Minerals

24 pages, 3631 KiB

Open AccessArticle

Mineral–Soil–Plant–Nutrient Synergism: Carbonate Rock Leachate Irrigation Enhances Soil Nutrient Availability, Improving Crop Yield and Quality

by Yifei Du, Xiao Ge, Yimei Du, Hongrui Ding and Anhuai Lu

Minerals 2025, 15(8), 825; https://doi.org/10.3390/min15080825 (registering DOI) - 2 Aug 2025

Abstract

In the rock–soil–biology–water ecosystem, rock weathering provides essential plant nutrients. However, its supply is insufficient for rising crop demands under population growth and climate change, while excessive fertilizer causes soil degradation and pollution. This study innovatively irrigated with carbonate rock leachates to enhance [...] Read more.

In the rock–soil–biology–water ecosystem, rock weathering provides essential plant nutrients. However, its supply is insufficient for rising crop demands under population growth and climate change, while excessive fertilizer causes soil degradation and pollution. This study innovatively irrigated with carbonate rock leachates to enhance soil nutrient availability. A pot experiment with lettuce showed that irrigation significantly increased soil NO₃⁻-N (+102.20%), available K (+16.45%), available P (+17.95%), Ca (+6.04%), Mg (+11.65%), and Fe (+11.60%), and elevated the relative abundance of Firmicutes. Lettuce biomass per plant rose by 23.78%, with higher leaf minerals (P, K, Ca, and Mg) and antioxidants (carotenoids and ascorbic acid). A field experiment further confirmed improvement of soil nutrient availability and peanut yield. This carbonate rock leachate irrigation technique effectively enhances soil quality and crop productivity/quality, offering a sustainable approach for green agriculture. Full article

(This article belongs to the Section Environmental Mineralogy and Biogeochemistry)

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14 pages, 3201 KiB

Open AccessArticle

Coupled Eu Anomalies and Fe Isotopes Reveal a Hydrothermal Iron Source for Superior-Type Iron Formations: A Case Study from the Wilgena Hill Iron Formation, South Australia

by Shuo Chen, Jian Sun, Xiangkun Zhu and Yuelong Chen

Minerals 2025, 15(8), 824; https://doi.org/10.3390/min15080824 (registering DOI) - 2 Aug 2025

Abstract

Superior-type iron formations (IFs) represent a globally significant source of iron ore; yet, their origin remains a subject of ongoing debate. Early models proposed a continental weathering source for the iron, whereas later interpretations—mainly supported by positive europium (Eu) anomalies—favored a hydrothermal source. [...] Read more.

Superior-type iron formations (IFs) represent a globally significant source of iron ore; yet, their origin remains a subject of ongoing debate. Early models proposed a continental weathering source for the iron, whereas later interpretations—mainly supported by positive europium (Eu) anomalies—favored a hydrothermal source. However, the hydrothermal model largely relies on REE systematics, and whether iron and REEs in Superior-type IFs share the same source remains uncertain. As iron isotopes directly trace the sources and fractionation history of iron, a spatial co-variation between Fe isotopes and Eu anomalies would shed new light on the iron source issue of IFs. In this study, we present new Fe isotope and REE data from the drill core WILDD004 at Wilgena Hill and integrate them with reported data for two additional drill cores: HKDD4 (Hawks Nest) and GWDD1 (Giffen Well). All three cores are stratigraphically equivalent to the Wilgena Hill Jaspilite Formation but span a lateral distance of ~100 km across the Gawler Craton, South Australia. While the Hawks Nest and Giffen Well samples exhibit both positive Eu anomalies and elevated δ⁵⁶Fe values, the Wilgena Hill samples show positive yet smaller Eu/Eu* (1.17–2.41) and negative δ⁵⁶Fe values (−0.60‰ to −1.63‰). The consistent presence of Eu anomalies and the systematic spatial correlation between δ⁵⁶Fe and Eu/Eu* across all three locations provide direct, Fe-based geochemical evidence for a hydrothermal source of iron in this Superior-type IF. Full article

(This article belongs to the Special Issue Geochemical, Isotopic, and Biotic Records of Banded Iron Formations)

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14 pages, 6561 KiB

Open AccessArticle

Overprinted Metamorphic Assemblages in High-Alumina Metapelitic Rocks in Contact with Varnous Pluton (NNW Greece)

by Foteini Aravani, Lambrini Papadopoulou, Antonios Koroneos, Alexandros Chatzipetros, Stefanos Karampelas and Kyriaki Pipera

Minerals 2025, 15(8), 823; https://doi.org/10.3390/min15080823 (registering DOI) - 1 Aug 2025

Abstract

The Varnous Mt. area in the northern Pelagonian Nappe is characterized by the intrusion of an Early Permian pluton, with its tectonic setting and igneous petrology well constrained in earlier studies. The metamorphic basement rocks warrant further detailed investigation due to their complex [...] Read more.

The Varnous Mt. area in the northern Pelagonian Nappe is characterized by the intrusion of an Early Permian pluton, with its tectonic setting and igneous petrology well constrained in earlier studies. The metamorphic basement rocks warrant further detailed investigation due to their complex history. These rocks are polymetamorphosed, preserving a sequence of overprinting metamorphic and deformational events. The metapelitic rocks have undergone an initial, pre-Carboniferous regional metamorphism of unknown grade before or during Hercynian Orogeny, followed by a thermal metamorphic event associated with the intrusion of the Varnous pluton at 297 Ma. The assemblage attributed to this event is And + Crd + Bt + Ms (west), while the first assemblage identified at the eastern part is Sil + Bt + Gt. Additionally, three regional tectonometamorphic events occurred during the Alpine Orogeny. For the Alpine events, the assemblages are as follows: first, the development of St + Gt + Chl + Kfs + Pl + Qtz at 150–130 Ma; second, retrograde metamorphism of these assemblages with Cld + Gt + Ser + Mrg + Chl ± Sil (Fi) at 110–90 Ma; and finally, mylonitization of all previous assemblages at 90–70 Ma with simultaneous annealing and formation of Cld + Chl + Ms. Full article

(This article belongs to the Section Mineral Geochemistry and Geochronology)

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16 pages, 1212 KiB

Open AccessArticle

Harnessing Mixed Fatty Acid Synergy for Selective Flotation of Apatite from Calcite and Quartz with Sodium Alginate

by Imane Aarab, Khalid El Amari, Abdelrani Yaacoubi, Abdelaziz Baçaoui and Abderahman Etahiri

Minerals 2025, 15(8), 822; https://doi.org/10.3390/min15080822 (registering DOI) - 1 Aug 2025

Abstract

Maximizing the efficient utilization of critical apatite resources through flotation necessitates the exploration of effective and innovative collectors. This study investigates the potential of a fatty acid mixture (FAM) synthesized from saturated palmitic and stearic acids, monounsaturated oleic and palmitoleic acids, and polyunsaturated [...] Read more.

Maximizing the efficient utilization of critical apatite resources through flotation necessitates the exploration of effective and innovative collectors. This study investigates the potential of a fatty acid mixture (FAM) synthesized from saturated palmitic and stearic acids, monounsaturated oleic and palmitoleic acids, and polyunsaturated linoleic acid. The saponified collector FAM and the depressant sodium alginate (NaAl) achieved a direct flotation of apatite from calcite and quartz (97% apatite, 10% calcite, and 7% quartz). The flotation performance with the tested combination exhibited a highly effective enrichment of apatite, mainly from calcite, which aligns with the surface chemistry assessments. Adsorption tests and zeta potential measurements confirmed the micro-flotation results. They provided compelling evidence of a chemisorption interaction between Ca²⁺ sites on calcite and the carboxyl and hydroxyl groups of NaAl. FTIR analyses suggested a reaction between the apatite surface and the carboxyl groups of saturated and unsaturated acid groups in FAM, even those conditioned with NaAl before, facilitating the complex formation. Remarkably, the synergistic effect of the functional groups demonstrates dual functionality, serving as both a hydrophilic entity for calcite and a hydrophobic entity for apatite flotation. The universal mechanism unveils substantial potential for the extensive application of FAM within apatite flotation. Full article

(This article belongs to the Special Issue Surface Chemistry and Reagents in Flotation)

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19 pages, 1627 KiB

Open AccessArticle

Separation of Rare Earth Elements by Ion Exchange Resin: pH Effect and the Use of Fractionation Column

by Clauson Souza, Pedro A. P. V. S. Ferreira and Ana Claudia Q. Ladeira

Minerals 2025, 15(8), 821; https://doi.org/10.3390/min15080821 (registering DOI) - 1 Aug 2025

Abstract

This work investigated the ion exchange technique for selective separation of rare earth elements (REE) from acid mine drainage (AMD), using different column systems, pH values, and eluent concentrations. Systematic analysis of pH and eluent concentration showed that an initial pH of 6.0 [...] Read more.

This work investigated the ion exchange technique for selective separation of rare earth elements (REE) from acid mine drainage (AMD), using different column systems, pH values, and eluent concentrations. Systematic analysis of pH and eluent concentration showed that an initial pH of 6.0 and 0.02 mol L⁻¹ NH₄EDTA are the optimal conditions, achieving 98.4% heavy REE purity in the initial stage (0 to 10 bed volumes). This represents a 32-fold increase compared to the original AMD (6.7% heavy REE). The speciation of REE and impurities was determined by Visual Minteq 4.0 software using pH 2.0, which corresponds to the pH at the inlet of the fractionation column. Under this condition, La and Nd and the impurities (Ca, Mg, and Mn) remained in the fractionation column, while Al was partially retained. In addition, the heavy REE (Y and Dy) were mainly in the form of REE-EDTA complexes and not as free cations, which made fractionation more feasible. The fractionation column minimized impurities, retaining 100% of Ca and 67% of Al, generating a liquor concentrated in heavy REE. This sustainable approach adopted herein meets the critical needs for scalable recovery of REE from diluted effluents, representing a circular economy strategy for critical metals. Full article

(This article belongs to the Section Mineral Processing and Extractive Metallurgy)

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17 pages, 13918 KiB

Open AccessArticle

Occurrence State and Controlling Factors of Methane in Deep Marine Shale: A Case Study from Silurian Longmaxi Formation in Sichuan Basin, SW China

by Junwei Pu, Tongtong Luo, Yalan Li, Hongwei Jiang and Lin Qi

Minerals 2025, 15(8), 820; https://doi.org/10.3390/min15080820 (registering DOI) - 1 Aug 2025

Abstract

Deep marine shale is the primary carrier of shale gas resources in Southwestern China. Because the occurrence and gas content of methane vary with burial conditions, understanding the microscopic mechanism of methane occurrence in deep marine shale is critical for effective shale gas [...] Read more.

Deep marine shale is the primary carrier of shale gas resources in Southwestern China. Because the occurrence and gas content of methane vary with burial conditions, understanding the microscopic mechanism of methane occurrence in deep marine shale is critical for effective shale gas exploitation. The temperature and pressure conditions in deep shale exceed the operating limits of experimental equipment; thus, few studies have discussed the microscopic occurrence mechanism of shale gas in deep marine shale. This study applies molecular simulation technology to reveal the methane’s microscopic occurrence mechanism, particularly the main controlling factor of adsorbed methane in deep marine shale. Two types of simulation models are also proposed. The Grand Canonical Monte Carlo (GCMC) method is used to simulate the adsorption behavior of methane molecules in these two models. The results indicate that the isosteric adsorption heat of methane in both models is below 42 kJ/mol, suggesting that methane adsorption in deep shale is physical adsorption. Adsorbed methane concentrates on the pore wall surface and forms a double-layer adsorption. Furthermore, adsorbed methane can transition to single-layer adsorption if the pore size is less than 1.6 nm. The total adsorption capacity increases with rising pressure, although the growth rate decreases. Excess adsorption capacity is highly sensitive to pressure and can become negative at high pressures. Methane adsorption capacity is determined by pore size and adsorption potential, while accommodation space and adsorption potential are influenced by pore size and mineral type. Under deep marine shale reservoir burial conditions, with burial depth deepening, the effect of temperature on shale gas occurrence is weaker than pressure. Higher temperatures inhibit shale gas occurrence, and high pressure enhances shale gas preservation. Smaller pores facilitate the occurrence of adsorbed methane, and larger pores have larger total methane adsorption capacity. Deep marine shale with high formation pressure and high clay mineral content is conducive to the microscopic accumulation of shale gas in deep marine shale reservoirs. This study discusses the microscopic occurrence state of deep marine shale gas and provides a reference for the exploration and development of deep shale gas. Full article

(This article belongs to the Special Issue Element Enrichment and Gas Accumulation in Black Rock Series)

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13 pages, 1750 KiB

Open AccessArticle

Mineral-Based Synthesis of CuFe₂O₄ Nanoparticles via Co-Precipitation and Microwave Techniques Using Leached Copper Solutions from Mined Minerals

by Carolina Venegas Abarzúa, Mauricio J. Morel, Gabriela Sandoval-Hevia, Thangavel Kavinkumar, Natarajan Chidhambaram, Sathish Kumar Kamaraj, Nagarajan Dineshbabu and Arun Thirumurugan

Minerals 2025, 15(8), 819; https://doi.org/10.3390/min15080819 (registering DOI) - 1 Aug 2025

Abstract

Environmental sustainability and responsible resource utilization are critical global challenges. In this work, we present a sustainable and circular-economy-based approach for synthesizing CuFe₂O₄ nanoparticles by directly utilizing copper oxide minerals sourced from Chilean mining operations. Copper sulfate (CuSO₄) [...] Read more.

Environmental sustainability and responsible resource utilization are critical global challenges. In this work, we present a sustainable and circular-economy-based approach for synthesizing CuFe₂O₄ nanoparticles by directly utilizing copper oxide minerals sourced from Chilean mining operations. Copper sulfate (CuSO₄) was extracted from these minerals through acid leaching and used as a precursor for nanoparticle synthesis via both chemical co-precipitation and microwave-assisted methods. The influence of different precipitating agents—NaOH, Na₂CO₃, and NaF—was systematically evaluated. XRD and FESEM analyses revealed that NaOH produced the most phase-pure and well-dispersed nanoparticles, while NaF resulted in secondary phase formation. The microwave-assisted method further improved particle uniformity and reduced agglomeration due to rapid and homogeneous heating. Electrochemical characterization was conducted to assess the suitability of the synthesized CuFe₂O₄ for supercapacitor applications. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements confirmed pseudocapacitive behavior, with a specific capacitance of up to 1000 F/g at 2 A/g. These findings highlight the potential of CuFe₂O₄ as a low-cost, high-performance electrode material for energy storage. This study underscores the feasibility of converting primary mined minerals into functional nanomaterials while promoting sustainable mineral valorization. The approach can be extended to other critical metals and mineral residues, including tailings, supporting the broader goals of a circular economy and environmental remediation. Full article

(This article belongs to the Special Issue Recent Advances in Separation Techniques for Critical Minerals/Metals, Circular Economy, and Sustainability)

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19 pages, 3999 KiB

Open AccessArticle

Recovery of Precious Metals from High-MgO-Content Pt-Pd Concentrates Using a Pyrometallurgical Smelting Process

by Chunxi Zhang, Lingsong Wang, Jiachun Zhao, Chao Wang, Yu Zheng and Haigang Dong

Minerals 2025, 15(8), 818; https://doi.org/10.3390/min15080818 (registering DOI) - 1 Aug 2025

Abstract

The Jinbaoshan Pt-Pd deposit is China’s largest independent PGM deposit. However, the deposit has not been utilized until now because of the low grade of precious metals, the complex mineral composition, and, notably, the presence of precious metals in the microgranular material disseminated [...] Read more.

The Jinbaoshan Pt-Pd deposit is China’s largest independent PGM deposit. However, the deposit has not been utilized until now because of the low grade of precious metals, the complex mineral composition, and, notably, the presence of precious metals in the microgranular material disseminated to other minerals. Its high MgO content, in particular, is regarded as a challenge for efficiently recovering precious metals via mature pyrometallurgical methods. In this research, the feasibility of a smelting process to recover precious metals from Jinbaoshan Pt-Pd concentrates at a conventional smelting temperature (1350 °C) with the addition of iron ore as a metal collector and SiO₂ and CaO as fluxes was verified on the basis of thermodynamic slag design and experimental analyses. Under the optimal conditions of 100 g of the Pt-Pd concentrates, 32.5 g of SiO₂, 7.5 g of CaO, and 30 g of iron ore at 1350 °C for 1 h, the extraction efficiencies of Au, Pt, and Pd were 94.66%, 96.75%, and 97.28%, respectively. This strategy enables the rapid collection of PGMs from Jinbaoshan Pt-Pd concentrates at the conventional temperature within a short time and minimizes the use of fluxes and collectors, contributing to energy and cost conservation. Full article

(This article belongs to the Special Issue Advances in Precious and Critical Mineral Beneficiation and Extraction)

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19 pages, 6409 KiB

Open AccessArticle

Recycling Quarry Dust as a Supplementary Cementitious Material for Cemented Paste Backfill

by Yingying Zhang, Kaifeng Wang, Zhengkun Shi and Shiyu Zhang

Minerals 2025, 15(8), 817; https://doi.org/10.3390/min15080817 (registering DOI) - 1 Aug 2025

Abstract

Quarry dust (QD) landfill causes environmental issues that cannot be ignored. In this study, we systematically explore its potential application as a supplementary cementitious material (SCM) in cemented paste backfill (CPB), revealing the activated mechanism of modified QD (MQD) and exploring the hydration [...] Read more.

Quarry dust (QD) landfill causes environmental issues that cannot be ignored. In this study, we systematically explore its potential application as a supplementary cementitious material (SCM) in cemented paste backfill (CPB), revealing the activated mechanism of modified QD (MQD) and exploring the hydration process and workability of CPB containing QD/MQD. The experimental results show that quartz, clinochlore and amphibole components react with CaO to form reactive dicalcium silicate (C₂S) and amorphous glass phases, promoting pozzolanic reactivity in MQD. QD promotes early aluminocarbonate (M_c) formation through CaCO₃-derived CO₃²⁻ release but shifts to hemicarboaluminate (H_c) dominance at 28 d. MQD releases active Al³⁺/Si⁴⁺ due to calcination and deconstruction, significantly increasing the amount of ettringite (AFt) in the later stage. With the synergistic effect of coarse–fine particle gradation, MQD-type fresh backfill can achieve a 161 mm flow spread at 20% replacement. Even if this replacement rate reaches 50%, a strength of 19.87 MPa can still be maintained for 28 days. The good workability and low carbon footprint of MQD-type backfill provide theoretical support for—and technical paths toward—QD recycling and the development of low-carbon building materials. Full article

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26 pages, 8845 KiB

Open AccessArticle

Occurrence State and Genesis of Large Particle Marcasite in a Thick Coal Seam of the Zhundong Coalfield in Xinjiang

by Xue Wu, Ning Lü, Shuo Feng, Wenfeng Wang, Jijun Tian, Xin Li and Hayerhan Xadethan

Minerals 2025, 15(8), 816; https://doi.org/10.3390/min15080816 (registering DOI) - 31 Jul 2025

Abstract

The Junggar Basin contains a large amount of coal resources and is an important coal production base in China. The coal seam in Zhundong coalfield has a large single-layer thickness and high content of inertinite, but large particle Fe-sulphide minerals are associated with [...] Read more.

The Junggar Basin contains a large amount of coal resources and is an important coal production base in China. The coal seam in Zhundong coalfield has a large single-layer thickness and high content of inertinite, but large particle Fe-sulphide minerals are associated with coal seams in some mining areas. A series of economic and environmental problems caused by the combustion of large-grained Fe-sulphide minerals in coal have seriously affected the economic, clean and efficient utilization of coal. In this paper, the ultra-thick coal seam of the Xishanyao formation in the Yihua open-pit mine of the Zhundong coalfield is taken as the research object. Through the analysis of coal quality, X-ray fluorescence spectrometer test of major elements in coal, inductively coupled plasma mass spectrometry test of trace elements, SEM-Raman identification of Fe-sulphide minerals in coal and LA-MC-ICP-MS test of sulfur isotope of marcasite, the coal quality characteristics, main and trace element characteristics, macro and micro occurrence characteristics of Fe-sulphide minerals and sulfur isotope characteristics of marcasite in the ultra-thick coal seam of the Xishanyao formation are tested. On this basis, the occurrence state and genesis of large particle Fe-sulphide minerals in the ultra-thick coal seam of the Xishanyao formation are clarified. The main results and understandings are as follows: (1) the occurrence state of Fe-sulphide minerals in extremely thick coal seams is clarified. The Fe-sulphide minerals in the extremely thick coal seam are mainly marcasite, and concentrated in the YH-2, YH-3, YH-8, YH-9, YH-14, YH-15 and YH-16 horizons. Macroscopically, Fe-sulphide minerals mainly occur in three forms: thin film Fe-sulphide minerals, nodular Fe-sulphide minerals, and disseminated Fe-sulphide minerals. Microscopically, they mainly occur in four forms: flake, block, spearhead, and crack filling. (2) The difference in sulfur isotope of marcasite was discussed, and the formation period of marcasite was preliminarily divided. The overall variation range of the δ³⁴S value of marcasite is wide, and the extreme values are quite different. The polyflake marcasite was formed in the early stage of diagenesis and the δ³⁴S value was negative, while the fissure filling marcasite was formed in the late stage of diagenesis and the δ³⁴S value was positive. (3) The coal quality characteristics of the thick coal seam were analyzed. The organic components in the thick coal seam are mainly inertinite, and the inorganic components are mainly clay minerals and marcasite. (4) The difference between the element content in the thick coal seam of the Zhundong coalfield and the average element content of Chinese coal was compared. The major element oxides in the thick coal seam are mainly CaO and MgO, followed by SiO₂, Al₂O₃, Fe₂O₃ and Na₂O. Li, Ga, Ba, U and Th are enriched in trace elements. (5) The coal-accumulating environment characteristics of the extremely thick coal seam are revealed. The whole thick coal seam is formed in an acidic oxidation environment, and the horizon with Fe-sulphide minerals is in an acidic reduction environment. The acidic reduction environment is conducive to the formation of marcasite and is not conducive to the formation of pyrite. (6) There are many matrix vitrinite, inertinite content, clay content, and terrigenous debris in the extremely thick coal seam. The good supply of peat swamp, suitable reduction environment and pH value, as well as groundwater leaching and infiltration, together cause the occurrence of large-grained Fe-sulphide minerals in the extremely thick coal seam of the Xishanyao formation in the Zhundong coalfield. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characteristics of Coal and Coal-Bearing Strata)

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22 pages, 5351 KiB

Open AccessArticle

Hydrometallurgical Leaching of Copper and Cobalt from a Copper–Cobalt Ore by Aqueous Choline Chloride-Based Deep Eutectic Solvent Solutions

by Emmanuel Anuoluwapo Oke, Yorkabel Fedai and Johannes Hermanus Potgieter

Minerals 2025, 15(8), 815; https://doi.org/10.3390/min15080815 (registering DOI) - 31 Jul 2025

Abstract

The sustainable recovery of valuable metals such as Cu and Co from ores is a pressing need considering environmental and economic challenges. Therefore, this study evaluates the effectiveness of deep eutectic solvents (DESs) as alternative leaching agents for Cu and Co extraction. Four [...] Read more.

The sustainable recovery of valuable metals such as Cu and Co from ores is a pressing need considering environmental and economic challenges. Therefore, this study evaluates the effectiveness of deep eutectic solvents (DESs) as alternative leaching agents for Cu and Co extraction. Four DESs were prepared using choline chloride (ChCl) as a hydrogen bond acceptor (HBA) and oxalic acid (OA), ethylene glycol (EG), urea (U) and thiourea (TU) as hydrogen bond donors (HBDs). Leaching experiments were conducted with DESs supplemented with 30 wt.% water at varying temperatures, various solid-to-liquid ratios, and time durations. The ChCl:OA DES demonstrated the highest leaching efficiencies among the DESs tested on pure CuO and CoO, achieving 89.2% for Cu and 92.4% for Co (60 °C, 400 rpm, 6 h, −75 + 53 µm particle size, and 1:10 solid-to-liquid ratio). In addition, the dissolution kinetics, analysed using the shrinking core model (SCM), showed that the leaching process was mainly controlled by surface chemical reactions. The activation energy values for Cu and Co leaching were 46.8 kJ mol⁻¹ and 51.4 kJ mol⁻¹, respectively, supporting a surface chemical control mechanism. The results highlight the potential of ChCl:OA as a sustainable alternative for metal recovery. Full article

(This article belongs to the Special Issue Innovations in Hydrometallurgy: Traditional and Emerging Approaches for Sustainable Metal Recovery)

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29 pages, 21967 KiB

Open AccessArticle

Ore Genesis Based on Microtextural and Geochemical Evidence from the Hydrothermal As–Sb Mineralization of the Matra Deposit (Alpine Corsica, France)

by Danis Ionut Filimon, John A. Groff, Emilio Saccani and Maria Di Rosa

Minerals 2025, 15(8), 814; https://doi.org/10.3390/min15080814 (registering DOI) - 31 Jul 2025

Abstract

The Matra As–Sb deposit (Alpine Corsica, France) is hosted in the normal N–S trending Matra Fault. Sulfide minerals in ore consist of realgar, stibnite, and pyrite with minor orpiment and hörnesite. The gangue includes quartz, dolomite, and calcite. In this study, the microstructural [...] Read more.

The Matra As–Sb deposit (Alpine Corsica, France) is hosted in the normal N–S trending Matra Fault. Sulfide minerals in ore consist of realgar, stibnite, and pyrite with minor orpiment and hörnesite. The gangue includes quartz, dolomite, and calcite. In this study, the microstructural analysis of selected ore samples has been combined with the geochemical characterization of the sulfides. The results depict a succession of events that record the evolution of the ore deposit related to fault movement. In the pre–ore stage, plumose, crustiform, jigsaw, and feathery textures of quartz testify to a short–lived boiling event. The mineral assemblage of the main–ore stage includes an Fe(–Zn) substage dominated by the formation of different textures of pyrite. In general, pyrite samples contain significant concentrations of As (≤32,231 ppm) and Sb (≤10,684 ppm), with lesser amounts of by Tl (≤1257 ppm) and Ni (≤174 ppm). This is followed by an Sb–As–Fe substage of pyrite–stibnite–realgar ±orpiment. The precipitation of the sulfides was mainly driven by changes in ƒS₂. The increasing level of oxidation is attributed to a progressive influx of meteoric water resulting from reactivation of the Matra Fault. Full article

(This article belongs to the Special Issue Using Mineral Chemistry to Characterize Ore-Forming Processes)

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26 pages, 6611 KiB

Open AccessArticle

The Geochronology, Geochemical Characteristics, and Tectonic Settings of the Granites, Yexilinhundi, Southern Great Xing’an Range

by Haixin Yue, Henan Yu, Zhenjun Sun, Yanping He, Mengfan Guan, Yingbo Yu and Xi Chen

Minerals 2025, 15(8), 813; https://doi.org/10.3390/min15080813 (registering DOI) - 31 Jul 2025

Abstract

The southern Great Xing’an Range is located in the overlap zone of the Paleo-Asian Ocean metallogenic domain and the Circum-Pacific metallogenic domain. It hosts numerous Sn-polymetallic deposits, such as Weilasituo, Bianjiadayuan, Huanggang, and Dajing, and witnessed multiple episodes of magmatism during the Late [...] Read more.

The southern Great Xing’an Range is located in the overlap zone of the Paleo-Asian Ocean metallogenic domain and the Circum-Pacific metallogenic domain. It hosts numerous Sn-polymetallic deposits, such as Weilasituo, Bianjiadayuan, Huanggang, and Dajing, and witnessed multiple episodes of magmatism during the Late Mesozoic. The study area is situated within the Huanggangliang-Ganzhuermiao metallogenic belt in the southern Great Xing’an Range. The region has witnessed extensive magmatism, with Mesozoic magmatic activities being particularly closely linked to regional mineralization. We present petrographic, zircon U-Pb chronological, lithogeochemical, and Lu-Hf isotopic analyses of the Yexilinhundi granites. The results indicate that the granite porphyry and granodiorite were emplaced during the Late Jurassic. Both rocks exhibit high SiO₂, K₂O + Na₂O, differentiation index (DI), and 10,000 Ga/Al ratios, coupled with low MgO contents. They show distinct fractionation between light and heavy rare earth elements (LREEs and HREEs), exhibit Eu anomalies, and have low whole-rock zircon saturation temperatures (T_zr), collectively demonstrating characteristics of highly fractionated I-type granites. The εHf(t) values of the granites range from 0.600 to 9.14, with young two-stage model ages (T_DM2 = 616.0~1158 Ma), indicating that the magmatic source originated from partial melting of Mesoproterozoic-Neoproterozoic juvenile crust. This study proposes that the granites formed in a post-collisional/post-orogenic extensional setting associated with the subduction of the Mongol-Okhotsk Ocean, providing a scientific basis for understanding the relationship between the formation of Sn-polymetallic deposits and granitic magmatic evolution in the study area. Full article

(This article belongs to the Section Mineral Geochemistry and Geochronology)

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31 pages, 29045 KiB

Open AccessArticle

Earliest Cambrian Carbonate Platform Evolution, Environmental Change, and Organic Matter Accumulation in the Northwestern Yangtze Block, South China

by Jincheng Liu, Qingchun Jiang, Yan Zhang, Jingjiang Liu, Yifei Ai, Pengzhen Duan and Guangyou Zhu

Minerals 2025, 15(8), 812; https://doi.org/10.3390/min15080812 (registering DOI) - 31 Jul 2025

Abstract

The earliest Cambrian (ca., 538.8–524.8 Ma) was an important period in geological history witnessing significant environmental change, during which organic-rich facies were developed in the Yangtze Platform, South China. However, the contemporaneous paleogeographic and stratigraphic framework within which the environmental change and organic [...] Read more.

The earliest Cambrian (ca., 538.8–524.8 Ma) was an important period in geological history witnessing significant environmental change, during which organic-rich facies were developed in the Yangtze Platform, South China. However, the contemporaneous paleogeographic and stratigraphic framework within which the environmental change and organic matter accumulation took place remains poorly understood. We investigate this based on facies, sequence stratigraphic, and geochemical analyses of the lowermost Cambrian Maidiping and Zhujiaqing formations in the northwestern Yangtze Block. The results show that the terminal Ediacaran rimmed platform changed into a foredeep carbonate ramp and backbulge basin after the onset of the earliest Cambrian transgression. Across the Ediacaran–Cambrian boundary, the shallow-marine redox condition rapidly transitioned from relative euxinia to an oxygen-rich state. During the late transgression to highstand normal regression, the foredeep carbonate ramp expanded to the cratonic interior, and nutrients brought by intensified continental weathering and upwelling promoted significant phytoplankton proliferation, an increase in oxygen level and primary productivity, and then organic matter enrichment. During the forced regression, the carbonate ramp gradually changed into a rimmed platform. The weakening continental weathering and expanding anoxic area during the forced to lowstand normal regression led to the significant organic carbon burial in the foredeep basin. Full article

(This article belongs to the Special Issue Organic Petrology and Geochemistry: Exploring the Organic-Rich Facies)

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17 pages, 6856 KiB

Open AccessArticle

Selection of Optimal Parameters for Chemical Well Treatment During In Situ Leaching of Uranium Ores

by Kuanysh Togizov, Zhiger Kenzhetaev, Akerke Muzapparova, Shyngyskhan Bainiyazov, Diar Raushanbek and Yuliya Yaremkiv

Minerals 2025, 15(8), 811; https://doi.org/10.3390/min15080811 (registering DOI) - 31 Jul 2025

Abstract

The aim of this study was to improve the efficiency of in situ uranium leaching by developing a specialized methodology for selecting rational parameters for the chemical treatment of production wells. This approach was designed to enhance the filtration properties of ores and [...] Read more.

The aim of this study was to improve the efficiency of in situ uranium leaching by developing a specialized methodology for selecting rational parameters for the chemical treatment of production wells. This approach was designed to enhance the filtration properties of ores and extend the uninterrupted operation period of wells, considering the clay content of the productive horizon, the geological characteristics of the ore-bearing layer, and the composition of precipitation-forming materials. The mineralogical characteristics of ore and precipitate samples formed during the in situ leaching of uranium under various mining and geological conditions at a uranium deposit in the Syrdarya depression were identified using an X-ray diffraction analysis. It was established that ores of the Santonian stage are relatively homogeneous and consist mainly of quartz. During well operation, the precipitates formed are predominantly gypsum, which has little impact on the filtration properties of the ore. Ores of the Maastrichtian stage are less homogeneous and mainly composed of quartz and smectite, with minor amounts of potassium feldspar and kaolinite. The leaching of these ores results in the formation of gypsum with quartz impurities, which gradually reduces the filtration properties of the ore. Ores of the Campanian stage are heterogeneous, consisting mainly of quartz with varying proportions of clay minerals and gypsum. The leaching of these ores generates a variety of precipitates that significantly reduce the filtration properties of the productive horizon. Effective compositions and concentrations of decolmatant (clog removal) solutions were selected under laboratory conditions using a specially developed methodology and a TESCAN MIRA scanning electron microscope. Based on a scanning electron microscope analysis of the samples, the effectiveness of a decolmatizing solution based on hydrochloric and hydrofluoric acids (taking into account the concentration of the acids in the solution) was established for the destruction of precipitate formation during the in situ leaching of uranium. Geological blocks were ranked by their clay content to select rational parameters of decolmatant solutions for the efficient enhancement of ore filtration properties and the prevention of precipitation formation. Pilot-scale testing of the selected decolmatant parameters under various mining and geological conditions allowed the optimal chemical treatment parameters to be determined based on the clay content and the composition of precipitates in the productive horizon. An analysis of pilot well trials using the new approach showed an increase in the uninterrupted operational period of wells by 30%–40% under average mineral acid concentrations and by 25%–45% under maximum concentrations with surfactant additives in complex geological settings. As a result, an effective methodology for ranking geological blocks based on their ore clay content and precipitate composition was developed to determine the rational parameters of decolmatant solutions, enabling a maximized filtration performance and an extended well service life. This makes it possible to reduce the operating costs of extraction, control the geotechnological parameters of uranium well mining, and improve the efficiency of the in situ leaching of uranium under complex mining and geological conditions. Additionally, the approach increases the environmental and operational safety during uranium ore leaching intensification. Full article

(This article belongs to the Section Mineral Processing and Extractive Metallurgy)

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3 pages, 118 KiB

Open AccessEditorial

Editorial for Special Issue “Genesis and Metallogeny of Non-Ferrous and Precious Metal Deposits”

by Sitong Chen, Qun Yang, Yunsheng Ren, Chan Li, Haozhe Li and Xiaolei Peng

Minerals 2025, 15(8), 810; https://doi.org/10.3390/min15080810 (registering DOI) - 31 Jul 2025

Abstract

In recent decades, an increasing number of non-ferrous and precious metal deposits have been discovered all over the world [...] Full article

(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits)

36 pages, 10414 KiB

Open AccessArticle

Forces During the Film Drainage and Detachment of NMC and Spherical Graphite in Particle–Bubble Interactions Quantified by CP-AFM and Modeling to Understand the Salt Flotation of Battery Black Mass

by Jan Nicklas, Claudia Heilmann, Lisa Ditscherlein and Urs A. Peuker

Minerals 2025, 15(8), 809; https://doi.org/10.3390/min15080809 - 30 Jul 2025

Abstract

The salt flotation of graphite in the presence of lithium nickel manganese cobalt oxide (NMC) was assessed by performing colloidal probe atomic force microscopy (CP-AFM) on sessile gas bubbles and conducting batch flotation tests with model lithium-ion-battery black mass. The modeling of film [...] Read more.

The salt flotation of graphite in the presence of lithium nickel manganese cobalt oxide (NMC) was assessed by performing colloidal probe atomic force microscopy (CP-AFM) on sessile gas bubbles and conducting batch flotation tests with model lithium-ion-battery black mass. The modeling of film drainage and detachment during particle–bubble interactions provides insight into the fundamental microprocesses during salt flotation, a special variant of froth flotation. The interfacial properties of particles and gas bubbles were tailored with salt solutions containing sodium chloride and sodium acetate buffer. Graphite particles can attach to gas bubbles under all tested conditions in the range pH 3 to pH 10. The attractive forces for spherical graphite are strongest at high salt concentrations and pH 3. The conditions for the attachment of NMC to gas bubbles were evaluated with simulations using the Stokes–Reynolds–Young–Laplace model for film drainage, under consideration of DLVO forces and a hydrodynamic slip to account for irregularities of the particle surface. CP-AFM measurements in the capillary force regime provide additional parameters for the modeling of salt flotation, such as the force and work of detachment. The contact angles of graphite and NMC particles during retraction and detachment from gas bubbles were obtained from a quasi-equilibrium model using CP-AFM data as input. All CP-AFM experiments and theoretical results suggest that pristine NMC particles do not attach to gas bubbles during flotation, which is confirmed by the low rate of NMC recovery in batch flotation tests. Full article

(This article belongs to the Special Issue Particle–Bubble Interactions in the Flotation Process)

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22 pages, 20436 KiB

Open AccessArticle

An Adaptive Decomposition Method with Low Parameter Sensitivity for Non-Stationary Noise Suppression in Magnetotelluric Data

by Zhenyu Guo, Cheng Huang, Wen Jiang, Tao Hong and Jiangtao Han

Minerals 2025, 15(8), 808; https://doi.org/10.3390/min15080808 - 30 Jul 2025

Abstract

Magnetotelluric (MT) sounding is a crucial technique in mineral exploration. However, MT data are highly susceptible to various types of noise. Traditional data processing methods, which rely on the assumption of signal stationarity, often result in severe distortion when suppressing non-stationary noise. In [...] Read more.

Magnetotelluric (MT) sounding is a crucial technique in mineral exploration. However, MT data are highly susceptible to various types of noise. Traditional data processing methods, which rely on the assumption of signal stationarity, often result in severe distortion when suppressing non-stationary noise. In this study, we propose a novel, adaptive, and less parameter-dependent signal decomposition method for MT signal denoising, based on time–frequency domain analysis and the application of modal decomposition. The method uses Variational Mode Decomposition (VMD) to adaptively decompose the MT signal into several intrinsic mode functions (IMFs), obtaining the instantaneous time–frequency energy distribution of the signal. Subsequently, robust statistical methods are introduced to extract the independent components of each IMF, thereby identifying signal and noise components within the decomposition results. Synthetic data experiments show that our method accurately separates high-amplitude non-stationary interference. Furthermore, it maintains stable decomposition results under various parameter settings, exhibiting strong robustness and low parameter dependency. When applied to field MT data, the method effectively filters out non-stationary noise, leading to significant improvements in both apparent resistivity and phase curves, indicating its practical value in mineral exploration. Full article

(This article belongs to the Special Issue Novel Methods and Applications for Mineral Exploration, Volume III)

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14 pages, 3902 KiB

Open AccessArticle

Navigating the Limits: Unraveling Unidentified Fossil Bone and Tooth Fragments Through Histology, Chemistry, and Multivariate Statistics

by Yannicke Dauphin

Minerals 2025, 15(8), 807; https://doi.org/10.3390/min15080807 - 30 Jul 2025

Abstract

For paleoenvironmental reconstruction, paleontologists prefer large, well-preserved fossils. Yet, such specimens are rare, and countless small fragments, though abundant, often go unused. These fragments lack visible internal structure, thus requiring etching, a procedure not permitted on large, intact specimens. Our research introduces a [...] Read more.

For paleoenvironmental reconstruction, paleontologists prefer large, well-preserved fossils. Yet, such specimens are rare, and countless small fragments, though abundant, often go unused. These fragments lack visible internal structure, thus requiring etching, a procedure not permitted on large, intact specimens. Our research introduces a three-step method to identify the nature of these small fragments. With their structures revealed, we can then analyze the chemical composition of identified tissues. The method was tested using samples of vertebrate fossils collected in Malawi. Even with a limited number of samples, multivariate analyses (Principal Component Analyses—PCA) of these chemical data effectively differentiate fossil and recent samples, as well as bone, dentin, and enamel. This approach successfully reveals the behavior of the mineralized tissues of fossil samples. Ultimately, by leveraging microstructural and chemical data, we can study previously unidentified fragments or rare fossils. This allows for the estimation of preservation state and helps to avoid biases in paleoenvironmental reconstructions. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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