Minerals

16 pages, 6741 KiB

Open AccessArticle

Geotechnical and Hydrogeological Zonation of Tailings Storage Facilities: Importance for Design, Construction, Operation, and Closure

by Roberto Rodríguez-Pacheco, Joanna Butlanska and Aldo Onel Oliva-González

Minerals 2025, 15(2), 105; https://doi.org/10.3390/min15020105 (registering DOI) - 22 Jan 2025

Abstract

This study introduces a conceptual model for understanding the hydromechanical behavior and zonation within tailings storage facilities (TSFs) constructed using the hydraulic backfill method, which constitutes over 98% of TSFs worldwide. The model identifies four distinct zones—dike, discharge, transition, and distal—each characterized by [...] Read more.

This study introduces a conceptual model for understanding the hydromechanical behavior and zonation within tailings storage facilities (TSFs) constructed using the hydraulic backfill method, which constitutes over 98% of TSFs worldwide. The model identifies four distinct zones—dike, discharge, transition, and distal—each characterized by unique physical, geotechnical, and hydraulic properties. Key findings highlight gradients in parameters which systematically vary from the dam toward the settling pond. This study observes that seven parameters such as grain size, friction angle, shear strength, dry density, permeability, shear wave velocities, and liquefaction capacity decrease in value from the dike to the lagoon. Conversely, thirteen parameters such as fine content, porosity, cohesion, plasticity, degree of saturation, volumetric and gravimetric water content, capillary height, specific and volumetric surface of tailings, suction, air and water entry value in the soil water characteristic curve increase in value from the dike to the lagoon. These trends underscore the complex behavior of tailings and their implications for stability, drainage, and environmental impact. By integrating geological, geotechnical, hydrogeological, and geophysical data, this study provides a holistic framework for TSF management, addressing both current challenges and long-term environmental considerations. Full article

(This article belongs to the Special Issue Tailings Dams: Design, Characterization, Monitoring, and Risk Assessment, 2nd Edition)

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12 pages, 3220 KiB

Open AccessArticle

Modeling Shapes of Coarse Particles for DEM Simulations Using Polyhedral Meta-Particles

by Felipe de A. Costa, Gabriel K. P. Barrios, Alan P. Fidalgo, Alan A. Arruda Tino and Luís Marcelo Tavares

Minerals 2025, 15(2), 103; https://doi.org/10.3390/min15020103 (registering DOI) - 22 Jan 2025

Abstract

Particles of selected materials, namely granulite quarry rock and itabirite iron ore, have been characterized regarding their shapes using reconstruction from 2D images and 3D laser scanning. Different levels of simplifications of particle geometry were initially proposed, with optimal fit-for-purpose shapes represented by [...] Read more.

Particles of selected materials, namely granulite quarry rock and itabirite iron ore, have been characterized regarding their shapes using reconstruction from 2D images and 3D laser scanning. Different levels of simplifications of particle geometry were initially proposed, with optimal fit-for-purpose shapes represented by polyhedral meta-particles containing 41 to 90 faces. From the distribution of aspect ratios, a total of 16 groups of shapes have been created. Preliminary validation of the shapes modeled was carried out by comparing bulk density measurements from simulations and experiments for granulite, resulting in very good agreement between the two. Further validation was then carried out by comparison of experiments for a gneiss rock and another itabirite sample to simulations, with good agreement between both. This database provides suitable representation of ore/rock shapes for DEM simulations in the software Rocky. Full article

(This article belongs to the Special Issue Process Modelling and Applications for Aggregate Production)

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26 pages, 8849 KiB

Open AccessArticle

The Evolution of Permian Mafic–Ultramafic Magma of the Yunhai Intrusion in the Northern Tianshan, Northwest China, and Its Implications for Cu-Ni Mineralization

by Yuxuan Pei, Mengting Chen, Yujing Zhao, Dahai Li, Jiashun Chen, Zhaoying Chen, Xiaojie Li and Shilin Sun

Minerals 2025, 15(2), 102; https://doi.org/10.3390/min15020102 - 22 Jan 2025

Abstract

The early Permian mafic–ultramafic intrusion-related Cu-Ni mineralization in Northern Tianshan offers valuable insights into the nature of the mantle beneath the Central Asian Orogenic Belt (CAOB) and enhances the understanding of magmatic sulfide mineralization processes in orogenic environments. The Yunhai intrusion, rich in [...] Read more.

The early Permian mafic–ultramafic intrusion-related Cu-Ni mineralization in Northern Tianshan offers valuable insights into the nature of the mantle beneath the Central Asian Orogenic Belt (CAOB) and enhances the understanding of magmatic sulfide mineralization processes in orogenic environments. The Yunhai intrusion, rich in Cu-Ni sulfides, marks a significant advancement for Cu-Ni exploration in the covered regions of the western Jueluotag orogenic belt in Northern Tianshan. This intrusion is well-differentiated, featuring a lithological assemblage of olivine pyroxenite, hornblende pyroxenite, gabbro, and diorite, and contains about 50 kilotons of sulfides with average grades of 0.44 wt% Ni and 0.62 wt% Cu. Sulfide mineralization occurs predominantly as concordant layers or lenses of sparsely and densely disseminated sulfides within the olivine pyroxenite and hornblende pyroxenite. In situ zircon U-Pb dating for the Yunhai intrusion indicates crystallization ages between 288 ± 1 and 284 ± 1 Ma, aligning with several Cu-Ni mineralization-associated mafic–ultramafic intrusions in Northern Tianshan. Samples from the Yunhai intrusion exhibit enrichment in light rare earth elements (LREE), distinct negative Nb and Ta anomalies, positive ε_Nd(t) values ranging from 2.75 to 6.56, low initial (⁸⁷Sr/⁸⁶Sr)_i ratios between 0.7034 and 0.7053, and positive ε_Hf(t) values from 9.27 to 15.9. These characteristics, coupled with low Ce/Pb (0.77–6.55) and Nb/U (5.47–12.0) ratios and high Ti/Zr values (38.7–102), suggest very restricted amounts (ca. 5%) of crustal assimilation. The high Rb/Y (0.35–4.27) and Th/Zr (0.01–0.03) ratios and low Sm/Yb (1.47–2.32) and La/Yb (3.10–7.52) ratios imply that the primary magma of the Yunhai intrusion likely originated from 2%–10% partial melting of weak slab fluids–metasomatized subcontinental lithospheric mantle (peridotite with 2% spinel and/or 1% garnet) in a post-collisional environment. The ΣPGE levels in the Yunhai rocks and sulfide-bearing ores range from 0.50 to 54.4 ppb, which are lower compared to PGE-undepleted Ni-Cu sulfide deposits. This PGE depletion in the Yunhai intrusion’s parental magma may have been caused by early sulfide segregation from the primary magma at depth due to the high Cu/Pd ratios (43.5 × 10³ to 2353 × 10³) of all samples. The fractional crystallization of minerals such as olivine and pyroxene might be a critical factor in provoking significant sulfide segregation at shallower levels, leading to the extensive disseminated Cu-Ni mineralization at Yunhai. These characteristics are similar to those of typical deposits in the eastern section of the Jueluotage orogenic belt (JLOB), which may indicate that the western and eastern sections of the belt have the same ore-forming potential. Full article

(This article belongs to the Special Issue Metallogenesis of the Central Asian Orogenic Belt)

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24 pages, 5610 KiB

Open AccessArticle

Relationship Between Thermodynamic Modeling and Experimental Process for Optimization Ferro-Nickel Smelting

by Erdenebold Urtnasan, Seong-Bong Heo, Joo-Won Yu, Chang-Ho Jung and Jei-Pil Wang

Minerals 2025, 15(2), 101; https://doi.org/10.3390/min15020101 - 22 Jan 2025

Abstract

Saprolite ores in nickel laterite deposits are pyrometallurgically processed to produce Fe-Ni alloy and Ni matte. The key to achieving the highest recovery degrees from nickel ore in electric arc furnaces and producing top-quality ferro-nickel alloys lies in maintaining optimal carbon consumption and [...] Read more.

Saprolite ores in nickel laterite deposits are pyrometallurgically processed to produce Fe-Ni alloy and Ni matte. The key to achieving the highest recovery degrees from nickel ore in electric arc furnaces and producing top-quality ferro-nickel alloys lies in maintaining optimal carbon consumption and carefully controlling the composition of the slag. This research work focused on finding the optimal smelting procedure for extracting ferro-nickel from calcined nickel ore. Comparing experimental data to the results of thermodynamic modeling using Factsage 8.2 software was a key part of the study. The nickel smelting process, which involved a carbon consumption of 4 wt.%, resulted in ferro-nickel with an Fe/Ni ratio of 4.89 and slag with a nickel content of just 0.017%. The structure and properties of nickel slag in the MgO-SiO₂-FeO system were investigated by observing the changes in the MgO/SiO₂ ratio. This study found a significant nickel recovery degree of 95.6% within the optimal M/S ratio range of 0.65 to 0.7. When the M/S ratio exceeds 0.7, iron-rich magnesium silicates (Mg_xFe_ySiO_2+n) are generated within the slag. These compounds are released downwards due to their higher specific weight, restricting the movement of small metal particles and contributing to increased metal loss through the slag. Optimized slags could revolutionize smelting, increasing metal recovery while minimizing environmental impact. Full article

(This article belongs to the Special Issue Slag Valorization for Advanced Metal Production, 2nd Edition)

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12 pages, 2691 KiB

Open AccessArticle

Experimental Study on the Thickening Characteristics of Ultrafine Tailings

by Jiandong Wang, Zhaolong Du, Xiaohui Liu and Aixiang Wu

Minerals 2025, 15(2), 100; https://doi.org/10.3390/min15020100 - 22 Jan 2025

Abstract

To investigate the thickening characteristics of ultrafine tailings and the relationship between bed height and underflow concentration, a series of experiments, including graduated cylinder sedimentation tests, small-scale dynamic thickening, and semi-industrial experiments, were conducted. The results show that adding flocculants accelerates settling velocity, [...] Read more.

To investigate the thickening characteristics of ultrafine tailings and the relationship between bed height and underflow concentration, a series of experiments, including graduated cylinder sedimentation tests, small-scale dynamic thickening, and semi-industrial experiments, were conducted. The results show that adding flocculants accelerates settling velocity, with a significant change occurring at 50 g/t when the bridging effect weakens. Solid flux increases initially with feed concentration but decreases after reaching a peak at 8%, where the maximum solid flux is 0.322 t·m⁻²·h⁻¹. Reducing solid flux, lowering flocculant dosage, and increasing bed height all contribute to higher underflow concentration, while reducing solid flux and increasing flocculant dosage lowers overflow turbidity. The variation in underflow concentration in the deep cone thickener (DCT) occurs in three phases: continuous feeding with no discharge, dynamic equilibrium with a stable bed height, and bed descent with increasing underflow discharge. At the same bed height, underflow concentration is lower during the bed descent phase compared to the continuous feeding phase. This study offers valuable insights for the precise control of underflow concentration in ultrafine tailing thickening processes. Full article

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32 pages, 13107 KiB

Open AccessArticle

Terminal Fan Deposition and Diagenetic Control in the Lower Paleogene of the Shahejie Formation, Bonan Sag, Bohai Basin, China: Insights into Reservoir Quality

by Arthur Paterne Mioumnde, Liqiang Zhang, Yiming Yan, Jonathan Atuquaye Quaye, Kevin Mba Zebaze, Victor Sedziafa, Carole Laouna Bapowa, Zeeshan Zafar and Shahab Aman e Room

Minerals 2025, 15(2), 99; https://doi.org/10.3390/min15020099 - 21 Jan 2025

Abstract

In the Bonan area, the lower fourth member of the Shahejie Formation (Es4x) is buried beneath a sedimentary pile ranging from 2500 to 5000 m. Understanding the impact of diagenetic alterations on these deeply buried reservoirs is crucial for effective hydrocarbon exploration and [...] Read more.

In the Bonan area, the lower fourth member of the Shahejie Formation (Es4x) is buried beneath a sedimentary pile ranging from 2500 to 5000 m. Understanding the impact of diagenetic alterations on these deeply buried reservoirs is crucial for effective hydrocarbon exploration and production. This study employs a terminal fan sedimentation model, encompassing depositional environments such as feeder channels, distributary channels, floodplains, and basinal zones, to provide insights into the spatial distribution of reservoir properties and their influence on the localization of optimal reservoirs within the sag. The analysis integrates diagenetic facies with well log responses, subsurface porosity trends, and permeability variations across the formation. The petrographic analysis indicates that the sandstone is composed primarily of litharenite, feldspathic litharenite, lithic arkose, and minor amounts of arkose. The dominant clay cement is illite, accompanied by mixed-layer smectite/illite, chlorite, and kaolinite. Thin section observations reveal secondary porosity formed through the dissolution of quartz grains, volcanic rock fragments, and feldspar, along with their associated cements. These sandstones exhibit relatively good sorting, with average porosity and air permeability values of 14.01% and 12.73 mD, respectively. Diagenetic alterations are categorized into three processes: porosity destruction, preservation, and generation. Key diagenetic mechanisms include compaction, cementation, replacement, and dissolution, with compaction exerting the most significant control on reservoir porosity reduction. Statistical analysis indicates that the average porosity loss due to compaction is approximately 13.3%, accounting for about 38% of the original porosity. The detrital rock cement predominantly comprises quartz (42%), feldspar (32%), clay minerals (14%), and carbonate (12%). Under the prevailing depositional conditions, porosity is enhanced by dissolution and fracturing, while late-stage diagenetic cementation by clay and carbonate minerals—excluding chlorite—adversely affects reservoir quality. Consequently, the distributary zone is identified as the primary target for exploration. Full article

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

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22 pages, 19268 KiB

Open AccessArticle

Key Characteristics and Controlling Factors of the Gas Reservoir in the Fourth Member of the Ediacaran Dengying Formation in the Penglai Gas Field, Sichuan Basin

by Hongwei Chen, Shilin Wang, Ahmed Mansour, Qirong Qin, Mohamed S. Ahmed, Yongjing Cen, Feng Liang, Yuan He, Yi Fan and Thomas Gentzis

Minerals 2025, 15(2), 98; https://doi.org/10.3390/min15020098 - 21 Jan 2025

Abstract

This study focuses on the PS8 well in the Penglai Gas Field (Sichuan Basin), a newly identified key exploration area, where high-yield gas testing has been achieved from the Ediacaran Fourth Member of the Dengying Formation. Comprehensive analyses of drilling cores, cuttings, thin [...] Read more.

This study focuses on the PS8 well in the Penglai Gas Field (Sichuan Basin), a newly identified key exploration area, where high-yield gas testing has been achieved from the Ediacaran Fourth Member of the Dengying Formation. Comprehensive analyses of drilling cores, cuttings, thin sections, analytical data, well logging, and production testing data were conducted to investigate the main characteristics of the gas reservoir and the factors controlling the formation model of the reservoir. The results reveal that the reservoir rocks in the Fourth Member of the Dengying Formation are primarily algal-clotted dolomite, algal-laminated dolomite, and arenaceous dolomite. The reservoir porosity is dominated by secondary pores, such as algal-bonded framework pores, intergranular dissolved pores, and intercrystalline dissolved pores, which contribute to the overall low porosity and extremely low permeability. The gas reservoir is classified as a unified structural–lithological reservoir, with the upper sub-member of the Fourth Member serving as a completely gas-bearing unit. This unit is characterized as an ultra-deep, dry gas reservoir with medium sulfur and medium CO₂ contents. The development of this gas reservoir follows a “laterally generated and laterally stored, upper generation and lower storage” reservoir formation model. Regional unconformities and fracture systems developed during the Tongwan II Episode tectonic movement provide efficient pathways for hydrocarbon migration and accumulation. The high-quality source rocks in the lower Cambrian Qiongzhusi Formation serve as both the direct cap rock and lateral seal of the gas reservoir, creating an optimal source–reservoir spatial configuration. This study provides valuable insights into the giant gas reservoir of the Dengying Formation, which can aid in optimizing exploration activities in the Sichuan Basin. Full article

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

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18 pages, 1476 KiB

Open AccessReview

Trends and Applications of Green Binder Materials for Cemented Paste Backfill Mining in China

by Jiandong Wang, Bolin Xiao, Xiaohui Liu and Zhuen Ruan

Minerals 2025, 15(2), 97; https://doi.org/10.3390/min15020097 - 21 Jan 2025

Abstract

The backfill binder material is the key to the cost and performance of cemented paste backfill. This study aims to understand the current situation of metal ore backfill binders, identify industry challenges, inspire research ideas, and explore development directions. Current research investigates trends [...] Read more.

The backfill binder material is the key to the cost and performance of cemented paste backfill. This study aims to understand the current situation of metal ore backfill binders, identify industry challenges, inspire research ideas, and explore development directions. Current research investigates trends and developments of backfill binders through literature review, experience summary, field research, statistical analysis, and other methods. Firstly, the main backfill binder types are summarized, including cement, metallurgical slag, thermal slag, chemical slag, and tailings binders. Secondly, the research progress regarding reactivity activation, hydration mechanism, harmful ion solidification, energy conservation, and carbon reduction is summarized. Thirdly, three industrial applications of new backfill binders are introduced and summarized. Cement is still the most common, followed by slag powder binder. The cases of steel slag binder and semi-hydrated phosphogypsum backfill have shown significant effects. Solid waste-based backfill binder materials are gradually replacing cement, which is a trend. Finally, further research is discussed, including hydration modeling and simulation, material properties under extreme environments, hardening process control, and technical standards for backfill binders. This work provides a reference and basis for promoting green and efficient paste backfill and sustainable industry development. Full article

(This article belongs to the Topic Innovative Strategies to Mitigate the Impact of Mining)

26 pages, 7681 KiB

Open AccessArticle

Gemstones from the Medicean Collection of the Natural History Museum of Florence (Italy): New Insights from Micro-Raman and PIXE-PIGE Analyses

by Lucilla Fabrizi, Massimo Chiari, Vanni Moggi Cecchi, Rosarosa Manca and Marco Benvenuti

Minerals 2025, 15(2), 96; https://doi.org/10.3390/min15020096 - 21 Jan 2025

Abstract

The initial nucleus of gemstones at the Natural History Museum of the University of Florence (Italy) is linked to the significant collection of the Medici family, who began it as early as the 15th century. The present research aims to study this collection [...] Read more.

The initial nucleus of gemstones at the Natural History Museum of the University of Florence (Italy) is linked to the significant collection of the Medici family, who began it as early as the 15th century. The present research aims to study this collection in order to (1) comprehensively review the archival and catalogue information available; (2) identify the mineralogical species correctly; and (3) gather information on the potential provenance of the gem deposits. To address these objectives, fifty gems were investigated using entirely non-invasive methods, ensuring the preservation of the collection’s precious and historical value. All specimens underwent autoptic observation and micro-Raman analysis, while a selection was further examined using PIXE-PIGE to characterise their chemical composition, including trace elements. The gems were attributed to seven mineral species: emerald, topaz, grossular, cordierite, quartz, orthoclase, and tourmaline. One gem was identified as a fake, made of glass and likely produced in the 17th century. Twenty-nine of the historical attributions in the catalogue were found to be incorrect and were subsequently revised. In some cases, the trace elements and mineral inclusions identified in the gems enabled the determination of potential provenance deposits, which were then compared with the available archival information. Full article

(This article belongs to the Special Issue Geomaterials and Cultural Heritage)

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30 pages, 7272 KiB

Open AccessArticle

A Genetic Model for the Biggenden Gold-Bearing Fe Skarn Deposit, Queensland, Australia: Geology, Mineralogy, Isotope Geochemistry, and Fluid Inclusion Studies

by Mansour Edraki, Alireza K. Somarin and Paul M. Ashley

Minerals 2025, 15(1), 95; https://doi.org/10.3390/min15010095 - 20 Jan 2025

Abstract

The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, [...] Read more.

The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, which formed in different tectonic settings, including island arc, back arc, and mid-ocean ridge. This group has experienced a hornblende-hornfels grade of contact metamorphism due to the intrusion of the Late Triassic Degilbo Granite. The intrusion is a mildly oxidized I-type monzogranite that has geochemical characteristics intermediate between those of granitoids typically associated with Fe-Cu-Au and Sn-W-Mo skarn deposits. The skarn mineralogy indicates that there was an evolution from prograde to various retrograde assemblages. Prograde garnet (Adr_11-99Grs_1-78Alm_0-8Sps_0-11), clinopyroxene (Di_30-92Hd_7-65Jo_0-9), magnetite, and scapolite formed initially. Epidote and Cl-bearing amphibole (mainly ferropargasite) were the early retrograde minerals, followed by chlorite, calcite, actinolite, quartz, and sulfides. Late-stage retrograde reactions are indicated by the development of nontronite, calcite, and quartz. Gold is mainly associated with sulfide minerals in the retrograde sulfide stage. The fluids in equilibrium with the ore-stage calcites had δ¹³C and δ¹⁸O values that indicate deposition from magmatically derived fluids. The calculated δ¹⁸O values of the fluids in equilibrium with the skarn magnetite also suggest a magmatic origin. However, the fluids in equilibrium with epidote were a mixture of magmatic and meteoric water, and the fluids that deposited chlorite were at least partly meteoric. δD values for the retrograde amphibole and epidote fall within the common range for magmatic water. Late-stage chlorite was deposited from metasomatic fluids depleted in deuterium (D), implying a meteoric water origin. Sulfur isotopic compositions of the Biggenden sulfides are similar to other skarn deposits worldwide and indicate that sulfur was most probably derived from a magmatic source. Based on the strontium (⁸⁷Sr/⁸⁶Sr) and lead (²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb) isotope ratios, the volcanic and sedimentary rocks of the Gympie Group may have contributed part of the metals to the hydrothermal fluids. Lead isotope data are also consistent with a close age relationship between the mineralization at Biggenden and the crystallization of the Degilbo Granite. Microthermometric analysis indicates that there is an overall decrease in fluid temperature and salinity from the prograde skarn to retrograde alterations. Fluid inclusions in prograde skarn calcite and garnet yield homogenization temperatures of 500 to 600 °C and have salinities up to 45 equivalent wt % NaCl. Fluid inclusions in quartz and calcite from the retrograde sulfide-stage homogenized between 280 and 360 °C and have lower salinities (5–15 equivalent wt % NaCl). In a favored genetic model, hydrothermal fluids originated from the Degilbo Granite at depth and migrated through the shear zone, intrusive contact, and permeable Gympie Group rocks and leached extra Fe and Ca and deposited magnetite upon reaction with the adjacent marble and basalt. Full article

(This article belongs to the Special Issue Geochemistry and Genesis of Hydrothermal Ore Deposits)

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22 pages, 9429 KiB

Open AccessArticle

Pyrite Textures, Trace Element Geochemistry and Galena Pb Iso-Topes of the Yanzhupo Gold Deposit in the Jiangnan Orogen, South China: Implications for Gold Mineralization Genesis

by Jia Liao, Xu Wang, Biao Chen, Buqing Wang, Zhenhua Zhu, Wentao Wang, Ding Peng, Qian Zhang, Zhuang Liu and Qiangqiang Xu

Minerals 2025, 15(1), 94; https://doi.org/10.3390/min15010094 - 20 Jan 2025

Abstract

The northeastern Hunan district in the Jiangnan Orogen (South China) holds significant gold resources, whose genesis remains perplexing, especially in terms of the gold source and mineralization process. Yanzhupo (2.50 t @ 2.52 g/t) is a newly discovered gold deposit in the northeastern [...] Read more.

The northeastern Hunan district in the Jiangnan Orogen (South China) holds significant gold resources, whose genesis remains perplexing, especially in terms of the gold source and mineralization process. Yanzhupo (2.50 t @ 2.52 g/t) is a newly discovered gold deposit in the northeastern Hunan district and is characterized by multiple generations of pyrite. Its alteration/mineralization can be divided into three stages: (I) quartz-ankerite-pyrite; (II) quartz-ankerite-chlorite-pyrite-gold; (III) quartz-ankerite-calcite-pyrite. Petrographic observations and back-scattered electron (BSE) imaging revealed six generations of pyrite: Cu-Au rich bright rims (Py1a) and porous cores (Py1b) in Stage I, Py2a with homogenous textures, Py2b with oscillatory zoning and Py2c with homogenous textures in Stage II and Py3 with homogenous textures in Stage III. Galena Pb isotopes, similar to the Wangu deposit, and pyrite chemical compositions show that the ore-forming materials of Yanzhupo came from deep magma, and some metal elements may be extracted from deep basement by fluid-mineral interactions during the upward migration of hydrothermal-magmatic fluid. The positive correlation between Cu and Au in pyrite reflects the oxidized ore-forming fluids. The enrichment of Cu and Au in Py1a reflects the precipitation of pyrite under high temperature fluid, forming the primary enrichment of Au. Porous Py1b is characterized by lower trace elements than Py1a, sharp reaction front and rich chalcopyrite and galena inclusions, indicating Py1b formed via coupled dissolution-reprecipitation (CDR) reactions of Py1a. The CDR reactions promoted by the oxidizing fluid itself re-release Au into the fluid. From Py2a to Py2c, the contents of As, Sb and Pb first increased and then decreased, which may reflect the increase of fluid pH caused by sulfidation of the wall rocks and the impoverishment of ore-forming fluids caused by the precipitation of a large number of elements. The sulfidation of the wall rocks in Stage II destroyed the stability of the Au(HS)₂⁻ and Au (HS)S₃⁻ complexes and led to the deposition of native gold. The barren ore-forming fluids precipitated homogenous Py3 in a stable environment. Therefore, we think that the Yanzhupo gold deposit may have been associated with magmatic-hydrothermal activity, and the mineralization mechanism may be CDR reactions and sulfidation of the wall rocks. Full article

(This article belongs to the Special Issue Native Gold as a Specific Indicator Mineral for Gold Deposits, 2nd Edition)

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20 pages, 6276 KiB

Open AccessArticle

Critical Minerals in Tibetan Geothermal Systems: Their Distribution, Flux, Reserves, and Resource Effects

by Di Wang, Fei Xue, Lijian Ren, Xin Li, Songtao Wang and Xie Qibei Er

Minerals 2025, 15(1), 93; https://doi.org/10.3390/min15010093 - 20 Jan 2025

Abstract

Critical mineral resources (CMRs) are essential for emerging high-tech industries and are geopolitically significant, prompting countries to pursue resource exploration and development. Tibetan geothermal systems, recognized for their CMR potential, have not yet been systematically evaluated. This study presents a comprehensive investigation of [...] Read more.

Critical mineral resources (CMRs) are essential for emerging high-tech industries and are geopolitically significant, prompting countries to pursue resource exploration and development. Tibetan geothermal systems, recognized for their CMR potential, have not yet been systematically evaluated. This study presents a comprehensive investigation of the spatial distributions, resource flux, reserves, and resource effects of CMRs, integrating and analyzing hydrochemical and discharge flow rate data. Geochemical findings reveal significant enrichment of lithium (Li), rubidium (Rb), cesium (Cs), and boron (B) in the spring waters and sediments, primarily located along the Yarlung Zangbo suture and north–south rift zones. Resource flux estimates include approximately 246 tons of Li, 54 tons of Rb, 233 tons of Cs, and 2747 tons of B per year, underscoring the mineral potential of the geothermal spring waters. Additionally, over 40,000 tons of Cs reserves are preserved in siliceous sinters in Tagejia, Gulu, and Semi. The Tibetan geothermal systems thus demonstrate considerable potential for CMRs, especially Cs, through stable discharge and widespread distribution, also serving as indicators for endogenous mineral exploration and providing potential sources for lithium in exogenous salt lakes. This study evaluates the CMR potential of the Tibetan geothermal systems, advancing CMR exploration while contributing to the future security of CMR supplies. Full article

(This article belongs to the Special Issue Critical Metal Minerals, 2nd Edition)

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25 pages, 36159 KiB

Open AccessArticle

Mineralogy and Geochemistry of Upper Cretaceous-Pliocene Sedimentary Rocks in the Yahşihan Basin, Central Anatolia, Türkiye: Provenance and Tectonic Implications

by Özgül Uyanık Sönmez, Abidin Temel, Muazzez Çelik Karakaya and Güllü Deniz Dogan-Kulahci

Minerals 2025, 15(1), 92; https://doi.org/10.3390/min15010092 - 19 Jan 2025

Abstract

The Yahşihan/Kırıkkale sedimentary basin, located in Central Anatolia within the İzmir-Ankara-Erzincan suture zone, mostly consists of Upper Cretaceous to Lower Pliocene sediments developed on the Ankara Melange, which is linked to the Northern Neo-Tethys Ocean. Although the stratigraphic, sedimentological, and tectono-stratigraphic characteristics of [...] Read more.

The Yahşihan/Kırıkkale sedimentary basin, located in Central Anatolia within the İzmir-Ankara-Erzincan suture zone, mostly consists of Upper Cretaceous to Lower Pliocene sediments developed on the Ankara Melange, which is linked to the Northern Neo-Tethys Ocean. Although the stratigraphic, sedimentological, and tectono-stratigraphic characteristics of the basin have been investigated by many researchers, its mineralogical and geochemical characteristics have not been studied extensively. In this study, the provenance, paleoclimatological properties, and tectonic structure of the sedimentary rocks were interpreted using detailed mineralogical and geochemical analysis data. Formations such as the Karadağ (Cenomanian-Campanian), Çiçekdağ (Santonian-Campanian), Samanlık (Maastrichtian), Dizilitaşlar (Paleocene-Early Eocene), Çayraz (Middle Eocene), İncik (Upper Eocene-Lower Miocene), Central Anatolia Group (Middle Miocene-Pliocene), and Quaternary alluvium were deposited in the basin. X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), and geochemical analyses were employed to determine the mineralogical and chemical composition of the units. Although highly oxic paleo-environmental conditions predominated in the basin, anoxic and suboxic conditions could also be present in the Dizilitaşlar and İncik formations. The units are primarily felsic with some mafic contributions, suggesting an oceanic island arc environment with varying paleoenvironmental conditions, reflecting seasonal changes between humid and arid periods. Full article

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

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20 pages, 10254 KiB

Open AccessArticle

Discernible Orientation for Tortuosity During Oxidative Precipitation of Fe(II) in Porous Media: Laboratory Experiment and Micro-CT Imaging

by Wenran Cao, Ekaterina Strounina, Harald Hofmann and Alexander Scheuermann

Minerals 2025, 15(1), 91; https://doi.org/10.3390/min15010091 - 19 Jan 2025

Abstract

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). [...] Read more.

In the mixing zone, where submarine groundwater carrying ferrous iron [Fe(II)] meets seawater with dissolved oxygen (DO), the oxidative precipitation of Fe(II) occurs at the pore scale (nm~μm), and the resulting Fe precipitation significantly influences the seepage properties at the Darcy scale (cm~m). Previous studies have presented a challenge in upscaling fluid dynamics from a small scale to a large scale, thereby constraining our understanding of the spatiotemporal variations in flow paths as porous media evolve. To address this limitation, this study simulated subsurface mixing by injecting Fe(II)-rich freshwater into a DO-rich saltwater flow within a custom-designed syringe packed with glass beads. Micro-computed tomography imaging at the representative elementary volume scale was utilized to track the development of Fe precipitates over time and space. Experimental observations revealed three distinct stages of Fe hydroxides and their effects on the flow dynamics. Initially, hydrous Fe precipitates were characterized by a low density and exhibited mobility, allowing temporarily clogged pathways to intermittently reopen. As precipitation progressed, the Fe precipitates accumulated, forming interparticle bonding structures that redirected the flow to bypass clogged pores and facilitated precipitate flushing near the syringe wall. In the final stage, a notable reduction in the macroscopic capillary number from 3.0 to 0.05 indicated a transition from a viscous- to capillary-dominated flow, which led to the construction of ramified, tortuous flow channels. This study highlights the critical role of high-resolution imaging techniques in bridging the gap between pore-scale and continuum-scale analyses of multiphase flows in hydrogeochemical processes, offering valuable insights into the complex groundwater–seawater mixing. Full article

(This article belongs to the Special Issue Mineral Dissolution and Precipitation in Geologic Porous Media)

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16 pages, 5907 KiB

Open AccessArticle

Investigation of the Possibility of Obtaining High-Purity Carbon Materials and Recovering Valuable Metals from Shungite Rocks

by Tatiana Aleksandrova, Anastasia Afanasova, Nadezhda Nikolaeva, Artyem Romashev, Valeriya Aburova and Evgeniya Prokhorova

Minerals 2025, 15(1), 90; https://doi.org/10.3390/min15010090 - 18 Jan 2025

Abstract

The increased consumption of strategic metals has led to the necessity to search for new and non-traditional sources of mineral raw materials. All this has resulted in the necessity to develop and justify new technological solutions for the integrated recovery of strategic metals [...] Read more.

The increased consumption of strategic metals has led to the necessity to search for new and non-traditional sources of mineral raw materials. All this has resulted in the necessity to develop and justify new technological solutions for the integrated recovery of strategic metals and the associated production of high-purity carbon materials. The purpose of this work was to substantiate the possibility of obtaining high-purity shungite carbon materials and metal-bearing concentrate containing valuable metals from shungite rocks using high-gradient magnetic separation and flotation with the use of an apolar collector emulsion in a frother solution. The conducted investigations using a complex of analysis methods allowed us to justify the obtaining of a metal-bearing concentrate containing iron, titanium, copper and zirconium and carbon material of high purity. By using high-gradient magnetic separation, we obtained a metal-bearing concentrate with a yield of 17.35% and a total metal content of 63.61% broken down as follows: Fe₂O₃ recovery of 87.66%, TiO₂ recovery of 56.03%, CuO recovery of 72.52% and ZrO₂ recovery of 54.42%. By using flotation, we obtained a shungite carbon concentrate with a yield of 31.41%, made of 88.15% carbon with a content and recovery of 88.09% and a sulphur content of 0.084%. The conducted studies showed the possibility of using classical beneficiation operations in the processing of non-traditional mineral raw materials to obtain commercial products. Full article

(This article belongs to the Special Issue Advances in Physical Separation of Gold, Iron Ore and Rare Earth Minerals)

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22 pages, 12695 KiB

Open AccessArticle

Simulation and Parameter Optimisation of Edge Effect in Ore Minerals Roll Crushing Process Based on Discrete Element Method

by Ruijie Gu, Wenzhe Wu, Shuaifeng Zhao, Hao Xing and Zhenzhong Qin

Minerals 2025, 15(1), 89; https://doi.org/10.3390/min15010089 - 18 Jan 2025

Abstract

The edge effect is caused by poor use of confinement systems, different roll aspect ratios, operating conditions and other factors, which result in uneven pressure distribution between the two crushing rolls along the roll width direction, affecting the overall roll crushing process. To [...] Read more.

The edge effect is caused by poor use of confinement systems, different roll aspect ratios, operating conditions and other factors, which result in uneven pressure distribution between the two crushing rolls along the roll width direction, affecting the overall roll crushing process. To reduce the edge effect, this paper investigates the simulation of the edge effect and parameter optimisation in the roll-crushing process of ore materials based on the discrete element method (DEM). Firstly, the parameters of the iron ore crushing model are experimentally calibrated, and the working process of HPGR is simulated by DEM. Secondly, the effects of roll speed, roll gap, roll diameter and roll width on edge effect and crushing effect of HPGR are analysed by the one-factor experiment. Finally, the roll pressure optimisation model is established based on the Response Surface Methodology (RSM) to obtain the optimal roll pressure parameters. The results show that, with the roll speed and roll diameter increase, the edge effect also increases, the roll gap shows the opposite trend, and the roll width has less influence. The change in roll diameter has the greatest influence on the crushing effect, roll gap is second, and roll speed and roll width have less influence on the crushing effect. When the feed particles are iron ore with a particle size of 32 mm, the optimisation results show that the edge effect and crushing effect of HPGR are significantly improved when the roll speed is 1.25 rad/s, the roll gap is 38 mm, the roll diameter is 2000 mm and the roll width is 742 mm. Full article

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

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15 pages, 6633 KiB

Open AccessArticle

Nioboixiolite-(□),(Nb_0.8□0.2)⁴⁺O₂, a New Mineral Species from the Bayan Obo World-Class REE-Fe-Nb Deposit, Inner Mongolia, China

by Yike Li, Changhui Ke, Denghong Wang, Zidong Peng, Yonggang Zhao, Ruiping Li, Zhenyu Chen, Guowu Li, Hong Yu, Li Zhang, Bin Guo and Yupu Gao

Minerals 2025, 15(1), 88; https://doi.org/10.3390/min15010088 - 17 Jan 2025

Abstract

Nioboixiolite-(□) is a new mineral found in a carbonatite sill from the Bayan Obo mine, Baotou City, Inner Mongolia, China. It occurs as anhedral to subhedral grains (100 to 500 μm in diameter) that are disseminated in carbonatite rock composed of dolomite, calcite, [...] Read more.

Nioboixiolite-(□) is a new mineral found in a carbonatite sill from the Bayan Obo mine, Baotou City, Inner Mongolia, China. It occurs as anhedral to subhedral grains (100 to 500 μm in diameter) that are disseminated in carbonatite rock composed of dolomite, calcite, magnetite, apatite, biotite, actionlike, zircon, and columbite-(Fe). Most of these grains are highly serrated, with numerous inclusions of columbite-(Fe). The mineral is gray to deep black in color; is opaque, with a semi-metallic luster; has a black streak; and is brittle, with an uneven conchoidal splintery. The Mohs hardness is 6–6½, and the calculated density is 6.05 g/cm³. The reflection color is gray with a blue tone, and there is no double reflection color. The measured reflectivity of nioboixiolite-(□) is about 10.6%~12.1%, close to that of ixiolite (11%–13%). Nioboixiolite-(□) is non-fluorescent under 254 nm (short-wave) and 366 nm (long-wave) ultraviolet light. The average chemical analysis results (wt.%) of twelve electron microprobe analyses are F 0.01, MnO 0.12, MgO 0.15, BaO 0.62, PbO 0.91, SrO 1.49, CaO 2.76, Al₂O₃ 0.01, TREE₂O₃ 1.58, Fe₂O₃ 3.57, ThO₂ 0.11, SiO₂ 1.69, TiO₂ 3.68, Ta₂O₅ 13.95, Nb₂O₅ 47.04, and UO₃ 21.56, with a total of 99.25. The simplified formula is [Nb⁵⁺, Ta⁵⁺,Ti⁴⁺, Fe³⁺,□,]O₂. X-ray diffraction data show that nioboixiolite-(□) is orthorhombic, belonging to the space group Pbcn (#60). The refined unit cell parameters are a = 4.7071(5) Å, b = 5.7097(7) Å, c = 5.1111(6) Å, V = 138.31(3), and β = 90(1) °Å³ with Z = 4. In the crystal structure of nioboixiolite-(□), all cations occupy a single M1 site. In these minerals, edge-sharing M₁O₆ octahedra form chains along the c direction. In this direction, the chains are connected with each other via common vertices of the octahedra. The strongest measured X-ray powder diffraction lines are [d in Å, (I/I0), (hkl)]: 3.662(20) (110), 2.975(100) (111), 2.501(20) (021), 1.770(20) (122), 1.458(20) (023). A type specimen was deposited in the Geological Museum of China with catalogue number M16118, No. 15, Yangrou Hutong, Xisi, Beijing 100031, People’s Republic of China. Full article

(This article belongs to the Collection New Minerals)

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63 pages, 15760 KiB

Open AccessReview

Mineral Resources for the Ceramic Industry: Survey of Feldspathic Raw Materials in Italy

by Michele Dondi, Sonia Conte, Chiara Molinari and Chiara Zanelli

Minerals 2025, 15(1), 87; https://doi.org/10.3390/min15010087 - 17 Jan 2025

Abstract

Feldspars are essential components in the ceramic industry, and the increasing demand for high-grade fluxes has recently elevated their status as critical raw materials for the European Union. This survey aims to evaluate, for the first time, Italy’s mining potential for the production [...] Read more.

Feldspars are essential components in the ceramic industry, and the increasing demand for high-grade fluxes has recently elevated their status as critical raw materials for the European Union. This survey aims to evaluate, for the first time, Italy’s mining potential for the production of ceramic fluxes through a methodological approach that considers lithology, technological value, degree of alteration and potential for mining exploitation. The most promising resources are identified in the Alps, the Apennines, Sardinia and the Calabro–Peloritan Arc, based on the chemical composition of rocks without any beneficiation. Key parameters include the equivalent feldspar content and the sum of Fe₂O₃ + TiO₂. Factors that may influence the feasibility of exploitation are critically discussed for granitoids and syenites, acidic volcanics, aplites and pegmatites, albitites, felsic metamorphics, silica-saturated and silica-undersaturated volcanics, arkosic sandstones and rocks that have undergone epithermal alteration. All resources are compared with deposits currently under extraction and assessed against benchmarks or well-recognized raw materials used as market proxies. This review lays the groundwork for operational mining exploration by clearly defining Italy’s potential for feldspathic fluxes. The exploratory assessment approach to feldspathic resources can also be applied in other countries. Full article

(This article belongs to the Section Mineral Deposits)

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14 pages, 2619 KiB

Open AccessArticle

Temperature: An Influencing Factor on the Rheological and Energetic Parameters of Acid Pressure Technology Operations

by Gabriel Hernández-Ramírez, Antonio Bernardo-Sánchez, Aristides Alejandro Legrá-Lobaina, Laura Álvarez de Prado, Rodney Martínez-Rojas, Liudmila Pérez-García, Leonel Garcell-Puyáns, Jose Fernández-Ordás and Javier Menéndez

Minerals 2025, 15(1), 86; https://doi.org/10.3390/min15010086 - 17 Jan 2025

Abstract

In this work, a study was carried out on the effect of temperature as the main influencing factor on the rheological behavior of lateritic suspensions, raw material for the operations of pressurized acid technology (HPAL) used to obtain nickel and cobalt from of [...] Read more.

In this work, a study was carried out on the effect of temperature as the main influencing factor on the rheological behavior of lateritic suspensions, raw material for the operations of pressurized acid technology (HPAL) used to obtain nickel and cobalt from of oxidized ores. From studies of X-ray diffraction, X-ray fluorescence, particle size analyzer, and mathematical modeling, the behavior of the interactions and rheological characteristics of the analyzed samples were obtained. In this study, it was concluded that the use of mathematical models that relate the temperature up to 90 °C and the energy parameters of the pumping system of flows, loads, hydraulic losses, power, and efficiency would allow finding ways to increase and stabilize the flow of fed hydromixture with a flow rate of 1600 m³/h and a solids concentration of 48% (w/w) and guarantee the efficiency of the technological process. Full article

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

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