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Minerals, Volume 11, Issue 9 (September 2021) – 116 articles

Cover Story (view full-size image): Eudialyte is the main source of Zr in the Mt. Alluaiv–Mt. Kedykvyrpakhk deposits. In the crystal structure of Zr, rich eudialyte occupies a special M1A site, leading to the lowering of total eudialyte symmetry from R-3m to R32. View this paper
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14 pages, 2301 KiB  
Article
Possibilities of Graphitization of Unburned Carbon from Coal Fly Ash
by Zdzisław Adamczyk, Joanna Komorek, Barbara Białecka, Joanna Całus-Moszko and Agnieszka Klupa
Minerals 2021, 11(9), 1027; https://doi.org/10.3390/min11091027 - 21 Sep 2021
Cited by 9 | Viewed by 2476
Abstract
The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with [...] Read more.
The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with an admixture of some minerals has been found in samples subjected to graphitization. However, the graphite phase is dominant in products subjected to graphitization. Studies have also shown a diverse grain morphology in individual samples. The presence of plate-shaped and tube-shaped grains was found. As the graphitization temperature of the starting material increases (2400 and 3000 °C), the specific surface area in the graphitization products decreases. The total pore volume in the samples after the graphitization process was significantly lower than the pore volume of active carbons produced from other unburned carbon. Average pore diameter is similar to the pore diameter in active carbons. The reflectance value of the matrix for the sample graphitized at 3000 °C is characteristic for graphite. Unburned carbon from Polish fly ash can be used as the starting material for graphitization. Full article
(This article belongs to the Special Issue Geochemistry and Mineralogy of Coal-Bearing Rocks)
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23 pages, 5098 KiB  
Article
Evolution of the Reaction and Alteration of Mudstone with Ordinary Portland Cement Leachates: Sequential Flow Experiments and Reactive-Transport Modelling
by Keith Bateman, Shota Murayama, Yuji Hanamachi, James Wilson, Takamasa Seta, Yuki Amano, Mitsuru Kubota, Yuji Ohuchi and Yukio Tachi
Minerals 2021, 11(9), 1026; https://doi.org/10.3390/min11091026 - 21 Sep 2021
Cited by 2 | Viewed by 2028
Abstract
The construction of a repository for geological disposal of radioactive waste will include the use of cement-based materials. Following closure, groundwater will saturate the repository and the extensive use of cement will result in the development of a highly alkaline porewater, pH > [...] Read more.
The construction of a repository for geological disposal of radioactive waste will include the use of cement-based materials. Following closure, groundwater will saturate the repository and the extensive use of cement will result in the development of a highly alkaline porewater, pH > 12.5; this fluid will migrate into and react with the host rock. The chemistry of the fluid will evolve over time, initially high [Na] and [K], evolving to a Ca-rich fluid, and finally returning to the groundwater composition. This evolving chemistry will affect the long-term performance of the repository, altering the physical and chemical properties, including radionuclide behaviour. Understanding these changes forms the basis for predicting the long-term evolution of the repository. This study focused on the determination of the nature and extent of the chemical reaction, as well as the formation and persistence of secondary mineral phases within a mudstone, comparing data from sequential flow experiments with the results of reactive transport modelling. The reaction of the mudstone with the cement leachates resulted in small changes in pH with the precipitation of calcium aluminium silicate hydrate (C-(A-)S-H) phases of varying compositions. As the system evolves, secondary C-(A-)S-H phases re-dissolve and are replaced by secondary carbonates. This general sequence was successfully simulated using reactive transport modelling. Full article
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25 pages, 8159 KiB  
Review
Thermochronology of Alkali Feldspar and Muscovite at T > 150 °C Using the 40Ar/39Ar Method: A Review
by Richard A. Spikings and Daniil V. Popov
Minerals 2021, 11(9), 1025; https://doi.org/10.3390/min11091025 - 21 Sep 2021
Cited by 10 | Viewed by 2657
Abstract
The 40Ar/39Ar method applied to K-feldspars and muscovite has been often used to construct continuous thermal history paths between ~150–600 °C, which are usually applied to structural and tectonic questions in many varied geological settings. However, other authors contest the [...] Read more.
The 40Ar/39Ar method applied to K-feldspars and muscovite has been often used to construct continuous thermal history paths between ~150–600 °C, which are usually applied to structural and tectonic questions in many varied geological settings. However, other authors contest the use of 40Ar/39Ar thermochronology because they argue that the assumptions are rarely valid. Here we review and evaluate the key assumptions, which are that (i) 40Ar is dominantly redistributed in K-feldspars and muscovite by thermally-driven volume diffusion, and (ii) laboratory experiments (high temperatures and short time scales) can accurately recover intrinsic diffusion parameters that apply to geological settings (lower temperatures over longer time scales). Studies do not entirely negate the application of diffusion theory to recover thermal histories, although they reveal the paramount importance of first accounting for fluid interaction and secondary reaction products via a detailed textural study of single crystals. Furthermore, an expanding database of experimental evidence shows that laboratory step-heating can induce structural and textural changes, and thus extreme caution must be made when extrapolating laboratory derived rate loss constants to the geological past. We conclude with a set of recommendations that include minimum sample characterisation prior to degassing, an assessment of mineralogical transformations during degassing and the use of in situ dating. Full article
(This article belongs to the Special Issue Thermochronology at Temperatures Higher than 150 °C)
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28 pages, 11814 KiB  
Article
Petrography, Mineralogy, and Geochemistry of Thermally Altered Coal in the Tashan Coal Mine, Datong Coalfield, China
by Xiaoxia Song, Hongtao Ma, Benjamin M. Saalidong and Kaijie Li
Minerals 2021, 11(9), 1024; https://doi.org/10.3390/min11091024 - 21 Sep 2021
Cited by 9 | Viewed by 3258
Abstract
A suite of coal samples near a diabase dike were collected to investigate the petrographic, mineralogical, and geochemical characteristics of thermally altered coal in Datong Coalfield, China. Proximate analysis, vitrinite reflectance measurement, and petrographic analysis were applied to identify and characterize the alteration [...] Read more.
A suite of coal samples near a diabase dike were collected to investigate the petrographic, mineralogical, and geochemical characteristics of thermally altered coal in Datong Coalfield, China. Proximate analysis, vitrinite reflectance measurement, and petrographic analysis were applied to identify and characterize the alteration halo; optical microscope observation, qualitative X-ray diffractometry, and SEM-EDS were applied to study the phases, occurrence, and composition of minerals; XRF, ICP-MS, and AFS were applied to determine concentrations of major and trace elements; and the occurrence modes of elements were studied by correlation and hierarchical cluster analysis as well as SEM-EDS. The results demonstrated that the 3.6 m dike has caused an alteration halo of approximately 2 m in diameter. In addition, the thermally altered coals were characterized by high vitrinite reflectance, low volatile matter, and the occurrence of thermally altered organic particles. Dolomite and ankerite in the thermally altered coal may be derived from hydrothermal fluids, while muscovite and tobelite may be transformed from a kaolinite precursor. The average concentration of Sr in the Tashan thermally altered coal reached 1714 μg/g, which is over 12 times that of the Chinese coal; the phosphate minerals and Sr-bearing kaolinite account for this significant enrichment. The cluster analysis classified elements with geochemical associations into four groups: group 1 and 2 were associated with aluminosilicates, clays, and carbonates and exhibited enrichment in the coal/rock contact zone, indicating that the dike may be the source of the elements; group 3 included P2O5, Sr, Ba, and Be, which fluctuate in coals, suggesting that their concentrations were influenced by multiple-factors; group 4 did not manifest obvious variations in coals, implying that the coal itself was the source. Full article
(This article belongs to the Special Issue Geochemistry and Mineralogy of Coal-Bearing Rocks)
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15 pages, 29140 KiB  
Article
Incorporation of Geometallurgical Input into Gold Mining System Simulation to Control Cyanide Consumption
by Javier Órdenes, Ryan Wilson, Felipe Peña-Graf and Alessandro Navarra
Minerals 2021, 11(9), 1023; https://doi.org/10.3390/min11091023 - 20 Sep 2021
Cited by 6 | Viewed by 2239
Abstract
The Alhué deposit (Melipilla, Chile) is an example of a hydrothermal Au-Ag-Zn(-Pb) vein system hosted within the volcanic rocks of the Las Chilcas Formation. The dominant ore minerals observed are free electrum and native gold associated with silver sulfosalts, and with magnetite and [...] Read more.
The Alhué deposit (Melipilla, Chile) is an example of a hydrothermal Au-Ag-Zn(-Pb) vein system hosted within the volcanic rocks of the Las Chilcas Formation. The dominant ore minerals observed are free electrum and native gold associated with silver sulfosalts, and with magnetite and base metal sulphides, including pyrite +/− sphalerite-galena-chalcopyrite. The alteration assemblage in the veins mainly consists of quartz epidote-chlorite-actinolite with lesser smectite, amphibole, and calcite-kaolinite-garnet. Mineralized veins also contain variable amounts of base metals, some of which (e.g., copper and iron) are considered harmful to the extraction of precious metals. Iron and especially copper minerals are known cyanide consumers; ore type classification schemes that do not consider the detrimental effects of such mineralogy or process elements can ultimately result in metal losses from ore feed restrictions, as well as spikes in cyanide consumption and higher operating costs. Mineralogical and geological variation can nonetheless be managed by applying alternating modes of operation as demonstrated in this paper; the decision to switch between modes is governed by current and forecasted stockpile levels feeding into the process. Simulations based on experiences at the Alhué deposit are provided that demonstrate the importance of standardized operational modes and their potential impact on cyanide consumption control. Full article
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14 pages, 3561 KiB  
Article
Recovery of Valuable Metals from Nickel Smelting Slag Based on Reduction and Sulfurization Modification
by Wei Sun, Xiong Li, Runqing Liu, Qilin Zhai and Jie Li
Minerals 2021, 11(9), 1022; https://doi.org/10.3390/min11091022 - 19 Sep 2021
Cited by 10 | Viewed by 4398
Abstract
Nickel smelting slag contains valuable metals including nickel and copper. Failure to recycle these metals wastes resources, and disposal of nickel slag in stockpiles results in environmental pollution. Nickel slag recycling is important, and metals can be recovered from slag by flotation. However, [...] Read more.
Nickel smelting slag contains valuable metals including nickel and copper. Failure to recycle these metals wastes resources, and disposal of nickel slag in stockpiles results in environmental pollution. Nickel slag recycling is important, and metals can be recovered from slag by flotation. However, considering the complex forms in which valuable metals occur in nickel slag, high yields are difficult to achieve by direct flotation. In this study, nickel slag was modified by reduction and sulfurization to render it more amenable to metal recovery through flotation. The mechanism was assessed based on thermodynamics and elements’ phase distributions. Thermodynamic analyses indicated the feasibility of nickel slag modification by reduction–sulfurization smelting. The results of chemical phase analysis show that the forms in which valuable metals occur in nickel slag can be modified by reduction–sulfurization, and the proportion of metals existing in sulfide and free metal states in nickel slag can be increased. Compared with the direct flotation of raw slag, the recovery of nickel and copper from top-blowing slag increased by 23.03% and 14.63%, respectively. The recoveries of nickel and copper from settling slag increased by 49.68% and 43.65%, respectively. Full article
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11 pages, 2110 KiB  
Article
Flotation of Carbonaceous Matter from a Double Refractory Gold Ore: The Effect of MIBC on Flotation Performance and Kinetics
by Sugyeong Lee, Charlotte E. Gibson and Ahmad Ghahreman
Minerals 2021, 11(9), 1021; https://doi.org/10.3390/min11091021 - 19 Sep 2021
Cited by 7 | Viewed by 2845
Abstract
The use of alkaline pressure oxidation to pretreat refractory gold ore often results in insufficient gold recovery (<60%) in downstream thiosulfate leaching. To improve gold recovery, flotation was considered for the separation of carbonaceous matter (C-matter). In this study, the effect of MIBC [...] Read more.
The use of alkaline pressure oxidation to pretreat refractory gold ore often results in insufficient gold recovery (<60%) in downstream thiosulfate leaching. To improve gold recovery, flotation was considered for the separation of carbonaceous matter (C-matter). In this study, the effect of MIBC on C-matter flotation was investigated to understand the role of the frother in bubble and froth formation and on flotation kinetics. MIBC dosages between 30 and 150 g/t were used in combination with 500 g/t of kerosene as a collector. The results showed that the recovery and selectivity of C-matter were improved with increasing MIBC dosages. Improved selectivity at higher MIBC dosages was attributed to faster C-matter recovery as bubble size decreased to the critical coalescence concentration (CCC) and to changes to the foam structure. Analysis of flotation kinetics showed that the flotation rate increased as the MIBC dosage increased due to the decreasing bubble size and the reduced induction time caused by the interaction between the collector and the frother. The results of this study explain the role of MIBC in C-matter flotation and can be used as a design basis for scavenger-cleaner flotation testing. Overall, the results show the potential for flotation as a means to improve gold recovery in thiosulfate leaching through the removal of C-matter. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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14 pages, 8235 KiB  
Article
Copper Extraction from Oxide Ore of Almalyk Mine by H2SO4 in Simulated Heap Leaching: Effect of Particle Size and Acid Concentration
by Chan-Ung Kang, Seung-Eun Ji, Thomas Pabst, Kung-Won Choi, Moonis Ali Khan, Rahul Kumar, Prakash Krishnaiah, Yosep Han, Byong-Hun Jeon and Do-Hyeon Kim
Minerals 2021, 11(9), 1020; https://doi.org/10.3390/min11091020 - 18 Sep 2021
Cited by 4 | Viewed by 5775
Abstract
In this investigation, a laboratory-scale study to extract copper (Cu) from its oxide ore (0.425–11.2 mm particle size) was conducted using varied sulfuric acid (H2SO4) concentrations (0.05–0.5 M) as a lixiviant. Through a physicochemical and mineralogical analysis of real [...] Read more.
In this investigation, a laboratory-scale study to extract copper (Cu) from its oxide ore (0.425–11.2 mm particle size) was conducted using varied sulfuric acid (H2SO4) concentrations (0.05–0.5 M) as a lixiviant. Through a physicochemical and mineralogical analysis of real field ore samples from the Almalyk mine heap site (Tashkent, Uzbekistan), malachite was identified as a Cu-bearing mineral. Extraction rates were analyzed according to the ore particle size and acid concentration. The Cu extraction with the smallest particle size (in 24 h) varied between 76.7% and 94.26% at varied H2SO4 concentrations (0.05–0.5 M). Almost half (50%) of Cu was extracted from the ore within 4 and 72 h of contact time for 0.425–2 mm and 5.6–11.2 mm particle sizes, respectively, using 0.15 M H2SO4. Weeklong leaching experiments with 0.5 M H2SO4 revealed a higher copper extraction rate (≥73%) from coarse ore particles (5.6–11.2 mm). Along with the copper extraction, iron (29.6 wt%), aluminum (70.2 wt%), magnesium (85.4 wt%), and calcium (44.4 wt%) were also leached out considerably through the dissolution of silicate and carbonate gangue minerals. In this study, an 80.0–94.26% copper extraction rate with reduced acid consumption (20%) proved to be a cost-effective approach. Full article
(This article belongs to the Special Issue Recent Advances in Copper Ore Processing and Extraction)
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27 pages, 16591 KiB  
Article
Geochemical Characteristics, Palaeoenvironment and Provenance of Uranium-Bearing Sandstone in the Sifangtai Formation, Northern Songliao Basin, Northeast China
by Yan Li, Feng-Jun Nie, Li-Cheng Jia, Sheng-Jun Lu and Zhao-Bin Yan
Minerals 2021, 11(9), 1019; https://doi.org/10.3390/min11091019 - 18 Sep 2021
Cited by 8 | Viewed by 2192
Abstract
During the Cretaceous period of the northern Songliao Basin (northeast of China), a 100 m thick layer of fluvial-phase sandstone (Sifangtai Formation) with uranium potential was widely deposited, but its geochemical characteristics, paleoenvironment, and provenance remain unknown. This research proposes a new set [...] Read more.
During the Cretaceous period of the northern Songliao Basin (northeast of China), a 100 m thick layer of fluvial-phase sandstone (Sifangtai Formation) with uranium potential was widely deposited, but its geochemical characteristics, paleoenvironment, and provenance remain unknown. This research proposes a new set of relevant geochemical data for sandstones to investigate their paleoenvironment, provenance and tectonic setting. The results revealed that: (1) The sandstone of the Sifangtai Formation was dominated by feldspar lithic sandstone. Geochemical signatures demonstrate that these sandstones have a high silicon content (SiO2 = 68.30~83.60 wt%) and total alkali content, but are poor in magnesium and calcium. They are also enriched in Rb, Th, U, K and LREE, and depleted HFSE (e.g., Nb, Ta), with crustal magmatic source. (2) The paleoclimate discriminant indicated that the rocks of the Sifangtai Formation might that the climate of Sifangtai Formation is semi-arid, and the chemical weathering of the source rocks is weak under the semi-arid climate environment. (3) The combination of element Sr/Ba, 100 MgO/Al2O3 and the combination of v/v + Ni, V/Cr, Ni/Co, and Sr/Cu indicated that the paleo-water medium was deposited in an oxygen-rich freshwater environment when the Sifangtai Formation was deposited. (4) The discriminate diagrams showed that almost all the sandstones of the Sifangtai Formation fell in the range of the active continental margin, indicating that the source area of the sandstones of Sifangtai Formations is an active continental margin tectonic environment, and the source is a felsic rock developed in the Xiaoxing’an Ridge and Zhangguangcailing area. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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18 pages, 8780 KiB  
Article
Dislocation Creep of Olivine and Amphibole in Amphibole Peridotites from Åheim, Norway
by Sejin Jung, Takafumi Yamamoto, Jun-ichi Ando and Haemyeong Jung
Minerals 2021, 11(9), 1018; https://doi.org/10.3390/min11091018 - 18 Sep 2021
Cited by 4 | Viewed by 2643
Abstract
Amphibole peridotite samples from Åheim, Norway, were analyzed to understand the deformation mechanism and microstructural evolution of olivine and amphibole through the Scandian Orogeny and subsequent exhumation process. Three Åheim amphibole peridotite samples were selected for detailed microstructural analysis. The Åheim amphibole peridotites [...] Read more.
Amphibole peridotite samples from Åheim, Norway, were analyzed to understand the deformation mechanism and microstructural evolution of olivine and amphibole through the Scandian Orogeny and subsequent exhumation process. Three Åheim amphibole peridotite samples were selected for detailed microstructural analysis. The Åheim amphibole peridotites exhibit porphyroclastic texture, abundant subgrain boundaries in olivine, and the evidence of localized shear deformation in the tremolite-rich layer. Two different types of olivine lattice preferred orientations (LPOs) were observed: B- and A-type LPOs. Electron backscatter diffraction (EBSD) mapping and transmission electron microscopy (TEM) observations revealed that most subgrain boundaries in olivine consist of dislocations with a (001)[100] slip system. The subgrain boundaries in olivine may have resulted from the deformation of olivine with moderate water content. In addition, TEM observations using a thickness-fringe method showed that the free dislocations of olivine with the (010)[100] slip system were dominant in the peridotites. Our data suggest that the subgrain boundaries and free dislocations in olivine represent a product of later-stage deformation associated with the exhumation process. EBSD mapping of the tremolite-rich layer revealed intracrystalline plasticity in amphibole, which can be interpreted as the activation of the (100)[001] slip system. Full article
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18 pages, 2850 KiB  
Article
Thermally Induced Bentonite Alterations in the SKB ABM5 Hot Bentonite Experiment
by Ritwick Sudheer Kumar, Carolin Podlech, Georg Grathoff, Laurence N. Warr and Daniel Svensson
Minerals 2021, 11(9), 1017; https://doi.org/10.3390/min11091017 - 18 Sep 2021
Cited by 10 | Viewed by 2985
Abstract
Pilot sites are currently used to test the performance of bentonite barriers for sealing high-level radioactive waste repositories, but the degree of mineral stability under enhanced thermal conditions remains a topic of debate. This study focuses on the SKB ABM5 experiment, which ran [...] Read more.
Pilot sites are currently used to test the performance of bentonite barriers for sealing high-level radioactive waste repositories, but the degree of mineral stability under enhanced thermal conditions remains a topic of debate. This study focuses on the SKB ABM5 experiment, which ran for 5 years (2012 to 2017) and locally reached a maximum temperature of 250 °C. Five bentonites were investigated using XRD with Rietveld refinement, SEM-EDX and by measuring pH, CEC and EC. Samples extracted from bentonite blocks at 0.1, 1, 4 and 7 cm away from the heating pipe showed various stages of alteration related to the horizontal thermal gradient. Bentonites close to the contact with lower CEC values showed smectite alterations in the form of tetrahedral substitution of Si4+ by Al3+ and some octahedral metal substitutions, probably related to ferric/ferrous iron derived from corrosion of the heater during oxidative boiling, with pyrite dissolution and acidity occurring in some bentonite layers. This alteration was furthermore associated with higher amounts of hematite and minor calcite dissolution. However, as none of the bentonites showed any smectite loss and only displayed stronger alterations at the heater–bentonite contact, the sealants are considered to have remained largely intact. Full article
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13 pages, 2963 KiB  
Article
Optimizing Slag Content to Control Ds-Type Inclusions in 10B21 Cold Heading Steel
by Zhaoqi Song, Wei Liu, Yuhang Liu, Yongfeng Chen, Xiaotan Zuo, Shufeng Yang and Jingshe Li
Minerals 2021, 11(9), 1016; https://doi.org/10.3390/min11091016 - 18 Sep 2021
Cited by 1 | Viewed by 2042
Abstract
Ds-type inclusions during production are an important factor affecting the performance and quality of manufactured 10B21 steel. To minimize Ds-type inclusions in steel and improve the production qualification rate of steelmaking plants, a refining slag system optimization scheme was proposed based on the [...] Read more.
Ds-type inclusions during production are an important factor affecting the performance and quality of manufactured 10B21 steel. To minimize Ds-type inclusions in steel and improve the production qualification rate of steelmaking plants, a refining slag system optimization scheme was proposed based on the analysis of current inclusion evolution during the steelmaking process, and industrial tests were conducted to verify improvements resulting from application of the proposed scheme. The results showed that the composition of Ds inclusions in 10B21 steel are mainly CaO–Al2O3–MgO–CaS–TiN, which exists in the form of calcium–magnesium aluminate coated with titanium nitride and calcium sulfide. The main reason for the formation of Ds inclusions is the poor fluidity of the refining slag and its low capability to absorb inclusions. The poor coverage of the refining slag on the molten steel during refining can easily cause secondary oxidation of the molten steel. Thus, the formation and growth of Ds-type inclusions are aggravated after the calcium feeding line and soft blowing operation. Here, we propose to minimize Ds inclusions using our optimized refined slag system. The mass percentage of the optimized slag system is CaO: 55–60%, Al2O3: 20–35%, SiO2: 3–7%, MgO: 4–8%, (MnO + FeO) < 1%, and the basicity is controlled within the range of 7–11. We observed that our optimized refining slag system has a significantly improved ability to remove inclusions, particularly Ds inclusions, which improves the qualification rate of 10B21 steel. Full article
(This article belongs to the Special Issue Slag Valorization for Advanced Metal Production)
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26 pages, 10999 KiB  
Article
Textural and Mineralogical Controls on Rock Strength Elucidated Using a Discrete Element Method Numerical Laboratory
by Temitope Oladele, Lawrence Bbosa and Dion Weatherley
Minerals 2021, 11(9), 1015; https://doi.org/10.3390/min11091015 - 18 Sep 2021
Cited by 4 | Viewed by 2081
Abstract
Numerical modelling techniques such as the discrete element method are now well established and extensively used in many applications including solid earth geoscience, materials science, geotechnical engineering and rock mechanics. The potential for this technique in understanding comminution mechanisms has been identified as [...] Read more.
Numerical modelling techniques such as the discrete element method are now well established and extensively used in many applications including solid earth geoscience, materials science, geotechnical engineering and rock mechanics. The potential for this technique in understanding comminution mechanisms has been identified as highly promising. This work utilizes the discrete element method as a numerical laboratory to conduct investigations relevant to comminution that would otherwise be costly or time-consuming to perform in the field or laboratory. A benchmark numerical model for impact breakage of rock specimens is first established and validated against results of controlled laboratory experiments. Thereafter, the model is utilized to systematically investigate the potential dependency of ore breakage properties upon the prevalence of pre-existing fractures, as well as the mineralogical composition of the ore. These numerical experiments serve to highlight the potential for quantitatively relating the mechanical response of ore to its textural and mineralogical characteristics. Tandem utilization of numerical and laboratory experimentation to formulate and test hypotheses is a promising avenue to illuminate such relationships. Full article
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18 pages, 6916 KiB  
Article
Development of a Physical Separation Route for the Concentration of Base Metals from Old Wasted Printed Circuit Boards
by Pedro Jorge Walburga Keglevich de Buzin, Weslei Monteiro Ambrós, Irineu Antônio Schadach de Brum, Rejane Maria Candiota Tubino, Carlos Hoffmann Sampaio and Josep Oliva Moncunill
Minerals 2021, 11(9), 1014; https://doi.org/10.3390/min11091014 - 18 Sep 2021
Cited by 2 | Viewed by 2230
Abstract
Wastes from old electronic devices represent a significant part of the electronic scrap generated in developing countries, being commonly sold by collectors as low-value material to recycling hubs abroad. Upgrading the quality of this waste type could drive the revenue of recyclers, and [...] Read more.
Wastes from old electronic devices represent a significant part of the electronic scrap generated in developing countries, being commonly sold by collectors as low-value material to recycling hubs abroad. Upgrading the quality of this waste type could drive the revenue of recyclers, and thus, boost the recycling market. On this basis, this study investigated the possibility of concentrating metals from old wasted printed circuit boards through a physical separation-based route. Preparation of samples comprised fragmentation, size classification, density, and magnetic separation steps, followed by chemical and macro composition analysis. Cu, Al, Fe, and Sn constituted the major metals encountered in the scraps, including some peak concentrations of Zn, Sb, Pb, Ba, and Mn. Four distinct concentrate products could be obtained after suitable processing: (a) a light fraction composed of plastics and resins; (b) an aluminum concentrate; (c) a magnetic material concentrate, containing mainly iron; (d) a final concentrate containing more than 50% in mass of copper and enriched with nonferrous metals. Preliminary evidence showed that further processes, like the separation of copper wires through drumming, can potentially improve the effectiveness of the proposed processing circuit and should guide future works. Full article
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8 pages, 2472 KiB  
Article
Preparation and Evaluation of Ammonium Adipate Solutions as Inhibitors of Shale Rock Swelling
by Sirong Xian, Shijun Chen, Yubo Lian, Weichao Du, Zhifei Song and Gang Chen
Minerals 2021, 11(9), 1013; https://doi.org/10.3390/min11091013 - 18 Sep 2021
Cited by 6 | Viewed by 2062
Abstract
This study aimed to evaluate the inhibitory effect of a series of ammonium adipate solutions (AASs) by using the linear expansion test, thermogravimetric analysis (TGA), and particle size distribution analysis, and to examine the underlying inhibitory mechanism. A series of AASs was prepared [...] Read more.
This study aimed to evaluate the inhibitory effect of a series of ammonium adipate solutions (AASs) by using the linear expansion test, thermogravimetric analysis (TGA), and particle size distribution analysis, and to examine the underlying inhibitory mechanism. A series of AASs was prepared from adipic acid and amines as small-molecule inhibitors of oil shale rock swelling. They were then evaluated by the bentonite linear expansion test. The best one, namely, AAS-8 (synthesized with adipic acid and tetraethylenepentamine in a ratio of acid group to amine group of 1:2), was evaluated in a water-based drilling fluid. The linear expansion test showed that the linear expansion rate of AAS-8 was the lowest (59.61%) when the concentration was 0.1%. The evaluation of the drilling fluid revealed that AAS-8 had a strong inhibitory effect on the swelling of hydrated bentonite particles in the water-based drilling fluid and was compatible with carboxymethyl cellulose (CMC) and modified starch. The inhibition mechanism of AAS-8 was investigated using TGA and particle size distribution analysis, which demonstrated that AAS-8 might enter the clay layer and bind the clay sheets together by electrostatic adsorption and hydrogen bonding. Full article
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13 pages, 4523 KiB  
Article
Rapid Atmospheric Leaching of Chalcopyrite Using a Novel Reagent of Trichloroisocyanuric Acid
by Guobao Chen, Jiarui Sun, Hongying Yang, Pengcheng Ma and Shixiong Gao
Minerals 2021, 11(9), 1012; https://doi.org/10.3390/min11091012 - 18 Sep 2021
Cited by 8 | Viewed by 2255
Abstract
With the decrease in high-grade chalcopyrite resources, the copper extraction from low-grade chalcopyrite has attracted more and more attention. However, the kinetic rates of chalcopyrite leaching with traditional oxidants are usually very slow due to the formation of the passivation layer. In this [...] Read more.
With the decrease in high-grade chalcopyrite resources, the copper extraction from low-grade chalcopyrite has attracted more and more attention. However, the kinetic rates of chalcopyrite leaching with traditional oxidants are usually very slow due to the formation of the passivation layer. In this study, a novel reagent of chlorinated oxidant, trichloroisocyanuric acid (TCCA), was used to leach chalcopyrite for the first time. The experimental results showed that when the initial oxidant concentration for TCCA was 0.054 mol·L−1, the leaching temperature was kept at 55 °C, and the pH of the pulp was controlled at 1, the oxidation efficiency of Cu can reach above 90% in less than 30 min. Various analyses of chalcopyrite mineral ore and its oxidized residues, such as chemical composition analysis, X-ray diffraction analysis, scanning electron microscopy analysis and X-ray photoelectron spectroscopy, were conducted, respectively. No obvious passivation layer was found on the chalcopyrite surface, though the sulfur product can also be generated during the leaching. Reaction kinetic analysis results showed that the different influence of surface reaction and diffusion process on the dissolution of chalcopyrite is little due to the fast leaching speed. After calculation, the activation energy of the whole leaching reaction is 9.06 kJ·mol−1, much lower than that in other reports. The mechanism was also proposed that TCCA was hydrolyzed in the solution to form hypochlorous acid, which is the strong oxidant, and cyanuric acid, which prevents the formation of a passivation layer. The processing in this study is expected to be applied as a novel method for atmospheric leaching of chalcopyrite. Full article
(This article belongs to the Special Issue Recent Advances in Copper Ore Processing and Extraction)
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19 pages, 5093 KiB  
Article
Tracking 40 Million Years of Migrating Magmatism across the Idaho Batholith Using Zircon U-Pb Ages and Hf Isotopes from Cretaceous Bentonites
by Jeffrey S. Hannon, Craig Dietsch, Warren D. Huff and Davidson Garway
Minerals 2021, 11(9), 1011; https://doi.org/10.3390/min11091011 - 17 Sep 2021
Cited by 2 | Viewed by 2230
Abstract
Cretaceous strata preserved in Wyoming contain numerous large bentonite deposits formed from the felsic ash of volcanic eruptions, mainly derived from Idaho batholith magmatism. These bentonites preserve a near-continuous 40 m.y. chronology of volcanism and their whole-rock and mineral chemistry has been used [...] Read more.
Cretaceous strata preserved in Wyoming contain numerous large bentonite deposits formed from the felsic ash of volcanic eruptions, mainly derived from Idaho batholith magmatism. These bentonites preserve a near-continuous 40 m.y. chronology of volcanism and their whole-rock and mineral chemistry has been used to document igneous processes and reconstruct the history of Idaho magmatism as emplacement migrated across the Laurentian margin. Using LA-ICP-MS, we analyzed the U-Pb ages and Hf isotopic compositions of nearly 700 zircon grains from 44 bentonite beds from the Bighorn Basin, Wyoming. Zircon populations contain magmatic autocrysts and antecrysts which can be linked to the main pulses of the Idaho batholith and xenocrysts ranging from approx. 250 Ma to 1.84 Ga from country rocks and basement source terranes. Initial εHf compositions of Phanerozoic zircons are diverse, with compositions ranging from −26 to nearly +12. Based on temporal trends in zircon ages and geochemistry, four distinct periods of plutonic emplacement are recognized during the Mid- to Late Cretaceous that follow plutonic emplacement across the Laurentian suture zone in western Idaho and into western Montana with the onset of Farallon slab shallowing. Our data demonstrate the utility of using zircons in preserved tephra to track the regional-scale evolution of convergent margins related to terrane accretion and the spatial migration of magmatism related to changes in subduction dynamics. Full article
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15 pages, 7760 KiB  
Article
Age and Geochemistry of Late Jurassic Mafic Volcanic Rocks in the Northwestern Erguna Block, Northeast China
by Yan Li, Feng-Jun Nie and Zhao-Bin Yan
Minerals 2021, 11(9), 1010; https://doi.org/10.3390/min11091010 - 17 Sep 2021
Viewed by 2268
Abstract
The northwestern Erguna Block, where a wide range of volcanic rocks are present, provides one of the foremost locations to investigate Mesozoic Paleo-Pacific and Mongol-Okhotsk subduction. The identification and study of Late Jurassic mafic volcanic rocks in the Badaguan area of northwestern Erguna [...] Read more.
The northwestern Erguna Block, where a wide range of volcanic rocks are present, provides one of the foremost locations to investigate Mesozoic Paleo-Pacific and Mongol-Okhotsk subduction. The identification and study of Late Jurassic mafic volcanic rocks in the Badaguan area of northwestern Erguna is of particular significance for the investigation of volcanic magma sources and their compositional evolution. Detailed petrological, geochemical, and zircon U-Pb dating suggests that the Late Jurassic mafic volcanic rocks formed at 157–161 Ma. Furthermore, the geochemical signatures of these mafic volcanic rocks indicate that they are calc-alkaline or transitional series with weak peraluminous characteristics. The rocks have a strong MgO, Al2O3, and total alkali content, and a SiO2 content of 53.55–63.68 wt %; they are enriched in Rb, Th, U, K, and light rare-earth elements (LREE), and depleted in high-field-strength elements (HFSE), similar to igneous rocks in subduction zones. These characteristics indicate that the Late Jurassic mafic volcanic rocks in the Badaguan area may be derived from the partial melting of the lithospheric mantle as it was metasomatized by subduction-related fluid and the possible incorporation of some subducting sediments. Subsequently, the fractional crystallization of Fe and Ti oxides occurred during magmatic evolution. Combined with the regional geological data, it is inferred that the studied mafic volcanic rocks were formed by lithospheric extension after the closure of the Mongol-Okhotsk Ocean. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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31 pages, 4737 KiB  
Review
Origin of Critical Metals in Fe–Ni Laterites from the Balkan Peninsula: Opportunities and Environmental Risk
by Maria Economou-Eliopoulos, Magdalena Laskou, Demetrios G. Eliopoulos, Ifigeneia Megremi, Sofia Kalatha and George D. Eliopoulos
Minerals 2021, 11(9), 1009; https://doi.org/10.3390/min11091009 - 16 Sep 2021
Cited by 7 | Viewed by 3758
Abstract
As the global energy sector is expected to experience a gradual shift towards renewable energy sources, access to special metals in known resources is of growing concern within the EU and at a worldwide scale. This is a review on the Fe–Ni ± [...] Read more.
As the global energy sector is expected to experience a gradual shift towards renewable energy sources, access to special metals in known resources is of growing concern within the EU and at a worldwide scale. This is a review on the Fe–Ni ± Co-laterite deposits in the Balkan Peninsula, which are characterized by multistage weathering/redeposition and intense tectonic activities. The ICP-MS analyses of those laterites indicated that they are major natural sources of Ni and Co, with ore grading from 0.21 to 3.5 wt% Ni and 0.03 to 0.31 wt% Co, as well as a significant Sc content (average 55 mg/kg). The SEM-EDS analyses revealed that fine Fe-, Ni-, Co-, and Mn-(hydr)oxides are dominant host minerals and that the enrichment in these elements is probably controlled by the post-formation evolution of initial ore redeposition. The paucity of rare earth element (REE) within the typical Fe–Ni laterite ore and the preferential occurrence of Co (up to 0.31 wt%), REE content (up to 6000 mg/kg ΣREE), and REE-minerals along with Ni, Co, and Mn (asbolane and silicates) towards the lowermost part of the Lokris (C. Greece) laterite ore suggest that their deposition is controlled by epigenetic processes. The platinum-group element (PGE) content in those Fe–Ni laterites, reaching up to 88 μg/kg Pt and 26 μg/kg Pd (up to 186 μg/kg Pd in one sample), which is higher than those in the majority of chromite deposits associated with ophiolites, may indicate important weathering and PGE supergene accumulation. Therefore, the mineralogical and geochemical features of Fe–Ni laterites from the Balkan Peninsula provide evidence for potential sources of certain critical metals and insights to suitable processing and metallurgical methods. In addition, the contamination of soil by heavy metals and irrigation groundwater by toxic Cr(VI), coupled with relatively high Cr(VI) concentrations in water leachates for laterite samples, altered ultramafic rocks and soils neighboring the mining areas and point to a potential human health risk and call for integrated water–soil–plant investigations in the basins surrounding laterite mines. Full article
(This article belongs to the Special Issue Geochemistry and Mineralogy of Ni-Co Laterite Deposits)
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21 pages, 35013 KiB  
Article
Depositional Conditions of Cretaceous Ironstones Deposit in the Chulym-Yenisey Basin (Western Siberia)
by Maxim Rudmin, Santanu Banerjee, Aigerim Dauletova and Aleksey Ruban
Minerals 2021, 11(9), 1008; https://doi.org/10.3390/min11091008 - 16 Sep 2021
Cited by 4 | Viewed by 2456
Abstract
This study reconstructs the depositional conditions of ironstones within the Chulym-Yenisey basin and assesses the iron source. The detrital minerals of the studied deposits include quartz and feldspar. The authigenic minerals are goethite, siderite, aragonite, dolomite, calcite, apatite, barite, and pyrite. The clay [...] Read more.
This study reconstructs the depositional conditions of ironstones within the Chulym-Yenisey basin and assesses the iron source. The detrital minerals of the studied deposits include quartz and feldspar. The authigenic minerals are goethite, siderite, aragonite, dolomite, calcite, apatite, barite, and pyrite. The clay components include minerals of the chlorite group (possible chamosite), nontronite, kaolinite, illite, and beidellite. Local bacterial sulfate reduction led to the formation of pyrite framboids in siltstone layers. The subsequent diagenetic iron reduction promoted the formation of chamosite from siderite. The goethite precipitation occurred in an oxidic aqueous environment. The Cretaceous continental sediments of the Ilek and Kia Formations of the Chulym-Yenisei depression consist of fine- and medium-grained, cross-stratified, poorly sorted litho-feldspatho-quartzose sandstones of fluvial channel origin alternating with bluish-gray siltstones and ironstones of floodplain–lacustrine–bog origin. Thin layers of iron-bearing rocks within siltstones formed in meromictic waters. The changes in geochemical proxies demonstrate fluctuations of paleoenvironmental conditions within the Cretaceous sequence. Siltstones and sandstones formed under humid and arid conditions, respectively. The primary iron source for sediments of the Chulym-Yenisey depression was determined as volcanogenic and igneous rocks of the Altai-Sayan mountainous region. Full article
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17 pages, 4648 KiB  
Article
Phase Transformation, Photocatalytic and Photoluminescent Properties of BiPO4 Catalysts Prepared by Solid-State Reaction: Degradation of Rhodamine B
by Abdessalam Bouddouch, Elhassan Amaterz, Bahcine Bakiz, Aziz Taoufyq, Frédéric Guinneton, Sylvie Villain, Jean-Raymond Gavarri, Jean-Christophe Valmalette and Abdeljalil Benlhachemi
Minerals 2021, 11(9), 1007; https://doi.org/10.3390/min11091007 - 15 Sep 2021
Cited by 9 | Viewed by 2317
Abstract
Polycrystalline bismuth phosphate BiPO4 was synthesized by solid-state reaction at different temperatures varying from 500 to 900 °C. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and Raman spectroscopy. The low-temperature phase of [...] Read more.
Polycrystalline bismuth phosphate BiPO4 was synthesized by solid-state reaction at different temperatures varying from 500 to 900 °C. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and Raman spectroscopy. The low-temperature phase of BiPO4 has monoclinic structure with a space group P21/n, and was transformed into the monoclinic phase P21/m with a slight distortion of monoclinic lattice when it was heated above 500 °C. The effect of the transformation on the structure, morphology and photocatalytic properties was examined. The photocatalytic activity of each sample, in presence of Rhodamine B (RhB) in aqueous solution, was carried out and analyzed under UV light irradiation. Photoexperiments showed that the material prepared at 500 °C is the best catalyst with degradation efficiency of the order of 96% after 12 min of reaction time under UV light irradiation. This high photocatalytic efficiency could be due to their structural and morphological changes. The photocatalytic degradation mechanism of RhB in the presence of the best photocatalyst BiP-500 °C is proposed. The stability of the catalyst was also examined by carrying out four successive tests of the degradation in the presence of BiP-500 °C. Total organic carbon (TOC) was used to further estimate the rate of mineralization in the presence of BiP-500 °C (83% TOC removal). Photoluminescence experiments performed under UV-laser light irradiation revealed emissions in the green-orange range, with optimal intensities for the mix systems observed at 550 °C. Full article
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12 pages, 4010 KiB  
Review
A Rational Interpretation of the Role of Turbulence in Particle-Bubble Interactions
by Ning Yao, Jingting Liu, Xun Sun, Yan Liu, Songying Chen and Guichao Wang
Minerals 2021, 11(9), 1006; https://doi.org/10.3390/min11091006 - 15 Sep 2021
Cited by 6 | Viewed by 2357
Abstract
Interactions between particles and bubbles have been cornerstone for the successful applications of froth flotation to the beneficiations of minerals or coal. Particle-bubble interactions are highly physio-chemical processes on the basis of surface science and hydrodynamics. Though these two aspects are deeply interwoven, [...] Read more.
Interactions between particles and bubbles have been cornerstone for the successful applications of froth flotation to the beneficiations of minerals or coal. Particle-bubble interactions are highly physio-chemical processes on the basis of surface science and hydrodynamics. Though these two aspects are deeply interwoven, we focus on the discussions of the effects of turbulence on the interactions between particles and bubbles, i.e., collision, attachment and detachment. It has to be mentioned this effect is not working in one direction and can affect flotation performance in a complicated way. Only when turbulence effects are well understood, flotation processes can be optimised by suitably changing equipment structure or operating parameters. The aim of this paper is to review the most recent progresses in this aspect and to identify the future development in successfully considering turbulence effects on flotation processes. Full article
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1 pages, 162 KiB  
Correction
Correction: Witkowski et al. Estimation of Mining-Induced Horizontal Strain Tensor of Land Surface Applying InSAR. Minerals 2021, 11, 788
by Wojciech T. Witkowski, Magdalena Łukosz, Artur Guzy and Ryszard Hejmanowski
Minerals 2021, 11(9), 1005; https://doi.org/10.3390/min11091005 - 15 Sep 2021
Cited by 2 | Viewed by 1640
Abstract
The authors wish to make the following corrections to this paper [...] Full article
16 pages, 4099 KiB  
Article
Metal Extraction and Recovery from Mobile Phone PCBs by a Combination of Bioleaching and Precipitation Processes
by Arrate Santaolalla, Piet N. L. Lens, Astrid Barona, Naiara Rojo, Ainhoa Ocio and Gorka Gallastegui
Minerals 2021, 11(9), 1004; https://doi.org/10.3390/min11091004 - 15 Sep 2021
Cited by 12 | Viewed by 3890
Abstract
Bearing in mind the metal rich composition of printed circuit boards (PCBs), this material represents a secondary source of valuable metals and offers an entrepreneurial opportunity in the metal sales market. Based on the ability of microorganisms to regenerate and produce the chemical [...] Read more.
Bearing in mind the metal rich composition of printed circuit boards (PCBs), this material represents a secondary source of valuable metals and offers an entrepreneurial opportunity in the metal sales market. Based on the ability of microorganisms to regenerate and produce the chemical oxidants that are responsible for metal leaching, bioleaching has become an efficient and affordable alternative to conventional metal recycling technologies, although further research is still necessary before industrial implementation. This study focuses on the recovery of metals contained in mobile phone PCBs through a combined process. Two different PCB pre-treatments were evaluated: grinding the whole piece and removing the epoxy cover from the piece without grinding. The benefit of A. ferrooxidans activity on the metal solubilization rate was analyzed. Additional chemical leaching assays were also conducted for comparison purposes and the reagents ferric iron (Fe3+) and sulfuric acid (H2SO4) were selected for these experiments. The copper extraction results obtained in Fe3+ experiments with and without bacteria (A. ferrooxidans) were similar after 260 h of operation, indicating the need for alternative strategies to ensure a controlled and continuous metal biodissolution rate. The contribution of H2SO4 to the leaching processes for copper and nickel was almost negligible during the first 50 h, and more significant thereafter. The recovered metals were precipitated from a synthetic solution simulating a real ferric leaching by adding sodium hydroxide (NaOH) and sodium sulfide (Na2S). The combination of both precipitants allowed an effective removal of metals from the leachate. Full article
(This article belongs to the Special Issue Bio-recovery of Copper, Lead and Zinc)
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13 pages, 3045 KiB  
Article
Study on the Stability Principle of Mechanical Structure of Roadway with Composite Roof
by Yang Yu, Jianfei Lu, Dingchao Chen, Yuxin Pan, Xiangqian Zhao and Lianying Zhang
Minerals 2021, 11(9), 1003; https://doi.org/10.3390/min11091003 - 14 Sep 2021
Cited by 9 | Viewed by 1509
Abstract
With the typical composite roof roadway and roof fall accidents in the Guizhou Province of China as the research background, the expression of damage parameters of composite roof was deduced according to Weibull statistical distribution, generalized Hooke’s law and Mises yield criterion, and [...] Read more.
With the typical composite roof roadway and roof fall accidents in the Guizhou Province of China as the research background, the expression of damage parameters of composite roof was deduced according to Weibull statistical distribution, generalized Hooke’s law and Mises yield criterion, and the influence of shape and scale parameters of Weibull on damage characteristic was discussed. Based on the infinite slab theory, the expressions of deflection and layer separation of each layer of the composite roof were obtained, the critical load expression of each delamination was determined, and the influence of roadway width, overlying strata load, elastic modulus, shape parameters and scale parameters on the stability of composite roof was explored. The research shows that the bolt support can effectively reduce the layer separation between the composite roofs and enhance the stability of the composite roof. On this basis, it is proposed that for the surrounding rock control problem of roadways with composite roof, the active support technology with bolts as the core should be adopted. Full article
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24 pages, 10713 KiB  
Article
Unique Association of Sulphosalts from the Kľačianka Occurrence, Nízke Tatry Mts., Slovak Republic
by Jiří Sejkora, Martin Števko, Jaroslav Pršek, Róbert Hovorič, Emil Makovicky and Martin Chovan
Minerals 2021, 11(9), 1002; https://doi.org/10.3390/min11091002 - 14 Sep 2021
Cited by 3 | Viewed by 2371
Abstract
Unique association of sulphosalts was discovered at the Kľačianka occurrence, Nízke Tatry Mts., Slovak Republic. It is bound to thin hydrothermal veins with Sb mineralization hosted by the Variscan muscovite-biotite granodiorite and granite of Prašivá type. Ore mineralogy and crystal chemistry of ore [...] Read more.
Unique association of sulphosalts was discovered at the Kľačianka occurrence, Nízke Tatry Mts., Slovak Republic. It is bound to thin hydrothermal veins with Sb mineralization hosted by the Variscan muscovite-biotite granodiorite and granite of Prašivá type. Ore mineralogy and crystal chemistry of ore minerals are studied here by ore microscopy, X-ray powder diffraction, electron microprobe analyses, and Raman spectroscopy. The early ore mineralization composed of pyrite and arsenopyrite is hosted in quartz gangue and is followed by abundant association of sulfosalts. Stibnite, zinkenite, robinsonite (including Cu-bearing variety), jamesonite, scainiite, dadsonite, disulfodadsonite, rouxelite, chovanite, semseyite, boulangerite, geocronite, tintinaite (with low Bi contents), tetrahedrite-(Fe), tetrahedrite-(Zn), bournonite, chalcostibite, bismuthinite, and gladite in association with sphalerite and rare galena and gold are identified here. The chlorine-rich character of the described sulphosalt association is its characteristic phenomenon. It is represented not only by the occurrence of Cl-sulphosalt and dadsonite, but increased Cl contents were detected in boulangerite, chovanite, disulfodadsonite, robinsonite, rouxelite, scainiite, or tintinaite. The presence of oxygen-containing sulphosalts, such as rouxelite, scainiite and chovanite, is also interesting. The crystallization of these rare chloro-, oxy- and oxy-chloro-sulphosalts at the Kľačianka occurrence required very specific conditions (elevated O2/S2 fugacity) and high chlorine activity in ore-forming fluids. Full article
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15 pages, 1497 KiB  
Article
Trends in Colouring Blue Glass in Central Europe in Relation to Changes in Chemical Composition of Glass from the Middle Ages to Modern Age
by Zuzana Zlámalová Cílová, Michal Gelnar and Simona Randáková
Minerals 2021, 11(9), 1001; https://doi.org/10.3390/min11091001 - 14 Sep 2021
Cited by 5 | Viewed by 3118
Abstract
The study deals with the development of the chemical composition of blue glass from the 13th to the 19th century in the region of Bohemia (Central Europe). Nearly 100 glass samples (colourless, greenish, and blue) were evaluated by an XRF method to distinguish [...] Read more.
The study deals with the development of the chemical composition of blue glass from the 13th to the 19th century in the region of Bohemia (Central Europe). Nearly 100 glass samples (colourless, greenish, and blue) were evaluated by an XRF method to distinguish the colouring components of blue glass. As early as in the 13th century, blue glass based on ash containing colouring ions of Co and Cu was produced here. To achieve the blue colour of glass, a copper-rich raw material was most likely applied. This information significantly complements the existing knowledge about glass colouring in the Middle Ages, as the glass of later periods was typically coloured with raw materials containing cobalt. Full article
(This article belongs to the Special Issue Characterization of Archaeological and Historic Vitreous Materials)
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4 pages, 156 KiB  
Editorial
Editorial for Special Issue “Characterisation of Mudrocks: Textures and Mineralogy”
by Jim Buckman
Minerals 2021, 11(9), 1000; https://doi.org/10.3390/min11091000 - 14 Sep 2021
Viewed by 1260
Abstract
Mudrocks are a volumetrically important part of many sedimentary basins, both in the present day and across geological time [...] Full article
(This article belongs to the Special Issue Characterisation of Mudrocks: Textures and Mineralogy)
26 pages, 1035 KiB  
Article
Do New-Generation Recycled Phosphorus Fertilizers Increase the Content of Potentially Toxic Elements in Soil and Plants?
by Magdalena Jastrzębska, Marta K. Kostrzewska, Agnieszka Saeid and Wiesław P. Jastrzębski
Minerals 2021, 11(9), 999; https://doi.org/10.3390/min11090999 - 13 Sep 2021
Cited by 8 | Viewed by 2613
Abstract
Phosphorus (P)-rich secondary raw materials can provide a valuable base for modern mineral fertilizers, provided that the new formulations do not load the soil–plant system with potentially toxic elements. Fertilizers from sewage sludge ash (SSA) and/or animal bones, activated by phosphorus-solubilizing bacteria ( [...] Read more.
Phosphorus (P)-rich secondary raw materials can provide a valuable base for modern mineral fertilizers, provided that the new formulations do not load the soil–plant system with potentially toxic elements. Fertilizers from sewage sludge ash (SSA) and/or animal bones, activated by phosphorus-solubilizing bacteria (Bacillus megaterium or Acidithiobacillus ferrooxidans), were tested in field experiments in north-eastern Poland. The reference provided treatments with superphosphate and treatment without phosphorus fertilization. In one experiment, all P-fertilizers were applied at a P dose of 21 kg·ha−1, and in the other three experiments, three P doses were adopted: 17.6, 26.4, and 35.2 kg·ha−1. The effect of recycled fertilizers on the content of arsenic (As), chromium (Cr), nickel (Ni), copper (Cu), and zinc (Zn) in the soil, in wheat grain and straw (test plant), weeds, and post-harvest residues was investigated. The application of recycled fertilizers in P amounts up to 35.2 kg·ha−1 did not change the As, Cr, Ni, Cu, or Zn contents in the soil and plant biomass. The contents of these elements in soil were below the permissible levels for arable land in Poland. Their concentrations in wheat grain and straw did not exceed the permissible or suggested limits for plant material to be used for food and feed, while in the weed and post-harvest residue biomass, they usually fell within the biological plant variability ranges. Full article
(This article belongs to the Special Issue Application of Mineral-Based Amendments, Volume II)
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15 pages, 23136 KiB  
Article
Acid Mine Drainage Sources and Impact on Groundwater at the Osarizawa Mine, Japan
by Naoto Nishimoto, Yosuke Yamamoto, Saburo Yamagata, Toshifumi Igarashi and Shingo Tomiyama
Minerals 2021, 11(9), 998; https://doi.org/10.3390/min11090998 - 13 Sep 2021
Cited by 18 | Viewed by 5194
Abstract
Understanding the origin of acid mine drainage (AMD) in a closed mine and groundwater flow system around the mine aids in developing strategies for environmental protection and management. AMD has been continuously collected and neutralized at Osarizawa Mine, Akita Prefecture, Japan, since the [...] Read more.
Understanding the origin of acid mine drainage (AMD) in a closed mine and groundwater flow system around the mine aids in developing strategies for environmental protection and management. AMD has been continuously collected and neutralized at Osarizawa Mine, Akita Prefecture, Japan, since the mine was closed in the 1970s, to protect surrounding river water and groundwater quality. Thus, water samples were taken at the mine and surrounding groundwaters and rivers to characterize the chemical properties and environmental isotopes (δ2H and δ18O). The results showed that the quality and stable isotope ratios of AMD differed from those of groundwater/river water, indicating that the recharge areas of AMD. The recharge area of AMD was evaluated as the mountain slope at an elevation of 400–500 m while that of the surrounding groundwater was evaluated at an elevation of 350–450 m, by considering the stable isotopes ratios. This indicates that the groundwater affected by AMD is limited to the vicinity of the mine and distributed around nearby rivers. Full article
(This article belongs to the Special Issue Environmental Geochemistry in the Mining Environment)
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