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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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16 pages, 2684 KiB  
Article
Machine-Learning Analysis of the Canadian Royalties Grinding Circuit
by Antonio Di Feo, Nasseh Khodaie, Matthieu Girard and Simon Michaud
Minerals 2024, 14(4), 356; https://doi.org/10.3390/min14040356 - 28 Mar 2024
Viewed by 1299
Abstract
This work aimed to understand the relationships between grinding variables and the P80 (80% passing size) of a grinding circuit (feed to flotation). Canadian Royalties want to obtain and reduce variations in the P80, which is currently 65 micrometres. Thus, principal component analysis [...] Read more.
This work aimed to understand the relationships between grinding variables and the P80 (80% passing size) of a grinding circuit (feed to flotation). Canadian Royalties want to obtain and reduce variations in the P80, which is currently 65 micrometres. Thus, principal component analysis (PCA), part of machine learning, was utilized to better understand the factors that significantly influence the P80. PCA is meant to be used as a guideline for plant metallurgists to determine how the grinding circuit factors influence P80; thus, the variables can be manipulated to lower P80 fluctuations. PCA revealed that the head grade of the ore (pentlandite (Pn), chalcopyrite (Cp), pyrrhotite (Po) and non-sulphide gangue (NSG)) and the primary ball mill power were weakly correlated with P80. However, the ore level in the silo, flowrate to cyclones, cyclone pressure, percent solids and the feed tonnage rate to the primary ball mill were strongly correlated with P80. This information can be used to develop a strategy to control the P80 of the grinding circuit and provide a more consistent grind size to the flotation circuit, which can positively impact metallurgical performance. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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22 pages, 7342 KiB  
Article
Computed Tomography of Scheelite Ore, Kara, Australia: Morphological Characterisation and Modal Mineralogy
by Leonard T. Krebbers, Julie A. Hunt and Bernd G. Lottermoser
Minerals 2024, 14(4), 345; https://doi.org/10.3390/min14040345 - 27 Mar 2024
Cited by 1 | Viewed by 3578
Abstract
Metal ores are mineralogically characterised to understand their genesis in order to allow informed decisions on mineral processing and to recognise likely environmental risks upon mining. However, standard mineralogical techniques generate only two-dimensional information at best, which in addition may be subject to [...] Read more.
Metal ores are mineralogically characterised to understand their genesis in order to allow informed decisions on mineral processing and to recognise likely environmental risks upon mining. However, standard mineralogical techniques generate only two-dimensional information at best, which in addition may be subject to sampling and stereological errors. By contrast, computed tomography (CT) is a non-destructive imaging technique that allows three-dimensional analysis of solid materials. In the present study, two ore types of the Kara Fe-W deposit (Australia) were characterised using CT to examine their mineral texture and modal mineralogy as well as scheelite distribution and ore grade (WO3). The results show that scheelite is primarily associated with hydrous phases (e.g., epidote, chlorite, amphibole) and occurs as massive or disseminated mineral as well as vein-fill at minor and trace concentrations. This study demonstrates that CT of scheelite ore enables accurate 3D texture visualisation (volume, grain size distribution) and yields valid quantitative data on modal mineralogy and WO3 grade of individual ore samples. Consequently, CT analysis of scheelite-bearing ore provides information relevant for ore genesis studies and comminution strategies for the possible recovery of scheelite as a by-product from metalliferous ores. Full article
(This article belongs to the Special Issue Microanalysis Applied to Mineral Deposits)
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15 pages, 10804 KiB  
Article
Isolation and Characterization of Indigenous Ureolytic Bacteria from Mindanao, Philippines: Prospects for Microbially Induced Carbonate Precipitation (MICP)
by Kryzzyl M. Maulas, Charla S. Paredes, Carlito Baltazar Tabelin, Mark Anthony Jose, Einstine M. Opiso, Takahiko Arima, Ilhwan Park, Walubita Mufalo, Mayumi Ito, Toshifumi Igarashi, Theerayut Phengsaart, Edrhea Villas, Sheila L. Dagondon, Ephrime B. Metillo, Mylene M. Uy, Al James A. Manua and Mylah Villacorte-Tabelin
Minerals 2024, 14(4), 339; https://doi.org/10.3390/min14040339 - 26 Mar 2024
Cited by 4 | Viewed by 4300
Abstract
Microbially induced carbonate precipitation (MICP), a widespread phenomenon in nature, is gaining attention as a low-carbon alternative to ordinary Portland cement (OPC) in geotechnical engineering and the construction industry for sustainable development. In the Philippines, however, very few works have been conducted to [...] Read more.
Microbially induced carbonate precipitation (MICP), a widespread phenomenon in nature, is gaining attention as a low-carbon alternative to ordinary Portland cement (OPC) in geotechnical engineering and the construction industry for sustainable development. In the Philippines, however, very few works have been conducted to isolate and identify indigenous, urease-producing (ureolytic) bacteria suitable for MICP. In this study, we isolated seven, ureolytic and potentially useful bacteria for MICP from marine sediments in Iligan City. DNA barcoding using 16s rDNA identified six of them as Pseudomonas stutzeri, Pseudomonas pseudoalcaligenes, Bacillus paralicheniformis, Bacillus altitudinis, Bacillus aryabhattai, and Stutzerimonas stutzeri but the seventh was not identified since it was a bacterial consortium. Bio-cementation assay experiments showed negligible precipitation in the control (without bacteria) at pH 7, 8, and 9. However, precipitates were formed in all seven bacterial isolates, especially between pH 7 and 8 (0.7–4 g). Among the six identified bacterial species, more extensive precipitation (2.3–4 g) and higher final pH were observed in S. stutzeri, and B. aryabhattai, which indicate better urease production and decomposition, higher CO2 generation, and more favorable CaCO3 formation. Characterization of the precipitates by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and attenuated total reflectance Fourier transform spectroscopy (ATR-FTIR) confirmed the formation of three carbonate minerals: calcite, aragonite, and vaterite. Based on these results, all six identified indigenous, ureolytic bacterial species from Iligan City are suitable for MICP provided that the pH is controlled between 7 and 8. To the best of our knowledge, this is the first report of the urease-producing ability and potential for MICP of P. stutzeri, P. pseudoalcaligenes, S. stutzeri, and B. aryabhattai. Full article
(This article belongs to the Special Issue Biomineralization and MICP in Wastewater, Reclaimed Water and Seawater)
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22 pages, 5606 KiB  
Article
Fluorite and Gibbsite Solubility Controls the Vertical Transport of Fluoride and Aluminum during Rainwater Percolation through Ashfall Deposits in La Palma (Canary Islands, Spain)
by Javier Sánchez-España, Ana M. Nieto Castillo, M. Pilar Mata, Javier Martínez-Martínez and Jose F. Mediato
Minerals 2024, 14(4), 338; https://doi.org/10.3390/min14040338 - 26 Mar 2024
Viewed by 1254
Abstract
This study addresses the in situ mobility of fluoride and aluminum in two different ashfall deposits accumulated during the 2021 eruption of the Tajogaite volcano (La Palma, Canary Islands, Spain), which were exposed to contrasting conditions of ambient humidity and precipitation. We selected [...] Read more.
This study addresses the in situ mobility of fluoride and aluminum in two different ashfall deposits accumulated during the 2021 eruption of the Tajogaite volcano (La Palma, Canary Islands, Spain), which were exposed to contrasting conditions of ambient humidity and precipitation. We selected one site to the east of the volcanic emission center, located near the top of Cumbre Vieja Ridge and exposed to continuous humidity and rain, and another site to the west of the volcano situated in a lowland and characterized by much drier conditions. The mobility of fluoride and aluminum is markedly different at both sites, with the first sequence suggesting a downwards migration of Al and F, and the second sequence showing no sign of mobility. The migration of aluminum and fluorine results from the dissolution of different fluoride salts (mostly AlF3 and CaF2, as suggested by scanning electron microscopy) followed by vertical transport as ionic complexes (AlF3, AlF2+, AlF4−) during the percolation of rainwater through the ashfall deposits. Geochemical calculations suggest that the mobility of fluorine at neutral to alkaline conditions (pH 7.0–9.0) is likely limited by the solubility of fluorite (CaF2), whereas at slightly acidic conditions (pH < 6.5), the aqueous concentration of aluminum seems to be controlled by the solubility of gibbsite (Al(OH)3). This study demonstrates that aluminum and fluoride can be transported from volcanic ash to the underlying soil or groundwater, which is an environmental concern that should be followed in the future. Full article
(This article belongs to the Section Environmental Mineralogy and Biogeochemistry)
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33 pages, 11185 KiB  
Article
Evaluation of Coarse Gold-Bearing Conglomerate Mineralisation at Beatons Creek, Pilbara, Western Australia: Sampling for Resource Development and Grade Control
by Simon C. Dominy, Janice C. Graham and Ian M. Glacken
Minerals 2024, 14(4), 337; https://doi.org/10.3390/min14040337 - 25 Mar 2024
Cited by 2 | Viewed by 1767
Abstract
Many styles of gold mineralisation are challenging to sample because of the presence of coarse gold and a high spatial heterogeneity. The coarse gold-bearing conglomerates of the Beatons Creek deposit provide some challenges related to the presence of gold particles up to 8 [...] Read more.
Many styles of gold mineralisation are challenging to sample because of the presence of coarse gold and a high spatial heterogeneity. The coarse gold-bearing conglomerates of the Beatons Creek deposit provide some challenges related to the presence of gold particles up to 8 mm and gold particle clusters (up to 500 mm3) at low in situ grades (<2 g/t Au). Novo has attempted to address these issues over the last six years of exploration, resource development and mining. The Beatons Creek open pit operation was the first Pilbara conglomerate-hosted gold deposit to go into production. Between January 2021 and September 2022, it produced 2.5 Mt at 1.2 g/t Au for 87,300 oz Au recovered. Gold is present within a matrix of multiple, narrow-stacked oxide and fresh (sulphide) conglomeritic reef horizons, which are interbedded with unmineralised conglomerate, sandstones and grits. It is strongly associated with detrital pyrite and authigenic nodules. Several sampling techniques have been applied across the project, including diamond core and RC drilling, trench channel sampling and bulk sampling. Assay methods applied include fire assay, screen fire assay, LeachWELL™ and more recently PhotonAssay™. The dominant sampling protocol applied for resource development and grade control utilised 0.5 m length RC samples; a 50% rig split (c. 8.5 kg) and laboratory crushing to 3 mm, followed by a 2.5 kg split and total assay via PhotonAssay™. For part of the 2022 RC programme, the detectORE™ technique was used to screen primary RC samples and reduce the feed to the laboratory. Novo operated a sampling and assay programme that aimed to reduce the impact of coarse gold on sample and assay preparation biases and to improve estimation. Full article
(This article belongs to the Section Mineral Exploration Methods and Applications)
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18 pages, 2383 KiB  
Review
Advancements in Machine Learning for Optimal Performance in Flotation Processes: A Review
by Alicja Szmigiel, Derek B. Apel, Krzysztof Skrzypkowski, Lukasz Wojtecki and Yuanyuan Pu
Minerals 2024, 14(4), 331; https://doi.org/10.3390/min14040331 - 24 Mar 2024
Cited by 8 | Viewed by 3978
Abstract
Flotation stands out as a successful and extensively employed method for separating valuable mineral particles from waste rock. The efficiency of this process is subjected to the distinct physicochemical attributes exhibited by various minerals. However, the complex combination of multiple sub-processes within flotation [...] Read more.
Flotation stands out as a successful and extensively employed method for separating valuable mineral particles from waste rock. The efficiency of this process is subjected to the distinct physicochemical attributes exhibited by various minerals. However, the complex combination of multiple sub-processes within flotation presents challenges in controlling this mechanism and achieving optimal efficiency. Consequently, there is a growing dependence on machine learning methods in mineral processing research. This paper provides a comprehensive overview of machine learning and artificial intelligence techniques, presenting their potential applications in flotation processes. The review demonstrates advancements discussed in scholarly research over the past decade and highlights a growing interest in utilizing machine learning methods for monitoring and optimizing flotation processes, as demonstrated by the increasing number of studies in this field. Recent trends also suggest that the course of flotation process monitoring, and control will increasingly focus on the refinement and deployment of deep learning networks developed specifically for froth image extraction and analysis. Full article
(This article belongs to the Special Issue Advances in Industrial Flotation Applications)
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14 pages, 6131 KiB  
Article
Eddavidite, Cu12Pb2O15Br2, a New Mineral Species, and Its Solid Solution with Murdochite, Cu12Pb2O15Cl2
by Melli Rosenblatt, Marcus J. Origlieri, Richard Graeme III, Richard Graeme IV, Douglas Graeme and Robert T. Downs
Minerals 2024, 14(3), 307; https://doi.org/10.3390/min14030307 - 15 Mar 2024
Viewed by 1810
Abstract
Eddavidite is a new mineral species (IMA2018-010) with ideal formula, Cu12Pb2O15Br2, and cubic Fm3¯m symmetry: a = 9.2407(9) Å; V = 789.1(2) Å3; Z = 2. Eddavidite is the bromine [...] Read more.
Eddavidite is a new mineral species (IMA2018-010) with ideal formula, Cu12Pb2O15Br2, and cubic Fm3¯m symmetry: a = 9.2407(9) Å; V = 789.1(2) Å3; Z = 2. Eddavidite is the bromine analog of murdochite, Cu12Pb2O15Cl2, with which it forms a solid solution series. The type locality is the Southwest mine, Bisbee, Cochise County, Arizona, U.S.A. Eddavidite also occurs in the Ojuela mine, Mapimí, Durango, Mexico. Eddavidite occurs as domains within mixed murdochite–eddavidite crystals. The empirical formula, normalized to 12 Cu apfu, is Cu12(Pb1.92Fe0.06Si0.06)(O15.08F0.02)-(Br0.99Cl0.89☐0.12). Type locality samples contain up to 67% eddavidite component, while Ojuela mine samples contain up to 62%. Mixed eddavidite–murdochite crystals show forms {100} and {111}; the habit grades from cubic through cuboctahedral to octahedral. Mixed eddavidite–-murdochite crystals exhibit good cleavage on {111}. Eddavidite is black, opaque with submetallic luster, and visually indistinguishable from intergrown murdochite. Its Mohs hardness is 4; dmeas. = 6.33 g/cm3, dcalc. = 6.45 g/cm3. The crystal structure, refined to R = 0.0112, consists of corner-sharing square planar CuO4 units, arranged in Cu12O24 metal oxide clusters, which encapsulate Br atoms. PbO8 cubes share edges with Cu12O24 clusters in a continuous framework. Eddavidite incorporates bromine remaining after desiccation of paleo-seawater at its two known localities, which were both once situated along the Western Interior Seaway. Full article
(This article belongs to the Collection New Minerals)
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15 pages, 13206 KiB  
Article
Immobilization Forms of Cadmium and Mercury in a Potassium-Activated Metakaolin-Based Geopolymer
by Pramesti Prihutami, Raudhatul Islam Chaerun, Yusuke Ohya, Tsubasa Otake, Ryosuke Kikuchi and Tsutomu Sato
Minerals 2024, 14(3), 311; https://doi.org/10.3390/min14030311 - 15 Mar 2024
Cited by 3 | Viewed by 1950
Abstract
Previous studies of cadmium and mercury immobilization in geopolymers have produced inconsistent results due to their different pozzolans, metal concentrations, and mixing procedures. Understanding the effects of these parameters on heavy metal immobilization is key to predicting their long-term stability. In this study, [...] Read more.
Previous studies of cadmium and mercury immobilization in geopolymers have produced inconsistent results due to their different pozzolans, metal concentrations, and mixing procedures. Understanding the effects of these parameters on heavy metal immobilization is key to predicting their long-term stability. In this study, cadmium and mercury were incorporated into a metakaolin-based K-activated geopolymer by three mixing procedures and concentrations of 0.02–1.00 wt.%. The samples were then immersed in water for 90 d to determine their stability. The results show that mercury is readily leached from the geopolymer, but cadmium is retained. Adding the heavy metals in salt form converts the metals into cadmium hydroxide and mercury oxide that reside at the bottom of the geopolymer. Mixing the salts with water forms soluble heavy metals prior to geopolymerization. This procedure produces more-homogeneous geopolymers. Cadmium is associated with silicate and aluminate, giving a better stability, whereas mercury forms mercury oxide. Different cadmium and mercury concentrations do not change the metal speciation as mercury is affected by relativistic contribution. Full article
(This article belongs to the Special Issue Environmental Mineralogy, 2nd Edition)
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18 pages, 2471 KiB  
Article
Linear Correlations of Gibbs Free Energy of REE Phosphates (Monazite, Xenotime, and Rhabdophane) and Internally Consistent Binary Mixing Properties
by Ruiguang Pan, Alexander P. Gysi, Artas Migdisov, Lei Gong, Peng Lu and Chen Zhu
Minerals 2024, 14(3), 305; https://doi.org/10.3390/min14030305 - 14 Mar 2024
Cited by 3 | Viewed by 2030
Abstract
Rare Earth Elements (REE) phosphates (monazite, xenotime, and rhabdophane) are critical REE-bearing minerals typically formed in hydrothermal and magmatic ore deposits. The thermodynamic properties of those REE minerals are crucial to understanding the solubility, speciation, and transport of REE complexes. However, the standard-state [...] Read more.
Rare Earth Elements (REE) phosphates (monazite, xenotime, and rhabdophane) are critical REE-bearing minerals typically formed in hydrothermal and magmatic ore deposits. The thermodynamic properties of those REE minerals are crucial to understanding the solubility, speciation, and transport of REE complexes. However, the standard-state Gibbs free energy of formation (∆G°f) values reported for these minerals in the literature vary by up to 25 kJ mol−1. Here, we present linear free energy relationships that allow the evaluation and estimation of the ∆G°f values at 25 °C and 1 bar for the three minerals from the ionic radius (rREE3+) and the non-solvation Gibbs free energy contribution to the REE3+ aqua ion (∆G°n, REE3+): ∆G°f,monazite − 399.71 rREE3+ = 1.0059 ∆G°n,REE3+ − 2522.51; ∆G°f,xenotime − 344.08 rREE3+ = 0.9909 ∆G°n,REE3+ − 2451.53; and ∆G°f,rhabdophane − 416.17 rREE3+ = 1.0067 ∆G°n, REE3+ − 2688.86. Moreover, based on the new dataset derived for REE end-members, we re-fitted the binary Margules parameter (W) from previous theoretical calculations into linear correlations: W + 0.00204 ∆G°’n,monazite = 39.3549 ∆V + 0.0641; W + 0.00255 ∆G°’n,xenotime = 25.4885 ∆V − 0.0062. The internally consistent thermodynamic properties of these REE phosphates are incorporated into the computer program Supcrtbl, which is available online at Zhu’s research website. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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23 pages, 24301 KiB  
Article
Numerical Simulation and Optimization of Screening Process for Vibrating Flip-Flow Screen Based on Discrete Element Method–Finite Element Method–Multi-Body Dynamics Coupling Method
by Ningning Xu, Xinwen Wang, Dongdong Lin and Weiran Zuo
Minerals 2024, 14(3), 278; https://doi.org/10.3390/min14030278 - 6 Mar 2024
Cited by 4 | Viewed by 2024
Abstract
Vibrating flip-flow screens are widely employed in the deep screening processes of coal washing, solid waste treatment, metallurgy, and other fields, playing a crucial role in enhancing product quality and production efficiency. The screen surface and material movement of vibrating flip-flow screens are [...] Read more.
Vibrating flip-flow screens are widely employed in the deep screening processes of coal washing, solid waste treatment, metallurgy, and other fields, playing a crucial role in enhancing product quality and production efficiency. The screen surface and material movement of vibrating flip-flow screens are highly complex, and there is currently insufficient understanding of their screening mechanism, limiting further optimization and application. In this paper, the Discrete Element Method (DEM), Finite Element Method (FEM), and Multi-Body Dynamics (MBD) were integrated to establish a numerical coupling model for vibrating flip-flow screens, considering material loads, screen surface deformation, and screen machine dynamics. The Response Surface Method was utilized to analyze the significant impact of relative amplitude, tension amount, amplitude of driving screen frame, vibration frequency, and screen surface inclination on screening efficiency and material velocity. The results indicate that the most significant factor influencing the screening of flip-flow screens is the screen surface inclination. Based on a BP neural network, a five-degree-of-freedom inclination surrogate model for flip-flow screens was established. The whale algorithm was employed for multi-objective optimization of the surrogate model, resulting in a screen surface inclination distribution that meets the requirements of different operating conditions. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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18 pages, 35994 KiB  
Article
A Case History of Graphite Exploration in North Norway Integrating Various Geophysical Surveys
by Vikas Chand Baranwal, Jan Steinar Rønning, Bjørn Eskil Larsen, Yang Su, Bo Zhang, Yunhe Liu, Xiuyan Ren, Håvard Gautneb and Jomar Gellein
Minerals 2024, 14(3), 266; https://doi.org/10.3390/min14030266 - 2 Mar 2024
Cited by 5 | Viewed by 2822
Abstract
Graphite is considered to be one of Europe’s most critical minerals. It is necessary for the transition from hydrocarbon fuel to electricity due to its use in batteries that power electronic devices and electric transport. In the past, high-quality exposed graphite was found [...] Read more.
Graphite is considered to be one of Europe’s most critical minerals. It is necessary for the transition from hydrocarbon fuel to electricity due to its use in batteries that power electronic devices and electric transport. In the past, high-quality exposed graphite was found in Norway without today’s advanced geophysical and geological methods. Norway is a key destination in Europe for graphite production. With an increasing demand for graphite, there have been efforts to systematically survey the country using modern geophysical and geological methods to find hidden graphite deposits. Among the various geophysical survey methods, electrical and electromagnetic (EM) methods are the first choice for the exploration of graphite due to the material’s high electrical conductivity. Airborne surveys are often used to cover a large area for a regional reconnaissance survey to locate the sites with potential mineral deposits before performing ground geophysical and geological surveys. Therefore, frequency-domain helicopter EM (HEM) and airborne magnetic surveys were performed in Northern Norway to locate interesting anomalies which were followed by ground surveys such as electrical resistivity tomography (ERT), charged-potential (CP), self-potential (SP), ground EM, and geological surveys. Some locations were also investigated with drilling and petrophysical core-sample analysis. In this paper, we present helicopter EM and magnetic data, 3D inversion of HEM data, and a successful ground follow-up survey result from the Vesterålen district in Northern Norway. The HEM survey identified previously known and new graphite occurrences, both partially exposed or buried, which were confirmed using ground surveys, drilling, and laboratory analysis of the samples. Full article
(This article belongs to the Special Issue Using Geophysical Inversion for Mineral Exploration: Methods and Applications)
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23 pages, 19609 KiB  
Article
Transformation of the Geological Environment under the Influence of Liquid Radioactive Waste (Russian Experience in Studying Historical Nuclear Disposal)
by Victoria Krupskaya, Sergey Zakusin and Mikhail Chernov
Minerals 2024, 14(3), 252; https://doi.org/10.3390/min14030252 - 28 Feb 2024
Viewed by 1417
Abstract
Due to various historical events, in the Russian Federation, in addition to the radioactive waste storage facilities used in world practice, there are various nuclear and radiation hazardous facilities that require special procedures for monitoring and decommissioning. One of these facilities is the [...] Read more.
Due to various historical events, in the Russian Federation, in addition to the radioactive waste storage facilities used in world practice, there are various nuclear and radiation hazardous facilities that require special procedures for monitoring and decommissioning. One of these facilities is the disposal site for LRW on the territory of the JSC Siberian Chemical Plant, where specially prepared waste is injected into sand reservoirs lying at depths of 300–350 m between clayey strata. This study examines in detail the features of the lithological and mineral composition of reservoir sands and aquitards. The processes of environmental transformation in reservoir sands, which lead to changes in the composition and structure of rocks, were characterized. These processes manifest themselves in the form of the development of leaching zones and their “healing” with newly formed smectite, the destruction of terrigenous grains, including the development of cracks, and the growth of newly formed smectite in the pore space of reservoirs. The forms of occurrence and localization of authigenic smectite formed as a result of technogenic impact are described. It has been shown that, despite the obvious impact of highly reactive solutions accompanying liquid radioactive waste, the insulating properties of the geological environment are maintained and even improved to some extent. Full article
(This article belongs to the Special Issue Adsorption Properties and Environmental Applications of Clay Minerals)
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23 pages, 3152 KiB  
Article
Deformation and Transformation Textures in the NaMgF3 Neighborite—Post-Perovskite System
by Estelle E. Ledoux, Michael Jugle, Stephen Stackhouse and Lowell Miyagi
Minerals 2024, 14(3), 250; https://doi.org/10.3390/min14030250 - 28 Feb 2024
Viewed by 1494
Abstract
The D″ region of the lower mantle, which lies just above the core–mantle boundary, is distinct from the bulk of the lower mantle in that it exhibits complex seismic heterogeneity and seismic anisotropy. Seismic anisotropy in this region is likely to be largely [...] Read more.
The D″ region of the lower mantle, which lies just above the core–mantle boundary, is distinct from the bulk of the lower mantle in that it exhibits complex seismic heterogeneity and seismic anisotropy. Seismic anisotropy in this region is likely to be largely due to the deformation-induced texture (crystallographic preferred orientation) development of the constituent mineral phases. Thus, seismic anisotropy can provide a marker for deformation processes occurring in this dynamic region of the Earth. Post-perovskite-structured (Mg,Fe)SiO3 is believed to be the dominant mineral phase in many regions of the D”. As such, understanding deformation mechanisms and texture development in post-perovskite is important for the interpretation of observed seismic anisotropy. Here, we report on high-pressure diamond anvil cell deformation experiments on NaMgF3 neighborite (perovskite structure) and post-perovskite. During deformation, neighborite develops a 100 texture, as has been previously observed, both in NaMgF3 and MgSiO3 perovskite. Upon transformation to the post-perovskite phase, an initial texture of {130} at high angles to compression is observed, indicating that the {100} planes of perovskite become the ~{130} planes of post-perovskite. Further compression results in the development of a shoulder towards (001) in the inverse pole figure. Plasticity modeling using the elasto-viscoplastic self-consistent code shows this texture evolution to be most consistent with deformation on (001)[100] with some contribution of glide on (100)[010] and (001)<110> in NaMgF3 post-perovskite. The transformation and deformation mechanisms observed in this study in the NaMgF3 system are consistent with the behavior generally observed in other perovskite–post-perovskite systems, including the MgSiO3 system. This shows that NaMgF3 is a good analog for the mantle bridgmanite and MgSiO3 post-perovskite. Full article
(This article belongs to the Special Issue Phase Transitions and Physical Properties of Minerals under Extreme Conditions of Pressure and Temperature)
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15 pages, 2175 KiB  
Article
Inversion for 3D Conductivity and Chargeability Models Using EM Data Acquired by the New Airborne TargetEM System in Ontario, Canada
by Leif H. Cox, Michael S. Zhdanov and Alexander Prikhodko
Minerals 2024, 14(3), 237; https://doi.org/10.3390/min14030237 - 26 Feb 2024
Cited by 3 | Viewed by 1684
Abstract
This paper introduces an original approach to the joint inversion of airborne electromagnetic (EM) data for three-dimensional (3D) conductivity and chargeability models using hybrid finite difference (FD) and integral equation (IE) methods. The inversion produces a 3D model of physical parameters, which includes [...] Read more.
This paper introduces an original approach to the joint inversion of airborne electromagnetic (EM) data for three-dimensional (3D) conductivity and chargeability models using hybrid finite difference (FD) and integral equation (IE) methods. The inversion produces a 3D model of physical parameters, which includes conductivity, chargeability, time constant, and relaxation coefficients. We present the underlying principles of this approach and an example of a high-resolution inversion of the data acquired by a new active time domain airborne EM system, TargetEM, in Ontario, Canada. The new TargetEM system collects high-quality multicomponent data with low noise, high power, and a small transmitter–receiver offset. This airborne system and the developed advanced inversion methodology represent a new effective method for mineral resource exploration. Full article
(This article belongs to the Section Mineral Exploration Methods and Applications)
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20 pages, 12869 KiB  
Article
Grinding of Australian and Brazilian Iron Ore Fines for Low-Carbon Production of High-Quality Oxidised Pellets
by Wuju Zhang, Qi Zhou, Jian Pan, Deqing Zhu and Congcong Yang
Minerals 2024, 14(3), 236; https://doi.org/10.3390/min14030236 - 26 Feb 2024
Cited by 3 | Viewed by 2662
Abstract
Oxidised pellets have become an indispensable high-quality charge for blast furnaces. Nevertheless, high-quality pellet feeds are becoming scarcer and scarcer. To broaden the range of sources of pellet feeds and reduce the production cost of pellets, more steel mills are predicted to use [...] Read more.
Oxidised pellets have become an indispensable high-quality charge for blast furnaces. Nevertheless, high-quality pellet feeds are becoming scarcer and scarcer. To broaden the range of sources of pellet feeds and reduce the production cost of pellets, more steel mills are predicted to use coarse iron ore fines with a relatively low iron grade and low impurities for the preparation of desirable pellet feeds through a typical wet grinding–settling–filtering process. In this work, the grinding, settling and filtering behaviour of Brazilian and Australian iron ore fines are studied and compared, with the aim of discovering the internal relationship between the mineralogical characteristics of different iron ore types and their grinding–settling–filtering performance. Additionally, the effects of ore blending on pellet preparation were investigated. The results show that, usually, the higher the hardness of the iron ore, the more grinding energy is required. Australian and Brazilian ore fines exhibit good grindability, with a Bond work index of about 10–15 kW·h/t. Furthermore, ore blending can reduce grinding energy consumption and improve settling and filtration rates, and the addition of finely ground Australian ores improves the balling performance of pellet mixtures. At the same bentonite content, the ball drop strength of the three blends with added Australian ore is significantly higher than that of the base blend, and the fired pellets obtained from Blend 1, Blend 2 and Blend 3 blends exhibit good metallurgical properties. Full article
(This article belongs to the Special Issue Advances in Pyrometallurgy of Minerals and Ores)
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18 pages, 3761 KiB  
Article
Determining the Metabolic Processes of Metal-Tolerant Fungi Isolated from Mine Tailings for Bioleaching
by Rosina Nkuna and Tonderayi S. Matambo
Minerals 2024, 14(3), 235; https://doi.org/10.3390/min14030235 - 26 Feb 2024
Cited by 3 | Viewed by 1856
Abstract
This study examined the metal tolerance and organic acid-producing capabilities of fungal isolates from South African tailings to assess their potential for future bioleaching applications. Four isolates were chosen for additional examination based on their capacity to generate organic acids and tolerance to [...] Read more.
This study examined the metal tolerance and organic acid-producing capabilities of fungal isolates from South African tailings to assess their potential for future bioleaching applications. Four isolates were chosen for additional examination based on their capacity to generate organic acids and tolerance to metals. In terms of tolerance to Al, Zn, Ni, and Cr, these four isolates—Trichoderma, Talaromyces, Penicillium_3, and Penicillium_6—displayed varying degrees of resistance, with Trichoderma displaying a better metal tolerance index. The growth rates under metal stress varied among the isolates, with Trichoderma displaying the highest growth rates. In high-performance liquid chromatography results, citric acid emerged as the primary organic acid produced by the four isolates, with Trichoderma achieving the highest yield in the shortest timeframe. Gas chromatography–mass spectrometry results showed that the citric acid cycle is one of the main pathways for organic acid production, though other pathways related to lipid biosynthesis and carbohydrate metabolism also play significant roles. Three compounds involved in furfural breakdown were abundant. Using KEGG, a link between these compounds and the citric acid cycle was established, where their breakdown generates an intermediate of the citric acid cycle. Full article
(This article belongs to the Special Issue Bioremediation of Contaminants in Mine Areas)
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23 pages, 14713 KiB  
Article
Effect of Low Viscosity Contrast between Quartz and Plagioclase on Creep Behavior of the Mid-Crustal Shear Zone
by Hiroto Endo, Katsuyoshi Michibayashi, Takamoto Okudaira and David Mainprice
Minerals 2024, 14(3), 229; https://doi.org/10.3390/min14030229 - 24 Feb 2024
Cited by 4 | Viewed by 1876
Abstract
Ultramylonites are among the most extreme fault rocks that commonly occur in the mid-crustal brittle–plastic transition and are mainly characterized by intensely sheared fine-grained microstructures and well-mixed mineral phases. Although the deformation mechanism of ultramylonites is key to understanding the rheological behavior of [...] Read more.
Ultramylonites are among the most extreme fault rocks that commonly occur in the mid-crustal brittle–plastic transition and are mainly characterized by intensely sheared fine-grained microstructures and well-mixed mineral phases. Although the deformation mechanism of ultramylonites is key to understanding the rheological behavior of the mid-crustal shear zone, their microstructural development is still controversial owing to their intensely fine-grained textures. To investigate the possible crustal deformation mechanisms, we studied 13 mylonites obtained from the Kashio shear zone along the Median Tectonic Line that is the largest strike-slip fault in Japan. In particular, we investigated various mixed quartz–plagioclase layers developed within tonalitic mylonite, which are representative of the common mean grain size and crystal fabric of quartz among the studied samples. A high-quality phase-orientation map obtained by electron backscattered diffraction showed not only a wide range of quartz–plagioclase mixing (10%–80% in quartz modal composition) but also revealed a correlation between grain size reduction and crystal fabric weakening in quartz, indicating a change in the deformation mechanism from dislocation creep to grain-size-sensitive creep in the mixed quartz-plagioclase layers. In contrast, plagioclase showed an almost consistent fine grain size and weak to random crystal fabrics regardless of modal composition, indicating that grain size-sensitive creep is dominant. Combined with laboratory-determined flow laws, our results show that the Kashio shear zone could have developed under deformation mechanisms in which the viscosities of quartz and plagioclase are nearly comparable, effectively within 1017–1019 Pa·s, thereby possibly enabling extensive shearing along the Median Tectonic Line. Full article
(This article belongs to the Section Crystallography and Physical Chemistry of Minerals & Nanominerals)
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14 pages, 3657 KiB  
Article
Microwave Treatment of Minerals and Ores: Heating Behaviors, Applications, and Future Directions
by Jin Chen, Xinpei Li, Lei Gao, Shenghui Guo and Fei He
Minerals 2024, 14(3), 219; https://doi.org/10.3390/min14030219 - 21 Feb 2024
Cited by 11 | Viewed by 4811
Abstract
The application of microwave technology in mineral metallurgy is a transformative approach to ore processing that offers new ideas about the current progressive depletion of resources and the environmental impact of mineral processing. This review delves into the principles, applications, and future directions [...] Read more.
The application of microwave technology in mineral metallurgy is a transformative approach to ore processing that offers new ideas about the current progressive depletion of resources and the environmental impact of mineral processing. This review delves into the principles, applications, and future directions of microwave treatment in mineral and ore processing. Microwave technology, characterized by its unique advantages such as rapid and uniform heating, selective heating, and energy efficiency, stands in contrast to traditional heating methods. It directly interacts with materials at the molecular level, enabling volumetric heating. The review encompasses a wide range of applications, including ore pre-treatment, drying, mineral processing, hydrometallurgy, smelting, and reduction. It highlights the role of microwave treatment in enhancing metal recovery, reducing energy consumption, and improving processing speeds. Future research directions are identified, focusing on enhanced equipment design, process optimization, integration with conventional methods, and technological innovations. The comprehensive overview assists researchers, engineers, and decision-makers in understanding the potential of microwave technology in mineral metallurgy, emphasizing its contribution to innovation and sustainability in the sector. Full article
(This article belongs to the Special Issue Microwave Treatment of Minerals and Ores: Heating Behaviours, Applications and Future Directions)
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28 pages, 7482 KiB  
Article
Coupled Microstructural EBSD and LA-ICP-MS Trace Element Mapping of Pyrite Constrains the Deformation History of Breccia-Hosted IOCG Ore Systems
by Samuel Anthony King, Nigel John Cook, Cristiana Liana Ciobanu, Kathy Ehrig, Yuri Tatiana Campo Rodriguez, Animesh Basak and Sarah Gilbert
Minerals 2024, 14(2), 198; https://doi.org/10.3390/min14020198 - 15 Feb 2024
Cited by 4 | Viewed by 2814
Abstract
Electron backscatter diffraction (EBSD) methods are used to investigate the presence of microstructures in pyrite from the giant breccia-hosted Olympic Dam iron–oxide copper gold (IOCG) deposit, South Australia. Results include the first evidence for ductile deformation in pyrite from a brecciated deposit. Two [...] Read more.
Electron backscatter diffraction (EBSD) methods are used to investigate the presence of microstructures in pyrite from the giant breccia-hosted Olympic Dam iron–oxide copper gold (IOCG) deposit, South Australia. Results include the first evidence for ductile deformation in pyrite from a brecciated deposit. Two stages of ductile behavior are observed, although extensive replacement and recrystallization driven by coupled dissolution–reprecipitation reaction have prevented widespread preservation of the earlier event. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) element maps of pyrite confirm that many pyrite grains display compositional zoning with respect to As, Co, and Ni, but that the zoning is often irregular, patchy, or otherwise disrupted and are readily correlated with observed microstructures. The formation of ductile microstructures in pyrite requires temperatures above ~260 °C, which could potentially be related to heat from radioactive decay and fault displacements during tectonothermal events. Coupling EBSD methods with LA-ICP-MS element mapping allows a comprehensive characterization of pyrite textures and microstructures that are otherwise invisible to conventional reflected light or BSE imaging. Beyond providing new insights into ore genesis and superimposed events, the two techniques enable a detailed understanding of the grain-scale distribution of minor elements. Such information is pivotal for efforts intended to develop new ways to recover value components (precious and critical metals), as well as remove deleterious components of the ore using low-energy, low-waste ore processing methods. Full article
(This article belongs to the Special Issue Microanalysis Applied to Mineral Deposits)
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20 pages, 15919 KiB  
Article
The Temporal Distribution of the Host Rocks to Gold, the Archean Witwatersrand Basin, South Africa
by Neil Phillips, Julian Vearncombe, Dave Craw and Arthur Day
Minerals 2024, 14(2), 199; https://doi.org/10.3390/min14020199 - 15 Feb 2024
Cited by 4 | Viewed by 3674
Abstract
The hosts to gold around the Witwatersrand Basin span over 400 my, through 14 km of stratigraphy in a variety of host rocks and in tectonic settings that include periods of rifting, thermal subsidence, foreland basin, flood basalt outpouring, graben development, and further [...] Read more.
The hosts to gold around the Witwatersrand Basin span over 400 my, through 14 km of stratigraphy in a variety of host rocks and in tectonic settings that include periods of rifting, thermal subsidence, foreland basin, flood basalt outpouring, graben development, and further thermal subsidence. A geological model that assumes placer processes to explain this diversity implies a super-long-lived and special source of the detrital gold, transport, and highly effective sorting processes over a time span of 400 my. There is no evidence of a special source and sorting over such a long time period. In the Phanerozoic, this would be equivalent to the special source and sorting processes operating continually over an equivalent period of geological time spanning from the Devonian up until the present day; this is as yet recognised nowhere else on the planet. With regard to the geological model that assumes a placer process, this is untenable because of these scientific shortcomings and its lack of success in exploration. A better use of funds may be to consider alternative approaches and epigenetic models in exploration. Full article
(This article belongs to the Special Issue Geological, Structural, Geochemical, Hyperspectral, and Geostatistical Modeling for Mineral Exploration)
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33 pages, 4723 KiB  
Article
Beneficiation of High-Density Tantalum Ore in the REFLUX™ Concentrating Classifier Analysed Using Batch Fractionation Assay and Density Data
by Simon M. Iveson, Nicolas Boonzaier and Kevin P. Galvin
Minerals 2024, 14(2), 197; https://doi.org/10.3390/min14020197 - 14 Feb 2024
Cited by 1 | Viewed by 1706
Abstract
A laboratory-scale REFLUX™ Concentrating Classifier was operated in continuous mode to beneficiate a sub 0.100 mm tantalum ore with a head grade of 0.56 wt.% Ta. The unit incorporated a lower section with a reduced diameter to accommodate a low yield. At a [...] Read more.
A laboratory-scale REFLUX™ Concentrating Classifier was operated in continuous mode to beneficiate a sub 0.100 mm tantalum ore with a head grade of 0.56 wt.% Ta. The unit incorporated a lower section with a reduced diameter to accommodate a low yield. At a yield to underflow product of 4.0 wt.%, a product grade of 13.3 wt.% was achieved (23.7 upgrade) at a recovery of 88.3%. Samples of the feed, product and reject were then fractionated in a batch REFLUX™ Classifier unit using dense lithium heteropolytungstate (LST) solution into 11 fractions. Each of these fractions was then screened into seven size intervals and analysed by pycnometry and X-ray fluorescence (XRF). Most of the material was found to reside in four relatively narrow density bands. A new analysis based on the recovery of selected tracer elements showed that the partition curve had good closure at both ends and that the density cut point and Ep both increased with decreasing particle size. For the +0.045 mm material, the density cut point was estimated to be around 3952 kg/m3 with an Ep of 317 kg/m3, but it was expected that this new method could overestimate Ep. An alternative novel approach for estimating the partition performance was developed. This method estimated the cut point and Ep values to be 3764 kg/m3 and 107 kg/m3, respectively. However, sensitivity analysis found that due to the near total absence of material in the density range from 3400 kg/m3 to 4700 kg/m3, the Ep could likely lie anywhere in the range from 0 to 250 kg/m3. The methodology proved useful in establishing these limitations in the analysis. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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29 pages, 7624 KiB  
Article
Chemical and Textural Peculiarities of Zircon from Peralkaline Granites and Quartz-Bearing Syenites
by Karel Breiter, Jindřich Kynický and Zuzana Korbelová
Minerals 2024, 14(2), 187; https://doi.org/10.3390/min14020187 - 10 Feb 2024
Viewed by 1906
Abstract
Zircon from four plutons of peralkaline granites and quartz-bearing syenites, differing in geotectonic positions, petrological and mineralogical compositions, and contents of volatile and trace elements, was studied using SEM, CL, and EPMA with the intention to define typical textural and chemical features of [...] Read more.
Zircon from four plutons of peralkaline granites and quartz-bearing syenites, differing in geotectonic positions, petrological and mineralogical compositions, and contents of volatile and trace elements, was studied using SEM, CL, and EPMA with the intention to define typical textural and chemical features of zircon from peralkaline rocks. In strongly peralkaline Na-pyroxene-bearing rocks represented by the Khan Bogd and Khalzan Buregte plutons (Mongolia), the primary zircon is scarce or missing. Most zircon grains are secondary, originating in hydrothermal stage from primary Zr silicates. They often form globular or radial aggregates. Chemical compositions of zircon in these rocks typically show high contents of Y, moderate contents of REE (thus high Y/Yb values) together with low contents of U and Th and low analytical totals. In mildly peralkaline mica-bearing rocks represented by Ivigtut stock (Groenland) and Madeira pluton (Brazil), the exclusive primary Zr mineral is zircon, mostly of orthomagmatic origin. Its analytical totals approach 100 wt%, enrichment in HREE, resulting in low Y/Yb values, is typical. Zircon populations from two types of peralkaline granitoids can be distinguished from each other and from zircon from S-type granites based on combination of the Zr/Hf, Y/Yb, and U/Th values, or on the Y-Hf-P ternary diagram. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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15 pages, 2827 KiB  
Article
Interactions of Perrhenate (Re(VII)O4−) with Fe(II)-Bearing Minerals
by Anthony W. N. Kilber, Maxim I. Boyanov, Kenneth M. Kemner and Edward J. O’Loughlin
Minerals 2024, 14(2), 181; https://doi.org/10.3390/min14020181 - 7 Feb 2024
Cited by 3 | Viewed by 1757
Abstract
Rhenium (Re) is an extremely rare element, with a crustal abundance of approximately 0.4 parts per billion (ppb) and a sea water concentration of 8.3 parts per trillion (ppt). However, Re concentrations in anoxic marine sediments range from 2 to 184 ppb, which [...] Read more.
Rhenium (Re) is an extremely rare element, with a crustal abundance of approximately 0.4 parts per billion (ppb) and a sea water concentration of 8.3 parts per trillion (ppt). However, Re concentrations in anoxic marine sediments range from 2 to 184 ppb, which is attributed to reduction of the highly soluble perrhenate ion (Re(VII)O4−) to insoluble Re(IV) species. Anoxic sediments typically contain Fe(II) and sulfide species, which could potentially reduce Re(VII) to Re(IV). In this study, we examined the interactions of KReO4 with magnetite (Fe3O4), siderite (FeCO3), vivianite (Fe3(PO4)2•8H2O), green rust (mixed Fe(II)/Fe(III) layered double hydroxide), mackinawite (FeS), and chemically reduced nontronite (NAu-1) using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy to determine the valence state and speciation of Re. Uptake of Re by green rust was rapid, with ~50% associated with the solids within 2 days. In contrast, there was <10% uptake by the other Fe(II) phases over 48 days. Reduction of Re(VII) to Re(IV) was only observed in the presence of green rust, producing clusters of bidentate-coordinated Re(IV)O6 octahedra.. These results suggest that except for green rust, the potential for other Fe(II)-bearing minerals to act as reductants for ReO4− in sedimentary environments requires further investigation. Full article
(This article belongs to the Special Issue Redox Reactivity of Iron Minerals in the Geosphere, 2nd Edition)
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20 pages, 2230 KiB  
Review
Calcium Orthophosphate–Clay Composites—Preparation, Characterisation, and Applications: A Review
by Monika Šupová
Minerals 2024, 14(2), 169; https://doi.org/10.3390/min14020169 - 4 Feb 2024
Cited by 2 | Viewed by 1859
Abstract
Calcium orthophosphates and clays and their composites are one of the most important groups in the field of new, modern, and technologically advanced materials that are accessible, inexpensive, and environmentally friendly. This review provides a summary of recent research on calcium orthophosphate–clay composites, [...] Read more.
Calcium orthophosphates and clays and their composites are one of the most important groups in the field of new, modern, and technologically advanced materials that are accessible, inexpensive, and environmentally friendly. This review provides a summary of recent research on calcium orthophosphate–clay composites, their preparation, characterisation, and use in various applications. An introduction to the subject is followed by a detailed description of the chemical and physical properties of calcium orthophosphates, clays, and clay minerals. This is followed by a general summary of preparation methods for calcium orthophosphate–clay composites. Particular attention is paid to the description of individual applications, i.e., environmental applications, biomaterials science (tissue engineering, pharmacology), and other emerging applications. Finally, future perspectives are summarised and discussed. Full article
(This article belongs to the Special Issue Clay Minerals and Waste Fly Ash Ceramics, Volume II)
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22 pages, 6645 KiB  
Article
Mineral Chemistry of Olivine, Oxy-Spinel, and Clinopyroxene in Lavas and Xenoliths from the Canary, Azores, and Cape Verde Islands (Macaronesia, North Atlantic Ocean): New Data and Comparisons with the Literature
by Federica Zaccarini, Giorgio Garuti, Reinhard Moser, Constantinos Mavrogonatos, Panagiotis Voudouris, Adriano Pimentel and Sabrina Nazzareni
Minerals 2024, 14(2), 161; https://doi.org/10.3390/min14020161 - 1 Feb 2024
Viewed by 2780
Abstract
An electron microprobe study was carried out on olivine, clinopyroxene, and oxy-spinel occurring in basalts and dunite xenoliths from the archipelagos of the Azores, the Canary Islands, and Cape Verde. By comparing our results with previously published data from the volcanic islands of [...] Read more.
An electron microprobe study was carried out on olivine, clinopyroxene, and oxy-spinel occurring in basalts and dunite xenoliths from the archipelagos of the Azores, the Canary Islands, and Cape Verde. By comparing our results with previously published data from the volcanic islands of Macaronesia, we confirmed the validity of the compositions of olivine, clinopyroxene, and oxy-spinel as geochemical tracers. The origin of olivine, i.e., crystallized in the lithospheric mantle or in volcanic rocks, was successfully discriminated. Olivine from Lanzarote dunite xenoliths, which represent fragments of the mantle transported to the surface by host magmas, exhibited higher Fo% values (Fo91.02 to Fo91.94) and a different distribution of minor elements Ca, Ni, and Mn (CaO up to 0.42 wt%, NiO 0.07–0.41 wt%, MnO 0.06–0.3 wt%) when compared with olivine occurring as phenocrysts in basaltic lavas from the Macaronesian islands. The highly variable forsterite contents (Fo75.1 to Fo94.4) in olivine from gabbro and peridotite xenoliths found across the islands of Macaronesia were attributed to fractional crystallization that started in a deep magma reservoir, suggesting that these xenoliths represent cumulate rocks and not mantle fragments. Alternatively, these xenoliths may have been affected by the interaction with metasomatic fluids. The composition of clinopyroxene phenocrysts was used to decipher formation conditions under extensional tectonics. Their composition suggests that the host lavas have an alkaline to calc-alkaline signature. Furthermore, clinopyroxene euhedral shapes and compositions suggest an origin by fractional crystallization in a closed magmatic system. The composition alone of oxy-spinel from Macaronesian basalts and xenoliths was not sufficient to draw conclusions about the geodynamic environment where they were formed. Nevertheless, the relationship between oxy-spinel and olivine crystallized in equilibrium was successfully used as oxybarometers and geothermometers. The oxy-spinel–olivine pairs show evidence that the basaltic lavas were crystallized from melts with higher oxygen fugacity and different cooling histories than those of the mantle xenoliths, as the latter crystallized and re-equilibrated much slower than the basalts. Full article
(This article belongs to the Special Issue Submarine Volcanism, Related Hydrothermal Systems and Mineralizations)
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15 pages, 3239 KiB  
Article
Enhancing the Grinding Efficiency of a Magnetite Second-Stage Mill through Ceramic Ball Optimization: From Laboratory to Industrial Applications
by Caibin Wu, Zhilong Chen, Ningning Liao, Chong Zeng, Yihan Wang and Jingkun Tian
Minerals 2024, 14(2), 160; https://doi.org/10.3390/min14020160 - 31 Jan 2024
Cited by 4 | Viewed by 2023
Abstract
Ceramic ball milling has demonstrated remarkable energy-saving efficiency in industrial applications. However, there is a pressing need to enhance the grinding efficiency for coarse particles. This paper introduces a novel method of combining media primarily using ceramic balls supplemented with an appropriate proportion [...] Read more.
Ceramic ball milling has demonstrated remarkable energy-saving efficiency in industrial applications. However, there is a pressing need to enhance the grinding efficiency for coarse particles. This paper introduces a novel method of combining media primarily using ceramic balls supplemented with an appropriate proportion of steel balls. Three grinding media approaches, including the utilization of steel balls, ceramic balls, and a hybrid combination, were investigated. Through an analysis of the grinding kinetics and the R–R particle size characteristic formulas, the study compares the breakage rate and particle size distribution changes for the three setups. The results indicate that employing binary media effectively improves the grinding efficiency for +0.3 mm coarse particles while maintaining the energy-saving advantages of ceramic ball milling. Simultaneously, the uniformity of the ground product is ensured. This proposed approach has been successfully validated in industrial applications, providing robust theoretical support for the expansion of ceramic ball milling applications. Full article
(This article belongs to the Special Issue Experimental and Numerical Studies of Mineral Comminution: 3rd Edition)
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13 pages, 2060 KiB  
Article
Using Manganese Oxidizing Fungi to Recover Metals from Electronic Waste
by Sarah A. Doydora, Oliver Baars, Marc A. Cubeta and Owen W. Duckworth
Minerals 2024, 14(1), 111; https://doi.org/10.3390/min14010111 - 20 Jan 2024
Cited by 1 | Viewed by 2120
Abstract
Discarded electronic materials (e-waste) contain economically valuable metals that can be hazardous to people and the environment. Current e-waste recycling approaches involve either energy-intensive smelting or bioleaching processes that capture metals in their dissolved forms. Our study aimed to use Mn oxidizing fungi [...] Read more.
Discarded electronic materials (e-waste) contain economically valuable metals that can be hazardous to people and the environment. Current e-waste recycling approaches involve either energy-intensive smelting or bioleaching processes that capture metals in their dissolved forms. Our study aimed to use Mn oxidizing fungi for recovering metals from e-waste that could potentially transform recycled metals directly into solid forms. We hypothesized that Mn oxidizing fungi can extract metals through chelation by siderophores and subsequent metal (or metal-chelate) adsorption to Mn oxides produced by fungi. Pure cultures of the three fungal species examined were grown on solidified Leptothrix medium with or without ground lithium ion batteries and incubated under ambient room temperature. The results showed Mn and Co were recovered at the highest concentrations of 8.45% and 1.75%, respectively, when grown with Paraconiothyrium brasiliensis, whereas the greatest concentration of Cu was extracted by Paraphaeosphaeria sporulosa at 20.6% per weight of e-waste-derived metals. Although metal-siderophore complexes were detected in the fungal growth medium, metal speciation data suggested that these complexes only occurred with Fe. This observation suggests that reactions other than complexation with siderophores likely solubilized e-waste metals. Elemental mapping, particularly of P. brasiliensis structures, showed a close association between Mn and Co, suggesting potential adsorption or (co)precipitation of these two metals near fungal mycelium. These findings provide experimental evidence for the potential use of Mn oxidizing fungi in recycling and transforming e-waste metals into solid biominerals. However, optimizing fungal growth conditions with e-waste is needed to improve the efficiency of metal recovery. Full article
(This article belongs to the Special Issue The Microbiology of Biomining: Microbial Communities, Consortia and Species Involved in Mineral Processing)
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28 pages, 13508 KiB  
Article
Hydrothermal Mineralization and Mineral Chemistry of Arsenides and Sulfarsenides in the Fe-Co-Ni-As-S System and Introduction of Three Unique Minerals, Port Radium Deposit, Canada
by Alireza K. Somarin, Li Zhou, Guodong Zheng and Xiangxian Ma
Minerals 2024, 14(1), 85; https://doi.org/10.3390/min14010085 - 11 Jan 2024
Cited by 3 | Viewed by 2023
Abstract
The Port Radium U-Cu-Ni-Co-Ag deposit in northwestern Canada is hosted within a mineral system that has generated a variety of mineralization styles from iron oxide-copper-gold to iron oxide-apatite, porphyry, skarn, and epithermal. Their genesis is linked to an extensive subduction-related magmatism that formed [...] Read more.
The Port Radium U-Cu-Ni-Co-Ag deposit in northwestern Canada is hosted within a mineral system that has generated a variety of mineralization styles from iron oxide-copper-gold to iron oxide-apatite, porphyry, skarn, and epithermal. Their genesis is linked to an extensive subduction-related magmatism that formed widespread dacite-rhyodacite-andesite volcanic and volcanoclastic sequences (~1.87 Ga), which have been intruded by their equivalent intrusive plutons. Pervasive and intensive hydrothermal alterations, including albitic, magnetite-actinolite-apatite, potassic ± albitic, phyllic, and propylitic occurred before the main sulfide, sulfarsenide, and uraninite vein-type mineralization. Although scarce sulfide minerals formed at the beginning of the hydrothermal activity, the main polymetallic arsenide-sulfarsenide-sulfide ± uraninite vein-type mineralization occurred during the epithermal stage. In addition to the common arsenides and sulfarsenides including nickeline, cobaltite, rammelsbergite, safflorite, skutterudite, gersdorffite, and arsenopyrite, three unique sulfarsenides were also found: Co0.67Ni0.32Fe0.02S0.19As2.80, which could be a sulfur-rich skutterudite, Ni0.85Co0.15S0.39As1.60, and Ni0.69Co0.31S0.47As1.52, which are chemically comparable to the Port Radium rammelsbergite with substantial addition of S and Co; they could be the solid solution product of gersdorffite-cobaltite or safflorite-rammelsbergite. Full article
(This article belongs to the Special Issue Footprints of Mineral Systems with IOCG, IOA and Affiliated Critical Metal Deposits: From Metasomatism to Metamorphism)
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18 pages, 5385 KiB  
Article
Monitoring of Mineral Processing Operations with Isolation Forests
by Chris Aldrich and Xiu Liu
Minerals 2024, 14(1), 76; https://doi.org/10.3390/min14010076 - 8 Jan 2024
Cited by 3 | Viewed by 2189
Abstract
Reliable monitoring of mineral process systems is key to more efficient plant operation. Multivariate statistical process control based on principal component analysis is well-established in industry but may not be effective when dealing with dynamic nonlinear or transient processes, where process behavior may [...] Read more.
Reliable monitoring of mineral process systems is key to more efficient plant operation. Multivariate statistical process control based on principal component analysis is well-established in industry but may not be effective when dealing with dynamic nonlinear or transient processes, where process behavior may change rapidly from time to time. Although a large variety of nonlinear models have been proposed to address these problems, the monitoring of complex dynamic process systems remains challenging. Isolation forests are unsupervised machine learning models that provide an interesting approach to process monitoring that has not been explored extensively yet. In this investigation, this approach is compared with traditional multivariate statistical process monitoring based on principal component models. Three real-world case studies are considered. The first case study is based on coal flotation, the second is based on features extracted from a platinum group metal flotation froth; and the third is based on data from an industrial semi-autogenous grinding circuit. In each case, the models were trained on data representing normal operating conditions and then tested on new process data that were generally different from the training data to test their ability to identify these data as out-of-control. The isolation forest models performed better than the principal component models when the data were nonlinear, but not when the data associated with normal operation and faulty conditions were linearly separable, as was the case with the flotation data. Full article
(This article belongs to the Special Issue Recent Developments in Sensors, Machine Learning, Data Analytics, and Process Optimisation in Minerals Processing and Extractive Metallurgy)
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14 pages, 2120 KiB  
Article
Linking the Neoproterozoic to Early Paleozoic Belts Bordering the West African and Amazonian Cratons: Review and New Hypothesis
by Michel Villeneuve and Camille Rossignol
Minerals 2024, 14(1), 48; https://doi.org/10.3390/min14010048 - 30 Dec 2023
Cited by 1 | Viewed by 1861
Abstract
Correlations between the Neoproterozoic belts surrounding the West African Craton and northern Brazilian cratons have long been a subject of interest and controversies. Due to the splitting of African and South American continents by the Atlantic oceanic domains, no direct links are preserved, [...] Read more.
Correlations between the Neoproterozoic belts surrounding the West African Craton and northern Brazilian cratons have long been a subject of interest and controversies. Due to the splitting of African and South American continents by the Atlantic oceanic domains, no direct links are preserved, requiring relying on various geological or geophysical characteristics to propose such correlations. In addition to the opening of the Atlantic oceanic domains, another difficulty arises from the covering of northern Brazilian belts by upper Paleozoic and Mesozoic basins, making these correlations speculative. Here, we propose new correlations based on the comparison between African and Brazilian belts. Recently, new geochronological and geodynamical data obtained in West Africa have evidenced four orogens in the Neoproterozoic belts of the western margin of the West Africa Craton, while the belts on the eastern side underwent only one orogeny. Similarities with the Pan-African I (900–650 Ma) and with the Pan-African II (650–480 Ma) orogenic events have been evidenced in the western Brazilian belts (Araguay and Paraguay). The first two orogens on the western margin (Pan-African I and Pan-African II) can thus be extended to the western Brazilian belts and can be considered as parts of a single geodynamic system running from the Mauritania to the Paraguay including the “Gurupi rift” as an aulacogen connected to the NNW-SSE Panafrican I and II oceanic domains. Consequently, the eastern Brazilian belt should rather be linked the Eastern Trans-Saharan belts. Full article
(This article belongs to the Special Issue Geological Evolution of South American Cratons)
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38 pages, 13006 KiB  
Review
Wrapping a Craton: A Review of Neoproterozoic Fold Belts Surrounding the São Francisco Craton, Eastern Brazil
by Alexandre Uhlein, Gabriel Jubé Uhlein, Fabrício de Andrade Caxito and Samuel Amaral Moura
Minerals 2024, 14(1), 43; https://doi.org/10.3390/min14010043 - 29 Dec 2023
Cited by 2 | Viewed by 3294
Abstract
A synthesis of the evolution of the Neoproterozoic belts or orogens surrounding the São Francisco craton (SFC) in northeastern and southeastern Brazil is presented. Emphasis is placed on recognizing the superposition of sedimentary basins, from rift to passive margin to retroarc and foreland, [...] Read more.
A synthesis of the evolution of the Neoproterozoic belts or orogens surrounding the São Francisco craton (SFC) in northeastern and southeastern Brazil is presented. Emphasis is placed on recognizing the superposition of sedimentary basins, from rift to passive margin to retroarc and foreland, as well as identifying three diachronic continental collisions in the formation of the SFC. The Tonian passive margin occurs in the southern Brasília Belt with the Vazante, Canastra, and Araxá Groups. During the Tonian, island magmatic arcs and basins developed in front and behind these arcs (fore- and back-arcs). Subsequently, in the Cryogenian–Ediacaran, a retroarc foreland basin developed with part of the Araxá Group and the Ibiá Group, and finally, a foreland basin developed, which was filled by the Bambuí Group. A tectonic structure of superimposed nappes, with subhorizontal S1–2 foliation, formed between 650 and 610 Ma, is striking. In the northern Brasília Belt, there is the Stenian passive margin of the Paranoá Group, the Tonian intrusion of the Mafic–Ultramafic Complexes, and the Mara Rosa Island magmatic arc, active since the Tonian, with limited volcanic–sedimentary basins associated with the arc. A thrust–fold belt structure is prominent, with S1 foliation and late transcurrent, transpressive tectonics characterized by the Transbrasiliano (TB) lineament. The Cryogenian–Ediacaran collision between the Paranapanema and São Francisco cratons is the first collisional orogenic event to the west. In the Rio Preto belt, on the northwestern margin of the São Francisco craton, the Cryogenian–Ediacaran Canabravinha rift basin is prominent, with gravitational sediments that represent the intracontinental termination of the passive margin that occurs further northeast. The rift basin was intensely deformed at the Ediacaran–Cambrian boundary, as was the Bambuí Group. On the northern and northeastern margins of the São Francisco craton, the Riacho do Pontal and Sergipano orogens stand out, showing a comparable evolution with Tonian and Cryogenian rifts (Brejo Seco, Miaba, and Canindé); Cryogenian–Ediacaran passive margin, where the Monte Orebe ophiolite is located; and Cordilleran magmatic arcs, which developed between 620 and 610 Ma. In the Sergipano fold belt, with a better-preserved outer domain, gravitational sedimentation occurs with glacial influence. A continental collision between the SFC and the PEAL (Pernambuco-Alagoas Massif) occurred between 610 and 540 Ma, with intense deformation of nappes and thrusts, with vergence to the south and accommodation by dextral transcurrent shear zones, such as the Pernambuco Lineament (PE). The Araçuaí belt or orogen was formed at the southeastern limit of the SFC by a Tonian intracontinental rift, later superimposed by a Cryogenian–Ediacaran rift–passive margin of the Macaúbas Group, with gravitational sedimentation and glacial influence, and distally by oceanic crust. It is overlain by a retroarc basin with syn-orogenic sedimentation of the Salinas Formation, partly derived from the Rio Doce cordilleran magmatic arc and associated basins, such as the Rio Doce and Nova Venécia Groups. A third continental collision event (SF and Congo cratons), at the end of the Ediacaran (580–530 Ma), developed a thrust–fold belt that deforms the sediments of the Araçuaí Belt and penetrates the Paramirim Corridor, transitioning to the south to a dextral strike-slip shear zone that characterizes the Ribeira Belt. Full article
(This article belongs to the Special Issue Geological Evolution of South American Cratons)
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17 pages, 3143 KiB  
Article
Old Sulfidic Ore Tailing Dump: Ground Features, Mineralogy, Biodiversity—A Case Study from Sibay, Russia
by Maxim Muravyov, Dmitry Radchenko, Maria Tsupkina, Vladislav Babenko and Anna Panyushkina
Minerals 2024, 14(1), 23; https://doi.org/10.3390/min14010023 - 25 Dec 2023
Cited by 2 | Viewed by 1556
Abstract
The Urals (Russia) are among the largest mining areas in the world, with millions of tons of mine waste deposited. An old sulfidic tailing dump formed over decades of mining activities at the Sibay ore-processing plant is a typical cause of acid mine [...] Read more.
The Urals (Russia) are among the largest mining areas in the world, with millions of tons of mine waste deposited. An old sulfidic tailing dump formed over decades of mining activities at the Sibay ore-processing plant is a typical cause of acid mine drainage (AMD) formation, posing a threat to ecosystems of neighboring environments. In this study, the formation of oxidized surface soil layers in four zones of the Sibay tailing dump was revealed, and their chemical–mineralogical and physical–mechanical characteristics were analyzed. According to the results of the metabarcoding of hypervariable regions of the 16S rRNA genes, oxidation in soil layers was associated with the activity of sulfur- and iron-oxidizing acidophiles represented by a few genera: Ferroacidibacillus, Sulfoacidibacillus, Sulfobacillus, and Ferroplasma. The structure of the microbial communities in soil layers differed depending on the zone and depth of sampling. In the samples characterized by the weak oxidation of sulfide minerals, microbial communities were dominated by bacteria of the genus Pseudomonas. The data obtained in this research are of importance to predict the oxidation/leaching processes in mine wastes and their negative environmental impacts in the mining region, as well as to develop technologies for processing these raw materials. Full article
(This article belongs to the Special Issue Microorganisms and Minerals in Natural and Engineered Environments, Volume II)
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12 pages, 8928 KiB  
Article
Evidence of a Scheduled End for Prism Growth in the Shell of Pinctada margaritifera: Closure of the Calcite Biomineralization Area by a Specific Organic Membrane
by Jean-Pierre Cuif, Cedrik Lo and Yannicke Dauphin
Minerals 2024, 14(1), 20; https://doi.org/10.3390/min14010020 - 24 Dec 2023
Cited by 3 | Viewed by 1685
Abstract
The shell of the pearl oyster Pinctada margaritifera is made up of two layers: an outer layer of calcite prisms and an inner layer of aragonite tablets. Recent studies have shown that the calcite layer develops in a series of steps. We found [...] Read more.
The shell of the pearl oyster Pinctada margaritifera is made up of two layers: an outer layer of calcite prisms and an inner layer of aragonite tablets. Recent studies have shown that the calcite layer develops in a series of steps. We found that the end of prism growth and the start of aragonite deposition are also complex processes. Contrary to the common belief that prism growth is interrupted by the expansion of the aragonite layer, we found that a specific membrane covers the calcite surface before aragonite deposition starts. The earliest aragonite depositions occur as granular spots located only on the surfaces covered by this organic membrane This membrane appears to be the final stage of the calcite biomineralization cycle. This new understanding of calcite development has implications for shell biomineralization research and the production of pearls. Full article
(This article belongs to the Section Biomineralization and Biominerals)
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18 pages, 14600 KiB  
Article
CoDA-Based Geo-Electrochemical Prospecting Prediction of Uranium Orebodies in Changjiang Area, Guangdong Province, China
by Rui Tang, Li Sun, Fei Ouyang, Keyan Xiao, Cheng Li, Yunhui Kong, Miao Xie, Yixiao Wu and Yaxin Gao
Minerals 2024, 14(1), 15; https://doi.org/10.3390/min14010015 - 21 Dec 2023
Cited by 1 | Viewed by 1597
Abstract
In order to achieve a breakthrough in the exploration of uranium orebodies in the Changjiang area of Guangdong province in China, the geo-electrochemical exploration method is used for mineral resource prediction. The logarithmically and isometric log-ratio (ilr) transformations are applied to the geo-electrochemical [...] Read more.
In order to achieve a breakthrough in the exploration of uranium orebodies in the Changjiang area of Guangdong province in China, the geo-electrochemical exploration method is used for mineral resource prediction. The logarithmically and isometric log-ratio (ilr) transformations are applied to the geo-electrochemical data in this study area to extract geochemical anomalies. The relationship between element associations and mineralization is revealed through descriptive statistical analysis and further biplot analysis. Then, the energy spectrum density–area fractal model (S-A model) is used to identify geochemical backgrounds and anomalies. The results show that: (i) the logarithmically and ilr-transformed data are more uniform, and they more or less obey the rules of normal distribution; (ii) the biplot shows that the ilr-transformed data eliminates the closure effect, and the robust principal component analysis (RPCA) has a better indicative significance for element associations—PC1 reveals the mineralization element association dominated by U and the multiple periods of hydrothermal activity; (iii) the S-A method could extract the local anomalies from different geochemical backgrounds, which indicates mineralization is more reliable. Finally, four favorable prospecting targets are delineated based on the geological and geochemical indicators. Full article
(This article belongs to the Special Issue Digital Geosciences and Mineral Exploration)
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32 pages, 11917 KiB  
Article
Miocene Volcanism in the Slovenský Raj Mountains: Magmatic, Space, and Time Relationships in the Western Carpathians
by Rastislav Demko, Marián Putiš, Qiu-Li Li, David Chew, Lukáš Ackerman and Ondrej Nemec
Minerals 2024, 14(1), 9; https://doi.org/10.3390/min14010009 - 19 Dec 2023
Viewed by 1914
Abstract
The Miocene volcanic-intrusive complex in the Slovenský Raj Mountains, middle Slovakia, comprises a swarm of subalkaline basalts and basaltic andesites with alkaline basalts, trachybasalts and basaltic trachyandesites. Basaltic to doleritic feeder dykes and sporadic hyaloclastite lavas are exposed in contact with the Triassic [...] Read more.
The Miocene volcanic-intrusive complex in the Slovenský Raj Mountains, middle Slovakia, comprises a swarm of subalkaline basalts and basaltic andesites with alkaline basalts, trachybasalts and basaltic trachyandesites. Basaltic to doleritic feeder dykes and sporadic hyaloclastite lavas are exposed in contact with the Triassic Bódvaszilas Formation of the Silica Nappe. The primary clinopyroxene, plagioclase, and Fe-Ti oxide assemblage also contains calcite spheroids inferred to represent carbonatitic melt. These spheroids are associated with subsolidus chlorite, actinolite, magnetite, titanite, calcite, and epidote. Micropoikilitic clinopyroxene, albite, and Ti-magnetite formed due to rapid quenching. There was an incorporation of host rock carbonate during the eruption. The erupted products are the result of magmatic differentiation of the parental basaltic tholeiitic magma with a redox of ∆QFM = +1 to +3, affected by varying degrees of 0%–50% fractionation and the assimilation of carbonate material in a shallow magmatic reservoir. REE geochemistry shows N-MORB-like type patterns with both LaN/YbN and LaN/SmN < 1 at near constant Eu/Eu* (~0.9). This is supported by εNd(t=13 Ma) values of +8.0 to +7.4 determined from the basaltic rocks. The REE values can be modeled by 1% fractional melting of garnet peridotite mixed with 7% melting of spinel peridotite of PM composition (1:9 proportions). SIMS and LA-ICP-MS U/Pb analysis of zircons yields a concordant age of 12.69 ± 0.24 Ma and a 13.3 ± 0.16 Ma intercept (Serravallian) age. The Middle Miocene volcanic activity was related to subduction-collision processes along the boundary of the Cenozoic ALCAPA (Alps–Carpathians–Pannonia) microplate and the southern margin of the European plate. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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27 pages, 9168 KiB  
Article
A Multiphysics Model for the Near-Field Evolution of a Geological Repository of Radioactive Waste
by Uy Vo, Mamadou Fall, Julio Ángel Infante Sedano and Thanh Son Nguyen
Minerals 2023, 13(12), 1535; https://doi.org/10.3390/min13121535 - 10 Dec 2023
Cited by 3 | Viewed by 2083
Abstract
The safety and robustness of Deep Geological Repositories (DGRs) are of paramount importance for the long-term management of spent nuclear fuel from electricity generation. The introduction of a multi-barrier system, which includes the host rock formation and an engineered barrier system (including the [...] Read more.
The safety and robustness of Deep Geological Repositories (DGRs) are of paramount importance for the long-term management of spent nuclear fuel from electricity generation. The introduction of a multi-barrier system, which includes the host rock formation and an engineered barrier system (including the bentonite buffer), has been a widely used approach to ensure the safety of DGRs. The assessment of the long-term safety of DGRs involves the mathematical modeling of the coupled thermal–hydraulic–mechanical–chemical (THMC) processes that occur in the near-field of the DGRs and their impact on the behaviour and engineering properties of the bentonite buffer. This paper presents a review of the THMC-coupled processes that arise in the bentonite buffer as well as a mathematical model governing such coupled processes. The model is verified against existing analytical solutions and validated against measured data of a thermal diffusion experiment in a sand bentonite column. Also, scoping analyses were performed to assess the influence of coupled THM processes on solute transport in clayrocks. The results of the numerical model closely matched those of the analytical solutions and experimental data demonstrating the capability of the provided mathematical model as well as the numerical approach in enhancing our comprehension of DGR behaviour. This enhanced comprehension will be valuable for safety prediction and assessment in the context of DGRs. The work presented in this paper is part of the Canadian Nuclear Safety Commission’s (CNSC) regulatory research to gain independent knowledge on the safety of the geological disposal of radioactive waste. Full article
(This article belongs to the Special Issue Implications of THMC Processes on Long-Term Safety of Geological Disposal of Radioactive Waste)
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15 pages, 3515 KiB  
Article
Distribution of Heavy Metals in Surface Sediments of a Tropical Mangrove Wetlands in Hainan, China, and Their Biological Effectiveness
by Gucheng Zhang, Shenghong Chen, Ruiling Long, Bo Ma, Yu Chang and Changping Mao
Minerals 2023, 13(12), 1476; https://doi.org/10.3390/min13121476 - 23 Nov 2023
Cited by 4 | Viewed by 1731
Abstract
The distribution and ecological risk of heavy metals in sediments were studied through the systematic collection and analysis of mangrove wetland sediments in Dongzhai Harbor, Hainan. The main insights obtained were as follows: (1) The distribution characteristics and influencing factors of heavy metals [...] Read more.
The distribution and ecological risk of heavy metals in sediments were studied through the systematic collection and analysis of mangrove wetland sediments in Dongzhai Harbor, Hainan. The main insights obtained were as follows: (1) The distribution characteristics and influencing factors of heavy metals in wetland sediments were analyzed by using the inverse-distance weight interpolation method. In terms of spatial distribution, the contents of heavy metals As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sr, Ti, and Zn in the western part of the wetland were significantly higher than in the eastern part. The contents of heavy metals Cd, Co, Cr, Cu, Hg, Mn, Ni, Zn, and Ti near the anthropogenic area were significantly higher than at other points. (2) The pollution sources and ecological risks of heavy metals in wetland sediments were explored by using correlation analysis, cluster analysis, and potential ecological risk index analysis. The results showed that As, Ba, Pb, and Sr mainly originated from natural processes; Co, Cr, Cu, Mn, Ni, Ti, and Zn mainly originated from industry; and agricultural heavy metals mainly originated from Cd and Hg. The ecological risk analysis showed that there were obvious ecological risks of heavy metals in the western and southeastern corners of the wetland, which were both located in the vicinity of land far away from the coastline and near the human activities, and featured mangrove forests with dense vegetation characteristics. Full article
(This article belongs to the Special Issue Heavy Metal and Rare Earth Element Pollution in Soil and Water: Sources, Geochemical Behaviors and Ecological Effects)
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17 pages, 5448 KiB  
Article
Mineralogical Constraints on Magma Recharge and Mixing of the Post-Collisional Potassic Volcanic Rocks in Dahongliutan, NW Tibetan Plateau
by Wenjian Yang, Bo Zhao, Hongmei Yu, Jiandong Xu, Feixiang Wei and Xiaoge Cui
Minerals 2023, 13(12), 1463; https://doi.org/10.3390/min13121463 - 22 Nov 2023
Cited by 1 | Viewed by 1586
Abstract
Post-collisional potassic magmatic rocks are widely distributed in the northwestern Tibetan Plateau, yet their magmatic processes remain poorly understood. Here, we present a comprehensive analysis of the whole-rock major and trace elements, as well as the mineral textures and chemistry of the Dahongliutan [...] Read more.
Post-collisional potassic magmatic rocks are widely distributed in the northwestern Tibetan Plateau, yet their magmatic processes remain poorly understood. Here, we present a comprehensive analysis of the whole-rock major and trace elements, as well as the mineral textures and chemistry of the Dahongliutan volcanic rocks in the NW Tibetan Plateau, aiming to reveal the magmatic processes prior to eruption and speculate on the triggering mechanism. The results show that the Dahongliutan volcanic rocks are potassic trachyandesites, which undergo polybaric crystallization during magma ascension. The phenocrysts in these potassic rocks exhibit various textural and compositional zoning styles. The green cores of green-core clinopyroxenes show textural (e.g., resorption texture) and chemical (Fe-rich) disequilibrium with the host rock compositions, suggesting that they may be antecrysts and crystallized from early batches of more evolved magmas. Additionally, alkali feldspar phenocrysts also display disequilibrium characteristics (e.g., overgrowth rim and sieve texture), indicating hot mafic magma recharge and mixing in the magma plumbing system. Therefore, we conclude that the disequilibrium textural and compositional features of green-core clinopyroxene and alkali feldspar phenocrysts provide evidence of magma recharge and mixing prior to eruption. Furthermore, it is likely that the eruption of the Dahongliutan volcano was triggered by magma recharge. Full article
(This article belongs to the Special Issue Petrogenesis, Magmatism and Geodynamics of Orogenic Belts)
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25 pages, 6134 KiB  
Article
Geochemical and Isotopic Fractionation in the Hypogene Ore, Gossan, and Saprolite of the Alvo 118 Deposit: Implications for Copper Exploration in the Regolith of the Carajás Mineral Province
by Pabllo Henrique Costa dos Santos, Marcondes Lima da Costa and Desiree Lisette Roerdink
Minerals 2023, 13(11), 1441; https://doi.org/10.3390/min13111441 - 15 Nov 2023
Cited by 1 | Viewed by 1772
Abstract
In the Carajás Mineral Province, gossan formation and lateritization have produced numerous supergene orebodies at the expense of IOCG deposits and host rocks. The Alvo 118 deposit comprises massive and disseminated hypogene copper sulfides associated with gossan and mineralized saprolites. The hypogene reserves [...] Read more.
In the Carajás Mineral Province, gossan formation and lateritization have produced numerous supergene orebodies at the expense of IOCG deposits and host rocks. The Alvo 118 deposit comprises massive and disseminated hypogene copper sulfides associated with gossan and mineralized saprolites. The hypogene reserves are 170 Mt, with 1% Cu and 0.3 ppm Au, while the supergenes are 55 Mt, comprised of 30% gossan and 70% saprolite, with 0.92% Cu and 0.03 ppm Au. The gossan includes goethite, malachite, cuprite, and libethenite zones. The saprolite comprises kaolinite, vermiculite, smectite, and relics of chlorite. In the hypogene mineralization, Ag, Te, Pb, Se, Bi, Au, In, Y, Sn, and U are mainly hosted by chalcopyrite and petzite, altaite, galena, uraninite, stannite, and cassiterite. In the gossan, Ag, Te, Pb, Se, and Bi are hosted by Cu minerals, while Au, In, Y, Sn, and U are associated with iron oxyhydroxides, in addition to Zn, As, Be, Ga, Ga, Mo, Ni, and Sc. As supporting information, δ65Cu values indicate that the gossan is immature and, at least partly, not affected by leaching. In the saprolite, Ga, Sc, Sn, V, Mn, Co, and Cr are associated with the iron oxyhydroxides, partially derived from the host rock weathering. The δ56Fe values indicate that hypogene low contribution of the hypogene mineralization to the saprolite iron content. The association of Al2O3, Hf, Zr, Th, TiO2, Ce, La, Ba, and Sr represents the geochemical signature of the host rocks, with dominant contributions from chlorites, while In, Y, Te, Pb, Bi, and Se are the main pathfinders of Cu mineralization. Full article
(This article belongs to the Special Issue Mineral Evolution and Mineralization during Weathering)
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19 pages, 8784 KiB  
Article
Dehydroxylation of Kaolinite and Halloysite-Rich Samples: An In Situ Study of the Texture and Structural Evolutions
by Imane Daou, Cristian Mocuta, Gisèle Laure Lecomte-Nana, Nicolas Tessier-Doyen, Claire Peyratout, René Guinebretière and Dominique Thiaudière
Minerals 2023, 13(11), 1418; https://doi.org/10.3390/min13111418 - 7 Nov 2023
Cited by 4 | Viewed by 1873
Abstract
Halloysite and kaolinite are dioctahedral TO phyllosilicates that drive the interest of scientists for formulating environmentally friendly materials, and consequently in the field of ceramics. The main scope of this study was the understanding of the texture evolution upon the dehydroxylation reaction and [...] Read more.
Halloysite and kaolinite are dioctahedral TO phyllosilicates that drive the interest of scientists for formulating environmentally friendly materials, and consequently in the field of ceramics. The main scope of this study was the understanding of the texture evolution upon the dehydroxylation reaction and the influence of the presence of halloysite. In situ synchrotron (002) and (111) poles figures were recorded on the DiffAbs beamline at SOLEIL Synchrotron, from room temperature to 1000 °C, on kaolinite and/or halloysite-rich samples shaped by tape casting. Commercial kaolins and halloysite provided by Imerys company were used. The samples were labeled KRG100, KCS100, H100, KRG50H50 and KRG59H50 in relation with the wt. % of kaolin (KRG, KCS) or halloysite (H) clays. In samples KCS100 and KRG100, a strong texture was observed until in situ annealing at 700 °C, with respect to the c-axis of kaolinite. On the contrary, the texture with respect to the c-axis of halloysite for the sample H100 was weak whatever the temperature was. Moreover, this weak texture disappeared before the complete dehydroxylation of halloysite. This is due to the opening of some halloysite tubes. When considering the samples KRG50H50 and KCS50H50, a significant texture was observed with the c-axis preferentially oriented perpendicular to the sample surface. The presence of kaolinite platelets predominated onto the alignment of halloysites tubes. Furthermore, it was noted that the halloysite influenced the (002) diffracted intensity into the temperature range 20 °C to 400 °C. Above 400 °C, the behavior obtained for the (002) reflection in samples KRG50H50 and KCS50H50 was similar to the behavior noticed for pure kaolins KRG100 and KCS100, respectively. The dehydroxylation temperature range appeared to be relevant with combined effect of kaolinite and halloysite transformations arising from KRG100 or KCS100 and H100 samples. Therefore, the onset point of dehydroxylation is 550 °C ± 25 °C for KRG100, KCS100, KRG50H50 and KCS50H50. For the pure halloysite H100 sample, the dehydroxylation starts at the lower temperature 475 °C. It was also noted that during the dehydroxylation of kaolinite, the characteristic portion of ring related to the diffracted intensity of the (111) reflection located at χ = 45° tended to disappear above 550 °C and led to the formation of a new transitory phase with a (111) reflection with perpendicular alignment to the c-axis. Indeed, an epitaxial relationship with the (111) kaolinite reflection could be assumed. Further X-ray scattering experiments allowed highlighting the effective offset temperature of the dehydroxylation, which was identified as close to 720 °C. The metakaolinite achieved structural transformation to another transitory phase at 1000 °C. Full article
(This article belongs to the Special Issue Microstructural Characterization in Applied Mineralogy)
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31 pages, 13388 KiB  
Article
Primary Composition of Kimberlite Melt
by Sergey Kostrovitsky, Anna Dymshits, Dmitry Yakovlev, Jing Sun, Tatiana Kalashnikova, Igor Ashchepkov and Olga Belozerova
Minerals 2023, 13(11), 1404; https://doi.org/10.3390/min13111404 - 1 Nov 2023
Cited by 3 | Viewed by 2781
Abstract
The compositions (mineralogy, major- and trace-element chemistry of rocks and minerals, and Sr-Nd-Hf isotope systematics) of two kimberlite bodies, the Obnazhennaya pipe and the Velikan dyke from the Kuoika field, Yakutian kimberlite province (YaKP), which are close to each other (1 km distance) [...] Read more.
The compositions (mineralogy, major- and trace-element chemistry of rocks and minerals, and Sr-Nd-Hf isotope systematics) of two kimberlite bodies, the Obnazhennaya pipe and the Velikan dyke from the Kuoika field, Yakutian kimberlite province (YaKP), which are close to each other (1 km distance) and of the same Upper Jurassic age, are presented. The kimberlites of the two bodies are contrastingly different in composition. The Obnazhennaya pipe is composed of pyroclastic kimberlite of high Mg and low Ti composition and is characterized by high saturation of clastic material of the lithospheric mantle (CMLM). The pyroclastic kimberlite contains rare inclusions of coherent kimberlite from previous intrusion phases. The Velikan dyke is represented by coherent kimberlite of relatively high Fe and high Ti composition, having neither mantle xenoliths nor olivine xenocrysts. The similarity of the isotopic geochemical characteristics for kimberlites from both bodies and their spatial and temporal proximity suggest that their formation is associated with the presence of a single primary magmatic source located in the asthenosphere. It is proposed that the asthenospheric melt differentiated into two parts: (1) a predominantly carbonate composition and (2) a carbonate–silicate composition, which, respectively, formed (a) low Fe and (b) Mg-Fe and high Fe-Ti petrochemical types of kimberlites. Both parts of the melt had different capabilities to capture the xenogenic material of the mantle rocks. The greater ability to destroy and, subsequently, capture CMLM belongs to the melt, which formed a high Mg type of kimberlite and which, according to the structural–textural classification, more often corresponds to the pyroclastic kimberlite. It is suggested that the primary kimberlite melt of asthenospheric origin is similar in composition to the high Fe, high Ti, coherent kimberlite from the Velikan dyke (in wt. %: SiO2–21.8, TiO2–3.5, Al2O3–4.0, FeO–10.6, MnO–0.19, MgO–21.0, CaO–17.2, Na2O–0.24, K2O–0.78, P2O5–0.99, CO2–12.6). It is concluded that the pyroclastic kimberlite contains only xenogenic Ol, whereas some of the Ol macrocrysts with high FeO content in the coherent kimberlite have crystallized from the melt. The similarity of Sr-Nd-Hf isotope systematics and trace element compositions for kimberlites of different ages (from Devonian to Upper Jurassic) in different parts of the YaKP (in the Kuoika, Daldyn and Mirny fields) indicates a single long-lived homogeneous magmatic asthenospheric source. Full article
(This article belongs to the Special Issue Kimberlites and Related Rocks: New Insight into Petrogenesis and Diamond Potential of Deeply-Derived Mantle Magmas)
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15 pages, 5522 KiB  
Article
Copper Isotopes and Constraints on the Ore Genesis Process of Cu-Co Ore Deposits at the Idaho Cobalt Belt, USA
by Nina Zaronikola, Elizabeth A. Holley, Ryan Mathur and Dan Pace
Minerals 2023, 13(11), 1355; https://doi.org/10.3390/min13111355 - 24 Oct 2023
Cited by 3 | Viewed by 2467
Abstract
Quantifying and identifying the introduction of metal in ore deposits that have experienced multiple overprinting hydrothermal events remains an elusive yet essential goal in metallogenic studies. Here, we constrain the origin of Co in the Idaho Cobalt Belt (ICB) that experienced two distinct [...] Read more.
Quantifying and identifying the introduction of metal in ore deposits that have experienced multiple overprinting hydrothermal events remains an elusive yet essential goal in metallogenic studies. Here, we constrain the origin of Co in the Idaho Cobalt Belt (ICB) that experienced two distinct metal-rich events that introduced Co and Cu. We performed a detailed petrographic study of sulfide ore at Iron Creek in the ICB, in concert with the quantification of trace metal element concentrations and copper isotope values to identify the introduction of Co in the system. The pyrite displays various degrees of alteration, with the highest Co concentrations (up to 6 wt.%) in less-altered pyrite grains (e.g., sharp edges, absence of altered boundaries and fissures) and highest δ65Cu isotope value. The most-altered pyrite grains (e.g., corroded grains, round and altered boundaries) have lower Co contents and lower δ65Cu isotope values that match the copper isotope values of the chalcopyrite. The least-altered pyrite shows a narrow δ65Cu range between −0.39‰ to −0.58‰. In contrast, the most-altered pyrite grains are isotopically depleted, showing a δ65Cu range from −1.35‰ to −0.90‰. Chalcopyrite shows a δ65Cu range between −1.07‰ and −0.77‰. We interpret, from the Cu isotope compositions and Co concentrations in pyrite, that the Co was originally introduced into the siliciclastic host rock package in a Mesoproterozoic SEDEX environment. The heavier Cu was then preferentially leached in a second event, resulting in isotopically lighter Cu in the altered pyrite. Remobilization of the SEDEX cobalt was likely associated with CO2-rich metamorphic fluids present in the region during the Mesoproterozoic East Kootenay orogeny, the late Mesoproterozoic Grenville orogeny, and the Late Jurassic to Late Cretaceous Cordilleran orogeny. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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11 pages, 2132 KiB  
Article
Flotation Performance and Adsorption Mechanism of Cerussite with Phenylpropenyl Hydroxamic Acid Collector
by Honghui Xie, Xiang Yao, Xinyang Yu, Linghan Mao, Yuhui Zeng, Feng Wu, Shuzheng Guo and Guichun He
Minerals 2023, 13(10), 1315; https://doi.org/10.3390/min13101315 - 11 Oct 2023
Cited by 28 | Viewed by 2172
Abstract
In this paper, the flotation separation of cerussite and quartz under different experimental conditions was studied by using phenylpropenyl hydroxamic acid (PHA) as a collector. The flotation performance of PHA was studied through experiments involving pure minerals and artificial mixed minerals, and the [...] Read more.
In this paper, the flotation separation of cerussite and quartz under different experimental conditions was studied by using phenylpropenyl hydroxamic acid (PHA) as a collector. The flotation performance of PHA was studied through experiments involving pure minerals and artificial mixed minerals, and the results showed that PHA has good selectivity and collecting ability for cerussite. The adsorption mechanism of the collector on the surface of cerussite was investigated via adsorption capacity experiments, zeta potential tests, FTIR spectroscopy, and XPS analysis. The adsorption capacity results showed that PHA can be well adsorbed on the surface of cerussite. The results of the zeta potential tests showed that PHA has strong chemical adsorption on the cerussite surface. FTIR and XPS analysis showed that PHA may form a Pb–PHA complex on the cerussite surface to improve the floatability of cerussite. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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37 pages, 8938 KiB  
Article
Connecting Obsidian Artifacts with Their Sources Using Multivariate Statistical Analysis of LIBS Spectral Signatures
by Russell S. Harmon, Chandra S. Throckmorton, Greg Haverstock, Dirk Baron, Robert M. Yohe II, Richard R. Hark and Jeffrey R. Knott
Minerals 2023, 13(10), 1284; https://doi.org/10.3390/min13101284 - 30 Sep 2023
Cited by 4 | Viewed by 3160
Abstract
With the recent introduction of handheld instruments for field use, laser-induced breakdown spectroscopy (LIBS) is emerging as a practical technology for real-time in situ geochemical analysis in the field. LIBS is a form of optical emission spectroscopy that is simultaneously sensitive to all [...] Read more.
With the recent introduction of handheld instruments for field use, laser-induced breakdown spectroscopy (LIBS) is emerging as a practical technology for real-time in situ geochemical analysis in the field. LIBS is a form of optical emission spectroscopy that is simultaneously sensitive to all elements with a single laser shot so that a broadband LIBS spectrum can be considered a diagnostic geochemical fingerprint. Sets of LIBS spectra were collected for seven obsidian centers across north-central California, with data processed using multivariate statistical analysis and pattern recognition techniques. Although all obsidians exhibit similar bulk compositions, different regional obsidian sources were effectively discriminated via partial least squares discriminant analysis. Obsidian artifacts from seven archaeological sites were matched to their putative sources with a high degree of confidence. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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22 pages, 3064 KiB  
Article
Characterization and Origin of Basalt-Derived Carnelian in the Mesozoic Newark Basin, New Jersey, USA
by Richard A. Volkert, Matthew L. Gorring, William H. Peck and Scott D. Stanford
Minerals 2023, 13(10), 1249; https://doi.org/10.3390/min13101249 - 24 Sep 2023
Cited by 1 | Viewed by 2425
Abstract
Carnelian occurs locally in New Jersey in the Newark basin as medium- to coarse-size pebbles in fluvial gravel and alluvium and colluvium formed from erosion of Lower Jurassic Preakness Basalt. Vesicles and molds of glauberite are preserved on lower surfaces and botryoidal textures [...] Read more.
Carnelian occurs locally in New Jersey in the Newark basin as medium- to coarse-size pebbles in fluvial gravel and alluvium and colluvium formed from erosion of Lower Jurassic Preakness Basalt. Vesicles and molds of glauberite are preserved on lower surfaces and botryoidal textures on the upper surfaces of some pieces. The microstructure consists of length-fast chalcedony characterized by parallel fibrous bundles overlain by repetitive, wavy extinction bands. Only peaks of ɑ-quartz and minor moganite are recognized in X-ray diffraction patterns. Carnelian contains 97–98 wt.% SiO2, ~1.0 wt.% Fe2O3, and 1.0–1.4 wt.% LOI; other major elements are <0.1 wt.%. Trace element abundances are low except for Y, Nb, Ta, W, Th, and U. Rare earth element (REE) patterns display heavy REE enrichment and large negative Eu anomalies. Most trace elements were mobilized from Proterozoic sources, whereas Si was likely derived from the alteration of basaltic glass in the Preakness. Carnelian δ18OVSMOW values are high and range from +18.3 to +31.2‰, comparable to global occurrences of volcanic rock-derived chalcedony. We propose that carnelian precipitated in the first Preakness flow from the mixing of hydrothermal fluid with meteoric water under conditions of low temperature (20–80 °C) and neutral to slightly alkaline pH. Full article
(This article belongs to the Special Issue Advances in Low-Temperature Mineralogy and Geochemistry)
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11 pages, 1425 KiB  
Article
Insights into the Heterogeneity of the Mercury Isotopic Fingerprint of the Idrija Mine (Slovenia)
by Dominik Božič, Igor Živković, Tatjana Dizdarević, Martina Peljhan, Marko Štrok and Milena Horvat
Minerals 2023, 13(9), 1227; https://doi.org/10.3390/min13091227 - 18 Sep 2023
Viewed by 1400
Abstract
To determine the range of the isotopic composition of mercury (Hg) from the Idrija mine, samples from the mine itself and from the Mercury Heritage Management Centre geological collection were analyzed. Samples from various geological periods, genesis types, ore types, formations, and excavation [...] Read more.
To determine the range of the isotopic composition of mercury (Hg) from the Idrija mine, samples from the mine itself and from the Mercury Heritage Management Centre geological collection were analyzed. Samples from various geological periods, genesis types, ore types, formations, and excavation fields and levels were analyzed. Both Hg concentration and isotopic composition were measured. The δ202Hg ranged from −1.35‰ to 0.46‰, and the Δ199Hg ranged from −0.18‰ to 0.16‰. A relatively homogenous ore fingerprint was obtained from one of the excavation fields; otherwise, the isotopic fingerprint of the Idrija mine seems to be heterogenous. This study presents the first statistically robust constraints on the isotopic composition of Hg from the Idrija mine, which may help in further studies of the isotopic composition of similar ore bodies or the potential tracing of Hg from the mine to the environment in the vicinity or downstream of the mine. Full article
(This article belongs to the Special Issue Isotope Geochemical Analysis Technology and Its Applications)
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9 pages, 1819 KiB  
Communication
Discovery of Mafic Granulites in the Muzhaerte Area, SW Tianshan, China
by Jun Yan, Ying Cui and Xiaoyu Liu
Minerals 2023, 13(9), 1214; https://doi.org/10.3390/min13091214 - 15 Sep 2023
Cited by 2 | Viewed by 1338
Abstract
Accretionary and collisional orogeny are often accompanied by the disturbance of the geothermal gradient, leading to high-temperature metamorphism. High-temperature metamorphic rocks are significant in their ability to help the reconstruction of the thermal histories of orogenic belts. The Tianshan Orogenic Belt, at the [...] Read more.
Accretionary and collisional orogeny are often accompanied by the disturbance of the geothermal gradient, leading to high-temperature metamorphism. High-temperature metamorphic rocks are significant in their ability to help the reconstruction of the thermal histories of orogenic belts. The Tianshan Orogenic Belt, at the southwest margin of the Central Asian Orogenic Belt, is a record of the long-term subduction–collision–post-collision orogenic process that has taken place in the Phanerozoic Eon. Here, we report the discovery of mafic granulites in the Muzhaerte area, SW Tianshan. Petrographic observation reveals that the mafic granulites underwent two metamorphic stages. The peak mineral assemblage of the first stage is dominated by clinopyroxene + orthopyroxene + plagioclase + quartz + hornblende (hb1) ± biotite, and the post-peak mineral assemblage of the second stage is dominated by clinopyroxene + plagioclase + quartz + hornblende (hb2) + biotite. The calculated results obtained from the two-pyroxene thermobarometers and the Al-in-hornblende barometer for the mafic granulites indicate that the metamorphic conditions of mafic granulites are 760–860 °C, <0.39–0.41 Gpa. The mafic granulites recorded a high-grade granulite facies thermal metamorphic event with the highest temperature limit currently recorded in the Central Tianshan Block. Full article
(This article belongs to the Special Issue Experimental Petrology: Metamorphic Evolution of Eclogite)
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21 pages, 7565 KiB  
Article
Depression of Arsenopyrite during Collectorless Flotation in Presence of Aqueous Metal Ions and Inorganic Compounds
by Martín Reyes, Edgar Martínez Rojo, Ramiro Escudero, Francisco Patiño, Iván A. Reyes, Mizraim U. Flores, Miguel Pérez, Julio Juárez and Francisco Raúl Barrientos
Minerals 2023, 13(9), 1200; https://doi.org/10.3390/min13091200 - 13 Sep 2023
Cited by 1 | Viewed by 1726
Abstract
Currently, the depression of arsenopyrite during the flotation of base metal mineral sulfides is being continuously studied to reduce its presence in sulfide concentrates of economic interest. In this work, the influence of aqueous metal ions (Fe2+, Cu2+, and [...] Read more.
Currently, the depression of arsenopyrite during the flotation of base metal mineral sulfides is being continuously studied to reduce its presence in sulfide concentrates of economic interest. In this work, the influence of aqueous metal ions (Fe2+, Cu2+, and Zn2+) in concentrations of 5, 25, and 75 g∗ton−1; mixtures of aqueous chlorides (ammonium and magnesium) and aluminum sulfate (AS)–sodium silicate (SS); and the use of only ordinary Portland cement (OPC) in all concentrations of 0.05 to 0.6 g∗ton−1 during the collectorless flotation and depression of a single-phase majority of arsenopyrite was analyzed. The results revealed a decrease in the hydrophobicity; its depression was greater with the use of OPC. At the concentration of 0.4 g∗ton−1 at alkaline pH and a pulp potential of +0.067 V, in 0.5 min, its flotation was 15.4 % w/w and the cumulative recovery at 10 min was 46.4 % w/w. The arsenopyrite depression was as follows: OPC > mixed chlorides > ASSS. Fe2+, Zn2+, Cu2+ ions activate flotation arsenopyrite. The solids obtained during the flotation were characterized using FTIR, and the functional groups responsible for the depression of arsenopyrite were identified. Full article
(This article belongs to the Special Issue Recent Advances in Flotation Process)
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17 pages, 11505 KiB  
Article
Paint, Colour, and Style: The Contribution of Minerals to the Palette of the Descent from the Cross, Attributed to the Portuguese Painter Francisco João (act. 1558–1595)
by Helena P. Melo, António João Cruz, Jana Sanyova, Sara Valadas and Ana Margarida Cardoso
Minerals 2023, 13(9), 1182; https://doi.org/10.3390/min13091182 - 8 Sep 2023
Cited by 1 | Viewed by 1934
Abstract
The paint materials and techniques of The Descent from Cross, a panel painting attributed to the Portuguese painter Francisco João (act. 1558–1595), were investigated with a combination of visible, ultraviolet, and infrared imaging and an analysis of paint samples with microscopic, spectroscopic, [...] Read more.
The paint materials and techniques of The Descent from Cross, a panel painting attributed to the Portuguese painter Francisco João (act. 1558–1595), were investigated with a combination of visible, ultraviolet, and infrared imaging and an analysis of paint samples with microscopic, spectroscopic, and chromatographic techniques. The colour palette is composed of lead white, lead–tin yellow, minium, vermilion, ochres of different colours, umber, smalt, azurite, verdigris, charcoal black, and a variety of different-coloured red lakes made of brazilwood and cochineal. An oil-based medium was identified. The characterisation of the pigment mixtures, paint build-up, and particular paint handling techniques enabled us to determine their role in the style and formal appearance of this painting and to discuss Portuguese painting practices in the larger context of 16th-century European painting. Mineral and elemental associations or impurities in the blue pigments, as well as degradation issues affecting minium, and smalt paints were reported. In particular, the deterioration of the glass matrix in some of the smalt particles mixed in lead white paint raises special concern. Full article
(This article belongs to the Special Issue Application of Spectrometric Analyses to Cultural Heritage)
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34 pages, 1192 KiB  
Review
Reactivity of Basaltic Minerals for CO2 Sequestration via In Situ Mineralization: A Review
by Muhammad Hammad Rasool and Maqsood Ahmad
Minerals 2023, 13(9), 1154; https://doi.org/10.3390/min13091154 - 31 Aug 2023
Cited by 19 | Viewed by 10075
Abstract
The underground storage of CO2 (carbon dioxide) in basalt presents an exceptionally promising solution for the effective and permanent sequestration of CO2. This is primarily attributed to its geochemistry and the remarkable presence of reactive basaltic minerals, which play a [...] Read more.
The underground storage of CO2 (carbon dioxide) in basalt presents an exceptionally promising solution for the effective and permanent sequestration of CO2. This is primarily attributed to its geochemistry and the remarkable presence of reactive basaltic minerals, which play a pivotal role in facilitating the process. However, a significant knowledge gap persists in the current literature regarding comprehensive investigations on the reactivity of basaltic minerals in the context of CO2 sequestration, particularly with respect to different basalt types. To address this gap, a comprehensive investigation was conducted that considered seven distinct types of basalts identified through the use of a TAS (total alkali–silica) diagram. Through a thorough review of the existing literature, seven key factors affecting the reactivity of basaltic minerals were selected, and their impact on mineral reactivity for each basalt type was examined in detail. Based on this analysis, an M.H. reactivity scale was introduced, which establishes a relationship between the reactivity of dominant and reactive minerals in basalt and their potential for carbonation, ranging from low (1) to high (5). The study will help in choosing the most suitable type of basalt for the most promising CO2 sequestration based on the percentage of reactive minerals. Additionally, this study identified gaps in the literature pertaining to enhancing the reactivity of basalt for maximizing its CO2 sequestration potential. As a result, this study serves as an important benchmark for policymakers and researchers seeking to further explore and improve CO2 sequestration in basaltic formations. Full article
(This article belongs to the Special Issue Carbon Dioxide Storage, Utilization & Reduction)
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