Subjects -> METALLURGY (Total: 58 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access  
Advanced Device Materials     Open Access   (Followers: 3)
American Journal of Fluid Dynamics     Open Access   (Followers: 47)
Archives of Metallurgy and Materials     Open Access   (Followers: 8)
Asian Journal of Materials Science     Open Access   (Followers: 5)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 20)
Complex Metals     Open Access   (Followers: 1)
Corrosion Communications     Open Access   (Followers: 5)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 19)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 10)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 3)
International Journal of Metals     Open Access   (Followers: 6)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 8)
International Journal of Mining and Geo-Engineering     Open Access  
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 4)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 23)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 32)
Journal of Advanced Joining Processes     Open Access  
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 7)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 1)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 18)
Journal of Metallurgical Engineering     Open Access   (Followers: 2)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Engineering     Open Access  
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 42)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 31)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research & Technology     Full-text available via subscription  
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 6)
Metallurgy and Foundry Engineering     Open Access  
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 33)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Rare Metals     Hybrid Journal   (Followers: 1)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access  
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 4)
Soldering & Surface Mount Technology     Hybrid Journal   (Followers: 1)
Stainless Steel World     Full-text available via subscription   (Followers: 17)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 4)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 1)
Welding in the World     Hybrid Journal   (Followers: 4)
Welding International     Hybrid Journal   (Followers: 7)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Mining, Metallurgy & Exploration
Number of Followers: 0  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2524-3462 - ISSN (Online) 2524-3470
Published by Springer-Verlag Homepage  [2469 journals]
  • Research on the Explosion Effects and Fracturing Mechanism of Liquid
           Carbon Dioxide Blasting

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      Abstract: Recently, liquid carbon dioxide (L-CO2) blasting technology has again attracted increasing attention due to its good fracturing effect and safety performance, especially in the research field of coal seam permeability improvement. However, the fracturing mechanism has not been explained. In this paper, the blasting effect of L-CO2 blasting technology was analyzed based on L-CO2 blasting experiments, and the fracturing mechanism of L-CO2 blasting technology was studied from the perspective of stress wave action via theoretical analysis and peridynamic simulations. The research results indicate that (1) after L-CO2 blasting, there is no crush zone around the blasting hole, and only 3 ~ 5 cracks are observed, while the proportion of large fragments is large. (2) A lower loading rate and strength of the stress wave are the main reasons why L-CO2 blasting technology achieves a good fracturing effect. (3) With increasing loading rate of the stress wave, a crush zone is readily formed around the blasting hole, the number of cracks increases, and the radius of the fractured zone decreases under the action of the stress wave.
      PubDate: 2022-01-19
       
  • Numerical Simulation of Mechanical Characteristics in Longwall Goaf
           Materials

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      Abstract: Coal mined-out areas have a significant impact on mining safety and affect the pressure distributions of neighboring coal faces. The PFC3D software is used to study the goaf mechanical characteristics, and the core loading test verifies the rationality of the numerical simulation method. The results from the numerical modeling showed that the void ratio, particle size ratio, and particle size distribution of the rock particle sample (RPS) had a significantly remarkable influence on the compression deformation characteristics of the rock block. The parallel-bond tensile strength and parallel-bond cohesion had a notable impact on the compression deformation traits of the rock block only when the axial stress level was lower than 12 MPa. By contrast, when the axial stress exceeded 5 MPa, the effective modulus significantly influenced the compression deformation features. However, the stiffness ratio, loading rate, and parallel-bond friction angle had almost no effect on the compression deformation characteristics. Furthermore, when the stress level was less than 10 MPa, the stress–strain curves from the rock core samples’ numerical simulation and loading tests were approximately linear. In addition, the Pearson correlation coefficients of the stress–strain curves suggest that the goaf zone’s core numerical simulation results had a robust correlation with the loading test results. The findings of this study can serve as a reference for the field application of PFC3D software and safety assessments in goaves.
      PubDate: 2022-01-18
       
  • Synergistic Extraction and Separation of Cobalt and Lithium Using D2EHPA
           and CYANEX 272

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      Abstract: The focus of this research was to evaluate the synergistic effect of bis(2,4,4-trimethylpentyl) phosphinic acid (CYANEX 272) and di-(2-ethylhexyl) phosphoric acid (D2EHPA), diluted in kerosene, on the extraction and separation of Co(II) and Li(I) from synthetic sulfate solution. The results indicated that using a mixture of CYANEX 272 and D2EHPA was efficient in extracting and separating Co(II) from Li(I). The optimum ratio of CYANEX 272/D2EHPA was found to be 5:1, in which the highest separation factor was obtained (5973.23), and ΔpH0.5 was 4.10. Adding tributyl phosphate (TBP) as a modifier and increasing the temperature improved the metals’ separation rate and extraction efficiency. Thermodynamic studies were also carried out, and ΔH, ΔS, and ΔG values were computed, revealing the endothermic nature of Co(II) and Li(I) extraction by CYANEX 272/D2EHPA mixture. The conducted experiments for the McCabe–Thiele diagram showed the possibility of using two stages to extract over 99% of Co(II) and Li(I). Slope analysis and Fourier transform infrared spectroscopy (FT-IR) were employed to comprehend the Co(II) and Li(I) extraction mechanism using a mixture of CYANEX 272 and D2EHPA. Graphical abstract
      PubDate: 2022-01-17
       
  • A New Method for Intuitively Reflecting the Deterioration Characteristics
           of the Rock Surrounding Roadways and Its Application Based on the Strain
           Softening Model

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      Abstract: To investigate how deformation failure occurs in roadways surrounding rock, the relationship between cohesion and plastic shear strain of the strain softening model and the equation for calculating the shear strain of a rock mass in the ultimate elastic state are derived. On this basis, the equality relationship between the built-in maximum shear strain increment and cohesion of FLAC 3D was established to give a more intuitive picture of how the cohesion of the roadway surrounding rock changes. The cohesion attenuation and deformation of the surrounding rock are analysed. The results show that significant deformation in the roadway surrounding rock was caused primarily by the development of large areas of highly softened plastic rock masses towards residual strength. Taking the floor overhead-mining roadway under different rock pillar thicknesses (RPTs) in the Xinglongzhuang Coal Mine as an example, the results demonstrate that investigating the cohesion distribution inside the roadway during mining operation can provide a more intuitive, more accurate description of the degree of failure of the surrounding rock at any point of the roadway, as well as the overall failure range of the surrounding rock. The simulation agrees well with the field monitoring result and seems to be more practically useful than simply analysing the coverage of shear plastic zones. Based on the failure range and degree of roadway surrounding rock with different RPTs, three support schemes are designed. Classified support was implemented for roadways under different RPTs, which realizes the effective control of roadway surrounding rock.
      PubDate: 2022-01-16
       
  • Strategies for Recycling of Primary and Secondary Resources for Germanium
           Extraction

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      Abstract: In this review, availability of germanium in primary and secondary resources and its recovery from these resources are presented. With nearly 40% germanium consumed in fiber optics and scarcity of resources, the global consumption outplays the primary production. Germanium exists as a substituted element in zinc sulfide matrix of lead–zinc sulfides and lignites. Nearly 60% of the germanium supply is met by zinc refining residues, and about 20–30% of germanium is produced from coal and its by-products. Germanium recovery from various resources such as zinc plant residues, coal and coal plant waste, spent optical fibers, and copper flue dust has been examined. Bioleaching was exploited by few researchers to extract germanium from zinc sulfides, sulfide tailings, jarosite, coal fly ash, and flue dust. This review covers the various work carried out by different chemical separation processes, viz., chemical precipitation, solvent extraction (SX), ion exchange (IX), and membrane processes, as well as biological approaches.
      PubDate: 2022-01-16
       
  • Heat Stress in Underground Mines and its Control Measures: A Systematic
           Literature Review and Retrospective Analysis

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      Abstract: Heat stress is a major concern for the health, safety and productivity of miners working in hot and humid underground mines. At greater depth, heat inside underground mines increases due to geothermal gradient, heat released from high-capacity machinery, exposed rock surface, auto-compression of air, human metabolism, etc. Prolonged physical work in thermal environments severely affects the health, safety and efficiency of miners. In order to address this important issue, a systematic literature review (SLR) has been conducted. This SLR aimed to identify the research gap in the area of heat stress effect on underground miners and its control. An extensive literature search was carried out on numerous digital databases, grey literature and conference proceedings to identify relevant research work for this review. Moreover, the impactful studies, methodologies and preventive measures undertaken during the past five decades on the effect of heat stress on underground miners were retrospectively analysed, with a broader aim to explore the need for further research on this pertinent topic. Overall, 571 references were identified from the literature review, out of which 51 research articles addressing the sources of heat, heat stress effects on miners, heat stress indices and control measures for heat stress in underground mines were selected as primary papers for detailed review. Pre-developed fatigue is one of the prime causes of health hazard, safety and productivity loss of miners working in underground high heat stress zones. Hence, development of a better heat stress index integrating personal, environmental parameters and pre-developed fatigue (PDF) of miners is essential.
      PubDate: 2022-01-14
       
  • Coal and Rock Classification with Rib Images and Machine Learning
           Techniques

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      Abstract: Classification of rock and coal is one preliminary problem for fully automated or intelligent mining. It assists for the automated rib stability analysis and enables the shearer to adjust the drums without human intervention. In this paper, the classification of rock from coal on rib images has been studied with machine learning techniques. A database of rock and coal image has been created by filtering photographs taken by NIOSH researchers in gateroad during site visits and only the images with fresh areas of rock and coal on the rib were selected. Machine learning was conducted on patches with a determined size, which are smaller images randomly extracted from each rock or coal image. After training, the classifier was validated with the testing dataset and an accuracy score of 0.9 was obtained. The influence of patch size and classifier was also investigated. The trained classifier was then applied to classify rock and coal on a new rib image with three rock layers of different thicknesses and good agreement was achieved.
      PubDate: 2022-01-13
       
  • Air Quality Impact Assessment and Management of Mining Activities Around
           an International Heritage Site in India

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      Abstract: A comprehensive field study has been carried out to measure the background air quality status and identify the air pollution sources from opencast mines around a heritage site in India. Air quality modeling has been carried out to envisage dust concentration due to the existing and closed mines in the region. The predicted total PM10 and PM2.5 levels at the selected receptor locations ranged from 86.39 to 194.89 and from 34.82 to 99.55 μg m−3, respectively. The air quality modeling exercise predicted that levels of PM10 and PM2.5 might increase from 3.2 to 23.1 and from 2.1 to 8.9 μg m−3 respectively due to mining activities when some of the closed mines will be operated in the region without the controlled emission. Hence, adequate measures have been suggested to control air pollution from mining activities. An intelligent dry fog system has been designed to suppress dust emission efficiently from mineral processing plants and opencast mines. The developed system has special features for facilitating eco-friendly mining.
      PubDate: 2022-01-12
       
  • A High-Precision Road Network Construction Method Based on Deep Learning
           for Unmanned Vehicle in Open Pit

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      Abstract: To solve the problem of time-consuming and low precision in updating the open-pit vehicle transportation network, a high precision road network model construction method for unmanned vehicles in open-pit mines is proposed. This method can be divided into two steps. In the first step, an improved deep learning image processing model named DeepLabv3 + C (DeepLabv3 + Concat) is presented. Then, the road information extracted by the DeepLabv3 + C network is used to construct a three-dimensional model of the open-pit mine road network. In the second step, aiming at the time-consuming problem of unmanned vehicle meeting in open-pit mines, a vehicle meeting strategy was proposed. This strategy is used to guide the navigation of unmanned vehicles in open-pit mines. Besides, the DeepLabv3 + C network is verified by comparing the mIOU (means Intersection Over Union), accuracy, and continuity of road image extraction with the mainstream networks. The road network model constructed in the first step is quantitatively analyzed, and its performance is compared with GPS trajectory clustering methods. At the end of the paper, vehicle running simulation is carried out on the road network model by using Unity (a 3D visualization simulation software). The results show that the road network model constructed by this method can meet the navigation requirements of unmanned vehicles in open-pit mines, and the feasibility of the vehicle meeting strategy is proved.
      PubDate: 2022-01-11
       
  • DEM Analysis of the Effect of Lamination Properties on the Stability of an
           Underground Coal Mine Entry with Laminated Shale Roof

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      Abstract: The effect of discontinuities on the fracturing and mechanical behavior of shale has been extensively investigated on a laboratory scale in previous works. It is well agreed that the lamination properties, including discontinuity and lamina properties, affect the behavior of shale. However, it is still unclear how the lamination properties are affecting the stability of the shale roof in an underground coal mine entry. This paper investigated the effect of lamination properties using discrete element method on a mine-scale entry model as an extension to the previous work conducted on laboratory scale models (Q. Shi and B. Mishra, Discrete Element Modeling of Delamination in Laboratory Scale Laminated Rock, Mining, Metallurgy & Exploration, vol. 37, no. 5, pp. 1–14, Sep. 2020). The microparameters for both the laminas and discontinuities were calibrated with laboratory data. In the calibration, a numerical laminated Brazilian disc was created and tested for comparison with laboratory results. The effects of lamina thickness, discontinuity strength, and supporting pressure on the model’s roof strength and the stress distribution were also investigated. Numerical results showed that the lamination properties and supporting pressure contribute significantly to the stress distribution in the roof and its stability. The horizontal stress at a fixed depth in the roof increased with the lamina thickness, discontinuity strength, and supporting pressure. The laminated roof strength was found to increase with the increase of lamina thickness but never exceeds the strength of an intact roof comprising the only matrix.
      PubDate: 2022-01-11
       
  • Experimental Quantification of Granular Material Fragmentation Due to
           Travel Distance

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      Abstract: In underground mining, rock fragment size is a key variable for productivity because it impacts equipment selection and mining structure design, such as for drawbells and ore passes. During ore flow, those structures are usually affected by interferences such as hang-ups and issues associated with oversized rocks or fine materials. Fine materials could imply problems with mudrush and/or inrush of fines. The rock fragment sizes must be estimated, in particular, in block caving where fragmentation develops naturally while the broken ore is being drawn. Nowadays, estimation tools and models are available to estimate fragmentation, but some variables have yet to be studied to understand their effect on the fragmentation process. One such variable whose mechanisms have yet to be studied is the residence time, which in block caving directly depends on the distance that fragments travel from their original position in the broken ore to the drawpoint. A greater degree of fragmentation is expected for longer distances. In this study, granular material fragmentation was characterized during its flow to understand its characteristics and mechanisms. Tests were done using a laboratory setup built to emulate various heights where material is drawn. The fragment-size distribution was measured before and after tests for clay, concrete fragments, and gravel. It was found that for 6 m of travel distance, fragmentation mainly occurs in minor sizes where d10 decreases by 4.7% for gravel, 6.2% for concrete, and by 63.1% for clay. The breakage of fragment singularities occurred mainly within medium and smaller sizes, increasing fine material. Thus, the main fragmentation mechanism in experiments was identified as abrasion between rock fragments where fine material continuously increases as distance increases in spite of the high rock strength and the piston flow movement used. Then, in block caving mines, the higher the draw column, the more fine material is expected to be generated.
      PubDate: 2022-01-10
       
  • Exploring Worker Experience as a Predictor of Routine and Non-routine
           Safety Performance Outcomes in the Mining Industry

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      Abstract: In recent years, there has been increasing interest in the role that individual factors play in health and safety (H&S) outcomes in the mining industry. Two surveys, one measuring self-reported routine safety performance and one measuring individual perceived competence in the non-routine knowledge, skills, and abilities (KSAs) critical to emergency response, were administered to two samples of mineworkers in separate research studies over a 2-year period (N = 2,020 and 696, respectively). Eight demographic items were common to both surveys and their associations with each performance outcome were tested in response to a series of exploratory research questions. Significant relationships were found between both safety outcome variables and individual factors, including the length of experience in current job, current mine, and mining industry, as well as participant workgroup and work schedule. Notably, the length of experience in the mining industry was the only variable significantly associated with both routine and non-routine safety performance. This analysis suggests that individual factors such as length of job, industry, and mine experience are predictive of routine and/or non-routine safety performance outcomes in significant and sometimes unexpected ways.
      PubDate: 2022-01-09
       
  • Spigot Design Modification to Alleviate Roping in Hydrocyclones

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      Abstract: Roping in hydrocyclones is a well-known phenomenon in mining and mineral industries which put serious restrictions on their continuous and maintenance free operation. Roping is mostly observed in association with high underflow solid concentrations which can be attributed to higher fraction of solids reporting to the underflow or the feed solid concentration itself being higher. This paper proposes a newly designed spigot with a truncated conical geometry which can allow for a rope-free discharge at higher feed solid concentrations. The experimental observations revealed that in the operation of a 50.8-mm-diameter hydrocyclone, roping ensued at 10% to 12.5% (wt%) feed solid concentration depending on feed inlet pressure for the cylindrical spigot, whereas with the modified spigot, rope free discharge was attained even at 25% (wt%) feed solid concentration.
      PubDate: 2022-01-08
       
  • Thermo-adhesive Separation: a Novel Dry Coal Beneficiation Technique

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      Abstract: Water is the mainstay for beneficiation of fine size coal and minerals; however, it is also the least desirable constituent in the final product. The basic concept of the novel process described in this paper is based on the differential surface heat conduction/absorption capacity of individual particles, which differs for different species of minerals. When a mixture of fine material is exposed to a radiant energy source, the various solids present in the mixture will absorb heat energy depending on their heat-conducting properties and there will be a difference in the surface temperature of the particles. When this differentially heated solid mixture is placed on a moving belt, which is coated with a low temperature melting resin, the hotter component of the mixture will stick to the belt and relatively cooler particles will stay free on the belt and fall off at the end of the belt run. Experiments were conducted with pyrite, coal, and quartz of 6 × 18 mesh particle size. The goal of the test program was to find the optimum conditions at which there exists a required temperature difference between minerals and coal particles by controlling the operating system variables. Preliminary tests results showed that there is a potential for separating mineral matter from coal using the thermo-adhesive separation technique.
      PubDate: 2022-01-06
       
  • Area Noise Assessment at Surface Stone, Sand, and Gravel Mines:
           Application for Reducing Worker Noise Exposure

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      Abstract: Repeated noise exposure and occupational hearing loss are common health problems across industries and especially within the mining industry. Large mechanized processes, blasting, grinding, drilling, and work that is often in close quarters put many miners at an increased risk of noise overexposure. In stone, sand, and gravel mining, noise is generated from a variety of sources, depending on the type of ore being mined as well as the final consumer product provided by that mine. Depending on the source of noise generation, different strategies to reduce and avoid that noise should be implemented. The National Institute for Occupational Safety and Health (NIOSH) has evaluated the noise profile at three operational surface stone, sand, and gravel mines. A-weighted sound level meter data as well as phase array beamforming data were collected throughout the mines in areas with high noise exposure or high personnel foot or vehicle traffic. Sound level meter data collected on a grid pattern was used to develop sound profiles of the working areas. These sound contour maps as well as phase array beamforming plots were provided to the mines as well as guidance to modify work areas or personnel traffic to reduce noise exposure.
      PubDate: 2022-01-06
       
  • Fundamentals and Applications of Green Modifiers for Froth Flotation

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      Abstract: Low-cost and environment-friendly green froth flotation modifiers of plant origin, such as guar gum, carboxymethyl cellulose (CMC), and starch, have been used in flotation of some sulfide and non-sulfide minerals. Certain green modifiers may be used as dispersants, flocculants, depressants, or activators. The functions of green modifiers in froth flotation highly depend on their molecular composition, flotation slurry chemistry, hydrodynamic conditions, etc. This paper will discuss the fundamentals, current applications, and potential new applications of guar gum, CMC, and corn starch in valuable minerals (phosphate, potash, and iron ores) and the unwanted gangue minerals (silica and clay minerals) flotation. In this study, improved flotation performance was achieved using some green modifiers in flotation columns with the more plug-flow environments than in conventional flotation cells approaching perfectly mixed conditions. This is because the hydrodynamic cavitation-generated ultrafine bubbles could help bridge ultrafine particles to form aggregates, promote the formation of flocs, and increase the stability of flocs.
      PubDate: 2022-01-06
       
  • A New High Charge Density Superplasticizer Regulates the Rheological
           Properties of Tailings Slurry and Cemented Paste Backfill Materials

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      Abstract: To improve the pumping capacity and engineering efficiency of fresh thickened tailings slurry, a high charge density superplasticizer was developed to improve the rheological properties of tailings slurry. The effects of superplasticizer content, the concentration and fineness of tailings, the proportion and type of cementitious materials, temperature, and hydration time on the rheological properties of unclassified tailings slurry and backfill materials were studied. The variation characteristics of the slurry yield stress, plastic viscosity, and thixotropy with different factors were measured by a Brookfield R/S-SST plus rheometer. The experimental results of fresh thickened tailings illustrated that the higher the concentration of the slurry and the finer the tailings, the worse the rheological properties of the slurry. The results of cemented paste backfill materials indicated that the rheological parameters increased as binder content and time increased. The rheological parameters decreased as the temperature increased. The addition of a superplasticizer reduced the rheological parameters and improved the rheological behavior of the fresh thickened tailings and cemented paste backfill materials, which was beneficial to the slurry’s pipeline transportation. This paper can provide technical guidance for slurry transportation in the backfill system and provide a reference for designing the superplasticizer used in tailings.
      PubDate: 2022-01-05
       
  • Preface to the MME Special Focus Issue in Memory of Emeritus Professor
           Frank F. Aplan: Between Theory and Practice

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      PubDate: 2022-01-03
       
  • Use of a New Insertion Apparatus for Improving Performances of the
           Friction Rock Stabilizers

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      Abstract: To improve the load bearing capacities and insertion efficiency of the split set type friction bolts, a new apparatus has been designed and produced within this study. A series of laboratory and site studies were carried out to investigate the usability of the new apparatus. According to the results, the new apparatus was found advantageous in terms of the insertion practicality and prevention of the buckling problem. Additionally, the new apparatus was determined to increase the load bearing capacities of the bolts according to the results obtained from the pull-out test. The new apparatus decreases the friction during the bolt insertion by a temporary diametric compression of the split tubes. By allowing increases in the ratio of bolt diameter to drill hole diameter without the buckling problem during the insertion, the new apparatus supplies higher normal stresses and friction capacity at the bolt and rock contacts after opening its clamping mechanism.
      PubDate: 2022-01-03
       
  • Oxidation of Pyrite Using Ozone Micro-Nano Bubbles

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      Abstract: Pyrite, a mineral associated with uranium ore, is closely related to uranium leaching. In this study, Ozone micro-nano bubbles (OMNBs), as an environmentally friendly advanced oxidation technology, were used for the first time to oxidize pyrite under experimental conditions to improve the leaching rate of uranium. A laboratory-scale agitation leaching experiment of pyrite was carried out with a pH of 1.0–3.0, gas flow of 1–3 L/min, ozone generation rate of 0.55–2.22 mg/s, and pyrite concentration of 0.1–5.0 g/L for 1 h. By adding three different co-oxidant: Mn(II), Mn(IV), and Fe(III), it was found that only Mn(IV) increased the oxidation rate of pyrite by 21.7%. The results of the scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) show that the formation of Fe(III)-O film on the surface of the ore suppresses the oxidation rate of pyrite to a certain extent. Pyrite can be rapidly oxidized up to 57.6% by OMNBs, which is beneficial to uranium leaching. This method is expected to be used for in situ acid leaching of uranium with OMNBs injected into the ground.
      PubDate: 2022-01-03
       
 
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