Minerals

16 pages, 2834 KB

Open AccessArticle

The Effect of Particle Size and Dodecylamine Concentration on the Flotation of Lepidolite in Alkaline Medium

by Martín Reyes Pérez, Francisco Patiño Cardona, Hernan Islas Vázquez, Iván Alejandro Reyes Domínguez, Mizraim Uriel Flores Guerrero, Miguel Pérez Labra, Julio Cesar Juárez Tapia, Dayli Yamileth Tolentino Mendoza and Miroslava Mishelle Sánchez Acosta

Minerals 2025, 15(9), 954; https://doi.org/10.3390/min15090954 (registering DOI) - 6 Sep 2025

Abstract

Currently, lepidolite is considered an important natural alternative for obtaining lithium, given the difficulty in processing other species containing this metal. However, its mechanical preparation and beneficiation present considerable challenges and play a critical role in its efficient separation by flotation. This study [...] Read more.

Currently, lepidolite is considered an important natural alternative for obtaining lithium, given the difficulty in processing other species containing this metal. However, its mechanical preparation and beneficiation present considerable challenges and play a critical role in its efficient separation by flotation. This study explores the effect of particle size and dodecylamine concentration during flotation in a laboratory Denver cell. The results indicate that particle size significantly affects the finding in which the optimum was −90 + 75 μm, with a separation efficiency of 94%, and with only 2.067 × 10⁻⁵ M of dodecylamine (DDA) (5 g/t) at pH 11.0. The hydrophobicity of lepidolite was generated by the effect of the chemisorption of the cationic collector and the FTIR results indicate detection of the characteristic bands of the adsorption of DDA to the surface of lepidolite. Full article

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

► Show Figures

Figure 1

18 pages, 4459 KB

Open AccessArticle

Geochemical Constraints on Antimony Mineralization in the Gutaishan Au–Sb Deposit, China: Insights from Trace Elements in Quartz and Sulfur Isotopes in Stibnite

by Jingping Feng, Linyan Kang, Bin Li and Peixuan Kang

Minerals 2025, 15(9), 953; https://doi.org/10.3390/min15090953 (registering DOI) - 6 Sep 2025

Abstract

The Gutaishan Au–Sb deposit is situated in the southern segment of the Jiangnan Orogenic Belt, a region characterized by a concentration of Au–Sb–W deposits. Previous research has predominantly concentrated on Au mineralization, whereas studies addressing the equally important Sb mineralization are relatively scarce. [...] Read more.

The Gutaishan Au–Sb deposit is situated in the southern segment of the Jiangnan Orogenic Belt, a region characterized by a concentration of Au–Sb–W deposits. Previous research has predominantly concentrated on Au mineralization, whereas studies addressing the equally important Sb mineralization are relatively scarce. To investigate key scientific questions regarding the source of ore-forming materials, the physicochemical conditions, and mineralization mechanisms of Sb in the Gutaishan deposit, we conducted systematic analyses of trace elements in hydrothermal quartz and sulfur isotopes in stibnite. Li, Al, Sb, B, Na, K, Ti, Ge, and As are the dominant trace elements in hydrothermal quartz from the Gutaishan deposit. The dominant substitution mechanism is (Al³⁺, Sb³⁺) + (Li⁺, Na⁺, K⁺, H⁺) ↔ Si⁴⁺. The relatively low but variable Al concentrations indicate that quartz precipitated from fluids with fluctuating pH and weakly acidic conditions, while variations in Ti and Ge reflect significant temperature changes. These features suggest that fluid mixing was the primary mineralization mechanism in the Gutaishan deposit. Hydrothermal quartz contains anomalously high B concentrations (14.36–30.64 ppm), far exceeding typical hydrothermal levels, while stibnite displays consistent magmatic sulfur isotope signatures (−3.50‰ to −4.2‰, with an average of −3.99 ± 0.2‰), which are markedly different from the in situ δ³⁴S values of sedimentary sulfides (+7.0‰ to +23.3‰) in the host rocks. This combination of evidence indicates a magmatic–hydrothermal origin for Sb mineralization. Integrating previous geochronological and isotopic constraints with our new observations, we interpret that the Gutaishan deposit represents an intrusion-related Au–Sb deposit formed in a post-collisional extensional setting, where Sb was precipitated after Au mineralization as a result of fluid mixing. Full article

(This article belongs to the Section Mineral Deposits)

► Show Figures

Figure 1

25 pages, 1812 KB

Open AccessArticle

YOLO-EDH: An Enhanced Ore Detection Algorithm

by Lei Wan, Xueyu Huang and Zeyang Qiu

Minerals 2025, 15(9), 952; https://doi.org/10.3390/min15090952 - 5 Sep 2025

Abstract

Mineral identification technology is a key technology in the construction of intelligent mines. In ore classification and detection, mining scenarios present challenges, such as diverse ore types, significant scale variations, and complex surface textures. Traditional detection models often suffer from insufficient multi-scale feature [...] Read more.

Mineral identification technology is a key technology in the construction of intelligent mines. In ore classification and detection, mining scenarios present challenges, such as diverse ore types, significant scale variations, and complex surface textures. Traditional detection models often suffer from insufficient multi-scale feature representation and weak dynamic adaptability, leading to the missed detection of small targets and misclassification of similar minerals. To address these issues, this paper proposes an efficient multi-scale ore classification and detection model, YOLO-EDH. To begin, standard convolution is replaced with deformable convolution, which efficiently captures irregular defect patterns, significantly boosting the model’s robustness and generalization ability. The C3k2 module is then combined with a modified dynamic convolution module, which avoids unnecessary computational overhead while enhancing the flexibility and feature representation. Additionally, a content-guided attention fusion (HGAF) module is introduced before the detection phase, ensuring that the model assigns the correct importance to various feature maps, thereby highlighting the most relevant object details. Experimental results indicate that YOLO-EDH surpasses YOLOv11, improving the precision, recall, and mAP50 by 0.9%, 1.7%, and 1.6%, respectively. In conclusion, YOLO-EDH offers an efficient solution for ore detection in practical applications, with considerable potential for industries like intelligent mine resource sorting and safety production monitoring, showing notable commercial value. Full article

► Show Figures

Figure 1

20 pages, 11264 KB

Open AccessArticle

Clay Mineral Characteristics and Smectite-to-Illite Transformation in the Chang-7 Shale, Ordos Basin: Processes and Controlling Factors

by Kun Ling, Ziyi Wang, Yaqi Cao, Yifei Liu and Lin Dong

Minerals 2025, 15(9), 951; https://doi.org/10.3390/min15090951 - 5 Sep 2025

Abstract

As critical components in continental shale systems, the composition and evolution of clay minerals are fundamental to their diagenetic processes and petrophysical properties. The Chang-7 shales in the Ordos Basin exhibit abundant clay mineral content, offering a valuable case study for clay mineral [...] Read more.

As critical components in continental shale systems, the composition and evolution of clay minerals are fundamental to their diagenetic processes and petrophysical properties. The Chang-7 shales in the Ordos Basin exhibit abundant clay mineral content, offering a valuable case study for clay mineral research under moderate diagenetic conditions. This study employed XRD analysis to determine the whole-rock mineralogy, clay mineral composition, and the evolution characteristics of illite-smectite mixed-layer minerals (I/S). Comprehensive clay mineral datasets compiled from 13 newly analyzed wells and existing literature revealed distinct lateral distribution patterns. Total Organic Carbon (TOC) analysis and vitrinite reflectance (R_o) measurements provided systematic quantification of organic matter abundance and thermal maturation parameters in the studied samples. The results reveal that the Chang-7 shale exhibits a characteristic clay mineral assemblage, with I/S (average 44.2%) predominating over illite (34.7%), followed by chlorite (15.6%) and limited kaolinite (5.4%). Frequent volcanic activities provided substantial precursor materials for smectite formation, which actively participated in subsequent illitization processes, while chlorite and kaolinite distributions were predominantly controlled by provenance inputs and sedimentary facies, respectively. Inconsistencies exist between diagenetic stages inferred from I/S mixed-layer ratios and R_o values, particularly in low-maturity samples exhibiting accelerated illitization. The observed negative correlation between TOC content and mixed-layer ratios in Well YY1 and YSC Section samples demonstrates the catalytic role of organic matter in facilitating smectite-to-illite transformation. These results systematically clarify the coupled effects of sedimentary-diagenetic processes, offering new insights into the mutual interactions between inorganic and organic phases during illitization under natural geological conditions. The findings advance the understanding of Chang-7 shale oil and gas systems and offer practical guidance for future exploration. Full article

(This article belongs to the Special Issue Reservoir and Geochemistry Characteristics of Black Shale, 2nd Edition)

► Show Figures

Figure 1

13 pages, 4027 KB

Open AccessArticle

Influence of Geological Origin on the Physicochemical Characteristics of Sepiolites

by Leticia Lescano, Silvina A. Marfil, Luciana A. Castillo and Silvia E. Barbosa

Minerals 2025, 15(9), 950; https://doi.org/10.3390/min15090950 - 5 Sep 2025

Abstract

In this study the influence of the geological formation environment on the physicochemical properties of two natural sepiolites, as collected, was investigated. The samples analyzed were a lacustrine-derived sample from Tolsa, Spain (ST), and a hydrothermal-derived sample from La Adela, Argentine (SA). Comprehensive [...] Read more.

In this study the influence of the geological formation environment on the physicochemical properties of two natural sepiolites, as collected, was investigated. The samples analyzed were a lacustrine-derived sample from Tolsa, Spain (ST), and a hydrothermal-derived sample from La Adela, Argentine (SA). Comprehensive characterization was carried out using chemical analysis (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and evaluations of hydrophobicity/hydrophilicity behavior. The results indicate that the ST sample exhibits a higher SiO₂/MgO ratio and contains amorphous silica impurities, while the SA sample shows a composition more closely aligned with the theoretical stoichiometry of sepiolite. Furthermore, the SA sample demonstrates greater crystallinity compared to the ST sample. Morphological analysis revealed that ST consists of compact, aggregated fibrous structures, while SA is composed of disaggregated, needle-like fibers with high aspect ratios and nanometric diameters. Both samples display predominantly hydrophilic behavior; however, only the SA sample exhibits suspended particles at the interface, suggesting a slightly higher hydrophobic character than ST sample. These findings highlight the significant impact of the geological formation environment on the structural and surface characteristics of sepiolite, which, in turn, influence its performance in applications involving dispersion, adsorption, and interfacial interactions. Full article

(This article belongs to the Special Issue Clay Minerals: From Paleoclimatic and Paleoenvironmental Indicators to Industrial Raw Materials)

► Show Figures

Graphical abstract

27 pages, 13959 KB

Open AccessArticle

Petrogenesis of Tholeiitic Basalts from CZK06 Drill Core on the Tianchi Volcano, China–North Korea Border

by Cheng Qian, Jintao Ge, Bo Pan, Zhen Tang, Bin Jiang, Tianri Cui and Lu Lu

Minerals 2025, 15(9), 949; https://doi.org/10.3390/min15090949 - 5 Sep 2025

Abstract

To constrain Tianchi Volcano basalt petrogenesis, this study focuses on tholeiitic basalts from the CZK06 drill core on the northern slope. Using elemental geochemistry and Mg isotope analyses, we investigate magma evolution, petrogenesis, and mantle source properties. The tholeiitic basalts formed during the [...] Read more.

To constrain Tianchi Volcano basalt petrogenesis, this study focuses on tholeiitic basalts from the CZK06 drill core on the northern slope. Using elemental geochemistry and Mg isotope analyses, we investigate magma evolution, petrogenesis, and mantle source properties. The tholeiitic basalts formed during the Pliocene-Early Pleistocene shield-forming stage, recording three stages of basaltic volcanism (Phases I to III). Classified as sodium-series basalts, they exhibit geochemical affinities with EM1-type OIB. Their δ²⁶Mg values (−0.420‰ to −0.150‰) show a substantially wider range than N-MORB. Their geochemical compositions are primarily controlled by source region characteristics and partial melting degree, with minor additional influences from fractional crystallization and crustal contamination. Fractional crystallization intensity shows a progressive increase from Phase I to III. Integrated with geochemical tracing studies of Changbaishan basalts, we propose that the tholeiitic basalts are derived predominantly from the partial melting of carbonatized pyroxenite, which originated from subducted ancient clay-rich altered oceanic crust. The carbonate melts driving the carbonatization were generated by low-pressure melting of recent oceanic sediments, transported by the deeply subducted carbonate-rich Pacific Plate within the Mantle Transition Zone. The tholeiitic magma formed in the Low-Velocity Zone at depths of 160–180 km beneath the lithospheric mantle. Full article

(This article belongs to the Special Issue Selected Papers from the 7th National Youth Geological Congress)

► Show Figures

Figure 1

15 pages, 3813 KB

Open AccessReview

Resource Recycling and Ceramsite Utilization of Coal-Based Solid Waste: A Review

by Han Wang, Chunfu Liu, Chenyu Zhu and Zhipeng Gong

Minerals 2025, 15(9), 948; https://doi.org/10.3390/min15090948 - 5 Sep 2025

Abstract

Coal-based solid waste refers to solid waste generated during coal mining and washing processes, and is one of the major types of industrial solid waste in China. Its resource utilization is a critical part of the clean and efficient use of coal, and [...] Read more.

Coal-based solid waste refers to solid waste generated during coal mining and washing processes, and is one of the major types of industrial solid waste in China. Its resource utilization is a critical part of the clean and efficient use of coal, and preparing ceramsite from coal-based solid waste is an important means to promote its “resourceful, large-scale, and high-value” utilization. This paper systematically summarizes the types and properties of coal-based solid waste, its resource utilization methods, and research progress in ceramsite preparation. The focus is on assessing the feasibility, process features, and application status of ceramsite made from coal-based solid waste in areas such as construction, heavy metal stabilization, and water treatment. Using coal-based solid waste to produce ceramsite offers cost reduction and pollution mitigation benefits while showcasing significant potential for resource recycling and sustainable development. This paper further outlines the development trends and technological innovation directions for coal-based solid waste ceramsite, providing theoretical support and practical guidance for advancing the resource utilization of industrial solid waste. Full article

(This article belongs to the Special Issue Recycling and Utilization of Metallurgical and Chemical Solid Waste)

► Show Figures

Figure 1

19 pages, 3396 KB

Open AccessArticle

Effect of Scale Inhibitors on the Nucleation and Crystallization of Calcium Carbonate

by Vanessa Pimentel Lages, Raquel Gonçalves, Fernanda Medeiros, Rubens Bisatto, André Linhares Rossi and Amaro Gomes Barreto Junior

Minerals 2025, 15(9), 947; https://doi.org/10.3390/min15090947 - 5 Sep 2025

Abstract

Effective control of calcium carbonate (CaCO₃) scale formation is crucial to improve the performance and economic efficiency of water systems. This study investigates the impact of various scale inhibitors on the nucleation and crystallization processes of CaCO₃. Calcium carbonate [...] Read more.

Effective control of calcium carbonate (CaCO₃) scale formation is crucial to improve the performance and economic efficiency of water systems. This study investigates the impact of various scale inhibitors on the nucleation and crystallization processes of CaCO₃. Calcium carbonate particles were synthesized by mixing CaCl₂·2H₂O and NaHCO₃ solutions, in the presence of various scale inhibitors that had not previously been investigated using the experimental techniques employed in this study. Particle size distribution and zeta potential were analyzed using dynamic light scattering (DLS), while Ca⁺² consumption and pH changes were monitored with ion-selective electrodes. Crystal morphology was evaluated using scanning electron microscopy (SEM) and cryo-transmission electron microscopy (cryo-TEM). We demonstrated that, in all samples, approximately 98% of the CaCO₃ particles (sized between 400 and 840 nm) are formed within the first 30 min of synthesis, and these particles then aggregate to form larger particles (840–1100 nm in size). Due to the solution’s high supersaturation, the inhibitors influence calcium consumption only after 5 min of synthesis. All inhibitors, especially DTPMP, decrease calcium consumption and particle size during synthesis. The zeta potential and morphology of the particles in the samples containing inhibitors differed from those in the control group. Cryo-TEM observations revealed distinct nanometric precursor phases in the calcite crystallization process without inhibitors and different nanostructures when scale inhibitors were used. Moreover, conchoidal fractures were observed in the nanoparticles formed in the presence of DTPMP. This study demonstrates the effectiveness of various inhibitors in reducing calcium consumption in solution and altering the morphology of CaCO₃ crystals, thereby preventing calcium carbonate (CaCO₃) scale formation. Full article

(This article belongs to the Section Crystallography and Physical Chemistry of Minerals & Nanominerals)

► Show Figures

Graphical abstract

14 pages, 1849 KB

Open AccessArticle

Isolation, Testing, and Adaptation of Bacteria to Bioleach Metals from Pyrite

by Anna Choińska-Pulit, Justyna Sobolczyk-Bednarek and Marcin Kania

Minerals 2025, 15(9), 946; https://doi.org/10.3390/min15090946 - 4 Sep 2025

Abstract

Bioleaching, mediated by selected microflora, offers a more environmentally friendly and cost-effective alternative to traditional mining techniques by transforming metals from sulfide ores into water-soluble forms. Pyrite ores often contain valuable rare or noble metals, such as gold (Au), silver (Ag), nickel (Ni), [...] Read more.

Bioleaching, mediated by selected microflora, offers a more environmentally friendly and cost-effective alternative to traditional mining techniques by transforming metals from sulfide ores into water-soluble forms. Pyrite ores often contain valuable rare or noble metals, such as gold (Au), silver (Ag), nickel (Ni), and cobalt (Co), which can be leached through the metabolic activity of specific chemoautotrophic microorganisms. This study investigates the adaptation process of the Acidithiobacillus ferriphilus bacterial strain, originally isolated from acid mine drainage (AMD), for the bioleaching of pyrite. The progress of the bioleaching process was evidenced by the release of iron (3.6 mg/mL) and significant quantities of gold (0.21 mg/L, equivalent to 3 g/t) into the post-culture liquid. The results indicate that the most effective bioleaching was achieved during the final adaptation stage, utilizing a medium with 7% pyrite content and a 0.75% supplement of an easily accessible energy source in the form of iron sulfate. These findings confirm the potential of the A. ferriphilus strain for pyrite bioleaching. Full article

(This article belongs to the Special Issue Advances in the Theory and Technology of Biohydrometallurgy)

► Show Figures

Figure 1

40 pages, 3732 KB

Open AccessReview

Applications and Prospects of Muography in Strategic Deposits

by Xingwen Zhou, Juntao Liu, Baopeng Su, Kaiqiang Yao, Xinyu Cai, Rongqing Zhang, Ting Li, Hengliang Deng, Jiangkun Li, Shi Yan and Zhiyi Liu

Minerals 2025, 15(9), 945; https://doi.org/10.3390/min15090945 - 4 Sep 2025

Abstract

With strategic mineral exploration extending to deep and complex geological settings, traditional methods increasingly struggle to dissect metallogenic systems and locate ore bodies precisely. This synthesis of current progress in muon imaging (a technology leveraging cosmic ray muons’ high penetration) aims to address [...] Read more.

With strategic mineral exploration extending to deep and complex geological settings, traditional methods increasingly struggle to dissect metallogenic systems and locate ore bodies precisely. This synthesis of current progress in muon imaging (a technology leveraging cosmic ray muons’ high penetration) aims to address these exploration challenges. Muon imaging operates by exploiting the energy attenuation of cosmic ray muons when penetrating earth media. It records muon transmission trajectories via high-precision detector arrays and constructs detailed subsurface density distribution images through advanced 3D inversion algorithms, enabling non-invasive detection of deep ore bodies. This review is organized into four thematic sections: (1) technical principles of muon imaging; (2) practical applications and advantages in ore exploration; (3) current challenges in deployment; (4) optimization strategies and future prospects. In practical applications, muon imaging has demonstrated unique advantages: it penetrates thick overburden and high-resistance rock masses to delineate blind ore bodies, with simultaneous gains in exploration efficiency and cost reduction. Optimized data acquisition and processing further allow it to capture dynamic changes in rock mass structure over hours to days, supporting proactive mine safety management. However, challenges remain, including complex muon event analysis, long data acquisition cycles, and limited distinguishability for low-density-contrast formations. It discusses solutions via multi-source geophysical data integration, optimized acquisition strategies, detector performance improvements, and intelligent data processing algorithms to enhance practicality and reliability. Future advancements in muon imaging are expected to drive breakthroughs in ultra-deep ore-forming system exploration, positioning it as a key force in innovating strategic mineral resource exploration technologies. Full article

(This article belongs to the Special Issue 3D Mineral Prospectivity Modeling Applied to Mineral Deposits)

► Show Figures

Figure 1

14 pages, 3347 KB

Open AccessArticle

Leaching Behavior and Mechanisms of Li, Rb, K, Sr, and Mg in Clay-Type Lithium Ore via a Roasting–Water Leaching Process

by Bo Feng, Dong An, Huaigang Cheng, Xiaoou Zhang and Jing Zhao

Minerals 2025, 15(9), 944; https://doi.org/10.3390/min15090944 - 4 Sep 2025

Abstract

The extraction of lithium from clay-type lithium ores has attracted significant attention, but the leaching behavior of associated elements, such as Rb, K, and Sr, remains less explored. This study quantitatively investigated the leaching behaviors and mechanisms of Li, Rb, K, Sr, and [...] Read more.

The extraction of lithium from clay-type lithium ores has attracted significant attention, but the leaching behavior of associated elements, such as Rb, K, and Sr, remains less explored. This study quantitatively investigated the leaching behaviors and mechanisms of Li, Rb, K, Sr, and Mg in clay-type lithium ore through water leaching and roasting–water leaching processes. The results show that during direct water leaching, the leaching efficiency of K ranged between 10% and 13%, while Li and Sr exhibited lower extraction rates, requiring prolonged high-temperature leaching. Rb dissolution was minimal, and the leaching efficiency of Mg was significantly affected by temperature. In contrast, roasting–water leaching significantly enhanced the leaching efficiency, achieving extraction rates of 90.65% for Li, 92.91% for Rb, 75.85% for K, and 36.99% for Sr. However, Mg leaching was suppressed to below 1%. Roasting disrupted the original silicate and carbonate lattices, generating new phases that altered the ore’s microstructure into aggregated dense phases and needle-like porous phases upon water leaching, thereby facilitating the release of Li, Rb, K, and Sr. A research finding was that the new phase generated by magnesium inhibited its leaching, which indirectly enhanced subsequent Li, Rb, K, and Sr extraction and separation. These findings provide a quantitative foundation for optimizing multi-element co-extraction from clay-type lithium ores. Full article

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

► Show Figures

Figure 1

19 pages, 1737 KB

Open AccessArticle

Recovery of Valuable Raw Materials Using KOMAG Jig Beneficiation Laboratory Studies and Industrial Implementations

by Daniel Kowol, Piotr Matusiak, Dariusz Prostański, Rafał Baron, Paweł Friebe, Marcin Lutyński and Konrad Kołodziej

Minerals 2025, 15(9), 943; https://doi.org/10.3390/min15090943 - 4 Sep 2025

Abstract

Gravity beneficiation is a key operation in mineral processing and waste recycling, enabling the production of concentrates with required quality. Among gravity separators, pulsating jigs remain widely applied due to their robustness and adaptability. This study evaluates the KOMAG laboratory jig for upgrading [...] Read more.

Gravity beneficiation is a key operation in mineral processing and waste recycling, enabling the production of concentrates with required quality. Among gravity separators, pulsating jigs remain widely applied due to their robustness and adaptability. This study evaluates the KOMAG laboratory jig for upgrading diverse feedstocks: hard coal with variable ash content, gravel aggregates with organic impurities, post-mining waste, and battery scrap. Tests were performed on a two-chamber jig with an air-pulsation system and advanced control. The results confirmed the feasibility of obtaining coal concentrates with 8%–10% ash at 59%–71% yield, complete removal of organic contaminants from aggregates with minimal losses, and recovery of combustible fractions from post-mining waste with favourable separation parameters (d₅₀ = 1.569 g/cm³, imperfection = 0.191). Beneficiation of shredded battery scrap achieved 74%–88% plastic removal and over 99% metallic recovery. Industrial implementations of KOMAG pulsating jigs validated these findings, showing high efficiency in coal, aggregate, and waste processing. This study demonstrates the versatility of pulsating jigging and its relevance in sustainable resource management, confirming that laboratory results can be effectively scaled to industrial practice. Full article

(This article belongs to the Special Issue Recycling of Mining and Solid Wastes)

► Show Figures

Figure 1

19 pages, 5973 KB

Open AccessArticle

Phase Transformation and Si/Al Leaching Behavior of High-Silica–Alumina Coal Gangue Activated by Sodium-Based Additives

by Hongwei Du, Ke Li, Xinghao Shi, Lingxian Fang and Zhao Cao

Minerals 2025, 15(9), 942; https://doi.org/10.3390/min15090942 - 4 Sep 2025

Abstract

High-silica–alumina coal gangue is rich in kaolinite, quartz, and other mineral components. The potential for resource utilization is huge, but the silica–aluminate structure is highly stable, and it is difficult to achieve efficient dissociation and elemental enrichment using traditional extraction processes. This study [...] Read more.

High-silica–alumina coal gangue is rich in kaolinite, quartz, and other mineral components. The potential for resource utilization is huge, but the silica–aluminate structure is highly stable, and it is difficult to achieve efficient dissociation and elemental enrichment using traditional extraction processes. This study selects typical high-silica–alumina coal gangue as the research object and systematically studies the rules of the physical phase transformation mechanism and ion migration behavior in the activation process of the sodium-based additives stage. In addition, a graded leaching and separation processing route is established, realizing the effective separation and extraction of silica–alumina. The key parameters were optimized using response surface methodology (RSM), obtaining the optimal activation conditions of 800 °C, 30 min, and an additives ratio of 0.8. Under these conditions, the highest dissolution rates of silica and alumina are 82.1% and 92.36%, respectively. Characterization techniques such as XRD, FTIR, and SEM reveal that the activation mechanism of coal gangue involves the decomposition of the aluminosilicate framework and the erosion of sodium ions. At the same time, the chemical bonding reorganization contributes to forming water-soluble sodium silicate (Na₂SiO₃) and insoluble nepheline (NaAlSiO₄), which significantly promotes the release of Si and Al. When the activation temperature is too high, the nepheline phase is transformed into amorphous glassy sodium aluminate and precipitated on the surface, which gradually encapsulates the sodium silicate. This encapsulation restricts dissolution pathways, thereby leading to system densification. Moreover, enhanced resistance to acid attack leads to a decrease in the dissolution rates of Si and Al. This study elucidates the mineral phase reconstruction and element migration mechanisms involved in sodium-based activation and presents a viable approach for the high-value utilization of coal gangue. Full article

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

► Show Figures

Figure 1

23 pages, 9916 KB

Open AccessArticle

Mineralization Age and Ore-Forming Material Source of the Yanshan Gold Deposit in the Daliuhang Gold Field in the Jiaodong Peninsula, China: Constraints from Geochronology and In Situ Sulfur Isotope

by Bin Wang, Zhengjiang Ding, Qun Yang, Zhongyi Bao, Junyang Lv, Yina Bai, Shunxi Ma and Yikang Zhou

Minerals 2025, 15(9), 941; https://doi.org/10.3390/min15090941 - 4 Sep 2025

Abstract

The newly discovered Yanshan gold deposit within the Qixia–Penglai mineralization belt is situated within the Daliuhang goldfield of Daliuhang Town, approximately 45 km southeast of Penglai City, the Jiaodong Peninsula. Quartz-vein–type gold orebodies are mainly distributed among the Guojialing granite and are controlled [...] Read more.

The newly discovered Yanshan gold deposit within the Qixia–Penglai mineralization belt is situated within the Daliuhang goldfield of Daliuhang Town, approximately 45 km southeast of Penglai City, the Jiaodong Peninsula. Quartz-vein–type gold orebodies are mainly distributed among the Guojialing granite and are controlled by NNE-trending faults. Native gold primarily occurs within the interiors of pyrite grains, forming inclusion gold and fracture gold. In this study, LA-ICP-MS zircon U-Pb dating and in situ sulfur isotope analysis of gold-bearing pyrite were conducted to constrain the ore genesis of the Yanshan gold deposit. Guojialing monzogranite and porphyritic granodiorite yielded weighted mean ²⁰⁶Pb/²³⁸U ages of 130 ± 2 Ma (MSWD = 1.8) and 131 ± 2 Ma (MSWD = 1.8), respectively, indicating that magmatism and gold mineralization occurred during the Early Cretaceous period. The in situ sulfur δ³⁴S values of euhedral crystalline pyrite (Py1) formed in the early stage ranged from 3.21% to 5.35‰ (n = 11), while the in situ sulfur δ³⁴S values of pyrite (Py2) formed in the later stage ranged from 6.32‰ to 9.77‰ (n = 10), suggesting that the sulfur of the Yanshan gold deposit primarily originates from magmatism, with contamination from stratigraphic materials. Granitoids are highly likely to provide the thermal drive for fluid activity; however, the origins of the fluids and ore-forming materials remain difficult to determine. Based on geological features, geochronological data, and in situ sulfur isotopic analysis, this study concludes that the Yanshan gold deposit is a mesothermal magmatic hydrothermal vein-type gold deposit. The mineralization of the Yanshan gold deposit is related to the subduction of the Mesozoic Paleo-Pacific Plate beneath the Eurasian continent and is mainly controlled by steep dip faults. This study provides theoretical guidance for further exploration and prospecting of the Yanshan gold deposit. Full article

(This article belongs to the Section Mineral Deposits)

► Show Figures

Figure 1

24 pages, 5892 KB

Open AccessArticle

Reactive Transport Model of Steel/Bentonite Interactions in the FEBEX In Situ Test

by Javier Samper, Alba Mon and Luis Montenegro

Minerals 2025, 15(9), 940; https://doi.org/10.3390/min15090940 - 3 Sep 2025

Abstract

Steel corrosion plays a major role in the geochemical evolution at the canister/bentonite interface of the engineered barrier systems of geological radioactive waste repositories. The interactions between corrosion products and bentonite can significantly affect bentonite properties and performance. These interactions have been investigated [...] Read more.

Steel corrosion plays a major role in the geochemical evolution at the canister/bentonite interface of the engineered barrier systems of geological radioactive waste repositories. The interactions between corrosion products and bentonite can significantly affect bentonite properties and performance. These interactions have been investigated by resorting to in situ tests conducted in underground laboratories, such as the FEBEX (Full-scale Engineered Barrier Experiment) test. The FEBEX in situ test, which was conducted at the Grimsel underground research laboratory in Switzerland from 1997 to 2015, demonstrated substantial corrosion of the steel liner in areas without a heater, primarily due to the presence of O₂. Here we report a reactive transport model that simulates steel corrosion products and their interactions with bentonite. The model builds on a previously published conceptual geochemical model and addresses its limitations by integrating a more detailed representation of temperature and unsaturated flow conditions, leveraging prior thermo–hydrodynamic–mechanical–chemical (THMC) models. Given the prevailing uncertainties in O₂ and redox conditions during the test and the limited data on liner corrosion and gas conditions at the liner–bentonite interface, liner corrosion was modeled by using a prescribed time-dependent function for the corrosion rate. Goethite, hematite, and magnetite were the Fe minerals allowed to precipitate in the model. The corrosion rate and the specific surface area of the hematite and magnetite were calibrated based on the profiles of goethite, hematite, and total Fe (including dissolved, exchanged and sorbed forms) observed at the post mortem analysis of the FEBEX in situ test. The model reproduces the observed goethite and hematite precipitation near the liner but underestimates the measured values at greater distances from the liner. The pattern of total calculated Fe concentrations reproduce the measured values except at a distance between 15 and 50 mm from the liner. Goethite is the predominant corrosion product in the model results, even under reducing conditions, owing to kinetic constraints on magnetite and hematite precipitation and to the enhanced stability of goethite driven by pH increase and thermal evolution. Full article

(This article belongs to the Special Issue Implications of THMC Processes on Long-Term Safety of Geological Disposal of Radioactive Waste, 2nd Edition)

► Show Figures

Graphical abstract

21 pages, 14576 KB

Open AccessArticle

The 3D Visibility of Rust: Micro Computed Tomography Investigations of a Roman Iron Nail from Aguntum

by Gerald Degenhart, Simon Wagner, Peter Tropper, Ulrike Töchterle and Martin Auer

Minerals 2025, 15(9), 939; https://doi.org/10.3390/min15090939 - 3 Sep 2025

Abstract

The restoration of iron finds is still a particularly complex area within the science of archaeological conservation, as severe signs of corrosion occur from the moment of recovery and the associated radical change in environmental parameters. The results of this study show that [...] Read more.

The restoration of iron finds is still a particularly complex area within the science of archaeological conservation, as severe signs of corrosion occur from the moment of recovery and the associated radical change in environmental parameters. The results of this study show that it is possible to create three-dimensional models of an iron find using non-invasive µCT examinations to identify the different layers and phases of corrosion based on mineralogical investigations and thus to assess the state of preservation of the iron object. The resulting visibility of the corrosion zones provides an important basis for further treatment of iron artefacts after recovery (packaging, desalination, storage, etc.), since the goal is the long-term preservation of cultural heritage made of iron. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Insights into Cultural Heritage Materials)

► Show Figures

Figure 1

26 pages, 15275 KB

Open AccessArticle

Application of Multispectral Data in Detecting Porphyry Copper Deposits: The Case of Aidarly Deposit, Eastern Kazakhstan

by Elmira Serikbayeva, Kuanysh Togizov, Dinara Talgarbayeva, Elmira Orynbassarova, Nurmakhambet Sydyk and Aigerim Bermukhanova

Minerals 2025, 15(9), 938; https://doi.org/10.3390/min15090938 - 3 Sep 2025

Abstract

The Koldar Massif in southeastern Kazakhstan is a geologically complex area with potential for porphyry copper and rare-metal mineralization. This study applies a multi-scale remote sensing approach to delineate hydrothermal alteration zones using medium-resolution ASTER imagery and very high-resolution WorldView-3 data. Image processing [...] Read more.

The Koldar Massif in southeastern Kazakhstan is a geologically complex area with potential for porphyry copper and rare-metal mineralization. This study applies a multi-scale remote sensing approach to delineate hydrothermal alteration zones using medium-resolution ASTER imagery and very high-resolution WorldView-3 data. Image processing techniques—including false color composites (FCCs), band ratios (BRs), and the Spectral Angle Mapper (SAM)—were employed across the VNIR and SWIR bands to detect alteration minerals such as kaolinite, illite, montmorillonite, chlorite, epidote, calcite, quartz, and muscovite. These minerals correspond to argillic, propylitic, and phyllic alteration zones. While ASTER supported regional-scale mapping, WorldView-3 enabled detailed analysis at the Aidarly deposit. Validation was performed using copper occurrences, lithogeochemical anomaly contours, and ore body boundaries. The results show a strong spatial correlation between the mapped alteration zones and known mineralization patterns. Importantly, this study reports the identification of a previously undocumented hydrothermal zone north of the Aidarly deposit, detected using WorldView-3 data. This zone exhibits concentric phyllic and argillic alterations, similar to those at Aidarly, and may represent an extension of the mineralized system. Unlike earlier studies on the Aktogay deposit based on ASTER and Landsat-8, this work focuses on the Aidarly deposit and introduces higher-resolution analysis and SAM-based classification, offering improved spatial accuracy and target delineation. The proposed methodology provides a reproducible and scalable workflow for early-stage mineral exploration in underexplored regions, especially where field access is limited. These results highlight the value of high-resolution remote sensing in detecting concealed porphyry copper systems in structurally complex terrains. Full article

(This article belongs to the Section Mineral Exploration Methods and Applications)

► Show Figures

Figure 1

18 pages, 2415 KB

Open AccessArticle

Fluoride Sorption Performance of a Layered Double-Hydroxide–Based Adsorbent Using Soil Extract Solution as the Solvent

by Miu Nishikata, Yohey Hashimoto, Kazumi Fujii, Tomohiro Kato and Tetsuo Yasutaka

Minerals 2025, 15(9), 937; https://doi.org/10.3390/min15090937 - 2 Sep 2025

Abstract

Rocks and soil excavated at construction sites can contain naturally occurring toxic substances. One low-cost means of managing the environmental burden posed by leaching of these substances is the attenuation layer method, which uses an adsorbent positioned between the fill and ground. Evaluation [...] Read more.

Rocks and soil excavated at construction sites can contain naturally occurring toxic substances. One low-cost means of managing the environmental burden posed by leaching of these substances is the attenuation layer method, which uses an adsorbent positioned between the fill and ground. Evaluation of adsorbent performance based on sorption tests is important for designing and optimizing attenuation layer methods; however, few studies have examined the effect of coexisting ions on sorption performance. Here, we examined the effects of these ions contained in soil extract solutions on the fluoride sorption performance of a commercial layered double-hydroxide (LDH)–based adsorbent used in the attenuation layer method. Batch and column sorption tests showed that the distribution coefficients in the presence of coexisting ions were 29%–72% lower than those in tests conducted without coexisting ions. Furthermore, the results of a solid-state analysis and various ion analyses suggest that competition for the sorption sites of LDH by sulfate ions in the soil extract solution was the cause of the reduced sorption performance. These findings imply that reliance only on deionized water-based sorption tests may overestimate the real-world sorption performance of LDH-based adsorbents. Full article

(This article belongs to the Special Issue Environmental Geochemistry of Heavy Metals: Contamination, Impacts, and Countermeasure Strategies)

► Show Figures

Figure 1

26 pages, 3138 KB

Open AccessArticle

Understanding the Geology of Mountain Foothills Through Hydrogeochemistry: Evaluating Critical Raw Materials’ Potential for the Energy Transition in the Salsomaggiore Structure (Northwestern Apennines, Italy)

by Simone Cioce, Andrea Artoni, Tiziano Boschetti, Alessandra Montanini, Stefano Segadelli, Maria Teresa de Nardo, Nicolò Chizzini, Luca Lambertini and Aasiya Qadir

Minerals 2025, 15(9), 936; https://doi.org/10.3390/min15090936 - 2 Sep 2025

Abstract

The energy transition is an issue of fundamental importance in the current global context, as an increasing number of countries are committed to searching for minerals and elements essential for the storage, distribution, and supply of energy derived from new renewable and sustainable [...] Read more.

The energy transition is an issue of fundamental importance in the current global context, as an increasing number of countries are committed to searching for minerals and elements essential for the storage, distribution, and supply of energy derived from new renewable and sustainable sources. In some countries, these elements (such as boron, lithium, and strontium) are considered to be critical raw materials (CRMs) because of their limited occurrence within their own borders and are commonly found in minerals and geothermal–formation waters, especially in brackish to brine waters. In the Italian territory, CRM-rich waters have already been identified by previously published studies (i.e., with mean concentrations in the Salsomaggiore Terme of 390 mg/L of boron, 76 mg/L of lithium, and 414 mg/L of strontium); however, their extraction is hampered by several knowledge gaps. In particular, a comprehensive understanding of the origin, accumulation processes, and migration pathways of these CRM-rich waters is still lacking. These factors are closely linked to the geological framework and evolutionary history of each specific area. To address these gaps, we investigated the Salsomaggiore Structure that is located at the northwestern front of the Apennine in Italy by integrating geological data with hydrogeochemical results. We constructed new preliminary distribution maps of the most significant CRMs around the Salsomaggiore Structure, which can be used in the future for the National Mineral Exploration Program drawn up in accordance with the European Critical Raw Materials Act. These maps, combined with the interpretation of seismic reflection profiles calibrated with surface geology and wells, allowed us to establish a close relationship between water geochemistry/CRM contents and the geological evolution of the Salsomaggiore Structure. This structure can be considered representative of the frontal ranges of the Northwestern Apennine and other mountain chains associated with the foreland basin systems. Full article

(This article belongs to the Special Issue Understanding the Geologic History of Italy: Perspectives from Geochemistry, Geology and Mineralization)

► Show Figures

Figure 1

Journal Description

Minerals

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI