citation: Minerals
      PubDate: 2022-06-16
      DOI: 10.3390/min12060764
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 765: The Gold–Palladium Ozernoe Occurrence
           (Polar Urals, Russia): Mineralogy, Conditions of Formation, Sources of Ore
           Matter and Fluid

    • Authors: Valery Murzin, Galina Palyanova, Татiana Mayorova, Tatiana Beliaeva
      First page: 765
      Abstract: We studied the mineralization and sulfur isotopic composition of sulfides of gold–palladium ores in olivine clinopyroxenites from the Dzelyatyshor massif made up of a continuous layered series of rocks: olivine-free clinopyroxenite–olivine clinopyroxenite–wehrlite. The primary igneous layering of rocks, manifested as different quantitative ratios of clinopyroxene and olivine in them, controls the local trends of variability in the chemistry of mineral-forming medium and the concentrations of ore components, including noble metals, and sulfur in each separate layer during its cooling. The replacement of primary rock-forming minerals by secondary minerals, when the temperature decreases, is a characteristic trend for pyroxenites: (a) olivine → serpentine, secondary magnetite, and (b) clinopyroxene → amphibole, secondary magnetite → chlorite. The deposition of native gold in parageneses with PGM and sulfides at the Ozernoe occurrence took place during the replacement of earlier rock-forming minerals by chlorite. This process completed mineral formation at the deposit and took place at temperatures 150–250 °С and at the high activity of S, Te, Sb, and As of fluid. The variability of mineral formation conditions during chloritization is reflected in the change of native-sulfide forms of Pd by arsenide-antimonide forms and the sulfur isotopic composition of sulfides. The Pd content in native gold increases in the series—Au-Ag solid solution (<1.5 wt.% Pd)—Au-Cu intermetallides (to 6 wt.% Pd)—Cu-Au-Pd solid solutions (16.2–16.9 wt.% Pd). The sulfur isotopic composition of pyrite, chalcopyrite, and bornite varies from −2.1 to −2.9‰. It is assumed that a deep-seated magmatic basic melt was the source of fluid, ore components, and sulfur.
      Citation: Minerals
      PubDate: 2022-06-16
      DOI: 10.3390/min12060765
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 766: Identification and Suppression of
           Magnetotelluric Noise via a Deep Residual Network

    • Authors: Liang Zhang, Zhengyong Ren, Xiao Xiao, Jintian Tang, Guang Li
      First page: 766
      Abstract: The magnetotelluric (MT) method is widely applied in petroleum, mining, and deep Earth structure exploration but suffers from cultural noise. This noise will distort apparent resistivity and phase, leading to false geological interpretation. Therefore, denoising is indispensable for MT signal processing. The sparse representation method acts as a critical role in MT denoising. However, this method depends on the sparse assumption leading to inadequate denoising results in some cases. We propose an alternative MT denoising approach, which can achieve accurate denoising without assumptions on datasets. We first design a residual network (ResNet), which has an excellent fitting ability owing to its deep architecture. In addition, the ResNet network contains skip-connection blocks to guarantee the robustness of network degradation. As for the number of training, validation, and test datasets, we use 10,000,000; 10,000; and 100 field data, respectively, and apply the gradual shrinkage learning rate to ensure the ResNet’s generalization. In the noise identification stage, we use a small-time window to scan the MT time series, after which the gramian angular field (GAF) is applied to help identify noise and divide the MT time series into noise-free and noise data. We keep the noise-free data section in the denoising stage, and the noise data section is fed into our network. In our experiments, we test the performances of different time window sizes for noise identification and suppression and record corresponding time consumption. Then, we compare our approach with sparse representation methods. Testing results show that our approach can obtain the desired denoising results. The accuracy and loss curves show that our approach can well suppress the MT noise, and our network has a good generalization. To further validate our approach’s effectiveness, we show the apparent resistivity, phase, and polarization direction of test datasets. Our approach can adjust the distortion of apparent resistivity and phase and randomize the polarization direction distribution. Although our approach requires the high quality of the training dataset, it achieves accurate MT denoising after training and can be meaningful in cases of a severe MT noisy environment.
      Citation: Minerals
      PubDate: 2022-06-16
      DOI: 10.3390/min12060766
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 767: The Effect of Zn Content and Granulation
           Temperature on Zn Leaching in an Fe-Saturated (FeXZn(1−X))2SiO4

    • Authors: Jakob Kero Andertun, Pasi Peltola, Fredrik Engström, Caisa Samuelsson
      First page: 767
      Abstract: The zinc in the fayalite slag of copper smelters, in which Zn-containing raw materials are used, is mainly found to be in oxidic phases, such as glassy iron silicate. During the slag water granulation process, the molten slag is heated, whereby the granulated slag achieves varying granulation temperatures. Therefore, in this study, we aimed to characterize and assess the leaching behavior of a synthesized Fe-saturated (FeX,Zn(1−X))2SiO4 system to understand the dependance of the zinc leaching behavior on the parameters of the ZnO content (1–10 wt.%) and granulation temperature (1300 or 1400 °C). It was found that the Zn leaching increased with the increasing Zn content and granulation temperature, using both batch and static pH leaching methods. Zn leaching was further increased at pH 5 using diluted nitric acid under oxidation conditions. Among the oxides in the samples—fayalite, spinel, and glass—glass was found to contribute to Zn leaching, owing to its weathering during pH-titration.
      Citation: Minerals
      PubDate: 2022-06-16
      DOI: 10.3390/min12060767
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 768: The Southwestern Boundary of Cenozoic Qaidam
           Basin: Constraints from Heavy Mineral Analysis

    • Authors: Xiaonan Ding, Ling Fu, Ping Guan, Daowei Zhang
      First page: 768
      Abstract: The formation of the Qaidam Basin plays an important role in unraveling the growth history of the Tibetan plateau. An extraordinary thick Cenozoic sedimentary succession of the Qaidam Basin is a great contributor to the study of the basin’s evolution history. To date, there has been disagreement on the southwestern boundary of the Paleogene Qaidam Basin. In this study, the method of heavy mineral analysis was adopted to reconstruct the southwestern boundary of the Qaidam Basin. The stable heavy minerals which represent the maturity of detrital sediments can roughly reflect the distance between the source and the deposit area. Therefore, the isogram of the stable heavy mineral index (ZTR = 20) was compiled to infer the location of the source area of the southwestern Qaidam Basin. The isogram shows that the boundary of the southwestern Qaidam Basin stretched southwesterly to the present-day Qiman Tagh Eastern Kunlun Mountains during the Paleogene. Additionally, the isolines present a remarkable northward migration since the late Eocene, which indicates the boundary of the Cenozoic Qaidam Basin that withdrew northward since the late Eocene. The specific location of the southern source area of the Qaidam Basin can be deduced at the Adatan fault, the middle of the present-day Eastern Kunlun Mountains. This result also supports the idea that the Qaidam Basin was an independent basin during the early Cenozoic era, and the Eastern Kunlun Mountains have already been exhumed during that time, serving as a prominent source of clastic sediments in the southwestern Qaidam Basin.
      Citation: Minerals
      PubDate: 2022-06-16
      DOI: 10.3390/min12060768
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 769: 3D Multi-Parameter Geological Modeling and
           Knowledge Findings for Mo Oxide Orebodies in the Shangfanggou
           Porphyry–Skarn Mo (–Fe) Deposit, Henan Province, China

    • Authors: Zhifei Liu, Ling Zuo, Senmin Xu, Yaqing He, Chunyi Wang, Luofeng Wang, Tao Yang, Gongwen Wang, Linggao Zeng, Nini Mou, Wangdong Yang
      First page: 769
      Abstract: The Shangfanggou Mo–Fe deposit is a typical and giant porphyry–skarn deposit located in the East Qinling–Dabie molybdenum (Mo) polymetallic metallogenic belt in the southern margin of the North China Block. In this paper, three-dimensional (3D) multi-parameter geological modeling and microanalysis are used to discuss the mineralization and oxidation transformation process of molybdenite during the supergene stage. Meanwhile, from macro to micro, the temporal–spatial–genetic correlation and exploration constraints are also established by 3D geological modeling of industrial Mo orebodies and Mo oxide orebodies. SEM-EDS and EPMA-aided analyses indicate the oxidation products of molybdenite are dominated by tungsten–powellite at the supergene stage. Thus, a series of oxidation processes from molybdenite to tungsten–powellite are obtained after the precipitation of molybdenite; eventually, a special genetic model of the Shangfanggou high oxidation rate Mo deposit is formed. Oxygen fugacity reduction and an acid environment play an important part in the precipitation of molybdenite: (1) During the oxidation process, molybdenite is first oxidized to a MoO2·SO4 complex ion and then reacts with a carbonate solution to precipitate powethite, in which W and Mo elements can be substituted by complete isomorphism, forming a unique secondary oxide orebody dominated by tungsten–powellite. (2) Under hydrothermal action, Mo4+ can be oxidized to jordisite in the strong acid reduction environment at low temperature and room temperature during the hydrothermal mineralization stage. Ilsemannite is the oxidation product, which can be further oxidized to molybdite.
      Citation: Minerals
      PubDate: 2022-06-17
      DOI: 10.3390/min12060769
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 770: Research on Uniaxial Compression Mechanics
           of Diorite under Flowing Acidic Solution Scouring

    • Authors: Wei Chen, Li Wu, Zhi Zeng, Wen Wan, Jie Liu, Xiaofan Wu, Wenqing Peng, Xiantao Zeng, Zhenhua Ren, Senlin Xie, Yu Zhou
      First page: 770
      Abstract: The bedrock used for underground construction has obvious traces of hydrodynamic scouring damage, and the mechanical properties of bedrock especially are severely damaged under a groundwater environment. On this basis, considering the excavated bedrock under various saturations, the uniaxial compression test of diorite is carried out. Meanwhile, scanning electron microscopy (SEM), electron energy spectroscopy (EDS) and X-ray diffraction (XRD) are used in the experiment. The variation law of the elastic p-wave velocity and microstructure and the response characteristics of the strength, deformation and mechanical parameters of rock under different flow rates and pH values are analyzed in detail. The results indicate that: (1) Saturations with a faster flow rate and lower pH value cause greater relative changes in the elastic longitudinal wave velocity of the samples. (2) The uniaxial compressive strength of the samples under various treatment conditions showed a decreasing trend. Compared with the dried samples, the uniaxial compressive strength of the samples under saturation with field flow rate v = 300 mm·s−1 and pH = 1 decreased by 46.08%, and the strength decreased by 35.67% under saturation with a field pH value = 6.56 and flow rate v = 900 mm-s−1. (3) The saturation with a stronger acidity, greater flow rate and longer action time causes the apparent dense structure of the diorite sample to be loose and accompanied by microcracks, which weakens its macromechanical properties. (4) Acid and hydrodynamic saturation produce water–rock chemical and physical effects on diorite, which weaken the connection force between mineral particles and the friction between fracture surfaces, reduce the elastic modulus, increase Poisson’s ratio and accelerate the failure of diorite.
      Citation: Minerals
      PubDate: 2022-06-17
      DOI: 10.3390/min12060770
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 771: Petrogenesis and Geological Significance of
           the Quartz Monzonites in the Jinling Area, Western Shandong Province

    • Authors: Zhao-Lu Zhang, Chao Zhang, Ye Li, Lu-Yuan Wang, Ji-Lei Gao, Ming Ma, Ya-Dong Li
      First page: 771
      Abstract: Jinling complex pluton is a key part of the Mesozoic magmatic belt in the eastern North China Craton. However, its petrogenesis is still being debated. The Jinling complex, mainly composed of biotite diorites, hornblende diorite, augite diorites, (quartz) monzonites, and quartz diorites, is outcropped in Huashan and Heitieshan. This paper studies the zircon geochronology, zircon Hf isotope, and Sr-Nd-Pb isotope of quartz monzonites. The samples have high contents of Cr, Ni, V, Al2O3, Ba, Sr, and are enriched in LREEs, LILEs (K, Ba, Sr), depleted in HREEs, and HFSEs (Nb, Ta, Ti). The samples with captured zircons of ~2.5Ga yield a weighted mean age of ~127 Ma, and the zircons have negative values of εHf (t) from −3.2 to −9.4 while the ratios of 208Pb/204Pb, 207Pb/204Pb, 206Pb/204Pb 37.75 ~ 38.15, 15.41 ~ 15.43, 17.59 ~ 17.98, respectively. The ratios of Th/U are from 3.77 to 3.82, while the values of μ and ω are 9.18 and from 35.72 to 36.15. Meanwhile, the ratios of 87Sr/86Sr are higher than the ones of the mantle. Geochemical and isotopic features indicate that the quartz monzonites derived from the subcontinental lithospheric mantle that probably assimilated ancient NCC upper crust materials (~15–20%) during the magma ascent in a lithospheric extension setting.
      Citation: Minerals
      PubDate: 2022-06-17
      DOI: 10.3390/min12060771
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 772: Bentonite Powder XRD Quantitative Analysis
           Using Rietveld Refinement: Revisiting and Updating Bulk Semiquantitative
           Mineralogical Compositions

    • Authors: Jaime Cuevas, Miguel Ángel Cabrera, Carlos Fernández, Carlos Mota-Heredia, Raúl Fernández, Elena Torres, María Jesús Turrero, Ana Isabel Ruiz
      First page: 772
      Abstract: Bentonite is a claystone formed by a complex mineralogical mixture, composed of montmorillonite, illite, and accessory minerals like quartz, cristobalite, feldspars, carbonates, and minor amounts of iron oxy-hydroxides. Bentonite presents complexity at various scales: (1): a single mineral may present different chemical composition within the same quarry (e.g., feldspars solid solutions); (2): montmorillonite presents variability in the cation-exchange distribution while illite may be presented as mixed-layer with smectite sheets; and (3): hardness and crystal size are larger in accessory minerals than in clay minerals, preventing uniform grinding of bentonite. The FEBEX bentonite used is originally from Almería (Spain), and it is a predominantly calcium, magnesium, and sodium bentonite. This Spanish FEBEX bentonite has been hydrothermally altered at laboratory scale for 7–14 years. A thermal gradient was generated by heating a disk of pressed iron powder, simulating the metal waste canister, in contact with the compacted bentonite sample. Hydration was forced from the opposite direction. XRD recorded patterns were very similar. In order to minimize the bias of XRD semi-quantitative determination methods, Rietveld refinement was performed using BGMN software and different structural models. Confidence in the quantification of the main phases allows us to convincingly detect other subtle changes such as the presence of calcite in the hydration front, right at the interface between the saturated and unsaturated bentonite, or the presence of goethite, and not hematite, in the saturated bentonite, near the source of hydration. Smectite component was 72 ± 3% and the refinement was consistent with the presence of ~10% illite, comparable with previous characterizations.
      Citation: Minerals
      PubDate: 2022-06-17
      DOI: 10.3390/min12060772
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 773: Influence of Clogging at the Filtration on
           Analysis of Dissolved and Particulate Forms of Chemical Elements in Boreal
           Rivers of the Russian Far East

    • Authors: Vladimir Shulkin, Natalia Bogdanova, Evgeniy Elovskiy
      First page: 773
      Abstract: Clogging is inevitable when membranes with 0.45 µm pore size are used for the separation of particulates from dissolved/colloidal forms in river water. This can lead to a shift in water quality assessment and evaluation of geochemical fluxes. We studied the influence of clogging on the concentration of trace elements, major anions, nitrate, and dissolved organic carbon (DOC) in the filtrates after a sequential pass from 0.1 to 0.5 L of river water samples through the same 47 mm membrane with 0.45 µm pore size. These experiments were carried out for the typical boreal rivers of the Russian Far East, including the biggest one, Amur R., with different quantities of suspended solids (SS) and anthropogenic load. The concentration of the major anions, nitrate, Si, DOC, and such trace elements as Li, B, Ni, Cu, As, Sr, Rb, Mo, Ba, U did not depend on the water volume filtered. However, filterable Al, Fe, Ti, Pb, Mn, Co, and most REEs showed a notable decrease in concentration at an increase in volume filtered, at more than 100–200 mL of river water. Clogging membranes with retention of colloids <0.45 µm was suggested as a reason for such a decrease. The quantity of suspended solids and their grain size are the major factors that control clogging itself. Still, the influence of clogging on the concentration of filterable forms depends on the share of coarse colloidal forms. Moreover, retention of colloids <0.45 µm by the clogged membrane can bias the assessment of particulate forms. Surpluses of particulate Fe, Al, Mn, Co due to clogging decline from 13–26% to 2–6% of suspended forms of these metals at the growth of SS in river waters from 10 mg/L to more than 50 mg/L. For particulate REEs, the share due to membrane clogging varies non-linearly from 2–9% to 23–39%, depending on the initial concentration of filterable forms of REEs in the river waters.
      Citation: Minerals
      PubDate: 2022-06-17
      DOI: 10.3390/min12060773
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 774: Differences in Properties between Pebbles
           and Raw Ore from a SAG Mill at a Zinc, Tin-Bearing Mine

    • Authors: Wenhan Sun, Jinlin Yang, Hengjun Li, Wengang Liu, Shaojian Ma
      First page: 774
      Abstract: Semi-autogenous (SAG) mills are widely used grinding equipment, but some ore with critical particle sizes cannot be effectively processed by SAG mills and turned into pebbles. This research aims to analyze and compare the properties of raw ore and pebbles from a zinc- and tin-bearing ore. The results show that the contents of sphalerite, cassiterite, biotite, antigorite, pyroxferroite, ferroactinolite, and ilvaite in the raw ore are higher than those in the pebbles, and that the pebbles have higher contents of hedenbergite, chlorite, epidote, actinolite, etc. Meanwhile, the abrasion and impact resistance of pebbles is greater than that of the raw ore. In addition, the sphalerite is evenly embedded, and the grinding process is regular. Fine cassiterite associated with harder minerals is difficult to dissociate; it is often found in softer or brittle minerals which may be easily ground into ore mud. The cassiterite in the pebbles is associated with hard and brittle hedenbergite and soft chlorite, making it difficult to recover. This research provides a good foundation for evaluating the recovery value of pebbles and improving the productivity of the SAG process.
      Citation: Minerals
      PubDate: 2022-06-17
      DOI: 10.3390/min12060774
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 775: The Hidden Magmatic Chamber from the Ponte
           Nova Mafic–Ultramafic Alkaline Massif, SE Brazil: Clues from
           Clinopyroxene and Olivine Antecrysts

    • Authors: Rogério Guitarrari Azzone, Lina Maria Cetina Tarazona, Mariana Robertti Ambrosio, Vincenza Guarino, Luanna Chmyz, Nicholas Machado Lima, Excelso Ruberti
      First page: 775
      Abstract: Clinopyroxene and olivine primocrysts in the intrusions of the Ponte Nova mafic–ultramafic alkaline massif (SE Brazil) present several textures and zoning that indicate open-system processes. Important compositional differences were found in the clinopyroxene. Diopside relict cores (mostly partially corroded) present higher Mg, Cr and Ni and lower Ti, Na, Al, REE and Sr than Ti-augite mantling and rims. Subordinately, two types of olivine crystals were recognized, one related to very zoned crystals with high Mg (Fo up to 86 mol.%) and Ni cores (mostly with corroded rims), and other almost without clear zonation and with lower Mg contents. Relict cores of high-Mg clinopyroxene and olivine crystals are representative of antecrysts formed in deeper chamber environments. Temperature and pressure estimates based on clinopyroxene-liquid geothermobarometers indicate crystallization of the antecrysts at ~1171 ± 10 °C and ~5.7 ± 0.3 kbar, pointing to a deeper hidden magmatic chamber, whereas mantling and rim compositions indicate a shallow chamber environment. Clinopyroxenes of this hidden chamber have progressive enrichments of incompatible elements with the Mg# decrement and inflection points in Sr and REE due to the starting of co-precipitation of apatite. The evolution trend of clinopyroxene antecrysts indicates that the main intrusions in the Ponte Nova shallow chamber were fed by a single deeper hidden chamber mainly controlled by typical fractional crystallization processes. These antecrysts indicate the presence of a complex plumbing system, which is also supported by similar antecrysts found in the lamprophyre and alkali basalt dikes of this region. The preferred petrological model for the Ponte Nova massif could be summarized as repeated influxes of antecryst-laden basanite magmas that deposited most of their suspended crystals on the floor of the upper-crust magma chamber.
      Citation: Minerals
      PubDate: 2022-06-18
      DOI: 10.3390/min12060775
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 776: Verification and Application of Sequence
           Stratigraphy to Reservoir Characterization of Horn River Basin, Canada

    • Authors: Juhwan Woo, Jiyoung Choi, Seok Hoon Yoon, Chul Woo Rhee
      First page: 776
      Abstract: Shale reservoirs, the most important unconventional resource, are difficult to characterize. Shale formations require detailed interpretation of geological, petrophysical, and geochemical analyses, and an integration of these disciplines. In terms of geological interpretation, the commonly used sequence stratigraphy analysis includes a lithofacies analysis. The application of sequence stratigraphy to shales facilitates the ability to relate between lithofacies and mineral composition, petrophysical parameters, and kerogen contents, which are affected by depositional setting. The classification of lithofacies is indispensable for reservoir quality prediction. In this study, porosity, permeability, and TOC content largely depend on lithofacies, and their correlation coefficient is relatively high. The sequence stratigraphic interpretation shows that organic carbon content usually increases within the maximum flooding surfaces and decreases stepwise. However, the relationship between total organic carbon contents and systems tract is less direct and redox dependent.
      Citation: Minerals
      PubDate: 2022-06-18
      DOI: 10.3390/min12060776
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 777: Searching Mass-Balance Analysis to Find the
           Composition of Martian Blueberries

    • Authors: Rif Miles Olsen
      First page: 777
      Abstract: Between 2004 and 2018, NASA’s rover Opportunity found huge numbers of small, hematite-rich spherules (commonly called blueberries) on the Meridiani Planum of Mars. The standard oxide composition distributions of blueberries have remained poorly constrained, with previous published analyses leaving hematite content somewhere in the broad range of 24–100 wt%. A searching mass-balance analysis is introduced and applied to constrain possible standard oxide composition distributions of blueberries consistent with the non-detection of silicates in blueberries by Opportunity’s instruments. This analysis found three groups of complete solution sets among the mass-balance ions consistent with the non-detection of silicates; although, a simple extension of the analysis indicates that one larger space of solutions incorporates all three groups of solutions. Enforcing consistency with the non-detection of silicates in blueberries constrains the hematite content in most of blueberry samples to between 79.5 and 99.85 wt%. A feature of the largest group of complete solution sets is that five oxides/elements, MgO, P2O5, Na2O, SO3, and Cl, collectively have a summed weight percentage that averages close to 6 wt%, while the weight percentage of nickel is close to 0.3 wt% in all solutions. Searches over multidimensional spaces of filtering composition distributions of basaltic and dusty soils were a methodological advance.
      Citation: Minerals
      PubDate: 2022-06-18
      DOI: 10.3390/min12060777
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 778: Experimental Investigation of Visible-Light
           and X-ray Emissions during Rock and Mineral Fracture: Role of Electrons
           Traveling between Fracture Surfaces

    • Authors: Toshihiko Kadono, Kazunori Ogawa, Kei Shirai, Masahiko Arakawa, Kosuke Kurosawa, Takaya Okamoto, Takafumi Matsui, Sunao Hasegawa, Ayako I. Suzuki, Hideyuki Kobayashi
      First page: 778
      Abstract: Radiation phenomena are usually observed during fracture of quartz-bearing rocks. Since quartz is a piezoelectric material, the associated electrical processes such as the electrification of fracture surface and the flight of electrons between fracture surfaces should be important for radiation during fractures. In this article, supposing that travelling electrons between crack surfaces cause the radiation, we experimentally investigate X-ray emission in a vacuum and visible-light emission in the atmosphere during rock and mineral fracture and verify the consistency of both emissions. The number of electrons in flight between surfaces during fracture that result in X-ray is estimated and the comparison with the number of photons in visible light suggests that one electron repeatedly collides with N2 molecules. The estimated number of collisions resulting in a visible-light emission is slightly less than the expected upper limit. This is reasonable because the collision would cause the light emission not always in the wavelengths of visible light. Moreover, the number of electrons resulting in X-rays is comparable with the number of electrons resulting in the emission of radio waves during fracture obtained in previous studies. Thus, we conclude that the radiations during fracture can be attributed to the flight of electrons between fracture surfaces. Finally, we evaluate the feasibility of observing the X-ray emission in planetary exploration and the radio waves and the visible light in natural earthquakes and find that these radiations are observable.
      Citation: Minerals
      PubDate: 2022-06-18
      DOI: 10.3390/min12060778
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 779: CO2-Enhanced Oil Recovery Mechanism in
           Canadian Bakken Shale

    • Authors: Majid Bizhani, Omid Haeri Ardakani, Steven B. Hawthorne, Jaime Cesar, Bethany Kurz, Jeanne B. Percival
      First page: 779
      Abstract: The recovery factor in unconventional reservoirs is typically 5-10%, with extensive hydraulic fracturing and infill drilling to maintain the production rate. Concurrently, the rush towards decarbonization is opening up new possibilities for CO2 utilization, enhanced oil recovery (EOR) being one example. CO2-EOR in unconventional reservoirs presents an opportunity for both financial gain through improved recovery factors, as well as reducing the carbon footprint of the produced oil. In this work, we examine the CO2-EOR potential in 4 organic-rich shale samples from the Canadian Bakken Formation. A number of characterization tests alongside CO2 extraction experiments were performed to gain insight into the controlling factors of CO2-EOR in these ultra-tight formations. The results show CO2 can penetrate the tight rock matrix and recover a substantial amount of hydrocarbon. Concentration gradient driven diffusion is the dominant form of recovery.
      Citation: Minerals
      PubDate: 2022-06-19
      DOI: 10.3390/min12060779
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 780: Geoenvironmental Model for Roll-Type Uranium
           Deposits in the Texas Gulf Coast

    • Authors: Katherine Walton-Day, Johanna Blake, Robert Seal, Tanya Gallegos, Jean Dupree, Kent Becher
      First page: 780
      Abstract: Geoenvironmental models were formulated by the U.S. Geological Survey in the 1990s to describe potential environmental effects of extracting different types of ore deposits in different geologic and climatic regions. This paper presents a geoenvironmental model for roll-front (roll-type) uranium deposits in the Texas Coastal Plain. The model reviews descriptive and quantitative information derived from environmental studies and existing databases to depict existing conditions and potential environmental concerns associated with mining this deposit type. This geoenvironmental model describes how features of the deposits including host rock; ore and gangue mineralogy; geologic, hydrologic, and climatic settings; and mining methods (legacy open-pit and in situ recovery [ISR]) influence potential environmental effects from mining. Element concentrations in soil and water are compared to regulatory thresholds to depict ambient surface water and groundwater conditions. Although most open-pit operations in this region have been reclaimed, concerns remain about groundwater quality at three of the four former mills that supported former open-pit mines and are undergoing closure activities. The primary environmental concerns with ISR mining are (1) radon gas at active ISR operations, (2) radiation or contaminant leakage during production and transport of ISR resin or yellowcake, (3) uranium excursions into groundwater surrounding active ISR operations, and (4) contamination of groundwater after ISR mining. Although existing regulations attempt to address these concerns, some problems remain. Researchers suggest that reactive transport modeling and a better understanding of geology, stratigraphy, and geochemistry of ISR production areas could minimize excursions into surrounding aquifers and improve results of groundwater restoration.
      Citation: Minerals
      PubDate: 2022-06-20
      DOI: 10.3390/min12060780
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 781: Geochemical Characteristics and Their
           Geological Significance of Lower Cambrian Xiaoerblak Formation in
           Northwestern Tarim Basin, China

    • Authors: Jianfeng Zheng, Yongjin Zhu, Lili Huang, Guo Yang, Fangjie Hu
      First page: 781
      Abstract: Lower Cambrian Xiaoerblak Formation is one of the major exploration targets in Cambrian pre-salt Tarim Basin; however, the exploration breakthrough is restricted by insufficient understanding of its sedimentary evolution and reservoir genesis. In this paper, based on a systematic description of the outcrop in the Xiaoerblak section, northwestern Tarim Basin, some samples were selected for tests of stable carbon and oxygen isotopic compositions, strontium isotopic composition, order degree, trace and rare earth elements, U-Pb isotopic age and clumped isotope. It is found that the Xiaoerblak Formation mainly develops nine types of dolomites, i.e., laminated microbial dolomite, thrombolite dolomite, stromatolite dolomite, foamy microbial dolomite, grain dolomite, etc. According to the lithofacies associations, it can be divided into three members: Xi 1, Xi 2, and Xi 3, of which member Xi 2 is subdivided into three submembers. The characteristics of lithofacies assemblage formed bottom to top indicate that it can be described as a third-order sequence. The Xiaoerblak Formation was deposited in a nearshore shallow seawater environment characterized by high water salinity and temperature under a warm and humid climate during the Early Cambrian, giving rise to the sedimentary sequence of inner ramp lagoon, subtidal microbial mound shoal and tidal flat in the carbonate ramp setting from bottom to top. Its dolomitization occurred in the penecontemporaneous–shallow burial period when the temperature was relatively low and high-salinity seawater acted as the main dolomitizaiton fluid. The reservoir space mainly comprises primary microbial framework pores and vugs formed by the atmospheric freshwater dissolution. Reservoirs were controlled by lithofacies, high-frequency sequence boundary and early dolomitization. The research results are of great significance for presalt Cambrian lithofacies paleogeographic mapping and reservoir prediction.
      Citation: Minerals
      PubDate: 2022-06-20
      DOI: 10.3390/min12060781
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 782: Porosity Distribution Law of Overlying
           Strata in the Goaf of the Adjacent Working Face: From the Perspective of
           Section Coal Pillar Types

    • Authors: Shuicheng Tian, Junrui Mao, Hongxia Li
      First page: 782
      Abstract: The porosity distribution law of overlying strata in the goaf has an important guiding role in distinguishing hidden disaster-causing factors in the goaf, such as the gas enrichment area and spontaneous combustion area. Existing research is concentrated on the overlying strata in the goaf of a single working face (GSWF), and the porosity distribution law of overlying strata in the goaf of an adjacent working face (GAWF) must be different from that in the GSWF. By selecting Longshan Coal Mine as an engineering background and applying theoretical analysis, numerical simulation and formula-fitting methods, the porosity distribution law of overlying strata in the GAWF was obtained for different section coal pillar types. The results demonstrate that (1) according to the supporting effect of different sections of coal pillar widths on overlying strata, the GAWF can be divided into three types: goaf of an adjacent working face with small-section coal pillar width type (GFST), goaf of an adjacent working face with moderate-section coal pillar width type (GFMT), and goaf of an adjacent working face with large-section coal pillar width type (GFLT). (2) In the goaf of a working face, the offset distance from the maximum porosity value area of each overlying rock stratum to the middle of the rock stratum is positively correlated with the distance between the overlying strata and the coal seam floor. In the area affected by the section coal pillar (ASCP), the porosity of each overlying rock stratum increases with an increase in the section coal pillar width, but is still smaller than its own initial porosity, and its increase rate continuously decreases. (3) From the coal seam floor upward, the porosity spatial form distribution of overlying strata in the GFST and GFMT is described as follows: partial “dustpan” shape–unilateral “concave-convex peak” combined shape. The porosity spatial form distribution of overlying strata in the GFLT is described as follows: “dustpan” shape–“concave-convex peak” combined shape-“Λ” shape.
      Citation: Minerals
      PubDate: 2022-06-20
      DOI: 10.3390/min12060782
      Issue No: Vol. 12, No. 6 (2022)
  • Minerals, Vol. 12, Pages 783: Investigation of Internal Classification in
           Coarse Particle Flotation of Chalcopyrite Using the CoarseAIRTM

    • Authors: Luke J. Crompton, Md. Tariqul Islam, Kevin P. Galvin
      First page: 783
      Abstract: This work introduces the CoarseAIR™, a novel system utilizing a three-phase fluidized bed and a system of inclined channels to facilitate coarse particle flotation and internal size classification. Internal classification in the CoarseAIR™ was investigated in a series of continuous steady-state experiments at different inclined channel spacings. For each experimental series, a low-grade chalcopyrite ore was milled to a top size of 0.53 mm and methodically prepared to generate a consistent feed. The air rate to the system was adjusted to determine the impact of the gas flux on coarse particle flotation and overall system performance, with a focus on maximizing both copper recovery and coarse gangue rejection. A new feed preparation protocol led to low variability in the state of the feed, and in turn strong closure in the material balance. Hence, clear conclusions were drawn due to the high-quality datasets. Inclined channel spacings of z = 6 and z = 9 mm were used. The z = 9 mm spacing produced more favourable copper recovery and gangue rejection. Higher gas fluxes of 0.30 to 0.45 cm/s had a measurable, adverse effect on the recovery of the coarser hydrophobic particles, while the gas flux of 0.15 cm/s delivered the best performance. Here, the cumulative recovery was 90%, and mass rejection was 60% at 0.50 mm, while the +0.090 mm recovery was 83% with a gangue rejection of 85%. The system displayed robust performance across all conditions investigated.
      Citation: Minerals
      PubDate: 2022-06-20
      DOI: 10.3390/min12060783
      Issue No: Vol. 12, No. 6 (2022)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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