Subjects -> MINES AND MINING INDUSTRY (Total: 81 journals)
Showing 1 - 42 of 42 Journals sorted alphabetically
American Mineralogist     Hybrid Journal   (Followers: 16)
Applied Earth Science : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Archives of Mining Sciences     Open Access   (Followers: 3)
AusiMM Bulletin     Full-text available via subscription   (Followers: 1)
BHM Berg- und Hüttenmännische Monatshefte     Hybrid Journal   (Followers: 2)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
Clay Minerals     Hybrid Journal   (Followers: 9)
Clays and Clay Minerals     Hybrid Journal   (Followers: 5)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 14)
Environmental Geochemistry and Health     Hybrid Journal   (Followers: 2)
European Journal of Mineralogy     Hybrid Journal   (Followers: 14)
Exploration and Mining Geology     Full-text available via subscription   (Followers: 3)
Extractive Industries and Society     Hybrid Journal   (Followers: 2)
Gems & Gemology     Full-text available via subscription   (Followers: 2)
Geology of Ore Deposits     Hybrid Journal   (Followers: 5)
Geomaterials     Open Access   (Followers: 3)
Geotechnical and Geological Engineering     Hybrid Journal   (Followers: 9)
Ghana Mining Journal     Full-text available via subscription   (Followers: 3)
Gold Bulletin     Hybrid Journal   (Followers: 2)
Inside Mining     Full-text available via subscription  
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: 1)
International Journal of Hospitality & Tourism Administration     Hybrid Journal   (Followers: 15)
International Journal of Mineral Processing     Hybrid Journal   (Followers: 8)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 11)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
International Journal of Mining and Mineral Engineering     Hybrid Journal   (Followers: 8)
International Journal of Mining Engineering and Mineral Processing     Open Access   (Followers: 6)
International Journal of Mining Science and Technology     Open Access   (Followers: 4)
International Journal of Mining, Reclamation and Environment     Hybrid Journal   (Followers: 6)
International Journal of Rock Mechanics and Mining Sciences     Hybrid Journal   (Followers: 9)
Journal of Analytical and Numerical Methods in Mining Engineering     Open Access  
Journal of Applied Geophysics     Hybrid Journal   (Followers: 17)
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of China Coal Society     Open Access  
Journal of China University of Mining and Technology     Full-text available via subscription   (Followers: 1)
Journal of Convention & Event Tourism     Hybrid Journal   (Followers: 6)
Journal of Geology and Mining Research     Open Access   (Followers: 10)
Journal of Human Resources in Hospitality & Tourism     Hybrid Journal   (Followers: 9)
Journal of Materials Research and Technology     Open Access   (Followers: 2)
Journal of Metamorphic Geology     Hybrid Journal   (Followers: 17)
Journal of Mining Institute     Open Access  
Journal of Mining Science     Hybrid Journal   (Followers: 5)
Journal of Quality Assurance in Hospitality & Tourism     Hybrid Journal   (Followers: 6)
Journal of Sustainable Mining     Open Access   (Followers: 3)
Journal of the Southern African Institute of Mining and Metallurgy     Open Access   (Followers: 6)
Lithology and Mineral Resources     Hybrid Journal   (Followers: 4)
Lithos     Hybrid Journal   (Followers: 12)
Mine Water and the Environment     Hybrid Journal   (Followers: 5)
Mineral Economics     Hybrid Journal   (Followers: 2)
Mineral Processing and Extractive Metallurgy : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 14)
Mineral Processing and Extractive Metallurgy Review     Hybrid Journal   (Followers: 5)
Mineralium Deposita     Hybrid Journal   (Followers: 5)
Mineralogia     Open Access   (Followers: 2)
Mineralogical Magazine     Hybrid Journal   (Followers: 1)
Mineralogy and Petrology     Hybrid Journal   (Followers: 5)
Minerals     Open Access   (Followers: 2)
Minerals & Energy - Raw Materials Report     Hybrid Journal   (Followers: 1)
Minerals Engineering     Hybrid Journal   (Followers: 14)
Mining Engineering     Full-text available via subscription   (Followers: 7)
Mining Journal     Full-text available via subscription   (Followers: 4)
Mining Report     Hybrid Journal   (Followers: 3)
Mining Technology : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Mining, Metallurgy & Exploration     Hybrid Journal  
Natural Resources & Engineering     Hybrid Journal  
Natural Resources Research     Hybrid Journal   (Followers: 4)
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: 4)
Réalités industrielles     Full-text available via subscription  
Rem : Revista Escola de Minas     Open Access  
Resources Policy     Hybrid Journal   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 5)
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 9)
Rocks & Minerals     Hybrid Journal   (Followers: 5)
Rudarsko-geološko-naftni Zbornik     Open Access  
Transactions of Nonferrous Metals Society of China     Hybrid Journal   (Followers: 9)
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Journal Prestige (SJR): 0.462
Citation Impact (citeScore): 2
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2075-163X
Published by MDPI Homepage  [233 journals]
  • Minerals, Vol. 10, Pages 728: Mine Waste Rock: Insights for Sustainable
           Hydrogeochemical Management

    • Authors: Bas Vriens, Benoît Plante, Nicolas Seigneur, Heather Jamieson
      First page: 728
      Abstract: Mismanagement of mine waste rock can mobilize acidity, metal (loid)s, and other contaminants, and thereby negatively affect downstream environments. Hence, strategic long-term planning is required to prevent and mitigate deleterious environmental impacts. Technical frameworks to support waste-rock management have existed for decades and typically combine static and kinetic testing, field-scale experiments, and sometimes reactive-transport models. Yet, the design and implementation of robust long-term solutions remains challenging to date, due to site-specificity in the generated waste rock and local weathering conditions, physicochemical heterogeneity in large-scale systems, and the intricate coupling between chemical kinetics and mass- and heat-transfer processes. This work reviews recent advances in our understanding of the hydrogeochemical behavior of mine waste rock, including improved laboratory testing procedures, innovative analytical techniques, multi-scale field investigations, and reactive-transport modeling. Remaining knowledge-gaps pertaining to the processes involved in mine waste weathering and their parameterization are identified. Practical and sustainable waste-rock management decisions can to a large extent be informed by evidence-based simplification of complex waste-rock systems and through targeted quantification of a limited number of physicochemical parameters. Future research on the key (bio)geochemical processes and transport dynamics in waste-rock piles is essential to further optimize management and minimize potential negative environmental impacts.
      Citation: Minerals
      PubDate: 2020-08-19
      DOI: 10.3390/min10090728
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 729: Capacity of Chlorate to Oxidize Ferrous
           Iron: Implications for Iron Oxide Formation on Mars

    • Authors: Kaushik Mitra, Eleanor L. Moreland, Jeffrey G. Catalano
      First page: 729
      Abstract: Chlorate is an important Cl-bearing species and a strong potential Fe(II) oxidant on Mars. Since the amount of oxychlorine species (perchlorate and chlorate) detected on Mars is limited (<~1 wt.%), the effectiveness of chlorate to produce iron oxides depends heavily on its oxidizing capacity. Decomposition of chlorate or intermediates produced during its reduction, before reaction with Fe(II) would decrease its effective capacity as an oxidant. We thus evaluated the capacity of chlorate to produce Fe(III) minerals in Mars-relevant fluids, via oxidation of dissolved Fe(II). Each chlorate ion can oxidize 6 Fe(II) ions under all conditions investigated. Mass balance demonstrated that 1 wt.% chlorate (as ClO3−) could produce approximately 6 to 12 wt.% Fe(III) or mixed valent mineral products, with the amount varying with the formula of the precipitating phase. The mineral products are primarily determined by the fluid type (chloride- or sulfate-rich), the solution pH, and the rate of Fe(II) oxidation. The pH at the time of initial mineral nucleation and the amount of residual dissolved Fe(II) in the system exert important additional controls on the final mineralogy. Subsequent diagenetic transformation of these phases would yield 5.7 wt.% hematite per wt.% of chlorate reacted, providing a quantitative constraint on the capacity of chlorate to generate iron oxides on Mars.
      Citation: Minerals
      PubDate: 2020-08-19
      DOI: 10.3390/min10090729
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 730: Optimization of Transport Performance and
           Strength of the Filling Slurry in Tailings Reservoir Waste by Adding Air
           Entraining Agent

    • Authors: Yaguang Qin, Jianhua Hu, Dongjie Yang, Ye Kuang, Fengwen Zhao, Tan Zhou
      First page: 730
      Abstract: At present, many mines adopt the filling method. It is particularly important to solve the problem of the long-distance transportation of slurry during the filling process. Based on the high-density filling material of Sanning mine, the experiments were designed to add sodium abietate (SA), triterpene saponin (SJ) and sodium dodecyl sulfonate (K12) with concentrations of 0.0%, 0.2%, 0.4% and 0.6%, respectively, which were used as air entraining agents (AEA). The filling body with the curing age of 7 and 28 days was prepared for various tests, including nuclear magnetic resonance (NMR), and alternating current (AC) impedance tests. The effects of the air entraining agent and curing time on the physical properties, pore structure and AC impedance properties of the filling were obtained. The results show that: (1) within the frequency range of 10−1–105 Hz, the variation trend of AC impedance of the filling body cannot be changed by adding the air entraining agent, and the filling body with the same ratio had a similar topological structure. (2) The filling body with different AEA and curing times can be represented by the same equivalent circuit model, while the maximum chi-square coefficient was 0.46%. (3) Under the condition of a high frequency of 105 Hz, the porosity and uniaxial compressive strength of the filling body with 7 day curing age were linearly correlated with the AC impedance. However, the porosity and uniaxial compressive strengths of the filling body with 28 days curing time were affected by the type of AEA at a high frequency of 105 Hz.
      Citation: Minerals
      PubDate: 2020-08-19
      DOI: 10.3390/min10090730
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 731: Exploring Offshore Sediment Evidence of the
           1755 CE Tsunami (Faro, Portugal): Implications for the Study of Outer
           Shelf Tsunami Deposits

    • Authors: Vincent Kümmerer, Teresa Drago, Cristina Veiga-Pires, Pedro F. Silva, Vitor Magalhães, Anxo Mena, Ana Lopes, Ana Isabel Rodrigues, Sabine Schmidt, Pedro Terrinha, Maria Ana Baptista
      First page: 731
      Abstract: Outer shelf sedimentary records are promising for determining the recurrence intervals of tsunamis. However, compared to onshore deposits, offshore deposits are more difficult to access, and so far, studies of outer shelf tsunami deposits are scarce. Here, an example of studying these deposits is presented to infer implications for tsunami-related signatures in similar environments and potentially contribute to pre-historic tsunami event detections. A multidisciplinary approach was performed to detect the sedimentary imprints left by the 1755 CE tsunami in two cores, located in the southern Portuguese continental shelf at water depths of 58 and 91 m. Age models based on 14C and 210Pbxs allowed a probable correspondence with the 1755 CE tsunami event. A multi-proxy approach, including sand composition, grain-size, inorganic geochemistry, magnetic susceptibility, and microtextural features on quartz grain surfaces, yielded evidence for a tsunami depositional signature, although only a subtle terrestrial signal is present. A low contribution of terrestrial material to outer shelf tsunami deposits calls for methodologies that reveal sedimentary structures linked to tsunami event hydrodynamics. Finally, a change in general sedimentation after the tsunami event might have influenced the signature of the 1755 CE tsunami in the outer shelf environment.
      Citation: Minerals
      PubDate: 2020-08-19
      DOI: 10.3390/min10090731
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 732: Comparative Study of the Hydrophobicity of
           Organo-Montmorillonite Modified with Cationic, Amphoteric and Nonionic

    • Authors: Georgy Lazorenko, Anton Kasprzhitskii, Victor Yavna
      First page: 732
      Abstract: In this work, a series of comparative studies for the effect of the nine commercially available cationic, amphoteric and nonionic surfactants on the structure and wettability of the montmorillonite based organoclays were performed. The pristine and modified clays were characterized by X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and water contact angle (CA) measurements. It has been observed that the maximum basal spacing and the hydrophobicity of the organoclays increased with the alkyl chain length and chain number of the surfactant. It was found out that this effect is most pronounced when using cationic surfactants. The maximum value of contact angle corresponded to the organoclay obtained using di(hydrogenated tallow) ammonium chloride (DDA). The outcomes of this study are important and relevant to the preparation of effective organoclays for geotechnical, petroleum and polymer nanocomposite applications.
      Citation: Minerals
      PubDate: 2020-08-19
      DOI: 10.3390/min10090732
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 733: Assessing the Combined Effect of Water
           Temperature and Complex Water Matrices on Xanthate Adsorption Using
           Multiple Linear Regression

    • Authors: Ngoni Mhonde, Nora Schreithofer, Kirsten Corin, Mikko Mäkelä
      First page: 733
      Abstract: The combined effect of dissolved ions and water temperature on the adsorption of a xanthate collector on chalcopyrite and pentlandite was investigated using multiple linear regression. Cationic species improved the adsorption of the collector on sulphide minerals through xanthate adsorption activation. Thiosulphate ions generally had a negative effect on collector adsorption, and the interaction of thiosulphate ions and cations effectively reduced collector adsorption on the sulphide minerals. With regards to temperature variation caused by seasonal variation, this study suggests that temperature can influence the adsorption of collectors in the flotation process and this should be approached on a case by case basis as it seems to differ with the type of mineral under investigation. These fundamental results prompt a discussion on how complex water matrices can affect interactions of reagents and sulphide minerals at the solid–liquid interface and the possible effect on flotation performance.
      Citation: Minerals
      PubDate: 2020-08-19
      DOI: 10.3390/min10090733
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 734: An LSTM Approach for SAG Mill Operational
           Relative-Hardness Prediction

    • Authors: Sebastian Avalos, Willy Kracht, Julian M. Ortiz
      First page: 734
      Abstract: Ore hardness plays a critical role in comminution circuits. Ore hardness is usually characterized at sample support in order to populate geometallurgical block models. However, the required attributes are not always available and suffer for lack of temporal resolution. We propose an operational relative-hardness definition and the use of real-time operational data to train a Long Short-Term Memory, a deep neural network architecture, to forecast the upcoming operational relative-hardness. We applied the proposed methodology on two SAG mill datasets, of one year period each. Results show accuracies above 80% on both SAG mills at a short upcoming period of times and around 1% of misclassifications between soft and hard characterization. The proposed application can be extended to any crushing and grinding equipment to forecast categorical attributes that are relevant to downstream processes.
      Citation: Minerals
      PubDate: 2020-08-20
      DOI: 10.3390/min10090734
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 735: The Cyclops Ophiolite as a Source of High-Cr
           Spinels from Marine Sediments on the Jayapura Regency Coast (New Guinea,

    • Authors: Karol Zglinicki, Krzysztof Szamałek, Irena Górska
      First page: 735
      Abstract: The first detailed mineralogy, geochemistry and origin of heavy minerals in marine sediments along the Jayapura Regency coast on the Indonesian part of New Guinea Island are reported as part of a larger set of investigations conducted since 2009. In these sediments, the following heavy minerals were identified: high-Al and high-Cr spinels, chromian andradite, Mg-olivine, magnetite, mixture of iron (III) oxyhydroxides (limonite) and minerals from serpentine-group minerals (lizardite, antigorite). The heavy mineral fraction of marine sediments contains increased concentrations of metals, including W (up to 257.72 ppm) and Ag (up to 1330.29 ppb) as well as minor amounts of Ni (7.1–3560.9 ppm) and Cr (68.0–5816.0 ppm). The present state of geological knowledge suggests that there are no known prospects for rich Ti, Ni, Co, Cr, Au deposits along the examined part of the Jayapura coast. However, the average content of Ag and W is high enough to provide an impulse for suggested further deposit research. The source of marine sediments is Cyclops ophiolite, which contains a typical ophiolite sequence. Cyclops Mountain rocks have undergone intense chemical weathering processes and the resulting eroded material has been deposited on the narrow continental shelf. The chemical composition of chromian spinels indicates that their source is depleted peridotites from the SSZ (supra-subduction zone) environment of the Cyclops ophiolite. A detailed geochemical examination indicates that the evolution of parental melt of these rocks evolved towards magma with geochemical parameters similar to mid-ocean ridge basalt (MORB).
      Citation: Minerals
      PubDate: 2020-08-20
      DOI: 10.3390/min10090735
      Issue No: Vol. 10, No. 9 (2020)
  • Minerals, Vol. 10, Pages 647: Geochemistry of Tourmaline from the Laodou
           Gold Deposit in the West Qinling Orogen, Central China: Implications for
           the Ore-Forming Process

    • Authors: Xiaoye Jin, Jixiang Sui
      First page: 647
      Abstract: The Laodou gold deposit, located in the West Qinling Orogen of central China, is a newly recognized intrusion-related gold deposit. It consists of auriferous quartz-sulfide-tourmaline and minor quartz-stibnite veins that are structurally controlled by fault zones transecting the host quartz diorite porphyry. Two types of tourmaline were identified in this study: Type 1 tourmaline occurs as quartz-tourmaline nodules within the quartz diorite porphyry, whereas type 2 tourmaline occurs as quartz-sulfide-tourmaline veins in auriferous lodes. Here, we present a major and trace element analysis by electron microprobe and laser ablation inductively coupled plasma mass spectrometry on these two types of tourmaline. Both tourmaline types fall into the alkali group, and are classified under the schorl-dravite solid solution series. The substitutions of FeMg–1, FeAl–1, AlO((Fe, Mg)(OH)) –1, and X-site vacancyCa–1 are inferred by the variations of their major element compositions. Field and mineralogy observations suggest that type 1 tourmaline is a product of the late crystallization process of the quartz diorite porphyry, whereas type 2 tourmaline coexists with Au-bearing arsenopyrite and is crystallized from the ore-forming fluids. Their rare earth element compositions record the related magmatic hydrothermal evolution. The Co and Ni concentrations of the coexisting type 2 tourmaline and arsenopyrite define a regression line (correlation coefficient = 0.93) with an angular coefficient of 0.66, which represents the Co/Ni ratio of the tourmaline and arsenopyrite-precipitating fluids. This value is close to the Co/Ni ratios of the host quartz diorite porphyry, indicating a magma origin of the ore-forming fluids. The substitution of Al3+ by Fe3+ in both tourmaline types shows that type 1 tourmaline approaches the end member of povondraite whereas type 2 tourmaline occurs in opposite plots near the end member of Oxy-dravite, reflecting a more oxidizing environment for type 2 tourmaline formation. Moreover, the redox-sensitive V and Cr values of type 2 tourmaline are commonly 1–2 orders of magnitude higher than those of type 1 tourmaline, which also suggests that type 2 tourmaline forms from more oxidizing fluids. Combined with gold occurrence and fluid properties, we propose that the increasing of oxygen fugacity in the ore-forming fluids is a trigger of gold precipitation.
      Citation: Minerals
      PubDate: 2020-07-22
      DOI: 10.3390/min10080647
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 648: Geologically Meaningful 40Ar/39Ar Ages of
           Altered Biotite from a Polyphase Deformed Shear Zone Obtained by in Vacuo
           Step-Heating Method: A Case Study of the Waziyü Detachment Fault,
           Northeast China

    • Authors: Wenbei Shi, Fei Wang, Lin Wu, Liekun Yang, Yinzhi Wang, Guanghai Shi
      First page: 648
      Abstract: Discordant biotite 40Ar/39Ar age spectra are commonly reported in the literature. These can be caused by a number of processes related to in vacuo heating, homogenization of the argon distribution, and production of misleadingly flat age spectra. Problematic samples are typically derived from metamorphic belts; thermal overprinting and chloritization are two of the main known causes of disturbed age spectra. Biotite and muscovite of the Waziyü detachment fault, Yiwulüshan metamorphic core complex, Jinzhou, China, yield highly variable 40Ar/39Ar data that hinder reconstruction of their deformation history. We combined mineralogical studies with detailed 40Ar/39Ar dating of biotite, phengitic white mica, and K-feldspar augen from this fault. We infer that argon within the biotite was modified by hydrothermal fluids during fault activity and associated epidotization, chloritization, and muscovitization such that bulk sample step-heating, single grain total fusion, and in situ laser ablation of biotite produced mixed 40Ar/39Ar ages. However, detailed step-heating of biotite shows that this mineral records the ages of cooling and later alteration based on data from a coexisting rigid feldspar porphyroblast and neo-crystallized phengite that record two periods of fault activity at ~120–113 and 18–12 Ma. Our data reveal that the discordant biotite 40Ar/39Ar age spectra might represent a mixed age and that only detailed step-heating methods can extract meaningful geological details of the deformation history of a fault. Therefore, the mineral and the method must be carefully considered if metamorphic or deformed samples are dated.
      Citation: Minerals
      PubDate: 2020-07-22
      DOI: 10.3390/min10080648
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 649: Comparison of Three Approaches for
           Bioleaching of Rare Earth Elements from Bauxite

    • Authors: Megan J. Barnett, Barbara Palumbo-Roe, Eimear A. Deady, Simon P. Gregory
      First page: 649
      Abstract: Approximately 300 million tonnes of bauxite are processed annually, primarily to extract alumina, and can contain moderate rare earth element (REE) concentrations, which are critical to a green energy future. Three bioleaching techniques (organic acid, reductive and oxidative) were tested on three karst bauxites using either Aspergillus sp. (organic acid bioleaching) or Acidithiobacillus ferrooxidans (reductive and oxidative bioleaching). Recovery was highest in relation to middle REE (generally Nd to Gd), with maximum recovery of individual REE between 26.2% and 62.8%, depending on the bauxite sample. REE recovery occurred at low pH (generally < 3), as a result of organic acids produced by Aspergillus sp. or sulphuric acid present in A. ferrooxidans growth media. Acid production was seen when A. ferrooxidans was present. However, a clear increase in REE recovery in the presence of A. ferrooxidans (compared to the control) was only seen with one bauxite sample (clay-rich) and only under oxidative conditions. The complex and varied nature of REE-bearing minerals in bauxite provides multiple targets for bioleaching, and although the majority of recoverable REE can be leached by organic and inorganic acids, there is potential for enhanced recovery by bioleaching.
      Citation: Minerals
      PubDate: 2020-07-22
      DOI: 10.3390/min10080649
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 650: Mineralogy and Metallogenesis of the Sanbao
           Mn–Ag (Zn-Pb) Deposit in the Laojunshan Ore District, SE Yunnan
           Province, China

    • Authors: Shengjiang Du, Hanjie Wen, Shirong Liu, Chaojian Qin, Yongfeng Yan, Guangshu Yang, Pengyu Feng
      First page: 650
      Abstract: The Sanbao Mn–Ag (Zn-Pb) deposit located in the Laojunshan ore district is one of the most important deposits that has produced most Ag and Mn metals in southeastern Yunnan Province, China. Few studies are available concerning the distribution and mineralization of Ag, restricting further resource exploration. In this study, detailed mineralogy, chronology, and geochemistry are examined with the aim of revealing Ag occurrence and its associated primary base-metal and supergene mineralization. Results show that manganite and romanèchite are the major Ag-bearing minerals. Cassiterite from the Mn–Ag ores yielded a U–Pb age of 436 ± 17 Ma, consistent with the Caledonian age of the Nanwenhe granitic pluton. Combined with other geochemical proxies (Zn-Pb-Cu-Sn), the Sanbao Mn–Ag deposit may originally be of magmatic hydrothermal origin, rather than sedimentary. The Ag-rich (Zn-Pb (Sn)-bearing) ore-forming fluids generated during the intrusion of the granite flowed through fractures and overprinted the earlier Mn mineralization. Secondary Ag (and possibly other base-metals) enrichment occurred through later supergene weathering and oxidation.
      Citation: Minerals
      PubDate: 2020-07-23
      DOI: 10.3390/min10080650
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 651: Evidence of Hydrocarbon-Rich Fluid
           Interaction with Clays: Clay Mineralogy and Boron Isotope Data from Gulf
           of Cádiz Mud Volcano Sediments

    • Authors: Rubén Martos-Villa, M. Pilar Mata, Lynda B. Williams, Fernando Nieto, Xabier Arroyo Rey, C. Ignacio Sainz-Díaz
      First page: 651
      Abstract: Clay dehydration at great depth generates fluids and overpressures in organic-rich sediments that can release isotopically light boron from mature organic matter, producing 10B-rich fluids. The B can be incorporated into the tetrahedral sites of authigenic illite during the illitization of smectite. Therefore, the crystal-chemical and geochemical characterization of illite, smectite or interlayered illite–smectite clay minerals can be an indicator of depth (temperature) and reactions with the basin fluids. The aim of this study was to determine the detailed clay mineralogy, B-content and isotopic composition in illite–smectite rich samples of mud volcanoes from the Gulf of Cádiz, in order to evaluate interactions of hydrocarbon-rich fluids with clays. Molecular modeling of the illite structure was performed, using electron density functional theory (DFT) methods to examine the phenomenon of B incorporation into illite at the atomic level. We found that it is energetically preferable for B to reside in the tetrahedral sites replacing Si atoms than in the interlayer of expandable clays. The B abundances in this study are high and consistent with previous results of B data on interstitial fluids, suggesting that hydrocarbon-related fluids approaching temperatures of methane generation (150 °C) are the likely source of B-rich illite in the studied samples.
      Citation: Minerals
      PubDate: 2020-07-23
      DOI: 10.3390/min10080651
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 652: Numerical Modeling of a Laboratory-Scale
           Waste Rock Pile Featuring an Engineered Cover System

    • Authors: Katherine E. Raymond, Nicolas Seigneur, Danyang Su, Bissé Poaty, Benoît Plante, Bruno Bussière, K. Ulrich Mayer
      First page: 652
      Abstract: Improved design to reduce contaminant mass loadings from waste rock piles is an increasingly important consideration. In certain cases, an engineered cover system containing a flow control layer (FCL) may be used to mitigate the release of metals out of a pile using capillary barrier effects (CBEs), diverting water away from reactive materials below. In this study, a reactive transport model was calibrated to observational data from a laboratory experiment designed to evaluate a cover system. The results show that the numerical model is capable of capturing flow rates out of multiple drainage ports and matching key effluent concentrations by including the spatial distribution of hydraulic parameters and mineral weathering rates. Simulations were also useful for characterizing the internal flow pathways within the laboratory experiment, showing the effectiveness of the cover in diverting the flow away from the reactive waste rock and identifying secondary CBEs between different rock types. The numerical model proved beneficial in building an improved understanding of the processes controlling the metal release and conceptualizing the system. The model was expanded to investigate the robustness of the cover system as a function of the applied infiltration rate, supporting that water diversion will occur with infiltration rates representative of field conditions.
      Citation: Minerals
      PubDate: 2020-07-23
      DOI: 10.3390/min10080652
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 653: Dissolution Test Protocol for Estimating
           Water Quality Changes in Minerals Processing Plants Operating With Closed
           Water Circulation

    • Authors: Thi Le, Nóra Schreithofer, Olli Dahl
      First page: 653
      Abstract: To save freshwater resources and comply with environmental regulations, minerals processing operations are transitioning to partially or fully closed water circulation. However, the accumulation of electrolytes and the addition of reagents lead to changes in water composition and may compromise flotation performance and plant maintenance. As a consequence, costly modifications are often required to cope with these challenges. Therefore, knowledge about water quality variation owing to closed water circulation and its potential effect on the flotation performance is crucial. The experimental methodology presented in this paper targeted three main objectives: (1) predicting the tendency of the accumulation of elements and compounds into the process water during comminution, flotation, and storage in tailings facilities; (2) establishing a relationship between laboratory results and plant historical water quality data; and (3) predicting the potential effect of recycling water on flotation performance. The results obtained with Boliden Kevitsa ore showed a good correlation between the water matrix of the actual process water on-site and that obtained in the ore dissolution tests done in the laboratory. The final water composition came close to the process water in terms of major elements and some of the minor elements. Additionally, the work presented in this paper demonstrated that a dissolution loop allowed us to predict the potential impact of the recycling water on the ore flotability. This methodology could serve as an aid for predicting water quality matrix variation and designing closed water circulation systems at existing and new plants.
      Citation: Minerals
      PubDate: 2020-07-23
      DOI: 10.3390/min10080653
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 654: Efficiency of Chemical and Biological
           Leaching of Copper Slag for the Recovery of Metals and Valorisation of the
           Leach Residue as Raw Material in Cement Production

    • Authors: Päivi Kinnunen, Jarno Mäkinen, Marja Salo, Ratana Soth, Konstantinos Komnitsas
      First page: 654
      Abstract: Copper slags produced in vast quantities in smelting operations could be considered as secondary material sources instead of stockpiling them in landfills. This study investigates the recovery of valuable metals from copper slag and the valorisation of the leach residue as construction material in line with the principles of a circular economy. By taking into account that the environmental characterization of the as-received copper slag did not allow its disposal in landfills without prior treatment, chemical and biological leaching were tested for the recovery of metals. Pre-treatment with acids, namely HNO3 and H2SO4, resulted in the extraction of several target metals and the production of an almost inert waste. Despite the clearly better oxidative conditions prevailing in the bioleaching reactors, chemical leaching resulted in the higher dissolution of Cu (71% vs. 51%), Co (70% vs. 36%), and Zn (65% vs. 44%). The acid consumption was much lower during the bioleaching experiments compared to the chemical leaching. The bioleach residue was suitable for its use as supplementary cementitious material, showing a better performance than the reference sample without causing any detrimental effects to the calcium aluminate cement (CAC) quality. The complete valorisation of copper slags is expected to improve the economics of the process, by avoiding landfill costs and producing saleable products with high added value.
      Citation: Minerals
      PubDate: 2020-07-23
      DOI: 10.3390/min10080654
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 655: Sulphate Removal from Flotation Process
           Water Using Ion-Exchange Resin Column System

    • Authors: İlkay Bengü Can, Özlem Bıçak, Seda Özçelik, Metin Can, Zafir Ekmekçi
      First page: 655
      Abstract: Water chemistry is one of the most important parameters affecting flotation performance. Various types of ions can dissolve and accumulate in process water depending on ore mineralogy, reagent scheme, grinding medium and chemistry of mine site water. Sulfur-based ions (sulfate, thiosulfate, polythionate) are generally observed in flotation of sulfide ores. High concentrations of these ions may reduce efficiency of the flotation process, causing scale problems. Removal of these ions from process water often requires complex water treatment plants with high capital and operating costs. In this study, partial cleaning of water was investigated as an alternative approach for decreasing high sulphate concentrations of 3000–3800 mg/L down to 1000–1500 mg/L, an acceptable concentration for most sulfide ore flotation plants, by using an ion-exchange resin. For this purpose, detailed adsorption tests were performed using a laboratory-scale column system to determine the most suitable type of resin for adsorption of sulfate and thiosalts, kinetics of adsorption and regeneration of the resins. A strong base anion ion exchange resin (Selion SBA2000) was used in the experiments. The findings from the laboratory scale studies were validated in a Cu-Pb-Zn Flotation Plant in an Iberian mine using a larger scale of column set-up. The results showed that 60–70% of sulphates could be successfully removed from process water. Adsorption capacity of the resin was determined as 80.3 mg SO4/g resin. Concentrations of thiosalts and polythionates were also reduced to nearly zero value from 500 mg/L and 1000 mg/L, respectively. Flowrate of water had a significant effect on adsorption performance. The resin could be regenerated successfully using 2% (w/v) NaOH solution and used multiple times for water treatment.
      Citation: Minerals
      PubDate: 2020-07-23
      DOI: 10.3390/min10080655
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 656: Spontaneous Symmetry-Breaking in the
           Corrosion Transformation of Ancient Bronzes

    • Authors: Yanpeng Yang, Xiaojuan Cao, Yang Li, Zhongchi Wang, Bingjie Li, Xudong Jiang, Junji Jia, Chunxu Pan
      First page: 656
      Abstract: In general, during long-term museum conservation, ancient bronzes will generate new corrosion products also called the “secondary corrosion” on the surface of the unearthed “primary corrosion” products due to various environmental conditions. In this paper, the corrosion stages of several ancient Chinese bronzes are characterized by using optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Raman spectrometer (Raman). It is found that there exist phase transformation relationships in between the “primary corrosion” and the “secondary corrosion” stages (i.e., (1) the crystal lattice type tends to transform from a high symmetry system to a low symmetry system; (2) in case of the same crystal lattice type, the corrosions exhibit an inter-transformation or symbiosis). It is interesting to note that these transformation rules are very consistent with the well-known physical law of “spontaneous symmetry-breaking”, which won the 2008 Nobel Prize in Physics and also has been considered to be general law of nature, in addition to the principle of Gibbs free energy reduction. The significance of this discovery allows us to achieve the predictability and controllability of the bronze corrosion products (i.e., to predict the corrosive trends in advance and control the “second corrosion” by adjusting the conservation conditions. This research provides a novel conservation concept of ancient bronzes.
      Citation: Minerals
      PubDate: 2020-07-24
      DOI: 10.3390/min10080656
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 657: Evolution of Fracture Aperture in Quartz
           Sandstone under Hydrothermal Conditions: Mechanical and Chemical Effects

    • Authors: Chaojie Cheng, Harald Milsch
      First page: 657
      Abstract: Fractures efficiently affect fluid flow in geological formations, and thereby determine mass and energy transport in reservoirs, which are not least exploited for economic resources. In this context, their response to mechanical and thermal changes, as well as fluid–rock interactions, is of paramount importance. In this study, a two-stage flow-through experiment was conducted on a pure quartz sandstone core of low matrix permeability, containing one single macroscopic tensile fracture. In the first short-term stage, the effects of mechanical and hydraulic aperture on pressure and temperature cycles were investigated. The purpose of the subsequent intermittent-flow long-term (140 days) stage was to constrain the evolution of the geometrical and hydraulic fracture properties resulting from pressure solution. Deionized water was used as the pore fluid, and permeability, as well as the effluent Si concentrations, were systematically measured. Overall, hydraulic aperture was shown to be significantly less affected by pressure, temperature and time, in comparison to mechanical aperture. During the long-term part of the experiment at 140 °C, the effluent Si concentrations likely reached a chemical equilibrium state within less than 8 days of stagnant flow, and exceeded the corresponding hydrostatic quartz solubility at this temperature. This implies that the pressure solution was active at the contacting fracture asperities, both at 140 °C and after cooling to 33 °C. The higher temperature yielded a higher dissolution rate and, consequently, a faster attainment of chemical equilibrium within the contact fluid. X-ray µCT observations evidenced a noticeable increase in fracture contact area ratio, which, in combination with theoretical considerations, implies a significant decrease in mechanical aperture. In contrast, the sample permeability, and thus the hydraulic fracture aperture, virtually did not vary. In conclusion, pressure solution-induced fracture aperture changes are affected by the degree of time-dependent variations in pore fluid composition. In contrast to the present case of a quasi-closed system with mostly stagnant flow, in an open system with continuous once-through fluid flow, the activity of the pressure solution may be amplified due to the persistent fluid-chemical nonequilibrium state, thus possibly enhancing aperture and fracture permeability changes.
      Citation: Minerals
      PubDate: 2020-07-24
      DOI: 10.3390/min10080657
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 658: Vitreous Tesserae from the Four Seasons
           Mosaic of the S. Aloe Quarter in Vibo Valentia–Calabria, Italy: A
           Chemical Characterization

    • Authors: Elia Fiorenza, Natalia Rovella, Maria D’Andrea, Marianna Musella, Fabrizio Sudano, Armando Taliano Grasso, Donatella Barca
      First page: 658
      Abstract: This work reports the results of the archaeometrical investigation performed on twenty glass tesserae collected in 2018, during the restoration of the Four Seasons mosaic, which dates between the second and the third century AD, in the archaeological area of the S. Aloe quarter in Vibo Valentia (Calabria, Italy). The coloured glass tesserae were analysed through a micro-analytical approach using an Electron Probe Micro Analyser with Wavelength-Dispersive Spectroscopy (EPMA-WDS) and Laser Ablation with Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The aims of the study were (1) the determination of the chemical composition and the technology of glass mosaic tesserae production; (2) the individuation of colouring and opacifying agents used for the production of the glass tesserae. The glasses show the typical soda–lime–silica composition. EPMA-WDS results prove the use of Sn–Pb antimonates to create yellow glass, and of cuprite to obtain the red colour. Copper and cobalt were employed in both green and blue glasses to produce different shades of colour (grey, tints of green, dark and light blue).
      Citation: Minerals
      PubDate: 2020-07-25
      DOI: 10.3390/min10080658
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 659: Organically Templated Layered Uranyl
           Molybdate [C3H9NH+]4[(UO2)3(MoO4)5] Structurally Based on Mineral-Related
           Modular Units

    • Authors: Evgeny Nazarchuk, Dmitri Charkin, Oleg Siidra, Stepan Kalmykov
      First page: 659
      Abstract: A new organically templated uranyl molybdate [C3H9NH+]4[(UO2)3(MoO4)5] was prepared by a hydrothermal method at 220 °C. The compound is monoclinic, Сс, a = 16.768(6), b = 20.553(8), c = 11.897(4) Å, β = 108.195(7), V = 3895(2) Å3, R1 = 0.05. The crystal structure is based upon [(UO2)3(MoO4)5]4− uranyl molybdate layers. The isopropylammonium cations are located in the interlayer. The layers in the structure of [C3H9NH+]4[(UO2)3(MoO4)5] are considered as modular architectures. Topological analysis of layers with UO2:TO4 ratio of 3:5 (TVI = S, Cr, Se, Mo) was performed. Modular description is employed to elucidate the relationships between different structural topologies of [(UO2)3(TO4)5]4− layers and inorganic uranyl-based nanotubules. The possible existence of uranyl molybdate nanotubules is discussed.
      Citation: Minerals
      PubDate: 2020-07-25
      DOI: 10.3390/min10080659
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 660: Parametric Optimization in Rougher Flotation
           Performance of a Sulfidized Mixed Copper Ore

    • Authors: Asghar Azizi, Mojtaba Masdarian, Ahmad Hassanzadeh, Zahra Bahri, Tomasz Niedoba, Agnieszka Surowiak
      First page: 660
      Abstract: The dominant challenge of current copper beneficiation plants is the low recoverability of oxide copper-bearing minerals associated with sulfide type ones. Furthermore, applying commonly used conventional methodologies does not allow the interactional effects of critical parameters in the flotation processes to be investigated, which is mostly overlooked in the literature. To tackle this issue, the present paper aimed at characterizing the behavior of five key effective factors and their interactions in a sulfidized copper ore. In this context, dosage of collector (sodium di-ethydithiophosphate, 60–100 g/t), depressant (sodium silicate, 80–120 g/t) and frother (methyl isobutyl carbinol (MIBC), 6–10 g/t), pulp pH (7–11) and agitation rate (900–1300 rpm) were examined and statistically analyzed using response surface methodology. Flotation experiments were conducted in a Denver type agitated flotation cell at the rougher stage. The experimental results showed that increasing the pH (from 8 to 10) at low agitation rate (1000 rpm) enhanced the recovery from 80.36% to 85.22%, while at high agitation rate (1200 rpm), a slight declination occurred in the recovery. Meanwhile, increasing the collector dosage at a lower frother value (7 g/t), caused a reduction of about 4.44% in copper recovery owing to the interactions between factors, whereas at a higher frother level (9 g/t), the recovery was almost unchanged. The optimization process was also performed using the goal function approach, and maximum copper recovery of 92.75% was obtained using ~70 g/t collector, 110 g/t depressant, 7 g/t frother, pulp pH of 10 and 1000 rpm agitation rate.
      Citation: Minerals
      PubDate: 2020-07-26
      DOI: 10.3390/min10080660
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 661: Relationship between Textural Parameters of
           Lamellar Products Obtained by Acid Activation of Pure and Commercial
           Vermiculites and Their Iron and Water Content

    • Authors: Celia Marcos, Alaa Adawy, Irene Rodríguez
      First page: 661
      Abstract: The relationship between textural parameters (specific superficial area (SBET) and porosity (Vp)) of lamellar products obtained from HNO3-activated vermiculites and their iron and water content has been established. Two commercial vermiculites, one thermoexfoliated commercial vermiculite, and one pure vermiculite were nitric-acid-treated at 4 and 8 M concentrations for 1, 3, and 7 days. Untreated and treated samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and N2 physisorption analysis. The untreated vermiculites showed a direct relationship between their iron content and the values of SBET, Vp, and pore size; an inverse relationship was observed in the case of the treated samples. The iron content may prevent further leaching of cations but not water loss, therefore forming lamellar products with lower SBET and Vp values. The SBET and Vp values of the studied thermoexfoliated sample were higher than those of the starting sample. The SBET and Vp values of the activated thermoexfoliated sample were lower than those of the activated non-thermoexfoliated sample.
      Citation: Minerals
      PubDate: 2020-07-26
      DOI: 10.3390/min10080661
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 662: High-Performance Recovery of Cobalt and
           Nickel from the Cathode Materials of NMC Type Li-Ion Battery by
           Complexation-Assisted Solvent Extraction

    • Authors: Wen-Yu Wang, Hong-Chi Yang, Ren-Bin Xu
      First page: 662
      Abstract: The annual global volume of waste lithium-ion batteries (LIBs) has been increasing over years. Although solvent extraction method seems well developed, the separation factor between cobalt and nickel is still relatively low—only 72 when applying conventional continuous-countercurrent extraction. In this study, we improved the separation factor of cobalt and nickel by complexation-assisted solvent extraction. Before solvent extraction procedure, leaching kinetic of Li, Ni, Co and Mn was studied and can be explained by the Avrami equation. Leached residues were also investigated by SEM and XRD. Operation parameters of complexation-assisted solvent extraction were examined, including volume ratio of extractant to diluent, types of diluent, type of complexing reagent, extractant saponification percentage and volume ratio of organic phase to aqueous phase. The optimal separation factor of complexation-assisted solvent extraction could be improved to 372, which is five times that of conventional solvent extraction. The separation tendency would be interpreted by the relationship between extraction equilibrium pH and log distribution coefficient.
      Citation: Minerals
      PubDate: 2020-07-26
      DOI: 10.3390/min10080662
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 663: Applications of Unmanned Aerial Vehicles in
           Mining from Exploration to Reclamation: A Review

    • Authors: Sebeom Park, Yosoon Choi
      First page: 663
      Abstract: Over the past decade, unmanned aerial vehicles (UAVs) have been used in the mining industry for various applications from mineral exploration to mine reclamation. This study aims to review academic papers on the applications of UAVs in mining by classifying the mining process into three phases: exploration, exploitation, and reclamation. Systematic reviews were performed to summarize the results of 65 articles (June 2010 to May 2020) and outline the research trend for applying UAVs in mining. This study found that UAVs are used at mining sites for geological and structural analysis via remote sensing, aerial geophysical survey, topographic surveying, rock slope analysis, working environment analysis, underground surveying, and monitoring of soil, water, ecological restoration, and ground subsidence. This study contributes to the classification of current UAV applications during the mining process as well as the identification of prevalent UAV types, data acquired by sensors, scales of targeted areas, and styles of flying control for the applications of UAVs in mining.
      Citation: Minerals
      PubDate: 2020-07-26
      DOI: 10.3390/min10080663
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 664: Fluid Evolution, H-O Isotope and Re-Os Age
           of Molybdenite from the Baiyinhan Tungsten Deposit in the Eastern Central
           Asian Orogenic Belt, NE China, and Its Geological Significance

    • Authors: Ruiliang Wang, Qingdong Zeng, Zhaochong Zhang, Yunpeng Guo, Jinhang Lu
      First page: 664
      Abstract: The quartz-vein-type Baiyinhan tungsten deposit is located at the eastern part of the Central Asian Orogenic Belt, NE China. Analyses of fluid inclusions, H-O isotope of quartz and Re-Os isotope of molybdenite were carried out. Three stages of mineralization were identified: The early quartz + wolframite + bismuth stage, the middle quartz + molybdenite stage and the late calcite + fluorite stage. Quartz veins formed in the three stages were selected for the fluid inclusion analysis. The petrographic observation and fluid inclusion microthermometry results revealed three types of fluid inclusions: CO2-H2O (C-type), liquid-rich (L-type) and vapor-rich (V-type). The homogenization temperatures of C-type, V-type and L-type inclusions were 233–374 °C, 210–312 °C, and 196–311 °C, respectively. The salinity of the three types of inclusions was identical, varying in the range of 5–12 wt%. The H-O isotope analyses results showed that quartz had δ18OH2O and δDSMOW compositions of −2.6‰ to 4.3‰ and −97‰ to −82‰, respectively, indicating that the ore-forming fluids were mainly derived from magmatic water with a minor contribution of meteoric water. The addition of meteoric water reduces the temperature and salinity of the ore-forming fluids, which leads to a decrease of the solubility of tungsten and molybdenum in the fluids and eventually the precipitation of minerals. Re-Os isotopic analysis of five molybdenite samples yielded an isochron age of 139.6 ± 7.6 Ma (2σ) with an initial 187Os of −0.05 ± 0.57 (MSWD = 3.5). Rhenium concentrations of the molybdenite samples were between 3.1 ug/g and 8.5 ug/g. The results suggest that the metals of the Baiyinhan deposit have a crust origin, and the mineralization is one episode of the Early Cretaceous tungsten mineralization epoch which occurred at the eastern part of the Central Asian Orogenic Belt.
      Citation: Minerals
      PubDate: 2020-07-26
      DOI: 10.3390/min10080664
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 665: Role of Mg Impurity in the Water Adsorption
           over Low-Index Surfaces of Calcium Silicates: A DFT-D Study

    • Authors: Chongchong Qi, Qiusong Chen, Andy Fourie
      First page: 665
      Abstract: Calcium silicates are the most predominant phases in ordinary Portland cement, inside which magnesium is one of the momentous impurities. In this work, using the first-principles density functional theory (DFT), the impurity formation energy (Efor) of Mg substituting Ca was calculated. The adsorption energy (Ead) and configuration of the single water molecule over Mg-doped β-dicalcium silicate (β-C2S) and M3-tricalcium silicate (M3-C3S) surfaces were investigated. The obtained Mg-doped results were compared with the pristine results to reveal the impact of Mg doping. The results show that the Efor was positive for all but one of the calcium silicates surfaces (ranged from −0.02 eV to 1.58 eV), indicating the Mg substituting for Ca was not energetically favorable. The Ead of a water molecule on Mg-doped β-C2S surfaces ranged from –0.598 eV to −1.249 eV with the molecular adsorption being the energetically favorable form. In contrast, the Ead on M3-C3S surfaces ranged from −0.699 eV to −4.008 eV and the more energetically favorable adsorption on M3-C3S surfaces was dissociative adsorption. The influence of Mg doping was important since it affected the reactivity of surface Ca/Mg sites, the Ead of the single water adsorption, as well as the adsorption configuration compared with the water adsorption on pristine surfaces.
      Citation: Minerals
      PubDate: 2020-07-26
      DOI: 10.3390/min10080665
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 666: Confined Bed Breakage of Fine Iron Ore

    • Authors: Túlio M. Campos, Gilvandro Bueno, Luís Marcelo Tavares
      First page: 666
      Abstract: High-pressure grinding rolls (HPGR) have gained great popularity in the mining industry in the last 25 years or so. One of the first successful applications of the technology has been in iron ore pressing prior to pelletization. Piston-and-die tests can provide good insights on the material response in an HPGR. This work analyzed confined bed breakage of four iron ore concentrates under different conditions. Saturation in breakage of particles contained in the top size in the tests was observed to occur at specific energies of about 2 kWh/t, whereas full saturation in breakage, with no additional increase in specific surface area of the material, occurred at energies above about 6 kWh/t. An expression was proposed to characterize the propensity of a material to break under confined bed conditions. The phenomenology involved in confined bed breakage of such materials was then analyzed in light of the results.
      Citation: Minerals
      PubDate: 2020-07-27
      DOI: 10.3390/min10080666
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 667: Estimates for the Effective Permeability of
           Intact Granite Obtained from the Eastern and Western Flanks of the
           Canadian Shield

    • Authors: A. P. S. Selvadurai, A. Blain-Coallier, P. A. Selvadurai
      First page: 667
      Abstract: Granitic rock from the western part of the Canadian Shield is considered as a potential host rock for the siting of a deep geological repository for the storage of heat-emitting high-level nuclear fuel waste. The research program focused on the use of surface permeability measurements conducted at 54 locations on a 300 mm cuboid of granite, obtained from the Lac du Bonnet region in Manitoba, to obtain an estimate for the effective permeability of the cuboid. Companion experiments are conducted on a 280 mm cuboid of granite obtained from Stanstead, Quebec, located in the eastern part of the Canadian Shield. The surface permeabilities for the cuboids of granite are developed from theoretical relationships applicable to experimental situations where steady flow is initiated at a sealed annular surface region with a pressurized central domain. The experimental values for the surface permeability are used with a kriging procedure to estimate the permeability variations within the cuboidal region. The spatial variations of permeability are implemented in computational models of the cuboidal regions to determine the one-dimensional permeabilities in three orthogonal directions. The effective permeability of the granite cuboids is estimated by appeal to the geometric mean. The research provides a non-destructive methodology for estimating the effective permeability of large specimens of rock and the experiments performed give estimates for the effective permeability of the two types of granitic rock obtained from the western and eastern flanks of the Canadian Shield.
      Citation: Minerals
      PubDate: 2020-07-27
      DOI: 10.3390/min10080667
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 668: Mg-Phengite in Carbonate Rock Syngenetically
           Formed from Hydrothermal Fluid: Micro-Textural Evidence and Mineral

    • Authors: Chaewon Park, Namsoo Kim, Sung-Ja Choi, Yungoo Song
      First page: 668
      Abstract: Phengite series is a dioctahedral solid solution between two end-members of muscovite [K1[Al2]VI[Al1,Si3]IVO10(OH)2] and celadonite [K1[(Fe3+,Al)1,(Mg,Fe2+)1]VI[Si4]IVO10(OH)2], which have a hetero-valent substitution of AlVIAlIV ↔ (Mg, Fe)VISiIV. In this study, we report a hydrothermal-originated authigenic Mg-phengite-series mineral, which occurred as polycrystalline aggregates (Type 1), pore-fillings (Type 2) and well-crystallized lath form (Type 3) from the Haengmae Formation, a dolomite–pebble-bearing fine sand-sized dolostone, in South Korea. Based on micro-textural observation, three types of Mg-phengite are associated with crystalline dolomite, and are followed by calcite precipitation as pore-filling, indicating that these should be formed by the influx of a Mg-rich hydrothermal fluid after the deposition of some clastic sediments and before calcite-filling. The structural formula based on O10(OH)2 shows that the number of Mg atoms per formula unit (apfu) of Mg-phengite ranges from 0.00 to 0.70 with no Fe, which is relatively high, compared with the previously reported metamorphic phengites. In REEs mineral chemistry, the Mg-phengites are characterized by the enrichment of REEs and by the particular enrichment of LREEs in the polycrystalline aggregates of Mg-phengite. It strongly suggests that the Mg-phengite should be formed by the infiltration of the highly evolved Mg- and REEs-enriched hydrothermal fluid into the clastic sedimentary rock (Haengmae Formation) as a strata-bound form, syngenetically or during early diagenesis.
      Citation: Minerals
      PubDate: 2020-07-27
      DOI: 10.3390/min10080668
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 669: In Situ Formation of Monohydrocalcite in
           Alkaline Saline Lakes of the Valley of Gobi Lakes: Prediction for Mg, Ca,
           and Total Dissolved Carbonate Concentrations in Enceladus’ Ocean and
           Alkaline-Carbonate Ocean Worlds

    • Authors: Keisuke Fukushi, Eigo Imai, Yasuhito Sekine, Takuma Kitajima, Baasansuren Gankhurel, Davaadorj Davaasuren, Noriko Hasebe
      First page: 669
      Abstract: The nature of mineral precipitations in terrestrial alkaline soda lakes provides insights into the water chemistry of subsurface oceans on icy bodies in the outer solar system. Saturation analyses of terrestrial alkaline lakes have shown that the solution chemistries of lake waters are generally controlled by the presence of monohydrocalcite (MHC) and amorphous Mg-carbonate (AMC). However, direct observations of the formation of these metastable carbonates in natural alkaline lakes have been limited. This study provides evidence of in situ MHC formation in alkaline lakes, based on the water chemistry and mineralogy of suspended matter in Olgoy, Boon Tsagaan, and Orog Lakes (Valley of Gobi Lakes, Mongolia). The solution chemistries were close to saturation with respect to MHC and AMC, consistent with other alkaline lakes worldwide. Suspended matter was separated by the ultracentrifugation of lake water following freeze-drying. Our results show that MHC is the common mineral phase in the suspended matter. These observations confirm that MHC is the direct authigenic product of evaporation in alkaline lakes. The carbonate fraction in suspended matter from Olgoy Lake has a Mg/Ca ratio of 0.4, suggesting the formation of AMC in association with MHC. Based on the dissolution equilibria of AMC and MHC, we predict the Mg2+, Ca2+, and total dissolved carbonate concentrations in Enceladus’ ocean to be ~1 mmol/kg, ~10 μmol/kg, and 0.06–0.2 mol/kg, respectively, in the presence of AMC and MHC. We propose that the measurements of Mg contents in plumes will be key to constraining the total dissolved carbonate concentrations and chemical affinities of subsurface oceans on Enceladus and other alkaline-carbonate ocean worlds.
      Citation: Minerals
      PubDate: 2020-07-27
      DOI: 10.3390/min10080669
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 670: Physico-Chemical, Mineralogical, and
           Chemical Characterisation of Cretaceous–Paleogene/Neogene Kaolins within
           Eastern Dahomey and Niger Delta Basins from Nigeria: Possible Industrial

    • Authors: Olaonipekun Oyebanjo, Georges-Ivo Ekosse, John Odiyo
      First page: 670
      Abstract: The demand for kaolinitic clays for various industrial applications is increasing globally. The present study evaluated the potential industrial applications of kaolins from the Eastern Dahomey and Niger Delta Basins, Nigeria. The colour, pH, electrical conductivity (EC), particle size distribution (PSD), plastic limits and liquid limits of the kaolins were determined. Mineralogical properties were assessed using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and differential thermal analysis (DTA). The chemical compositions of the kaolins were determined using X-ray fluorescence spectrometry (XRF). The kaolins were generally acidic, with pH less than 7 with low EC. The moderate plasticity indices (PI ≥ 10%) for the kaolins suggested their potential use in the manufacturing of structural clay products without extrusion. Kaolinite was the only kaolin mineral present with anhedral–subhedral–euhedral crystals. The platy morphology of the kaolinites in the Cretaceous kaolins are very important in paper production. Other minerals present in the kaolins were quartz, muscovite, anatase and goethite. The major oxide contents of the kaolins were dominated by SiO2, Al2O3, Fe2O3 and TiO2. Based on chemical specifications, the raw kaolins are not suitable for most industrial applications except for the Cretaceous Lakiri kaolins in the paper and ceramic industries (except for TiO2 and K2O content). The study concluded that the kaolin deposits would require beneficiation for large-scale industrial applications.
      Citation: Minerals
      PubDate: 2020-07-28
      DOI: 10.3390/min10080670
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 671: Magnetic Survey for Iron-Oxide-Copper-Gold
           (IOCG) and Alkali Calcic Alteration Signatures in Gadarwara, M.P, India:
           Implications on Copper Metallogeny

    • Authors: P.V. Sunder Raju, K. Satish Kumar
      First page: 671
      Abstract: A government airborne geophysical survey flown in the late 1970s detected a large Magnetic anomaly at Gadarwara, Madhya Pradesh, in north-central India. Deep drilling indicates that the oval-shaped Magnetic anomaly is caused by underlying Magnetite-bearing banded iron formation belonging to the Mahakoshal Formation of Archean to Early Proterozoic age. The anomaly is hosted in a tectonic rift zone (Narmada-Son Lineament). After drilling alluvium up to 312 m thick, rocks intersected to depths of 612 m provided core samples for research. Broadly speaking, the samples contain banded hematite jaspilite (BHJ) and banded Magnetite (BM) iron formation with pervasive carbonate alterations. Three vertical diamond drill holes were drilled along a 1.4 km long N-S transect across the center of the geophysical anomaly. DDH-1, near the northern edge of the anomaly, went through 309 m of alluvium before intersecting bedrock and then cored 303 m of bedrock for a total depth of 612 m. Copper mineralization with appreciable amounts of cobalt, zinc, molybdenum, silver, rare earth elements, uranium and other elements was intersected. The litho-units are highly oxidised and intensely brecciated with hydrothermal overprinting of Na-K metasomatism alteration mineralogy. The second borehole, DDH-2 failed as the core drilling bit stuck in the alluvium and further drilling was abandoned, whereas the third borehole DDH-3 didnot intersect a Magnetite-hematite association and cored only siltstone. Two-dimensional model studies suggest that the signature of high Magnetic anomaly is at a depth of 0.4 km from the surface, with a width of 3.5 km, dipping at 45∘ in a northerly direction. The causative body has a Magnetic susceptibility of 0.0052 C.G.S. units, suggestive of a hematite with quartz veinlets lithology. Based on predictive Magnetic exploration models for Iron-Oxide-Copper-Gold (IOCG), such deposits can be inferred from geological observations combined with petrophysical data and forward modelling of the observed Magnetic signatures. This paper reports a prospective IOCG-like mineralization style hosted in a rift (Narmada-Son) type of tectonic environment.
      Citation: Minerals
      PubDate: 2020-07-29
      DOI: 10.3390/min10080671
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 672: Valorization of Brick and Glass CDWs for the
           Development of Geopolymers Containing More Than 80% of Wastes

    • Authors: Dimitris Kioupis, Aggeliki Skaropoulou, Sotirios Tsivilis, Glikeria Kakali
      First page: 672
      Abstract: One of the areas of priority in a circular economy, regarding waste management, regards the valorization of construction and demolition wastes (CDW). This study suggests the synthesis of geopolymeric binders based almost entirely on construction and demolition wastes. Ceramic waste was used as the aluminosilicate precursor of the geopolymer synthesis, while glass waste was applied in the preparation of the activation solution. A fractional experimental design defined the optimum synthesis parameters, based on compressive strength values. The final products were characterized by means of X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The glass waste was appropriately processed in order to prepare the activation solution for the geopolymerization of brick waste. In this work, CDW-based geopolymers were produced with a compressive strength in the range 10–44 MPa. The developed products contained 80–90 wt.% CDWs, depending on the method of activator preparation.
      Citation: Minerals
      PubDate: 2020-07-29
      DOI: 10.3390/min10080672
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 673: Electron Microscopy Evidence of Zn
           Bioauthigenic Sulfides Formation in Polluted Organic Matter-Rich Sediments
           from the Chicamocha River (Boyacá-Colombia)

    • Authors: Claudia Patricia Quevedo, Juan Jiménez-Millán, Gabriel Ricardo Cifuentes, Rosario Jiménez-Espinosa
      First page: 673
      Abstract: Electron microscopy and sediment geochemical data from a river basin (the upper Chicamocha river basin, UCRB, Boyacá province, Colombia) affected by anthropogenic activities (wastewater discharges, smelting and agricultural activities) showed the existence of heterogeneously distributed Zn particles in the sediments and sediments with Zn contents above the regional background (42 mg/kg). The objective of this study was to evidence the ZnS sedimentary neoformation in organic matter rich sediments deposited in anthropogenic reservoirs to reveal the processes involved in the sedimentary uptake of Zn from potential pollution sources. The highest Zn concentrations are found in clay minerals and organic matter-rich sediments (up to 427 mg/kg) deposited in slow-flowing reaches of the river associated to La Playa dam. Quartz-rich sediments poor in organic matter deposited in fast flowing segments of the river show very low Zn contents (1–12 mg/kg). Electron microscopy images showed ZnS nanoparticles forming cell-shaped aggregates suggesting that sulfate-reducing microorganisms acted as templates for the partial binding of Zn and for the nucleation and growth of zinc sulfide minerals. A good correlation of Zn with total organic carbon (r = 0.936) and the low potential redox of these sediments (−233 mV) suggest that organic matter was able to maintain oxygen depleted conditions appropriate to the Zn accumulation in the sediments. Our results demonstrate that potentially toxic Zn, originating from anthropic activities, was partially immobilized in organic matter-rich sediments through the precipitation of sulfides.
      Citation: Minerals
      PubDate: 2020-07-29
      DOI: 10.3390/min10080673
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 674: Manganese Nodules in Chile, an Alternative
           for the Production of Co and Mn in the Future—A Review

    • Authors: Norman Toro, Ricardo I. Jeldres, Javier A. Órdenes, Pedro Robles, Alessandro Navarra
      First page: 674
      Abstract: Given the active growth of emerging technology industries, it has become essential to have large quantities of critical metals to meet the current demand. In the Chilean mining industry, there is a depletion of high-grade mineral ores, and there is hence a need to increase production levels in the copper industry and diversify its market by extracting other elements. One of the strategies is to foster the production of lithium batteries, but the manufacture requires reserves of cobalt (Co) and manganese (Mn). Currently, Co reserves are not being exploited in Chile, and Mn production is almost negligible. This is due to the apparent shortage of high-grade ores on the land surface of the country. Given this scenario, the seabed manganese nodules are presented as a good alternative due to their high average grades of Co and Mn, which in turn would allow the growth of strategic value-added industries including lithium battery production. Chile’s current environmental regulations prevent the exploitation of marine resources. However, given technological advances worldwide, both in collection mechanisms and extractive processes, in addition to the needs generated from the future strategic plans, leads us to think about a project to exploit manganese nodules locally.
      Citation: Minerals
      PubDate: 2020-07-29
      DOI: 10.3390/min10080674
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 675: The Characteristics of Iron Ore Slimes and
           Their Influence on The Flotation Process

    • Authors: Neymayer Pereira Lima, Klaydison Silva, Thiago Souza, Lev Filippov
      First page: 675
      Abstract: The flotation has been successfully applied to process the iron ore for the particle size (Ps) from 10 µm up to 150 µm. The presence of the slimes (Ps < 10 µm) is harmful on the reverse flotation of quartz, so they are usually prior removed by hydrocyclones. The main effects of the presence of slimes on the flotation are related to the increase on reagents consumption, the froth stability, and decrease on the selectivity. The lower floatability of coarse quartz particles (+74 µm) combined with the presence of slimes, even in small quantities, drastically affect the flotation response. This paper shows a study of characterization of a typical iron ore slime, aiming to create a better understanding of its role on the concentration by flotation. The main characteristics of typical slimes from the Iron Ore Quadrangle in Brazil are the presence of almost 70% of hematite, 25% of quartz, and 5% of kaolinite, as the main silicates gangue minerals. Furthermore, the particle size distribution revealed that 80% of the hematite and the kaolinite are below 20 µm. The affinity between the ultrafine kaolinite of the slimes with the corn starch is harmful to the reverse flotation of quartz, as the starch has an important depressing action over the hematite. The presence of 20% of hematite −20 µm decreased the recovery to the froth of quartz + 74 µm from 97% to 62%, where the slimes coating seems to be the main responsible.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080675
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 676: Use of Radial Basis Function Network to
           Predict Optimum Calcium and Magnesium Levels in Seawater and Application
           of Pretreated Seawater by Biomineralization as Crucial Tools to Improve
           Copper Tailings Flocculation

    • Authors: Grecia Villca, Dayana Arias, Ricardo Jeldres, Antonio Pánico, Mariella Rivas, Luis A. Cisternas
      First page: 676
      Abstract: The combined use of the Radial Basis Function Network (RBFN) model with pretreated seawater by biomineralization (BSw) was investigated as an approach to improve copper tailings flocculation for mining purposes. The RBFN was used to set the optimal ranges of Ca2+ and Mg2+ concentration at different Ph in artificial seawater to optimize the performance of the mine tailings sedimentation process. The RBFN was developed by considering Ca2+ and Mg2+ concentration as well as pH as input variables, and mine tailings settling rate (Sr) and residual water turbidity (T) as output variables. The optimal ranges of Ca2+ and Mg2+ concentration were found, respectively: (i) 169–338 and 0–130 mg·L−1 at pH 9.3; (ii) 0–21 and 400–741 mg·L–1 at pH 10.5; (iii) 377–418 and 703–849 mg·L−1 at pH 11.5. The settling performance predicted by the RBFN was compared with that measured in raw seawater (Sw), chemically pretreated seawater (CHSw), BSw, and tap water (Tw). The results highlighted that the RBFN model is greatly useful to predict the settling performance in CHSw. On the other hand, the highest Sr values (i.e., 5.4, 5.7, and 5.4 m·h–1) were reached independently of pH when BSw was used as a separation medium for the sedimentation process.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080676
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 677: Mineralogy of a High-Temperature Skarn, in
           High CO2 Activity Conditions: The Occurrence from Măgureaua Vaţei
           (Metaliferi Massif, Apuseni Mountains, Romania)

    • Authors: Ştefan Marincea, Delia-Georgeta Dumitraş, Cristina Sava, Frédéric Hatert, Fabrice Dal Bo
      First page: 677
      Abstract: A shallow-level monzodioritic to quartz-monzodioritic pluton of the Upper Cretaceous age caused contact metamorphism of Tithonic–Kimmeridgian reef limestones at Măgureaua Vaţei (Metaliferi Massif, Apuseni Mountains, Romania). The preserved peak metamorphic assemblage includes gehlenite (Ak 33.64–38.13), monticellite, wollastonite-2M, Ti-poor calcic garnet, and Ca-Tschermak diopside (with up to 11.15 mol.% Ca-Tschermak molecule). From the monzodioritic body to the calcitic marble, the periplutonic zoning can be described as: monzodiorite/agpaitic syenite-like inner endoskarn/wollastonite + perovskite + Ti-poor grossular + Al-rich diopside/wollastonite + Ti-poor grossular + diopside + vesuvianite/gehlenite + wollastonite + Ti poor grossular + Ti-rich grossular (outer endoskarn)/wollastonite + vesuvianite + garnet (inner exoskarn)/wollastonite + Ti-rich garnet + vesuvianite + diopside (outer exoskarn)/calcitic marble. Three generations of Ca garnets could be identified, as follows: (1) Ti-poor grossular (Grs 53.51–81.03 mol.%) in equilibrium with gehlenite; (2) Ti-rich grossular (Grs 51.13–53.47 mol.%, with up to 19.97 mol.% morimotoite in solid solution); and (3) titanian andradite (Grs 32.70–45.85 mol.%), with up to 29.15 mol.% morimotoite in solid solution. An early hydrothermal stage produced retrogression of the peak paragenesis toward vesuvianite, hydroxylellestadite (or Si-substituted apatite), clinochlore, “hibschite” (H4O4-substituted grossular). A late hydrothermal event induced the formation of lizardite, chrysotile, dickite, thaumasite, okenite and tobermorite. A weathering paragenesis includes allophane, C-S-H gels and probably portlandite, unpreserved because of its transformation in aragonite then calcite. Overprints of these late events on the primary zoning are quite limited.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080677
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 678: Sequential Scheelite Mineralization of
           Quartz–Scheelite Veins at the Sangdong W-Deposit: Microtextural and
           Geochemical Approach

    • Authors: Woohyun Choi, Changyun Park, Yungoo Song, Chaewon Park, Ha Kim, Chulgyoo Lee
      First page: 678
      Abstract: The Sangdong W (tungsten)-deposit is known as one of the world’s largest W-deposits, a magmatic–hydrothermal ore deposit including both skarn and hydrothermal alteration zones. The strata-bound characteristic of the deposit resulted in three major orebodies (hanging wall, main, footwall). The main ore mineral is a scheelite (CaWO4)–powellite (CaMoO4) solid solution. We examined the fluid evolution and scheelite formation process of the quartz–scheelite veins of the ore deposit, based on the microtextures and geochemical characteristics of the scheelite. After the initial magmatic–hydrothermal fluid release from the granitic body, prograde skarn is formed. In the later prograde stage, secondary fluid rises and precipitates stage I scheelite. Well-developed oscillatory zoning with the highest Mo content indicates continuous fluid infiltration under an open system. Pressure rises as mineralization occurs, generating the pressure release of the retrograde fluid. Fluid migrates downward by the gravitational backflow mechanism, forming stage II to IV scheelites. Dented oscillatory zoning of stage II scheelite is strong evidence of this pressure release. Stage III and IV scheelite do not show specific internal structures with pure scheelite composition. Retrograde scheelites are formed by fractional crystallization under a closed system. The observation of systematical fractional crystallization in the quartz–scheelite vein system is a meaningful result of our research. The geochemical characteristics and microtextural evidence imprinted in scheelites from each stage provide crucial evidence for the understanding of sequential scheelite mineralization of the quartz–scheelite vein system of the Sangdong W-deposit.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080678
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 679: Backtracking to Parent Maceral from Produced
           Bitumen with Raman Spectroscopy

    • Authors: Seyedalireza Khatibi, Arash Abarghani, Kouqi Liu, Alexandra Guedes, Bruno Valentim, Mehdi Ostadhassan
      First page: 679
      Abstract: In order to assess a source rock for economical exploitation purposes, many parameters should be considered; regarding the geochemical aspects, the most important ones are the amount of organic matter (OM) and its quality. Quality refers to the thermal maturity level and the type of OM from which it was formed. The origin of the OM affects the ability of the deposited OM between sediments to generate oil, gas, or both with particular potential after going through thermal maturation. Vitrinite reflectance and programmed pyrolysis (for instance, Rock-Eval) are common methods for evaluating the thermal maturity of the OM and its potential to generate petroleum, but they do not provide us with answers to what extent solid bitumen is oil-prone or gas-prone, as they are bulk geochemical methods. In the present study, Raman spectroscopy (RS), as a powerful tool for studying carbonaceous materials and organic matter, was conducted on shale and coal samples and their individual macerals to show the potential of this technique in kerogen typing and to reveal the parent maceral of the examined bitumen. The proposed methodology, by exhibiting the chemical structure of different organic matters as a major secondary product in unconventional reservoirs, can also detect the behavior of solid bitumen and its hydrocarbon production potential for more accurate petroleum system evaluation.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080679
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 680: High-Grade Flake Graphite Deposits in
           Metamorphic Schist Belt, Central Finland—Mineralogy and Beneficiation of
           Graphite for Lithium-Ion Battery Applications

    • Authors: Thair Al-Ani, Seppo Leinonen, Timo Ahtola, Dandara Salvador
      First page: 680
      Abstract: More than 40 m length of drill cores were collected from four boreholes drilled by Geological Survey of Finland (GTK) and Outokumpu Oy in high-grade metamorphic rocks of Rautalampi and Käypysuo, Central Finland. The hosted rocks of the graphite mineralization were mica–quartz schist and biotite gneiss. The graphite-bearing rocks and final concentrated graphite powder were studied with petrographic microscope, scanning electron microscope (SEM-EDS), Raman spectroscopy, and X-ray analysis (XRD and XRF). A majority of the studied graphite had a distinctly flakey (0.2–1 mm in length) or platy morphology with a well-ordered crystal lattice. Beneficiation studies were performed to produce high-purity graphite concentrate, where rod milling and froth flotation produced a final concentrate of 90% fixed carbon with recoveries between 67% and 83%. Particle size reduction was tested by a ball and an attritor mill. Graphite purification by alkaline roasting process with 35% NaOH at 250 °C and leached by 10% H2SO4 solution at room temperature could reach the graphite purity level of 99.4%. Our analysis suggested that purifying by multistage flotation processes, followed by alkaline roasting and acid leaching, is a considerable example to obtain high-grade graphite required for lithium-ion battery production.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080680
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 681: Collecting Agent–Mineral Interactions in
           the Reverse Flotation of Iron Ore: A Brief Review

    • Authors: Guixia Fan, Liguang Wang, Yijun Cao, Chao Li
      First page: 681
      Abstract: Froth flotation has been widely used in upgrading iron ores. Iron ore flotation can be performed in two technical routes: direct flotation of iron oxides and reverse flotation of gangue minerals with depression of iron oxides. Nowadays, reverse flotation is the most commonly used route in iron ore flotation. This review is focused on the reverse flotation of iron ores, consisting of reverse cationic flotation and reverse anionic flotation. It covers different types of collecting agents used in reverse iron ore flotation, the surface characteristics of minerals commonly present in iron ores (e.g., iron oxides, quartz, alumina-bearing minerals, phosphorus-bearing minerals, iron-bearing carbonates, and iron-bearing silicates), and the adsorption mechanisms of the collecting agents at the mineral surface. The implications of collecting agent–mineral interactions for improving iron ore flotation are discussed.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080681
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 682: Yoko–Dovyren Layered Massif: Composition,
           Mineralization, Overburden and Dump Rock Utilization

    • Authors: Evgeniy V. Kislov, Lyudmila I. Khudyakova
      First page: 682
      Abstract: Ultramafic–mafic complexes are widely developed in the Earth’s crust. They contain deposits of various minerals. The Yoko–Dovyren intrusive in the North Baikal Region, Russia, is considered an example of an intrusive containing diverse mineralization: Ni-Cu, Platinum group elements, Cr, Zr, B, and blue diopside. During the development of the deposit, a huge amount of magnesium-containing rocks are moved to dumps and have a negative impact on the environment. To minimize this process, overburden and host rocks need to be involved in production, thereby avoiding the movement of rocks into dumps. The construction materials production is main industry using this rocks. Therefore, the purpose of these studies was to determine the quality of magnesium-containing rocks and the possibility of their use in construction. As a result of the complex works performed, it has been determined that these rocks have required physical and mechanical characteristics. Concretes in large and small aggregates from magnesium-containing rocks were obtained. It has been concluded that they are superior to concrete from granite rubble and quartz sand in terms of their strength indicators. The use of magnesium-containing rocks, without allowing them to fall into dumps, will allow us to create clean, environmentally safe mining enterprises.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080682
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 683: REE Characteristics of Lower Cretaceous
           Limestone Succession in Gümüşhane, NE Turkey: Implications for Ocean
           Paleoredox Conditions and Diagenetic Alteration

    • Authors: Merve Özyurt, M. Ziya Kırmacı, Ihsan Al-Aasm, Cathy Hollis, Kemal Taslı, Raif Kandemir
      First page: 683
      Abstract: Trace and rare earth elements (REEs) are considered to be reliable indicators of chemical processes for the evolution of carbonate systems. One of the best examples of ancient carbonate successions (Berdiga Formation) is widely exposed in NE Turkey. The Lower Cretaceous limestone succession of Berdiga Formation may provide a case study that reveals the effect of ocean paleoredox conditions on diagenetic alteration. Measurement of major, trace and REEs was carried out on the Lower Cretaceous limestones of the Berdiga Formation, to reveal proxies for paleoredox conditions and early diagenetic controls on their geochemistry. Studied micritic limestone microfacies (MF-1 to MF-3) indicate deposition in the inner platform to a deep shelf or continental slope paleoenvironment during the Hauterivian-Albian. The studied limestone samples mainly exhibit low Mg-calcite characteristics with the general chemical formula of Ca98.35–99.34Mg0.66–1.65(CO3). They are mostly represented by a diagnostic REE seawater signature including (1) slight LREE depletion relative to the HREEs (ave. 0.72 of Nd/YbN and ave. 0.73 of Pr/YbN), (2) negative Ce anomalies (Ce/Ce* = 0.38–0.81; ave. 0.57), (3) positive La anomaly (La/La* = 0.21–3.02; ave. 1.75) and (4) superchondritic Y/Ho (ave. 46.26). Studied micritic limestones have predominantly low Hf (bdl to 0.5 µg/g), Sc (bdl to 2 µg/g) Th (bdl to 0.9 µg/g) contents suggesting negligible to minor shale contamination. These findings imply that micritic limestones faithfully record chemical signals of their parental and diagenetic fluids. The succession also exhibits high ratios of Eu/Eu* (1.01–1.65; ave. 1.29 corresponding to the positive Eu anomalies), Sm/Yb (1.26–2.74; ave. 1.68) and La/Yb ratios (0.68–1.35; ave. 0.9) compared to modern seawater and wide range of Y/Ho ratios (29.33–70.00; ave. 46.26) which are between seawater and hydrogenetic Fe-Mn crusts. Several lines of geochemical evidence suggest water-rock interaction between parental seawater and basaltic rocks at elevated temperatures triggered by hydrothermal activity associated with Early Cretaceous basaltic magma generation. The range of Ce/Ce* values is suggestive of mostly oxic to dysoxic paleoceanographic conditions, with a sudden change to dysoxic conditions (Ce/Ce* = 0.71–0.81), in the uppermost part of the MF-1. This is followed by an abrupt deepening paleoenvironment with a relative increase in the oxic state of the seawater and deposition of deeper water sediments (MF-2 and MF-3) above a sharp transition. The differences in microfacies characteristics and foraminifera assemblage between MF-1 and overlying facies (MF-2 and MF-3) may also confirm the change in paleoceanographic conditions. Therefore, REEs data obtained from studied limestones have the potential to contribute important information as to regional paleoceanographic conditions of Tethys during an important period in Earth history.
      Citation: Minerals
      PubDate: 2020-07-30
      DOI: 10.3390/min10080683
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 684: Paleoproterozoic Adakitic Rocks in
           Qingchengzi District, Northeastern Jiao-Liao-Ji Belt: Implications for
           Petrogenesis and Tectonism

    • Authors: Jian Li, Hanlun Liu, Keyong Wang, Wenyan Cai
      First page: 684
      Abstract: Herein, zircon U-Pb geochronology, Lu-Hf isotopes, and whole-rock major and trace element geochemistry are presented for two Palaeoproterozoic granitic rocks in Qingchengzi district, northeastern Jiao-Liao-Ji Belt (JLJB). These new geochronological and geochemical data provide reference clues for exploring the petrogenesis and tectonic setting of Paleoproterozoic magmatic rocks in the Qingchengzi district, which further constrain the tectonic nature of the JLJB. Our zircon U-Pb dating denotes that the Paleoproterozoic magmatic events in the Qingchengzi district were emplaced at ~2163 Ma and ~1854 Ma, represented by granite porphyry and biotite granite, respectively. Geochemically, these Palaeoproterozoic rocks are characterized by high Sr (760–842 ppm), SiO2 (69.72–70.89 wt.%), and Al2O3 (15.53–16.78 wt.%) contents, low Y (2.1–9.0 ppm) and Yb (0.25–0.80 ppm) contents, which indicate an adakite affinity. Combined with Hf isotopic composition (εHf(t) = −1.5~+4.8; TDM2 = 3109~2560 Ma), we believe that the Paleoproterozoic adakitic magma originated from partial melting of the thickened lower crust material in the Meso-Neoarchean. Moreover, these rocks are enriched in light rare earth elements and large ion lithophilic elements (e.g., K, Rb, and Cs), and depleted in heavy rare earth elements and high field strength elements (e.g., Nb and Ta). These features are similar to magmatic rocks formed in an arc environment (either island arc or active continental margin) and are not consistent with an intraplate/intracontinental environment. According to this study and previous research results, we conclude that the arc–continent collision model is conducive to the Paleoproterozoic tectonic attribute of the JLJB, and the oceanic crust subduction between the Namgrim and Longgang blocks may have induced the widespread occurrence of magmatic events in the region.
      Citation: Minerals
      PubDate: 2020-07-31
      DOI: 10.3390/min10080684
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 685: Mineralogy and Genesis of the Kihabe Zn-Pb-V
           Prospect, Aha Hills, Northwest Botswana

    • Authors: Nicola Mondillo, Maria Boni, Giuseppina Balassone, Nigel Forrester, Francesco Putzolu, Licia Santoro
      First page: 685
      Abstract: The Kihabe Zn-Pb-V > (Cu-Ag-Ge) prospect is located at the boundary between Namibia and Botswana (Aha Hills, Ngamiland District) in a strongly deformed Proterozoic fold belt, corresponding to the NE extension of the Namibian Damara Orogen. The Kihabe prospect contains Zn-Pb resources of 14.4 million tonnes at 2.84% zinc equivalent, Ag resources of 3.3 million ounces, and notable V-Ge amounts, still not evaluated at a resource level. The ores are represented by a mixed sulfide–nonsulfide mineralization. Sulfide minerals consist mainly of sphalerite, galena and pyrite in a metamorphic quartzwacke. Among the nonsulfide assemblage, two styles of mineralization occur in the investigated samples: A first one, characterized by hydrothermal willemite and baileychlore, and a second one consisting of supergene smithsonite, cerussite, hemimorphite, Pb-phosphates, arsenates and vanadates. Willemite is present in two generations, which postdate sulfide emplacement and may also form at their expenses. These characteristics are similar to those observed in the willemite occurrences of the nearby Otavi Mountainland, which formed through hydrothermal processes, during the final stages of the Damara Orogeny. The formation of the Kihabe willemite is likely coeval. Baileychlore is characterized by textures indicating direct precipitation from solutions and dissolution–crystallization mechanisms. Both processes are typical of hydrothermal systems, thus suggesting a hydrothermal genesis for the Kihabe Zn-chlorite as well. Baileychlore could represent an alteration halo possibly associated either with the sulfide or with willemite mineralization. The other nonsulfide minerals, smithsonite, cerussite, various Pb-phosphates and vanadates, are clearly genetically associated with late phases of supergene alteration, which overprinted both the sulfide and the willemite- and baileychlore-bearing mineralizations. Supergene alteration probably occurred in this part of Botswana from the Late Cretaceous to the Miocene.
      Citation: Minerals
      PubDate: 2020-07-31
      DOI: 10.3390/min10080685
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 686: Re-Os Isotope Systematics of Sulfides in
           Chromitites and Host Lherzolites of the Andaman Ophiolite, India

    • Authors: José González-Jiménez, Sisir Mondal, Biswajit Ghosh, William Griffin, Suzanne O’Reilly
      First page: 686
      Abstract: Laser ablation MC-ICP-MS was used to measure the Os-isotope compositions of single sulfide grains, including laurite (RuS2) and pentlandite [(Fe,Ni)9S8], from two chromitite bodies and host lherzolites from ophiolites of North Andaman (Indo-Burma-Sumatra subduction zone). The results show isotopic heterogeneity in both laurite (n = 24) and pentlandite (n = 37), similar to that observed in other chromitites and peridotites from the mantle sections of ophiolites. Rhenium-depletion model ages (TRD) of laurite and pentlandite reveal episodes of mantle magmatism and/or metasomatism in the Andaman mantle predating the formation of the ophiolite (and the host chromitites), mainly at ≈0.5, 1.2, 1.8, 2.1 and 2.5 Ga. These ages match well with the main tectonothermal events that are documented in the continental crustal rocks of South India, suggesting that the Andaman mantle (or its protolith) had a volume of lithospheric mantle once underlaying this southern Indian continental crust. As observed in other oceanic lithospheres, blocks of ancient subcontinental lithospheric mantle (SCLM) could have contributed to the development of the subduction-related Andaman–Java volcanic arc. Major- and trace-element compositions of chromite indicate crystallization from melts akin to high-Mg IAT and boninites during the initial stages of development of this intra-oceanic subduction system.
      Citation: Minerals
      PubDate: 2020-07-31
      DOI: 10.3390/min10080686
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 687: Ladle Steel Slag in Activated Systems for
           Construction Use

    • Authors: Diego Aponte, Oriol Soto Martín, Susana Valls del Barrio, Marilda Barra Bizinotto
      First page: 687
      Abstract: The construction industry needs to reduce greenhouse gases, in which cement production is currently responsible for generating between 4% and 6% of the total CO2 released into the atmosphere. Similarly, many industries produce large amounts of solid waste, which often have low value-added applications or are directly taken to landfills, with consequent negative environmental impacts. One of these industries is the steel industry, which in 2016 generated 18.4 Mt of slag (melting and refining slag) among all European Union countries. In terms of refining steel slag (ladle or white slag), it is estimated that for each ton of steel, between 20 and 30 kg of slag is produced; that is, in 2016, more than 700,000 tons of white slag were generated. It is also known that this material has cementitious properties and can be used as a precursor in alkaline activation processes. Depending on the concentrations used of the activating agent, a higher or lower mechanical performance of the developed materials can be obtained. This work studied the alkali activation of a ladle slag used to manufacture mortars, subjecting them to an initial curing of 24 h at different temperatures (20, 40, and 70 °C). Sodium silicate and sodium hydroxide were used as activating agents, using percentages of Na2O between 5% and 10% to obtain an optimal dosage of the activator. The physical and mechanical properties of the mortars were evaluated at different ages of curing. In addition, monitoring was undertaken of linear shrinkage due to drying and the mineralogical changes due to activation and curing time.
      Citation: Minerals
      PubDate: 2020-07-31
      DOI: 10.3390/min10080687
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 688: Geochemical Features and Mineral
           Associations of Differentiated Rocks of the Norilsk 1 Intrusion

    • Authors: Nadezhda Tolstykh, Gennadiy Shvedov, Aleksandr Polonyankin, Vladimir Korolyuk
      First page: 688
      Abstract: The purpose of this study is to show the patterns of distribution of disseminated sulfide in layered rocks based on the numerous geochemical and mineralogical data obtained for eight boreholes of the Norilsk intrusion (southern part of the Norilsk 1 deposit). There is a common trend of sulfide liquid fractionation in the Main Ore Horizon, which is composed of picritic and taxite (or olivine) gabbro-dolerites: the Ni/Cu in both rock types decreases down all sections, indicating an increase in the degree of fractionation of the sulfide liquid from top to bottom. On the contrary, the Ni/Fe ratios in pentlandite increase in this direction due to an increase in sulfur fugacity. However, picrite and taxite/olivine gabbro-dolerites are very distinctly separated by Ni/Cu values: these values are >1 in picritic gabbro-dolerite while they are always <1 in taxite/olivine gabbro-dolerite. These rock types are distinguished by sulfide assemblages. The first includes troilite, Fe-rich pentlandite, chalcopyrite, cubanite, talnahite, bornite and copper (low sulfur association); the second one is composed of monoclinic pyrrhotite, chalcopyrite, Ni-rich pentlandite and pyrite (high sulfur association). A two-stage magma injection with different ore specializations is supposed for picritic and taxite/olivine gabbro-dolerites.
      Citation: Minerals
      PubDate: 2020-07-31
      DOI: 10.3390/min10080688
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 689: Uranium (VI) Recovery from Black Shale
           Leaching Solutions Using Ion Exchange: Kinetics and Equilibrium Studies

    • Authors: Omirserik Baigenzhenov, Alibek Khabiyev, Brajendra Mishra, M. Deniz Turan, Merey Akbarov, Tatyana Chepushtanova
      First page: 689
      Abstract: This work studies the removal of uranium ions from chemically leached solutions by sorption using two weak and two strong base anionites. Batch sorption experiments were performed to evaluate the optimum conditions at pH 1.2–2.2, 1.0 g resin dose for 1–12 h contact time at room temperature. These experiments addressed sorption kinetics and sorption isotherm. The maximum sorption capacity reached 55.8 mg/g at room temperature. The kinetics data are well described by the pseudo-second-order kinetic model at initial uranium concentration of 0.62 mg·L−1. To describe sorption kinetics pseudo-first-order, pseudo-second-order and intraparticle diffusion models were proposed. Studies indicated that the sorption of uranium can be fitted by a pseudo-second-order kinetic model very well. Equilibria were described by Langmuir, Freundlich, and Dubinin–Radushkevich equations. The experimental sorption isotherm is successfully described by the Langmuir model.
      Citation: Minerals
      PubDate: 2020-07-31
      DOI: 10.3390/min10080689
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 690: Tunable Mn Oxidation State and Redox
           Potential of Birnessite Coexisting with Aqueous Mn(II) in Mildly Acidic

    • Authors: Juan Liu, Yixiao Zhang, Qian Gu, Anxu Sheng, Baogang Zhang
      First page: 690
      Abstract: As the dominant manganese oxide mineral phase in terrestrial and aquatic environments, birnessite plays an important role in many biogeochemical processes. The coexistence of birnessite with aqueous Mn2+ is commonly found in the subsurface environments undergoing Mn redox cycling. This study investigates the change in Mn average oxidation state (AOS) of birnessite after reaction with 0.1–0.4 mM Mn2+ at pH 4.5–6.5, under conditions in which phase transformation of birnessite by Mn2+ was not detectable. The amount of Mn2+ uptake by birnessite and the equilibrium concentration of Mn(III) proportionally increased with the initial concentration of Mn2+. The Mn AOS of birnessite particles became 3.87, 3.75, 3.64, and 3.53, respectively, after reaction with 0.1, 0.2, 0.3, and 0.4 mM Mn2+ at pH 5.5. Oxidation potentials (Eh) of birnessite with different AOS values were estimated using the equilibrium concentrations of hydroquinone oxidized by the birnessite samples, indicating that Eh was linearly proportional to AOS. The oxidation kinetics of bisphenol A (BPA), a model organic pollutant, by birnessite suggest that the logarithms of surface area-normalized pseudo-first-order initial rate constants (log kSA) for BPA degradation by birnessite were linearly correlated with the Eh or AOS values of birnessite with AOS greater than 3.64.
      Citation: Minerals
      PubDate: 2020-08-02
      DOI: 10.3390/min10080690
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 691: Lower Cretaceous Rodby and Palaeocene Lista
           Shales: Characterisation and Comparison of Top-Seal Mudstones at Two
           Planned CCS Sites, Offshore UK

    • Authors: Richard H. Worden, Michael J. Allen, Daniel R. Faulkner, James E. P. Utley, Clare E. Bond, Juan Alcalde, Niklas Heinemann, R. Stuart Haszeldine, Eric Mackay, Saeed Ghanbari
      First page: 691
      Abstract: Petroleum-rich basins at a mature stage of exploration and production offer many opportunities for large-scale Carbon Capture and Storage (CCS) since oil and gas were demonstrably contained by low-permeability top-sealing rocks, such as shales. For CCS to work, there must be effectively no leakage from the injection site, so the nature of the top-seal is an important aspect for consideration when appraising prospective CCS opportunities. The Lower Cretaceous Rodby Shale and the Palaeocene Lista Shale have acted as seals to oil and gas accumulations (e.g., the Atlantic and Balmoral fields) and may now play a critical role in sealing the Acorn and East Mey subsurface carbon storage sites. The characteristics of these important shales have been little addressed in the hydrocarbon extraction phase, with an understandable focus on reservoir properties and their influence on resource recovery rates. Here, we assess the characteristics of the Rodby and Lista Shales using wireline logs, geomechanical tests, special core analysis (mercury intrusion) and mineralogical and petrographic techniques, with the aim of highlighting key properties that identify them as suitable top-seals. The two shales, defined using the relative gamma log values (or Vshale), have similar mean pore throat radius (approximately 18 nm), splitting tensile strength (approximately 2.5 MPa) and anisotropic values of splitting tensile strength, but they display significant differences in terms of wireline log character, porosity and mineralogy. The Lower Cretaceous Rodby Shale has a mean porosity of approximately 14 %, a mean permeability of 263 nD (2.58 × 10−19 m2), and is calcite rich and has clay minerals that are relatively rich in non-radioactive phases such as kaolinite. The Palaeocene Lista Shale has a mean porosity of approximately 16% a mean permeability of 225 nD (2.21 × 10−19 m2), and is calcite free, but contains abundant quartz silt and is dominated by smectite. The 2% difference in porosity does not seem to equate to a significant difference in permeability. Elastic properties derived from wireline log data show that Young’s modulus, material stiffness, is very low (5 GPa) for the most shale (clay mineral)-rich Rodby intervals, with Young’s modulus increasing as shale content decreases and as cementation (e.g., calcite) increases. Our work has shown that Young’s modulus, which can be used to inform the likeliness of tensile failure, may be predictable based on routine gamma, density and compressive sonic logs in the majority of wells where the less common shear logs were not collected. The predictability of Young’s modulus from routine well log data could form a valuable element of CCS-site top-seal appraisals. This study has shown that the Rodby and Lista Shales represent good top-seals to the Acorn and East Mey CCS sites and they can hold CO2 column heights of approximately 380 m. The calcite-rich Rodby Shale may be susceptible to localised carbonate dissolution and increasing porosity and permeability but decreasing tendency to develop fracture permeability in the presence of injected CO2, as brittle calcite dissolves. In contrast, the calcite-free, locally quartz-rich, Lista Shale will be geochemically inert to injected CO2 but retain its innate tendency to develop fracture permeability (where quartz rich) in the presence of injected CO2.
      Citation: Minerals
      PubDate: 2020-08-03
      DOI: 10.3390/min10080691
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 692: Production of a Phosphate Concentrate from
           the Tailings of a Niobium Ore Concentrator

    • Authors: Anthony Clapperton, Claude Bazin, Dominic Downey, Jean-Sébastien Marois
      First page: 692
      Abstract: Apatite is the main source of phosphorous for the making of chemical fertilizers. While apatite is usually recovered from phosphate orebodies as the primary product of a mining exploitation, this paper documents the approach taken to produce a phosphate concentrate as a secondary product from the tailings of a niobium ore concentrator. The conventional desliming/flotation scheme used to process phosphate ores was tested and adapted to process one of the reject streams of a niobium concentrator in order to produce a salable phosphate concentrate. For that particular material, it was found that the reverse flotation of apatite yielded better results than the commonly used direct flotation of apatite. The recommended approach to produce the phosphate concentrate is desliming followed by reverse flotation of apatite and an acid leaching of the apatite concentrate to lower the MgO content below the specification for a phosphate concentrate. The obtained phosphate concentrate assays more than 32% P2O5 at a P2O5 recovery of 41%, which although low is found to be economic for the case of processing plant reject tailings.
      Citation: Minerals
      PubDate: 2020-08-04
      DOI: 10.3390/min10080692
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 693: Erratum: Tychkov, N.S., et al. Types of
           Xenogenic Olivine from Siberian Kimberlites. Minerals 2020, 10, 302

    • Authors: Nikolay S. Tychkov, Alexey M. Agashev, Nikolay P. Pokhilenko, Vladimir A. Tsykh, Nikolay V. Sobolev
      First page: 693
      Abstract: The authors wish to make the following erratum to this paper [...]
      Citation: Minerals
      PubDate: 2020-08-04
      DOI: 10.3390/min10080693
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 694: Recovery of Ultra-Fine Tungsten and Tin from
           Slimes Using Large-Scale SLon-2400 Centrifugal Separator

    • Authors: Tao Xiong, Xiangjun Ren, Meifang Xie, Yuhuan Rao, Yongjun Peng, Luzheng Chen
      First page: 694
      Abstract: China is very rich in tungsten and tin resources, but most of them are finely disseminated with gangues, and thus, fine grinding is required for effective separation, which results in the abundant production of ultra-fine tungsten and tin values into slimes and tailings. The SLon centrifugal separator is highly effective in recovering ultra-fine heavy particles, because it operates on the centrifugal acceleration of particles in the flowing film of a few millimeters thick. The recovery of ultra-fine tungsten minerals from a slime assaying 0.22% WO3, in which 81.85% distributed in −40 µm fraction, was investigated using large-scale SLon-2400 centrifugal separator. Under optimized operating conditions, it produced a primary tungsten concentrate assaying 1.65% WO3 at a high recovery of 77.83%. Moreover, it produced a primary tin concentrate assaying 1.56% Sn at a high recovery of 79.85% from a tin slime assaying 0.27% Sn, in which 74.78% Sn was distributed in −40 µm fraction; then, followed by the flotation cleaning process, a final tin concentrate assaying 16.23% Sn with 66.7% recovery was produced. It was particularly noted that in this large-scale centrifugal separator, the three-conical separation drum stuck with abrasion-resistant ceramic slices on its inner surface played a key role for achieving high constant separation performance. It was concluded that the SLon centrifugal separator has important application prospects for high-efficient recovery of ultra-fine heavy minerals from slimes and tailings.
      Citation: Minerals
      PubDate: 2020-08-05
      DOI: 10.3390/min10080694
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 695: Semi-Continuous Froth Discharge to Reduce
           Entrainment of Fine Particles in Flotation Cells Subject to
           Low-Mineralized Froths

    • Authors: Juan Yianatos, Paulina Vallejos, Luis Vinnett, Sebastián Arriagada
      First page: 695
      Abstract: An operational strategy is proposed to improve the metallurgical performance of flotation cells subject to low-mineralized froths. This strategy consists of using a semi-continuous discharge into the concentrate, in which the froth is operated under loading and unloading periods. A transient model is developed to evaluate the proposed approach. The model is calibrated using experimental data from two industrial flotation banks. The metallurgical performances of the last cells of these banks are then simulated, considering the semi-continuous froth discharge. The results show that the semi-continuous mode significantly reduces gangue entrainment, improving the concentrate grade while maintaining approximately the same recovery. The semi-continuous strategy demonstrates good potential to enhance the metallurgical indexes under low-mineralized froths, as those in the last cells of rougher flotation banks.
      Citation: Minerals
      PubDate: 2020-08-05
      DOI: 10.3390/min10080695
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 696: Simultaneous Partitioning of Divalent Metal
           Ions between Alabandite and 1 mol/L (Ni, Mg, Co, Zn, Fe)Cl2 Aqueous
           Solutions under Supercritical Conditions

    • Authors: Etsuo Uchida, Motoki Murasugi, Shuichi Okuda
      First page: 696
      Abstract: To clarify the element partitioning behavior between minerals and aqueous chloride solutions, we conducted experiments to investigate simultaneous partitioning of Ni2+, Mg2+, Co2+, Zn2+, Fe2+, and Mn2+ ions between alabandite (MnS) and 1 mol/L (Ni, Mg, Co, Zn, Fe)Cl2 aqueous solutions at 500–800 °C and 100 MPa. The bulk partition coefficients calculated using the following equation were in the order of Fe2+ > Co2+ > Ni2+ ≈ Zn2+ > Mn2+ >> Mg2+; KPN = (xMeS/mMeaq)/(xMnS/mMnaq). A partition coefficient-ionic radius (PC-IR) curve was plotted with the logarithmic value of the partition coefficient on the y-axis and the ionic radius at the six-fold coordinated site on the x-axis. The peak of this curve was located near the ionic radius of Fe2+ and not near the ionic radius of Mn2+. Zn2+ showed a slight negative partitioning anomaly, which increased in the order of sulfide minerals < arsenic sulfide minerals < arsenide minerals as the covalent bond became stronger. Ni2+ showed a positive partitioning anomaly, which indicated that it preferred an octahedral structure. The width of the PC-IR curve decreased in the order of sulfide minerals > arsenic sulfide minerals > arsenide minerals as the covalent bond became stronger, that is, the ion selectivity became stronger.
      Citation: Minerals
      PubDate: 2020-08-05
      DOI: 10.3390/min10080696
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 697: Derivation of Predicted No Effect
           Concentrations (PNECs) for Heavy Metals in Freshwater Organisms in Korea
           Using Species Sensitivity Distributions (SSDs)

    • Authors: Jinhee Park, Sang Don Kim
      First page: 697
      Abstract: Natural and artificial heavy metal exposure to the environment requires finding thresholds to protect aquatic ecosystems from the toxicity of heavy metals. The threshold is commonly called a predicted no effect concentration (PNEC) and is thought to protect most organisms in an ecosystem from a chemical. PNEC is derived by applying a large assessment factor (AF) to the toxicity value of the most sensitive organism to a chemical or by developing a species sensitivity distribution (SSD), which is a cumulative distribution function with many toxicity data for a chemical of diverse organisms. This study developed SSDs and derived PNECs using toxicity data of organisms living in Korea for four heavy metals: copper (Cd), cadmium (Cu), lead (Pb), and zinc (Zn). Five distribution models were considered with log-transformed toxicity data, and their fitness and uncertainty were investigated. As a result, the normal distribution and Gumbel distribution fit the data well. In contrast, the Weibull distribution poorly accounted for the data at the lower tails for all of the heavy metals. The hazardous concentration for 5% of species (HC5) derived from the most suitable model for each heavy metal was calculated to be the preferred PNEC by AF 2 or AF 3. PNECs, obtained through a suitable SSD model with resident species and reasonable AF, will help protect freshwater organisms in Korea from heavy metals.
      Citation: Minerals
      PubDate: 2020-08-06
      DOI: 10.3390/min10080697
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 698: Epithermal Mineralization in the Busang
           Southeast Zone, Indonesia: New Insight into the Au Prospect at the Center
           of the Bre-X Fraud

    • Authors: Evan Slater, Jacob Hanley, Thomas Mulja, Marcos Zentilli, Corwin Trottier
      First page: 698
      Abstract: The Busang mineral prospect in Kalimantan, Indonesia, was reported to host a large Au resource until 1997 when it was revealed that drill core samples had been deliberately and systematically contaminated (“salted”) with extraneous Au to falsify resource estimates. One month before the fraud was uncovered, Dr. G. Milligan, then professor emeritus of geology, visited the site to collect a suite of core samples for academic study that was deemed representative of the host rocks, alteration, and mineralization of the Busang Southeast Zone. These samples were re-examined here by optical microscopy, electron microprobe (EMPA), whole-rock geochemistry, and fluid inclusion microthermometry to characterize the subsurface geology and hydrothermal mineralization, and to assess reasons why the system is of uneconomic character. The host rocks were variably altered calc-alkaline porphyritic subvolcanic diorites, typical of the lithological units along the mineralized trend in the Kalimantan Gold Belt. Early hydrothermal mineralization with quartz-sulfide (pyrite, chalcopyrite, Cu-sulfosalts) stockwork veinlets associated with pervasive phyllic and propylitic alteration was overprinted by crudely banded quartz-carbonate-sulfide/sulfosalt (pyrite, sphalerite, chalcopyrite, galena, tennantite-tetrahedrite, bournonite-seligmannite) veins. The stockwork veins were associated with up to 140 ppb bulk rock Au, some of which was hosted by Cu-sulfosalts. Microthermometry on quartz-hosted aqueous fluid inclusion assemblages (FIA; n = 13) and single inclusions (non-FIA; n = 20) in quartz-carbonate-sulfide/sulfosalt veins yielded an overall range in homogenization temperatures (Th) between 179 °C and 366 °C and bulk salinities between 1.1 wt.% to 8.6 wt.% NaCl equivalent, with much smaller data ranges for individual FIA (e.g., FIA 3; 239.1 °C to 240.5 °C and 0.5 wt.% to 1.4 wt.% NaCl equivalent). Primary FIA along growth zones in quartz were identified, providing constraints on fluid characteristics at the time of quartz growth. Carbonate-hosted FIA (n = 3) and single inclusions (non-FIA; n = 3) in the same veins yielded Th between 254 °C and 343 °C and bulk salinities of 1.1 wt.% to 11.6 wt.% NaCl equivalent. Likewise, data ranges for individual FIA were much smaller. Many of the geological characteristics of the Busang Southeast Zone were compatible with a telescoped, intermediate-sulfidation epithermal system, having formed from diluted magmatic fluids that precipitated weak base metal mineralization. However, the system was unproductive with respect to Au and Ag, at least within the studied area. Of note, vein textures and fluid inclusion characteristics indicative of boiling or efficient fluid mixing—processes both considered critical for the formation of economic lode gold deposits—were absent in the samples.
      Citation: Minerals
      PubDate: 2020-08-06
      DOI: 10.3390/min10080698
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 699: Microstructure Investigation of Oil-Bearing
           Rhyolites: A Case Study from the Hailar Basin, NE China

    • Authors: Anqi Mao, Han Zheng, Xiaomeng Sun
      First page: 699
      Abstract: Understanding the microstructure of rhyolites may greatly promote exploration efforts on rhyolitic hydrocarbon reservoirs; however, related studies are sparse. In this contribution, the microstructure and related porosity of oil-bearing rhyolitic lavas from the Hailar Basin (NE China) were investigated using a combination of optical microscopy, fluorescence image analysis, and scanning electron microscopy. The direct visual and quantitative analyses show that the rhyolites are heterogeneous and porous rocks and have complex microstructures. Phenocryst-rich rhyolitic lava, perlitic lava, and spherulitic rhyolite may be favorable targets for rhyolitic hydrocarbon exploration. For the phenocryst-rich rhyolitic lavas, embayment pores, cleavages, cavitational and shear fractures, and intracrystalline sieve pores are commonly observed in the phenocrysts; while flow-parallel laminar and micropores are ubiquitous in the groundmass. Perlitic lavas are characterized by the occurrence of numerous perlitic fractures which can also be produced in the glassy groundmass of other lavas. Spherulitic rhyolites mainly consist of small-sized (<1 mm) clustered or large-sized (>1 mm) isolated spherulites. Clustered spherulites are characterized by the development of interspherulite pores. Isolated spherulites contain numerous radiating micropores. Both types of spherulites may have water expulsion pores formed in the spherulite–glass border. The formation of the microstructure and related porosity of rhyolites is controlled by pre-, syn- (e.g., deuteric crystal dissolution, cavitation, ductile–brittle deformation, and high-T devitrification), and post-volcanic (e.g., hydration and low-T devitrification) processes. Although pores with diameters > 50 μm are often observed, small pores dominate in pore-size distribution. Small (<15 μm) and large (>300 μm) pores give the most volumetric contribution in most cases. Medium-sized pores with diameters ranging from ~150–300 μm are the least developed and contribute the least to the total volume. The results of this paper can be beneficial to further the understanding of the microstructure and pore system of rhyolites and may be applied to rhyolitic lava hydrocarbon reservoirs elsewhere.
      Citation: Minerals
      PubDate: 2020-08-06
      DOI: 10.3390/min10080699
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 700: Composition and Technological Properties of
           Clays for Structural Ceramics in Limpopo (South Africa)

    • Authors: Lawrence Diko-Makia, Rofhiwa Ligege
      First page: 700
      Abstract: This study evaluated the potential of raw clays from the Mukondeni region for structural ceramics and pottery based on traditional firing techniques. Physical properties were identified by particle size distribution, consistency limits, and clay activity. Mineralogical and chemical properties were investigated by X-ray diffraction (XRD) and X-ray fluorescence (XRF). Extruded clay bodies were fired at 900 °C. Technological characteristics were measured by weight loss (WL), bulk density (BD), dry linear shrinkage (DLS), fired linear shrinkage (FLS), water absorption (WA), and flexural strength (FS). The clays were low in <2 µm fractions (≤19%) and of medium to high plasticity with a clayey silt texture. Smectite was the dominant clay mineral while quartz and feldspar were major non clay minerals. The most abundant oxides were SiO2 (63.57–68.73%), Al2O3 (13.9–15.61%), and Fe2O3 (4.86–6.18%), whereas K2O, CaO, MgO, Na2O, TiO2, and P2O5 were depleted. Characterization based on the clay workability chart, Winkler’s diagram, and compositional ternary diagrams revealed acceptable extrusion properties and suitability for structural ceramics and earthenware. The clays showed acceptable WL, BD, LS, and WA, but unsatisfactory FS (≤1.08 MPa). Low mechanical strength was attributed to presence of smectites and inert nature of feldspar at 900 °C. Beneficiation through mixing with carbonate-rich raw materials is recommended.
      Citation: Minerals
      PubDate: 2020-08-07
      DOI: 10.3390/min10080700
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 701: The Effect of Alkali Roasting Pretreatment
           on Nickel Extraction from Limonite Ore by Using Dissolved SO2-Air

    • Authors: Winny Wulandari, Meiyer Marthen Kinda, Rahmaditha Murida, Tjokorde Walmiki Samadhi
      First page: 701
      Abstract: Extraction of limonite ore using dissolved SO2–air is an alternative hydrometallurgical method for nickel recovery. This process is carried out at atmospheric pressure and is shown to have good selectivity of nickel over iron, but with a low recovery yield. The literature refers to the application of alkali roasting as pretreatment in laterite ore leaching to increase nickel recovery. Thus, this study aims to apply the combination method of alkali roasting and leaching to extract nickel from limonite ore (1.33% Ni, 46.61% Fe) from the Southeast Sulawesi region. Three alkali compounds were included in the study (NaOH, Na2CO3 and Na2SO4). The batch-leaching process was carried out at pH 1 and 3 and temperatures of 55 and 80 °C for 180 min. The leach liquors were sampled at 15, 60, 90 and 120 min, and concentrations of the extracted metals were measured by Atomic Absorption Spectrometry (AAS). A mineralogy characterization of the raw ore and its residue after leaching was undertaken by using X-Ray Diffraction (XRD), while the thermal decomposition behavior of the ore was characterized by Thermogravimetry Analyzer (TGA)/Differential Scanning Calorimetry (DSC). The addition of Na2CO3, Na2SO4 and NaOH in the ore pretreatment increases nickel recovery from 14.80% without alkali roasting to 23.99%, 28.15% and 39.22%, respectively. The optimum extraction condition for nickel recovery is at pH 1 and a temperature of 80 °C. However, the highest Ni/Fe selectivity of 24,947 is obtained at pH 3 and a temperature of 80 °C, preceded by roasting in the absence of alkali. Compared to other hydrometallurgical processes, the process studied in this work exhibits lower recovery, but provides an alternative to extract nickel from low-grade limonite ore.
      Citation: Minerals
      PubDate: 2020-08-07
      DOI: 10.3390/min10080701
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 702: Fedorite from Murun Alkaline Complex
           (Russia): Spectroscopy and Crystal Chemical Features

    • Authors: Ekaterina V. Kaneva, Roman Yu. Shendrik, Tatiana A. Radomskaya, Ludmila F. Suvorova
      First page: 702
      Abstract: Fedorite is a rare phyllosilicate, having a crystal structure characterized by SiO4-tetrahedral double layers located between continuous layers formed by edge-sharing (Ca,Na)-octahedra, and containing interlayer K, Na atoms and H2O molecules. A mineralogical-petrographic and detailed crystal-chemical study of fedorite specimens from three districts of the Murun alkaline complex was performed. The sequence of the crystallization of minerals in association with fedorite was established. The studied fedorite samples differ in the content of interlayer potassium and water molecules. A comparative analysis based on polyhedral characteristics and deformation parameters was carried out. For the first time, EPR, optical absorption and emission spectra were obtained for fedorite. The raspberry-red coloration of the mineral specimens could be attributed to the presence of Mn4+ ions.
      Citation: Minerals
      PubDate: 2020-08-07
      DOI: 10.3390/min10080702
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 703: Formation of Spessartine and CO2 via
           Rhodochrosite Decarbonation along a Hot Subduction P-T Path

    • Authors: Yuliya V. Bataleva, Aleksei N. Kruk, Ivan D. Novoselov, Yuri N. Palyanov
      First page: 703
      Abstract: Experimental simulation of rhodochrosite-involving decarbonation reactions resulting in the formation of spessartine and CO2-fluid was performed in a wide range of pressures (P) and temperatures (T) corresponding to a hot subduction P-T path. Experiments were carried out using a multi-anvil high-pressure apparatus of a “split-sphere” type (BARS) in an MnCO3–SiO2–Al2O3 system (3.0–7.5 GPa, 850–1250 °C and 40–100 h.) with a specially designed high-pressure hematite buffered cell. It was experimentally demonstrated that decarbonation in the MnCO3–SiO2–Al2O3 system occurred at 870 ± 20 °C (3.0 GPa), 1070 ± 20 °C (6.3 GPa), and 1170 ± 20 °C (7.5 GPa). Main Raman spectroscopic modes of the synthesized spessartine were 349–350 (R), 552(υ2), and 906–907 (υ1) cm−1. As evidenced by mass spectrometry (IRMS) analysis, the fluid composition corresponded to pure CO2. It has been experimentally shown that rhodochrosite consumption to form spessartine + CO2 can occur at conditions close to those of a hot subduction P-T path but are 300–350 °C lower than pyrope + CO2 formation parameters at constant pressures. We suppose that the presence of rhodocrosite in the subducting slab, even as solid solution with Mg,Ca-carbonates, would result in a decrease of the decarbonation temperatures. Rhodochrosite decarbonation is an important reaction to explain the relationship between Mn-rich garnets and diamonds with subduction/crustal isotopic signature.
      Citation: Minerals
      PubDate: 2020-08-07
      DOI: 10.3390/min10080703
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 704: Aboveground and Belowground Colonization of
           Vegetation on a 17-Year-Old Cover with Capillary Barrier Effect Built on a
           Boreal Mine Tailings Storage Facility

    • Authors: Alex Proteau, Marie Guittonny, Bruno Bussière, Abdelkabir Maqsoud
      First page: 704
      Abstract: Acid mine drainage is an important environmental risk linked to the surface storage of reactive mine tailings. To manage this problem, a cover with a capillary barrier effect (CCBE) can be used. This oxygen barrier cover relies on maintaining a fine-grained material layer (moisture-retaining layer, MRL) with a high degree of saturation. CCBEs can be colonized by surrounding plants. Plant roots pump water and could impact CCBE’s performance. This performance is predicted with unsaturated water flow numerical models in which vegetation parameters can be included. Vegetation parameters may be specific in a CCBE environment. Therefore, analyzing and quantifying the vegetation that colonizes this type of cover is necessary. Plant colonization was investigated through cover and density surveys on 12 transects on a 17-year-old CCBE in the mixed forest of Quebec, Canada. Then, aboveground vegetation and root colonization intensity at three depths in the MRL were characterized on 25 plots of five dominant vegetation types (Salix, Populus, Alnus, Picea sp., and herbaceous species). The mean root length density under plots dominated by Salix sp. was higher than in the other plots. Root colonization of the MRL was concentrated in the first 10 cm and occurred under all woody and herbaceous species as well. This work quantitatively describes, for the first time, the vegetation colonizing a CCBE both at the above- and belowground levels. These data will be useful to better predict the long-term performance of this engineered reclamation cover.
      Citation: Minerals
      PubDate: 2020-08-08
      DOI: 10.3390/min10080704
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 705: Steel Slag Characterisation—Benefit of
           Coupling Chemical, Mineralogical and Magnetic Techniques

    • Authors: Maud Herbelin, Jérôme Bascou, Véronique Lavastre, Damien Guillaume, Mhammed Benbakkar, Steve Peuble, Jean-Philippe Baron
      First page: 705
      Abstract: Steel-making slag is largely used today in road construction and other applications, but significant volumes are landfilled and cannot be recycled for excessive contents in hazardous metals, such as chromium or vanadium. The long-term behaviour of this material is still little known, and the characterisation of large volume slag dumps remains an environmental challenge. In this study various analytical techniques are used to characterise Electric Arc Furnace (EAF) slag landfilled for several decades and exposed to chemical weathering and erosion. Coupling chemical, mineralogical and magnetic techniques helps to understand the relations between hazardous metals and mineral phases. A special interest is given to Fe-bearing minerals microstructure so as to link the magnetic properties of the material to its mineralogical composition. The studied slag presents high amounts of chromium (between 1 and 3 wt. %) and very high magnetic susceptibility values (near 60 × 10−6 m3/kg), explained by the presence of magnetite and a spinel solid solution. Some correlations are found between magnetic susceptibility and potentially hazardous metals, providing new perspectives for future environmental investigations.
      Citation: Minerals
      PubDate: 2020-08-09
      DOI: 10.3390/min10080705
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 706: Considerations About Bi and Pb in the
           Crystal Structure of Cu-Bearing Tourmaline

    • Authors: Andreas Ertl, Peter Bačík
      First page: 706
      Abstract: Copper- and Mn-bearing elbaitic tourmaline (“Paraíba tourmaline”) sometimes contains significant amounts of Pb and Bi. Their position in the tourmaline crystal structure was studied with correlation analysis and bond valence calculations. Correlations between the F content and the X-site charge allow predicting the X-site occupancy. Three sets of tourmaline analyses were studied: (1) Pb-rich tourmalines from the Minh Tien pegmatite, Vietnam; (2) Cu-, Pb- and Bi-bearing tourmalines from the Mulungu mine, Brazil; (3) Cu- and Bi-bearing tourmalines from the Alto dos Quintos mine, Brazil. Two correlations were plotted: (1) the charge by considering only Na1+, Ca2+ and K1+; (2) the charge by adding Pb2+ and Bi3+ to the X-site charge. When plotting correlations for the Minh Tien tourmalines, the correlation significantly improves by adding Pb2+ to the X site. For the Alto dos Quintos tourmalines, only a slight increase of the correlation coefficient is observed, while such a correlation for tourmalines from Mulungu interestingly shows a slight decrease of the correlation coefficient. Bond valence calculations revealed that Bi3+ and Pb2+ can indeed occupy the X site via BiLi(NaAl)−1, PbLi(NaCu)−1 and possibly PbCu(NaAl)−1 substitutions as seen in the investigated tourmaline samples. At the Y site, Pb4+ can be substituted via PbLi(AlCu)−1, and PbVO(AlVOH)−1, while Bi5+ does not have any stable arrangement in Cu-bearing fluor-elbaite. The occurrence of Pb4+ at the Y site could be one explanation for the results of the correlations of the Mulungu tourmalines. Another explanation could be that during the tourmaline crystallization some additional Bi and Pb came into the pegmatitic system and hence disturbed the correlation between the average X-site charge and the F content. Further plots of such correlations in “Paraíba tourmaline” samples might also help to distinguish between the worldwide localities of these rare and sought-after tourmalines.
      Citation: Minerals
      PubDate: 2020-08-10
      DOI: 10.3390/min10080706
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 707: Effectiveness of Fly Ash and Red Mud as
           Strategies for Sustainable Acid Mine Drainage Management

    • Authors: Viktoria Keller, Srećko Stopić, Buhle Xakalashe, Yiqian Ma, Sehliselo Ndlovu, Brian Mwewa, Geoffrey S. Simate, Bernd Friedrich
      First page: 707
      Abstract: Acid mine drainage (AMD), red mud (RM) and coal fly ash (CFA) are potential high environmental pollution problems due to their acidity, toxic metals and sulphate contents. Treatment of acidic mine water requires the generation of enough alkalinity to neutralize the excess acidity. Therefore, red mud types from Germany and Greece were chosen for the neutralization of AMD from South Africa, where this problem is notorious. Because of the high alkalinity, German red mud is the most promising precipitation agent achieving the highest pH-values. CFA is less efficient for a neutralization and precipitation process. An increase in temperature increases the adsorption kinetics. The maximum pH-value of 6.0 can be reached by the addition of 100 g German red mud at 20 °C to AMD-water with an initial pH value of 1.9. German red mud removes 99% of the aluminium as aluminium hydroxide at pH 5.0. The rare earth elements (yttrium and cerium) are adsorbed by Greek red mud with an efficiency of 50% and 80% at 60 °C in 5 min, respectively.
      Citation: Minerals
      PubDate: 2020-08-10
      DOI: 10.3390/min10080707
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 708: Genesis of Two Types of Carbonaceous
           Material Associated with Gold Mineralization in the Bumo Deposit, Hainan
           Province, South China

    • Authors: Zhengpeng Ding, Teng Deng, Deru Xu, Zenghua Li, Shaohao Zou, Lirong Li, Ke Xu, Yan Hai, Wen Ma
      First page: 708
      Abstract: Carbonaceous material (CM) is common in meta-sediments and is generally interpreted to be intimately associated with gold mineralization. For the Bumo deposit in Hainan Province, South China, CM is mainly hosted by greenschist facies—to amphibolite-facies metamophic rocks of the Paleo—to the Mesoproterozoic Baoban Group, and by auriferous veins which could be used as an important gold prospecting indicator. However, the genesis of CM and its relationship with gold mineralization are still unclear. From the field work and thin section observations two types of CM occur, i.e., layered and veinlet. The layered CM occurred in CM-bearing black shales, up to meters thick, and prevails in the deposit. More importantly, Au-bearing sulfides are commonly distributed along the boundary between the quartz veins and layered CM. In contrast, the veinlet CM, co-precipitated with native gold and sulfides, has the thickness of micro- to centi-meters, and these thin veins occur in quartz veins and hydrothermally altered rocks. In addition, layered CM has a stringy shape and laminate structure, while veinlet CM occurs as isometric particles based on the Scanning Electron Microscope (SEM) analysis. The Raman carbonaceous material geothermometer indicates that layered CM with a high maturity is formed at elevated temperatures of 400–550 °C, consistent with X-ray diffraction (XRD) analysis. In contrast, veinlet CM with a low maturity is formed at 200–350 °C and generally consistent with gold mineralization. In addition, layered CM has δ13C values ranging from −30 to −20%, demonstrating a biogenic origin. Consequently, it is interpreted that layered CM is formed by a pre-ore metamorphic event during Caledonian, and its reducing nature promotes gold precipitation via destabilization of aqueous Au complexes or facilitating sulfidation. Veinlet CM is of hydrothermal origin, and its precipitation modified the chemical conditions of ore fluids, leading to the destabilization of Au complexes, which therefore are favorable for mineralization.
      Citation: Minerals
      PubDate: 2020-08-10
      DOI: 10.3390/min10080708
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 709: A Process Mineralogical Evaluation of
           Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa

    • Authors: Thomas Dzvinamurungu, Derek Hugh Rose, Karel Stephanus Viljoen, Antoine Floribert Mulaba-Bafubiandi
      First page: 709
      Abstract: A process mineralogical study based on three texturally and mineralogically different chromite-bearing ore types at the Nkomati nickel mine was undertaken, with focus on chromite. Chromite is a by-product of the Ni-Cu-Co-PGE ore at Nkomati Nickel mine. These being the PCMZ_MG (medium-grade Ni-Cu sulphide silicate ore with disseminated chromite), PCMZ_HG (high-grade Ni-Cu sulphide silicate ore containing disseminated chromite) and MCHR (massive chromite unit) ore types. These were processed using benchtop flotation followed by gravity concentration using a shaking table at different grind sizes. Quantitative mineralogical data was obtained using a 600F Mineral Liberation Analyser for the unprocessed and processed ores at three selected target grinds. The Mineral Liberation Analyser data indicated that increased milling does not relate to increased chromite grades and recoveries, particularly for the disseminated PCMZ type ores based on laboratory-scale gravity concentration. The recovery is controlled largely by the chromite chemistry. The results also showed that the MCHR samples that underwent a pre-flotation stage before gravity separation had better Cr2O3 grades (45% to 47%) and recoveries (52% to 61%) than MCHR ore that did not undergo a pre-flotation stage, which recorded grades ranging from 44% to 46% and recoveries ranging from 43% to 60%. This holds promise for the blending of MCHR ores with the PCMZ ores. The PCMZ ores also displayed better Cr2O3 grades and recoveries at coarser grinds. The optimal target grind to process all three ore types is a P80 of 75 μm, which is the current grind size employed at Nkomati Nickel mine. Due to the low nickel price and grade the Nkomati Nickel mine is currently under care and maintenance.
      Citation: Minerals
      PubDate: 2020-08-12
      DOI: 10.3390/min10080709
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 710: Development of a More Descriptive Particle
           Breakage Probability Model

    • Authors: Murray M. Bwalya, Ngonidzashe Chimwani
      First page: 710
      Abstract: Single-particle breakage test is becoming increasingly popular, as researchers seek to understand fracture response that is purely a function of the material being tested, instead of that which is based on the performance of the comminution device being used. To that end, an empirical breakage probability model that builds on previous work was proposed. The experimental results demonstrate the significance of both energy input and the number of repeated breakage attempts. Four different materials were compared, to gain a better insight into the breakage response. This modelling work goes further from previous research of the authors, by showing that not only does size related threshold energy and repeated impacts characterize particle breakage properties, but each material exhibits unique trends in terms of how its threshold energy and its rate of deterioration varies with particle size and each impact, respectively. This behaviour can be attributed to the different mechanical characteristics of the material and their flaw distribution. The importance of these aspects was highlighted.
      Citation: Minerals
      PubDate: 2020-08-12
      DOI: 10.3390/min10080710
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 711: Removal of Pollutants from an AMD from a
           Coal Mine by Neutralization/Precipitation Followed by “In Vivo”
           Biosorption Step with the Microalgae Scenedesmus sp.

    • Authors: Karine Batista dos Santos, Vítor Otacílio de Almeida, Jéssica Weiler, Ivo André Homrich Schneider
      First page: 711
      Abstract: This work evaluates the benefits of a complementary treatment step of acid mine drainage (AMD) using the algae Scenedesmus sp. in terms of algae biomass production, residual metal removal, and the toxicity of the discharged water. Conventional treatment by neutralization/precipitation of an AMD from a coal mine in Brazil was conducted with Ca(OH)2 at pH 8.7. Algal growth studies were performed in the treated AMD, with and without a nutrient supply. The raw effluent and treatments were compared in terms of residual concentration of metals and sulfate, conductivity, and toxicity with the Allium cepa and Daphnia magna test organisms. The results show that the conventional treatment allowed a major metal removal, reduction in the conductivity, and good indices in the toxicological parameters evaluated. The biosorption with in vivo microalgae improved the quality of the effluent for residual metals. No significant toxicity was observed to Allium cepa in all treatments performed, while the Daphnia magna test indicated a reduction in toxicity after the biosorption step. It was concluded that algae growth can be carried out in treated mine waters, providing algae biomass and helping to achieve the standards for water discharge.
      Citation: Minerals
      PubDate: 2020-08-12
      DOI: 10.3390/min10080711
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 712: Predicting the Logarithmic Distribution
           Factors for Coprecipitation into an Organic Salt: Selection of Rare Earths
           into a Mixed Oxalate

    • Authors: Harry Watts, Yee-Kwong Leong
      First page: 712
      Abstract: Thermodynamic modelling of a leaching system that involves concurrent precipitation depends on an understanding of how the metals distribute into the precipitate before an assessment of solubility can be made. It has been suggested in the past that a pair of rare earths (A and B) in solution will separate from each other by oxalate precipitation according to a logarithmic distribution coefficient (λ), determined by the kinetics of the precipitation. By contrast, the present study hypothesises that λ may be approximated from thermodynamic terms, including the solubility product (KSp) of each rare earth oxalate and the stability constant (β1) for the mono-oxalato complex of each rare earth. The proposed model was used to calculate λ between pairs of rare earths. An experimental study was conducted to determine λ between selected pairs using homogenous precipitation through the hydrolysis of an oxalic acid ester, with fairly close agreement to the values under the proposed model. Though this model requires more thorough testing, as well as application to other organic salts, it may provide insight into distribution factors of a precipitate formed by a sequence of organic complexes.
      Citation: Minerals
      PubDate: 2020-08-12
      DOI: 10.3390/min10080712
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 713: Comparison of the Calcareous Shells of
           Belemnitida and Sepiida: Is the Cuttlebone Prong an Analogue of the
           Belemnite Rostrum Solidum'

    • Authors: M. Isabel Benito, Matías Reolid
      First page: 713
      Abstract: The microstructure of the rostrum solidum of Jurassic belemnites is compared with that of Sepia cuttlebones, in order to examine possible convergences in their style of growth. For this study, transmitted and polarized light, cathodoluminescence, epifluorescence, scanning electron and backscattered electron microscopy have been employed. Despite differences in the primary mineralogy of the studied belemnites and sepiids, calcite and aragonite, respectively, many similarities have been observed between the microstructure of the belemnite rostra and the prong of Sepia cuttlebone: (1) In both, crystals start growing from successive spherulites, from which crystals emerge radially towards the apex and the external walls, displaying internally micro-fibrous texture. (2) Both display concentric growth layering, comprising an alternation of organic-rich and organic-poor layers, which, in turn, is traverse by the radially-arranged micro-fibrous crystals. (3) The highest organic matter content and porosity have been observed along the apical area of the Sepia prong, similarly to that interpreted for belemnite rostra. The strong convergences observed suggest that the growth of belemnites occurred similarly to that of the prong of sepiids and that the Sepia prong is the analog of the belemnite rostrum. Additionally, non-classical crystallization processes are proposed to be involved in the formation Sepia endoskeleton.
      Citation: Minerals
      PubDate: 2020-08-12
      DOI: 10.3390/min10080713
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 714: Mineralogical Characteristics of Early
           Permian Paragonite-Bearing Coal (No. 3) in the Jinyuan Mine, Tengxian
           Coalfield, Shandong Province, Eastern China

    • Authors: Wenmu Guo, Jinxiao Li, Zhenzhen Wang, Ke Zhang, Zheng Gao, Jialiang Ma, Cunliang Zhao
      First page: 714
      Abstract: The Early Permian coal is of great value in the Tengxian Coalfield, Shandon Province, Eastern China. This work deals with the new data focusing on mineralogical characteristics in the Early Permian Shanxi Formation No. 3 coal from the Jinyuan Mine. The Jinyuan coal is a low ash and highly volatile A bituminous coal. Minerals in the No. 3 coal mainly comprise of kaolinite, ankerite, illite, calcite, siderite, and quartz, with varying compositions of trace amounts of pyrite, jarosite, bassanite, anatase, and rutile. According to mineral assemblage in the coal plies, three Types (A to C) can be identified in the No. 3 coal. The dominant minerals in Type A are poorly-ordered kaolinite, illite, quartz, pyrite, and jarosite. Type B is mainly composed of well-ordered kaolinite, illite, siderite, ankerite, and calcite. Type C, with just one sample (JY-3-7c), which contains high proportions of calcite (54%) and ankerite (34%). Terrigenous minerals are elevated in coal plies that typically have relatively high contents of ash yield. The formation of syngenetic pyrite was generally due to seawater, while the sulphate minerals (jarosite and coquimbite) were derived from the oxidation of pyrite. Epigenetic vein-like or fracture-fillings carbonate minerals (ankerite, calcite, and siderite), kaolinite, and pyrite, as well as authigenic quartz were derived from the influx of hydrothermal fluids during different periods, from the authigenic to epigenetic. The paragonite in the coal may have been formed by the precipitated from Na-rich hydrothermal fluids. No effects of magmatic intrusion on mineralogy were investigated in this research.
      Citation: Minerals
      PubDate: 2020-08-12
      DOI: 10.3390/min10080714
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 715: Decarbonation Reactions Involving Ankerite
           and Dolomite under upper Mantle P,T-Parameters: Experimental Modeling

    • Authors: Yuliya V. Bataleva, Aleksei N. Kruk, Ivan D. Novoselov, Olga V. Furman, Yuri N. Palyanov
      First page: 715
      Abstract: An experimental study aimed at the modeling of dolomite- and ankerite-involving decarbonation reactions, resulting in the CO2 fluid release and crystallization of Ca, Mg, Fe garnets, was carried out at a wide range of pressures and temperatures of the upper mantle. Experiments were performed using a multi-anvil high-pressure apparatus of a “split-sphere” type, in CaMg(CO3)2-Al2O3-SiO2 and Ca(Mg,Fe)(CO3)2-Al2O3-SiO2 systems (pressures of 3.0, 6.3 and 7.5 GPa, temperature range of 950–1550 °C, hematite buffered high-pressure cell). It was experimentally shown that decarbonation in the dolomite-bearing system occurred at 1100 ± 20 °C (3.0 GPa), 1320 ± 20 °C (6.3 GPa), and 1450 ± 20 °C (7.5 GPa). As demonstrated by mass spectrometry, the fluid composition was pure CO2. Composition of synthesized garnet was Prp83Grs17, with main Raman spectroscopic modes at 368–369, 559–562, and 912–920 cm−1. Decarbonation reactions in the ankerite-bearing system were realized at 1000 ± 20 °C (3.0 GPa), 1250 ± 20 °C (6.3 GPa), and 1400 ± 20 °C (7.5 GPa). As a result, the garnet of Grs25Alm40Prp35 composition with main Raman peaks at 349–350, 552, and 906–907 cm−1 was crystallized. It has been experimentally shown that, in the Earth’s mantle, dolomite and ankerite enter decarbonation reactions to form Ca, Mg, Fe garnet + CO2 assemblage at temperatures ~175–500 °C lower than CaCO3 does at constant pressures.
      Citation: Minerals
      PubDate: 2020-08-13
      DOI: 10.3390/min10080715
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 716: A Trace Element Classification Tree for
           Chalcopyrite from Oktyabrsk Deposit, Norilsk–Talnakh Ore District,
           Russia: LA-ICPMS Study

    • Authors: Alexander E. Marfin, Alexei V. Ivanov, Vera D. Abramova, Tatiana N. Anziferova, Tatiana A. Radomskaya, Tamara Y. Yakich, Ksenia V. Bestemianova
      First page: 716
      Abstract: The Oktyabrsk PGE-Cu-Ni deposit is one of the largest resources in the Norilsk–Talnakh ore district, Russia, and it is viewed as an ore giant on a global scale. It contains three types of ores: massive, disseminated and veinlet-disseminated. The two former ore types were formed by a liquation process, whereas the latter was associated with fluid-induced selective metasomatic replacement of metamorphosed wall rocks. One of the major ore minerals in all ore types is chalcopyrite. In this study, we determined concentrations of trace elements in this mineral using laser ablation inductively coupled plasma mass spectrometry. It appeared that standard geochemical tools, such as plotting the data in the form of diagrams of normalized concentrations, binary and ternary plots, do not allow one to distinguish chalcopyrite from visually and genetically different ore types. In contrast, more advanced statistical methods such as cluster analysis show different groupings of elements for each ore type. Based on the element clustering, a classification tree was suggested, which allowed for the differentiation of massive, disseminated and veinlet-disseminated ore types of the Oktyabrsk deposit by Se, Te, Cd and Pb concentrations in chalcopyrite with a success rate of 86%. The general feature is that chalcopyrite of veinlet-disseminated ore is poorer in these elements compared to chalcopyrite of the two other ore types. Chalcopyrite of massive ore is poorer in Se and Te when compared to chalcopyrite of disseminated ore.
      Citation: Minerals
      PubDate: 2020-08-14
      DOI: 10.3390/min10080716
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 717: DEM Simulation of Laboratory-Scale Jaw
           Crushing of a Gold-Bearing Ore Using a Particle Replacement Model

    • Authors: Gabriel Kamilo Barrios, Narcés Jiménez-Herrera, Silvia Natalia Fuentes-Torres, Luís Marcelo Tavares
      First page: 717
      Abstract: The Discrete Element Method (DEM) is a numerical method that is able to simulate the mechanical behavior of bulk solids flow using spheres or polyhedral elements, offering a powerful tool for equipment design and optimization through modeling and simulation. The present work uses a Particle Replacement Model (PRM) embedded in the software EDEM® to model and simulate operation of a laboratory-scale jaw crusher. The PRM was calibrated using data from single particle slow compression tests, whereas simulations of the jaw crusher were validated on the basis of experiments, with very good agreement. DEM simulations described the performance of the crusher in terms of throughput, product size distribution, compressive force on the jaws surface, reduction ratio, and energy consumption as a function of closed side setting and frequency.
      Citation: Minerals
      PubDate: 2020-08-14
      DOI: 10.3390/min10080717
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 718: The Occurrence of Authigenic Clay Minerals
           in Alkaline-Saline Lakes, Pantanal Wetland (Nhecolândia Region, Brazil)

    • Authors: Isis Armstrong Dias, Leonardo Fadel Cury, Bruno Guimarães Titon, Gustavo Barbosa Athayde, Guilherme Fedalto, Larissa da Rocha Santos, Ana Paula Soares, Camila de Vasconcelos Müller Athayde, Anelize Manuela Bahniuk Rumbeslperger
      First page: 718
      Abstract: Mg clay minerals are usually associated with carbonates in alkaline-saline environments, precipitated from solution and/or transformation from other minerals. The aim of this research is to identify the mineralogy and geochemistry of clay minerals in different alkaline lakes in the Nhecolândia region, the southernmost region of the Pantanal wetland (Brazil). Sediment samples were analyzed by X-ray diffraction, X-ray fluorescence, scanning electron microscopy and transmission electron microscopy. Water samples were analyzed, determining their main cations and anions, in order to understand their relationship with the clays. The analyses allowed classifying the water bodies as saline, oligosaline and freshwater lakes. The sediments are composed mainly of quartz and a fine-clay fraction, dominated by illite, kaolinite and smectite. The XRD results showed illite and smectite mixed-layered in the saline lakes at Barranco Alto farm, whereas at Nhumirim farm, trioctahedral smectite was only observed in one lake. The smectite minerals were normally identified coupled with calcite at the top of the sequences, associated with exopolymeric substances (EPS) in the lakes, suggesting that these minerals are precipitating due to the physical-chemical and biological conditions of the water bodies.
      Citation: Minerals
      PubDate: 2020-08-17
      DOI: 10.3390/min10080718
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 719: Formation of Natural Silicate Hydrates by
           the Interaction of Alkaline Seepage and Sediments Derived from
           Serpentinized Ultramafic Rocks at Narra, Palawan, the Philippines

    • Authors: Misato Shimbashi, Shingo Yokoyama, Yasutaka Watanabe, Tsutomu Sato, Tsubasa Otake, Ryosuke Kikuchi, Minoru Yamakawa, Naoki Fujii
      First page: 719
      Abstract: In radioactive waste disposal facilities, low-permeability engineered barrier materials are important for inhibiting radionuclide migration. However, dissolution–precipitation reactions under alkaline conditions change the permeability of engineered barriers. To understand long-term dissolution–precipitation reactions under alkaline conditions in chemically complex systems, trenches and drill holes were excavated at Narra in Palawan, where alkaline fluids (pH > 11) have been naturally produced, seeping into clastic sediments derived from serpentinized ultramafic rocks and gabbro of Palawan ophiolite. Interaction between the alkaline seepage and clastic sediments, which have been deposited since 15,000 radiocarbon years before present (14C yr BP), led to dissolution of minerals and the precipitation of Si-bearing phases which were divided into two main categories: Fe-Mg-Si infillings and Ca-Si infillings. The former category was composed of iron-magnesium-silicate-hydrate (F-M-S-H) and a nontronite-like mineral and was widely recognized in the clastic sediments. The nontronite-like mineral likely formed by interaction between silicates and alkaline seepage mixed with infiltrated seawater, whereas F-M-S-H formed by the reaction of silicates with alkaline seepage in the absence of seawater infiltration. Ca-Si infillings included 14 Å tobermorite and were precipitated from alkaline seepage combined with the Ca and Si supplied by the dissolution of calcite and silicates in the clastic sediments.
      Citation: Minerals
      PubDate: 2020-08-17
      DOI: 10.3390/min10080719
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 720: New Data on the Isomorphism in
           Eudialyte-Group Minerals. 2. Crystal-Chemical Mechanisms of Blocky
           Isomorphism at the Key Sites

    • Authors: Ramiza K. Rastsvetaeva, Nikita V. Chukanov
      First page: 720
      Abstract: The review considers various complex mechanisms of isomorphism in the eudialyte-group minerals, involving both key positions of the heteropolyhedral framework and extra-framework components. In most cases, so-called blocky isomorphism is realized when one group of atoms and ions is replaced by another one, which is accompanied by a change in the valence state and/or coordination numbers of cations. The uniqueness of these minerals lies in the fact that they exhibit ability to blocky isomorphism at several sites of high-force-strength cations belonging to the framework and at numerous sites of extra-framework cations and anions.
      Citation: Minerals
      PubDate: 2020-08-17
      DOI: 10.3390/min10080720
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 721: Assessing Options for Remediation of
           Contaminated Mine Site Drainage Entering the River Teign, Southwest

    • Authors: Abigail Jordan, Rachel Hill, Adrienne Turner, Tyrone Roberts, Sean Comber
      First page: 721
      Abstract: The river Teign in Devon has come under scrutiny for failing to meet environmental quality standards for ecotoxic metals due to past mining operations. A disused mine known as Bridford Barytes mine, has been found to contribute a significant source of Zn, Cd and Pb to the river. Recently, studies have been focused on the remediation of such mine sites using low-cost treatment methods to help reduce metal loads to the river downstream. This paper explores the metal removal efficiency of red mud, a waste product from the aluminium industry, which has proven to be an attractive low-cost treatment method for adsorbing toxic metals. Adsorption kinetics and capacity experiments reveal metal removal efficiencies of up to 70% within the first 2 h when red mud is applied in pelletized form. Further, it highlights the potential of biochar, another effective adsorbent observed to remove >90% Zn using agricultural feedstock. Compliance of the Teign has been investigated by analysing dissolved metal concentrations and bioavailable fractions of Zn to assess if levels are of environmental concern. By applying a real-world application model, this study reveals that compressed pellets and agricultural biochar offer an effective, low-cost option to reducing metal concentrations and thus improving the quality of the river Teign.
      Citation: Minerals
      PubDate: 2020-08-17
      DOI: 10.3390/min10080721
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 722: Production, Reserves, and Processing of
           Feldspar and Feldspathoid Rocks in the Czech Republic from 2005 to
           2019—An Overview

    • Authors: Jan Zahradník, Jakub Jirásek, Jaromír Starý, Martin Sivek
      First page: 722
      Abstract: This paper aims to characterize and interpret the trends in reserves, resources, and mine production of feldspar and feldspathoid rocks during 2005–2019 in the Czech Republic. With over 101 Mt of total resources and 22 Mt of reserves, feldspar belongs to the crucial industrial minerals of the Czech Republic. With annual outputs of approximately 400–450 kt of feldspars and 20–35 kt of feldspathoid rocks (nepheline syenite), the Czech Republic ranks among the top European and world feldspar producers. Most of the production comes from leucocratic granitoid rocks (key active deposit: Krásno-Vysoký Kámen), followed by sedimentary rocks (key active deposit: Halámky), and granitic pegmatites (key active deposit: Luženičky). Nepheline syenite is mined at a single deposit. All deposits are extracted from open pits (quarries). Ongoing geological prospecting and exploration for new deposits are increasing available reserves and resources. The feldspar raw materials are used in the domestic glass and ceramic industries, while more than 50% is exported, generally to Poland and Germany.
      Citation: Minerals
      PubDate: 2020-08-17
      DOI: 10.3390/min10080722
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 723: Editorial for the Special Issue
           “Properties of Melt and Minerals at High Pressures and High

    • Authors: Claudia Romano
      First page: 723
      Abstract: This Special Volume sets out to summarize knowledge in the rapidly developing area of the high-pressure and high-temperature properties and structure of silicate melts and minerals [...]
      Citation: Minerals
      PubDate: 2020-08-18
      DOI: 10.3390/min10080723
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 724: pXRF Measurements on Soil Samples for the
           Exploration of an Antimony Deposit: Example from the Vendean Antimony
           District (France)

    • Authors: Bruno Lemière, Jeremie Melleton, Pascal Auger, Virginie Derycke, Eric Gloaguen, Loïc Bouat, Dominika Mikšová, Peter Filzmoser, Maarit Middleton
      First page: 724
      Abstract: Mineral exploration is increasingly challenging in inhabited areas. To evaluate the potential of soil analysis by pXRF (portable X-ray fluorescence) as a low-footprint exploration technique, we revisited a historic Sb district in an agricultural area and performed shallow-soil sampling (Ah and B horizons) along profiles across known veins to capture the endogenic geochemical anomaly signals. Despite an expected bias between pXRF measurements and laboratory analyses, the former effectively located the Sb veins, especially when using their multi-element capabilities. Composition data processing (CoDa) and horizon-selective sampling significantly improved the method’s efficiency. On-site measurements allow dynamic sampling and mapping, helping with faster, cost-effective sample selection for further laboratory investigations. Based on this case study, where similar geochemical patterns were obtained for both horizons, application of an on-site approach to a humic horizon can increase survey efficiency and decrease impacts.
      Citation: Minerals
      PubDate: 2020-08-18
      DOI: 10.3390/min10080724
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 725: Application of Historical Geophysical
           Materials in Searching for Cu-Ag Ore Deposits—A New Direction of

    • Authors: Stanisław Speczik, Lidia Dziewińska, Waldemar Jóźwiak, Krzysztof Zieliński
      First page: 725
      Abstract: This paper presents a new instrument in geological exploration, which uses historical geophysical data for the indication of potential zones of the occurrence of Cu-Ag ore, based on the example of the newly discovered Nowa Sól deposit in south-western Poland. Basic historical seismic and gravimetric data were applied along with transformed maps. The new method of effective reflection coefficients (ERC) allowed the utilization of archival seismic records for a more precise determination of the most vaguely traced interfaces within the Permian Zechstein unit. Compared to an amplitude-based seismic section, an ERC section is characterized by its highly increased resolution of imaging. The tracing of changes in the facies and the tectonics of Zechstein sediments, particularly in a zone of their contact with Rotliegend rocks, along with the new ERC method, enabled the establishing of precise locations of prospecting boreholes. The combined use of ERC and historical well logs also allowed more precise identification of the shape of oxidized areas and the adjacent orebodies.
      Citation: Minerals
      PubDate: 2020-08-18
      DOI: 10.3390/min10080725
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 726: Rheology of Alkali-Activated Mortars:
           Influence of Particle Size and Nature of Aggregates

    • Authors: Sara Gismera, María del Mar Alonso, Marta Palacios, Francisca Puertas
      First page: 726
      Abstract: The effect of two precursors (slag and fly ash), different particle size distribution, and three types of aggregate (siliceous sand, limestone, and recycled concrete) on alkali-activated material (AAM) mortar rheology were studied and compared to their effect on an ordinary Portland Cement (OPC) mortar reference. Stress growth and flow curve tests were conducted to determine plastic viscosity and static and dynamic yield stress of the AAM and OPC mortars. In both OPC and AAM mortars, a reduction of the aggregate size induces a rise of the liquid demand to preserve the plastic consistency of the mortar. In general terms, an increase of the particle size of the siliceous aggregates leads to a decrease of the measured rheological parameters. The AAM mortars require higher liquid/solid ratios than OPC mortars to attain plastic consistency. AAM mortars proved to be more sensitive than OPC mortars to changes in aggregate nature. The partial replacement of the siliceous aggregates with up to 20% of recycled concrete aggregates induced no change in mixing liquid uptake, in either AAM or OPC mortars. All the AAM and OPC mortars studied fitted to the Bingham model.
      Citation: Minerals
      PubDate: 2020-08-18
      DOI: 10.3390/min10080726
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 727: Hydrologic and Water Quality Modeling of the
           Pebble Mine Project Pit Lake and Downstream Environment after Mine Closure

    • Authors: Ann Maest, Robert Prucha, Cameron Wobus
      First page: 727
      Abstract: The Pebble Project in Alaska is one of the world’s largest undeveloped copper deposits. The Environmental Impact Statement (EIS) proposes a 20-year open-pit extraction, sulfide flotation, and deposition of separated pyritic tailings and potentially acid-generating waste rock in the pit at closure. The pit will require perpetual pump and treat management. We conducted geochemical and integrated groundwater–surface water modeling and streamflow mixing calculations to examine alternative conceptual models and future mine abandonment leading to failure of the water management scheme 100 years after mine closure. Using EIS source water chemistry and volumes and assuming a well-mixed pit lake, PHREEQC modeling predicts an acidic (pH 3.5) pit lake with elevated copper concentrations (130 mg/L) under post-closure conditions. The results are similar to water quality in the Berkeley Pit in Montana, USA, another porphyry copper deposit pit lake in rocks with low neutralization potential. Integrated groundwater–surface water modeling using MIKE SHE examined the effects of the failure mode for the proposed 20-year and reasonably foreseeable 78-year expansion. Simulations predict that if pumping fails, the 20-year pit lake will irreversibly overtop within 3 to 4 years and mix with the South Fork Koktuli River, which contains salmon spawning and rearing habitat. The 78-year pit lake overtops more rapidly, within 1 year, and discharges into Upper Talarik Creek. Mixing calculations for the 20-year pit show that this spillover would lead to exceedances of Alaska’s copper surface water criteria in the river by a factor of 500–1000 times at 35 miles downstream. The combined modeling efforts show the importance of examining long-term failure modes, especially in areas with high potential impacts to stream ecological services.
      Citation: Minerals
      PubDate: 2020-08-18
      DOI: 10.3390/min10080727
      Issue No: Vol. 10, No. 8 (2020)
  • Minerals, Vol. 10, Pages 636: β-Lactoglobulin Adsorption Layers at the
           Water/Air Surface: 4. Impact on the Stability of Foam Films and Foams

    • Authors: Georgi G. Gochev, Vamseekrishna Ulaganathan, Inga Retzlaff, Cécile Gehin-Delval, Deniz Z. Gunes, Martin Leser, Ulrich Kulozik, Reinhard Miller, Björn Braunschweig
      First page: 636
      Abstract: The complexity and high sensitivity of proteins to environmental factors give rise to a multitude of variables, which affect the stabilization mechanisms in protein foams. Interfacial and foaming properties of proteins have been widely studied, but the reported unique effect of pH, which can be of great interest to applications, has been investigated to a lesser extent. In this paper, we focus on the impact of pH on the stability of black foam films and corresponding foams obtained from solutions of a model globular protein—the whey β-lactoglobulin (BLG). Foam stability was analyzed utilizing three characteristic parameters (deviation time, transition time and half-lifetime) for monitoring the foam decay, while foam film stability was measured in terms of the critical disjoining pressure of film rupture. We attempt to explain correlations between the macroscopic properties of a foam system and those of its major building blocks (foam films and interfaces), and thus, to identify structure-property relationships in foam. Good correlations were found between the stabilities of black foam films and foams, while relations to the properties of adsorption layers appeared to be intricate. That is because pH-dependent interfacial properties of proteins usually exhibit an extremum around the isoelectric point (pI), but the stability of BLG foam films increases with increasing pH (3–7), which is well reflected in the foam stability. We discuss the possible reasons behind these intriguingly different behaviors on the basis of pH-induced changes in the molecular properties of BLG, which seem to be determining the mechanism of film rupture at the critical disjoining pressure.
      Citation: Minerals
      PubDate: 2020-07-17
      DOI: 10.3390/min10070636
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 637: Influence of Titaniferous Phases on Tungsten
           Mineralizing Processes at the Giant Sisson Brook W-Mo Deposit, New
           Brunswick, Canada: Mineral-Chemical and Geochronological Assessment

    • Authors: Aaron L. Bustard, Wei Zhang, David R. Lentz, Christopher R. M. McFarlane
      First page: 637
      Abstract: The Sisson Brook deposit is a low-grade, large-tonnage W-Mo deposit with notable Cu located in west-central New Brunswick, Canada, and is one of several W-Mo deposits in New Brunswick associated with fluids sourced from granitic plutons emplaced during the Devonian Acadian Orogeny. The younger Devonian-aged stockwork and replacement scheelite-wolframite-molybdenite (and chalcopyrite) mineralization straddles the faulted boundary between Cambro-Ordovician metasedimentary rocks with Ordovician felsic volcaniclastic rocks and the Middle Silurian Howard Peak Granodiorite, with dioritic and gabbroic phases. U-Pb dating of magmatic titanite in the host dioritic phase of the Howard Peak Granodiorite using LA ICP-MS resulted in a 204Pb-corrected concordant age of 432.1 ± 1.9 Ma. Petrologic examination of selected mineralization combined with elemental mapping of vein selvages using micro-XRF and metasomatic titanite and ilmenite grains using LA ICP-MS indicates that saturation of titaniferous phases influenced the distribution of scheelite versus wolframite mineralization by altering the aFe/aCa ratio in mineralizing fluids. Ilmenite saturation in Ti-rich host rocks lowered the relative aFe/aCa and led to the formation of scheelite over wolframite. Altered magmatic titanite and hydrothermal titanite also show increased W and Mo concentrations due to interaction with and/or saturation from mineralizing fluids.
      Citation: Minerals
      PubDate: 2020-07-18
      DOI: 10.3390/min10070637
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 638: Contribution to the Mineral Chemistry of the
           Proterozoic Aravalli Mafic Meta-Volcanic Rocks from Rajasthan, NW India

    • Authors: Janina Wiszniewska, Anna Grabarczyk, Ewa Krzemińska, Talat Ahmad
      First page: 638
      Abstract: Field, petrological and mineral chemistry for meta-volcanic rocks from the Aravalli sequence (Aravalli Craton, India) are presented. Field evidence such as volcanic flows and suspect pillow lava structures, dominant Fe-tholeiite lava flows intercalated with quartzites and argillaceous sediments, indicate rift tectonic environment. Primary mineralogy was obliterated during post-magmatic processes such as metamorphism corresponding to the greenschist to lower amphibolite facies conditions. The rock’s mineral composition was overprinted by plagioclase–chlorite–amphibole–epidote assemblage. The relicts of clinopyroxene were observed. The P-T estimation indicates a temperature of 550–600 °C for the pressure ranging from 3.0 to 7.0 kbar for the majority of amphiboles and 8.0–10.7 kbar for the minority. Geochemically, these rocks are komatiitic (picritic) and high-Fe tholeiitic basalts with 45.06−59.2 wt.% SiO2 and MgO content from 5 to 22.4 wt.% and Mg# of 17 to 71. They show large-ion lithophile elements (LILE) and light rare-earth elements (LREE) enrichment. Chondrite normalized rare-earth elements (REE) patterns for the Aravalli lava are moderately enriched with (La/Sm)N = 1.1−3.85, (La/Yb)N from 1.49 (komatiites) to 14.91 (komatiitic basalts). The trace element systematics with the negative Nb, P and Zr anomalies reflect their derivation from enriched sub-continental lithospheric sources, although minor crustal contamination cannot be ruled out. Aravalli rocks are considered to represent the transition from continental rift magmatism to shallow submarine eruption.
      Citation: Minerals
      PubDate: 2020-07-18
      DOI: 10.3390/min10070638
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 639: Rietveld Analysis of Elpidite Framework
           Flexibility Using in Situ Powder XRD Data of Thermally Treated Samples

    • Authors: Vladislav V. Kostov-Kytin, Thomas N. Kerestedjian
      First page: 639
      Abstract: The present study demonstrates the capabilities of the Rietveld procedure to track the structural transformations and framework flexibility on the example of the natural water-containing zirconosilicate elpidite, subjected (in bulk) to thermal treatment from room temperature to 300 °C. The methodological approach to the performed refinements and the obtained results are in accordance with the previously reported data from in situ single crystal X-ray diffraction studies on heated samples of the same mineral. More light has been drawn on the temperature interval in which the non-reconstructive topotactic phase transition occurs upon partial dehydration. The framework flexibility observed as a response to the water loss and subsequent thermal expansion was evaluated in terms of intentionally introduced set of geometric parameters characterizing the spatial orientation of symmetrically related zirconium octahedra in the structure, the coordination polyhedra volumes, their distortion indices, and bond angle variances.
      Citation: Minerals
      PubDate: 2020-07-19
      DOI: 10.3390/min10070639
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 640: The State of Trace Elements (In, Cu, Ag) in

    • Authors: Nikolay D. Trofimov, Alexander L. Trigub, Boris R. Tagirov, Olga N. Filimonova, Polina V. Evstigneeva, Dmitriy A. Chareev, Kristina O. Kvashnina, Maximilian S. Nickolsky
      First page: 640
      Abstract: The oxidation state and local atomic environment of admixtures of In, Cu, and Ag in synthetic sphalerite crystals were determined by X-ray absorption spectroscopy (XAS). The sphalerite crystals doped with In, Cu, Ag, In–Cu, and In–Ag were synthesized utilizing gas transport, salt flux, and dry synthesis techniques. Oxidation states of dopants were determined using X-ray absorption near edge structure (XANES) technique. The local atomic structure was studied by X-ray absorption fine structure spectroscopy (EXAFS). The spectra were recorded at Zn, In, Ag, and Cu K-edges. In all studied samples, In was in the 3+ oxidation state and replaced Zn in the structure of sphalerite, which occurs with the expansion of the nearest coordination shells due to the large In ionic radius. In the presence of In, the oxidation state of Cu and Ag is 1+, and both metals can form an isomorphous solid solution where they substitute for Zn according to the coupled substitution scheme 2Zn2+ ↔ Me+ + In3+. Moreover, Ag K-edges EXAFS spectra fitting, combined with the results obtained for In- and Au-bearing sphalerite shows that the Me-S distances in the first coordination shell in the solid solution state are correlated with the ionic radii and increase in the order of Cu < Ag < Au. The distortion of the atomic structure increases in the same order. The distant (second and third) coordination shells of Cu and Ag in sphalerite are split into two subshells, and the splitting is more pronounced for Ag. Analysis of the EXAFS spectra, coupled with the results of DFT (Density Function Theory) simulations, showed that the In–In and Me+–In3+ clustering is absent when the metals are present in the sphalerite solid solution. Therefore, all studied admixtures (In, Cu, Ag), as well as Au, are randomly distributed in the matrix of sphalerite, where the concentration of the elements in the “invisible” form can reach a few tens wt.%.
      Citation: Minerals
      PubDate: 2020-07-20
      DOI: 10.3390/min10070640
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 641: Cement Render and Mortar and Their Damages
           Due to Salt Crystallization in the Holy Trinity Church, Dominicans
           Monastery in Cracow, Poland

    • Authors: Mariola Marszałek, Krzysztof Dudek, Adam Gaweł
      First page: 641
      Abstract: The investigations focused on the façade of the 17th-century Myszkowskis chapel at the 13th-century Church of the Holy Trinity in Cracow, Poland. Most of the chapel’s façade is made of rusticated limestone blocks, but its lower part is covered with cement render, and the basement consists of irregular pieces of limestone and sandstone, bound and partly replaced with cement mortar. The façade exhibited clearly visible damages: gray soiling of the surface, cracks, scaling, and efflorescence. The study presents characteristics of the cement render and mortar used for stone repair and/or substitution, as well as efflorescence from the lower part of the Myszkowskis chapel façade. The materials were analyzed with optical microscopy, scanning electron microscopy (SEM-EDS), Raman microspectroscopy, X-ray diffractometry (XRPD), and mercury intrusion porosimetry. The analyses demonstrated that the render covering some of the decayed limestone blocks was prepared using Portland cement (residual clinker grains represent alite and belite) as a binding agent, mixed with crushed stone as an aggregate. The cement mortar consisted of rounded quartz grains, rock fragments, and feldspars in very fine-grained masses of calcite and gypsum, also containing relics of cement clinker (alite, belite, ferrite, and aluminate). All these components point out the use of the ordinary Portland cement. Analyses of the efflorescence allowed us to distinguish several secondary salts, among others, thenardite, aphthitalite, and darapskite. The appearance of these phases is related to the composition and physicochemical properties of the building materials, atmospheric alteration agents, air pollution, and some other anthropogenic factors.
      Citation: Minerals
      PubDate: 2020-07-20
      DOI: 10.3390/min10070641
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 642: Constraints on the Petrogenesis and
           Metallogenic Setting of Lamprophyres in the World-Class Zhuxi W–Cu Skarn
           Deposit, South China

    • Authors: Wei Zhang, Shao-Yong Jiang, Tianshan Gao, Yongpeng Ouyang, Di Zhang
      First page: 642
      Abstract: Whole-rock and apatite geochemical analyses and zircon U–Pb dating were carried out on the lamprophyres in the world-class Zhuxi W–Cu skarn deposit in northern Jiangxi, South China, in order to understand their origin of mantle sources and their relationship with the deposit, as well as metallogenic setting. The results show the lamprophyres were formed at ca. 157 Ma, just before the granite magmatism and mineralization of the Zhuxi deposit. These lamprophyres have from 58.98–60.76 wt% SiO2, 2.52–4.96 wt% K2O, 5.92–6.41 wt% Fe2O3t, 3.75–4.19 wt% MgO, and 3.61–5.06 wt% CaO, and enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE), and depletion of high-field-strength elements (HFSE). Apatites in the lamprophyres are enriched in LREE and LILE, Sr, S, and Cl, and have 87Sr/86Sr ratios ranging from 0.7076 to 0.7078. The conclusions demonstrate that the lithospheric mantle under the Zhuxi deposit was metasomatized during Neoproterozoic subduction. Late Jurassic crustal extension caused upwelling of the asthenospheric mantle and consecutively melted the enriched lithospheric mantle and then crustal basement, corresponding to the formation of lamprophyres and mineralization-related granites in the Zhuxi deposit, respectively.
      Citation: Minerals
      PubDate: 2020-07-20
      DOI: 10.3390/min10070642
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 643: Comparison of Detrital Zircon U-Pb and
           Muscovite 40Ar/39Ar Ages in the Yangtze Sediment: Implications for
           Provenance Studies

    • Authors: Xilin Sun, Klaudia F. Kuiper, Yuntao Tian, Chang’an Li, Zengjie Zhang, Jan R. Wijbrans
      First page: 643
      Abstract: Detrital zircon U-Pb and muscovite 40Ar/39Ar dating are useful tools for investigating sediment provenance and regional tectonic histories. However, the two types of data from same sample do not necessarily give consistent results. Here, we compare published detrital muscovite 40Ar/39Ar and zircon U-Pb ages of modern sands from the Yangtze River to reveal potential factors controlling differences in their provenance age signals. Detrital muscovite 40Ar/39Ar ages of the major tributaries and main trunk suggest that the Dadu River is a dominant sediment contributor to the lower Yangtze. However, detrital zircon data suggest that the Yalong, Dadu, and Min rivers are the most important sediment suppliers. This difference could be caused by combined effects of lower reaches dilution, laser spot location on zircons and difference in closure temperature and durability between muscovite and zircon. The bias caused by sediment laser spot targeting a core or rim of zircon and zircon reworking should be considered in provenance studies.
      Citation: Minerals
      PubDate: 2020-07-20
      DOI: 10.3390/min10070643
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 644: Ti-Magnetite Crystallization in Melt
           Inclusions of Trachytic Rocks from the Dokdo and Ulleung Islands, South
           Korea: Implications for Hydrous and Oxidized Magmatism

    • Authors: Inkyeong Moon, Hyunwoo Lee, Jonguk Kim, Jihye Oh, Donghoon Seoung, Chang Hwan Kim, Chan Hong Park, Insung Lee
      First page: 644
      Abstract: The Dokdo and Ulleung islands (Korea) are volcanic islands in the East Sea (Sea of Japan), formed in the late Cenozoic. These volcanic islands, in the back-arc basin of the Japanese archipelago, provide important information about magma characteristics in the eastern margin of the Eurasian plate. The origin of the Dokdo and Ulleung intraplate volcanism is still controversial, and the role of fluids, especially water, in the magmatism is poorly understood. Here, we comprehensively analyzed the melt inclusions (10–100 m in diameter) hosted in clinopyroxene phenocrysts of trachyte, trachyandesite, and trachybasalt. In particular, we observed Ti-magnetite and amphibole which were crystallized as daughter mineral phases within melt inclusions, suggesting that Ti-magnetite was formed in an oxidized condition due to H2O dissociation and H2 diffusion. The Ti-magnetite exhibited compositional heterogeneities of MgO (average of 8.28 wt %), Al2O3 (average of 8.68 wt %), and TiO2 (average of 8.04 wt %). The positive correlation of TiO2 with Cr2O3 is probably attributed to evolutionary Fe–Ti-rich parent magma. Correspondingly, our results suggested hydrous and oxidized magmatism for the Dokdo and Ulleung volcanic islands.
      Citation: Minerals
      PubDate: 2020-07-20
      DOI: 10.3390/min10070644
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 645: Phosphorus Species in Deep-Sea Carbonate
           Deposits: Implications for Phosphorus Cycling in Cold Seep Environments

    • Authors: Junlie Zhou, Mengran Du, Jiwei Li, Hengchao Xu, Kaiwen Ta, Shun Chen, Xiaotong Peng
      First page: 645
      Abstract: Phosphorus (P) is an important nutrient for biological communities in cold seeps. However, our knowledge on the source, species, and cycling of P in cold seep environments is limited. In this study, the concentration, species, and micro to nanometer scale distribution of P in seep carbonates were examined at three deep-sea cold seeps in the South China Sea and East China Sea. The Ca-P accounts for the largest proportion of P—followed by detrital-P, Fe-P, organic-P, and exchangeable-P. The distribution patterns of Ca-P, detrital-P, and organic-P in the seep carbonates differ from one another, as shown by elemental mapping with NanoSIMS and scanning electron microscopy. The covariation of P with Ca and C reveals that Ca-P co-precipitates with Ca-carbonate, which is linked to the process of sulfate-driven anaerobic oxidation of methane. Organic-P is also observed within biofilm-like organic carbon aggregates, revealing the microbial enrichment of P by fluids in the process of anaerobic oxidation of methane. P with a granulated morphology was identified as detrital-P derived from deep sediments. Most importantly, it is evident that Ca-P is positively correlated to the Fe content in all the seep carbonates. This indicates the likelihood that the dissolved P in cold-seep fluids is released primarily from Fe oxides through Fe-driven anaerobic oxidation of methane in deep sediments. These processes associated with different species of P may have significant implications for P geochemical cycling and anaerobic oxidation of methane impelled by Fe and sulfate reduction in cold seep environments.
      Citation: Minerals
      PubDate: 2020-07-21
      DOI: 10.3390/min10070645
      Issue No: Vol. 10, No. 7 (2020)
  • Minerals, Vol. 10, Pages 646: Investigations of Feldspar-Quartz Raw
           Materials After Firing: Effect of Various Na2O/K2O Ratio and Synthetic
           Pigments Addition

    • Authors: Ewa Lewicka, Anita Trenczek-Zajac
      First page: 646
      Abstract: Different techniques (chemical analysis, X-ray diffraction, Mössbauer spectroscopy, UV-Vis-NIR spectrophotometry and chromaticity measurements) were used to study the color variation of feldspathic raw materials after firing at 1200 °C. Two varieties of feldspar-quartz grits (with Na2O or K2O prevalence) doped with synthetic pigments (hematite and rutile) were heat-treated in an oxidizing atmosphere. The results obtained indicate that the color of the ceramic body after firing may not only depend on the presence and analytical content of coloring elements (such as iron and titanium), but on their valence state and the chemical characteristics of the melt itself. The prevalence of larger alkali K+ ions over Na+ ions may cause the reduction of the coordination number of iron. This has a significant effect on the length of the Fe–O bond, which in turn influences the capacity for light absorption of a specific wavelength. The results of spectrophotometric measurements showed pronounced disparity between the raw materials and samples doped with coloring oxides. The introduction of synthetic pigments caused clear changes in the spectral dependence of the total absorbance. The absorbance increased in the whole measuring range, in particular in the visible part of the spectrum. Furthermore, a red-shift of the absorption bands towards longer wavelengths attributed to oxygen-metal charge transfer (OMCT) interactions between Fe3+ and O2− ions as well as to d-d transitions within Fe3+ ions was observed.
      Citation: Minerals
      PubDate: 2020-07-21
      DOI: 10.3390/min10070646
      Issue No: Vol. 10, No. 7 (2020)
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Heriot-Watt University
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