Minerals

13 pages, 1524 KiB

Open AccessArticle

The New Paradigm Caused by Regulation (EU) 2024/1252 on the Upcycling of Landfilled Ferrous Slags—Case Study: Iron and Steel Slag Dumps in Romania

by Andrei-Lucian Timiș, Ion Pencea, Zbynek Karas, Philipp Gründken, Adrian Priceputu, Constantin Ungureanu, Florentina Niculescu, Ramona-Nicoleta Turcu, Gheorghe Iacob and Dragoș-Florin Marcu

Minerals 2025, 15(3), 260; https://doi.org/10.3390/min15030260 (registering DOI) - 1 Mar 2025

Abstract

Romania has some huge ferrous slag stockpiles that are secondary resources of minerals. Although a sizable portion of ferrous slags is recycled for use in building roads and other infrastructure, a sizable portion is still dumped. By November 2026, Member States must submit [...] Read more.

Romania has some huge ferrous slag stockpiles that are secondary resources of minerals. Although a sizable portion of ferrous slags is recycled for use in building roads and other infrastructure, a sizable portion is still dumped. By November 2026, Member States must submit information on the quantity of critical raw materials (CRMs) in their secondary resources, as well as the quantification techniques employed, in accordance with Regulation (EU) 2024/1252. Therefore, the XRFS reliable measurements carried on ferrous slags were addressed to prevent dissipative loss of CRMs in cases where an improper slag recycling route is operated. The main novelty of this paper is the method of ensuring the reliability of the XRFS results based on weighted arithmetic mean and on the maximum likelihood approach. Secondly, the XRFS measurements carried on ferrous slags demonstrate that they contain CRMs like Ba, Sr, Y, etc.; however, below the minimum cut-off grade for CRMs, recovery XRFS cannot detect light CRMs. Our preliminary LIBS measurements on ferrous slags disclosed the presence of Li and Be. The drawbacks of the XRFS technique impose further research to develop an integrated XRFS, LIBS, and XRD procedure for comprehensive and trustworthy CRMs screening in extractive waste piles. Full article

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

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17 pages, 1747 KiB

Open AccessArticle

Economic Valuation of Metal Recovery from Mobile Phones in India

by Pushkal Jaiswal, Shalini Verma, Akshoy Ranjan Paul, Nawshad Haque and Warren Bruckard

Minerals 2025, 15(3), 259; https://doi.org/10.3390/min15030259 (registering DOI) - 1 Mar 2025

Abstract

This study analyses Indian export–import and domestic production data of mobile phones and smartphones to quantify historically generated e-waste from discarded devices over a 20-year period (2001–2021). An exponential time smoothing method was used to forecast the waste generation trends for 2022–2035. The [...] Read more.

This study analyses Indian export–import and domestic production data of mobile phones and smartphones to quantify historically generated e-waste from discarded devices over a 20-year period (2001–2021). An exponential time smoothing method was used to forecast the waste generation trends for 2022–2035. The metal recovery and embedded values of the metals (precious metals, base metals, and rare earth battery metals) in the PCBs and displays of mobile phones and smartphones were assessed for the same period. The findings indicate that in the PCBs, Au and Pd contribute the most, while Ag is the dominant contributor in displays of mobile phones. The potential economic value of metals varies mainly because of the fluctuating prices of metals in the international market. Full article

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

19 pages, 20868 KiB

Open AccessArticle

Gemmological Properties of Opals from Spencer, Idaho, USA

by Ugo Hennebois, Stefanos Karampelas, Emmanuel Fritsch, Maxence Vigier, Jean-Yves Mevellec, Nicolas Stephant, Quentin Dartois and Aurélien Delaunay

Minerals 2025, 15(3), 258; https://doi.org/10.3390/min15030258 (registering DOI) - 1 Mar 2025

Abstract

Fifteen opal samples of gem quality from the Spencer Opal Mines in Idaho (USA) were examined. These opals display play-of-colour, with three of them having a pink body colour. The analysis was conducted using standard gemmological tools, along with non-destructive spectroscopic, chemical, and [...] Read more.

Fifteen opal samples of gem quality from the Spencer Opal Mines in Idaho (USA) were examined. These opals display play-of-colour, with three of them having a pink body colour. The analysis was conducted using standard gemmological tools, along with non-destructive spectroscopic, chemical, and imaging methods. All samples were identified as opal-A, with their play-of-colour resulting from a regular stacking of hydrated silica spheres. However, at times, the spheres are large to allow diffraction. Opal-A are only occasionally found in nature as gems. Inclusion observed in the studied samples included alunite (KAl₃(SO₄)₂(OH)₆), anhydrite (CaSO₄), and iron-rich spherules (hematite). The pink body colour in the studied specimens is caused by the scattering of light from reddish dendrites. The samples show significant stratification, with fluorescence ranging from green to blue to orange, the latter of which represents a new phenomenon in opals not associated with quinones. Additionally, the orange fluorescence is accompanied by emissions from Sm²⁺ in anhydrite inclusions. Full article

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

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17 pages, 5477 KiB

Open AccessArticle

The Impact of pH on the Pore and Structural Characteristics of Acid-Modified Bentonites in Oxalate Solutions

by Maria Taxiarchou, Danai Tsakiri and Iliana Douni

Minerals 2025, 15(3), 257; https://doi.org/10.3390/min15030257 (registering DOI) - 1 Mar 2025

Abstract

The present study aims to create porous materials through the acid activation of bentonites using 0.5 M oxalic acid at different pH values. Two types of bentonites (containing aluminum montmorillonite and ferruginous montmorillonite) were treated with oxalate solutions at pH 1 to 5. [...] Read more.

The present study aims to create porous materials through the acid activation of bentonites using 0.5 M oxalic acid at different pH values. Two types of bentonites (containing aluminum montmorillonite and ferruginous montmorillonite) were treated with oxalate solutions at pH 1 to 5. During acid activation at the three pH values, Al, Fe, Mg and Si kinetics were monitored; the porosity of the samples was modified; and the specific surface area increased, while the crystal structure did not completely collapse. The optimum conditions occurred at pH 1, where the highest metal leaching was obtained for both samples. For the sample with aluminum smectite, the specific surface increased from 28.1 m²/g to 149 m²/g and the pore volume quadrupled. In the case of samples with ferruginous smectite, the specific surface area rose from 63. 2 m²/g to 372 m²/g and the pore volume increased sixfold. The mechanism of smectite activation was investigated, revealing that at the optimum experimental conditions, which is ferruginous bentonite activation at pH 1, the products have the highest concentration of small 30 to 50 Å pores, which is attributed to the creation of an adequate number of active sites and the formation of aluminum complexes with the oxalate anions. The modified bentonites have elevated porosity; therefore, they could be used as adsorbents in industry. Full article

(This article belongs to the Collection Clays and Other Industrial Mineral Materials)

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53 pages, 35092 KiB

Open AccessArticle

Alteration Lithogeochemistry of an Archean Porphyry-Type Au(-Cu) Setting: The World-Class Côté Gold Deposit, Canada

by Laura R. Katz, Daniel J. Kontak and Benoit Dubé

Minerals 2025, 15(3), 256; https://doi.org/10.3390/min15030256 (registering DOI) - 28 Feb 2025

Abstract

Charactering alteration and its geochemical signature provides critical information relevant to ore-deposit genesis and its related footprint; for porphyry-type deposits, zoned potassic-phyllic-propylitic alteration and metal enrichment are critical features. Here we integrate earlier lithological and mineralogical studies of the (10+ Moz Au) Archean [...] Read more.

Charactering alteration and its geochemical signature provides critical information relevant to ore-deposit genesis and its related footprint; for porphyry-type deposits, zoned potassic-phyllic-propylitic alteration and metal enrichment are critical features. Here we integrate earlier lithological and mineralogical studies of the (10+ Moz Au) Archean Côté Gold porphyry-type Au(-Cu) deposit (Ontario, Canada) with identified alteration types to provide exploration vectors. The ca. 2740 tonalite-quartz diorite-diorite intrusive complex and co-temporal Au(-Cu) mineralization as disseminations, breccias and veins are co-spatial with ore-related alteration types (amphibole, biotite, muscovite). An early, locally developed amphibole event coring the deposit is followed by emplacement of a Au(-Cu) mineralized biotite-rich magmatic-hydrothermal breccia body and broad halo of disseminated biotite and quartz veining. These rocks record gains via mass balance calculations of K, Fe, Mg, LILE, and LREE with Au, Cu, Mo, Ag, Se and Bi. Later muscovite alteration is enriched in K, Rb, Cs, Ba, CO₂, and LOI with varied Au, Cu, Mo, Te, As, and Bi values. A strong albite overprint records extreme Na gains with the loss of most other elements, including ore metals (i.e., Au, Cu). Together these data define an Au-Cu-Mo-Ag-Te-Bi-Se core co-spatial with biotite breccia versus a peripheral stockwork and sheeted vein zone with a Te-Se-Zn-Pb-As association. These features further support the posited porphyry-type model for the Côté Gold Au(-Cu) deposit. Full article

(This article belongs to the Special Issue New Discovery and Exploration Methods of Porphyry and Epithermal Mineral Deposits)

16 pages, 27499 KiB

Open AccessArticle

The Segmentation of Tunnel Faces in Underground Mines Based on the Optimized YOLOv5

by Chundi Ma, Kechao Li, Jilong Pan, Jiashuai Zheng, Qinli Zhang and Chongchong Qi

Minerals 2025, 15(3), 255; https://doi.org/10.3390/min15030255 - 28 Feb 2025

Abstract

Tunnel faces in underground mines, as the front line of mining, play an important role in both mine safety and mining intelligence. However, the engineering quality of tunnel faces is still evaluated based on visual observations by technicians, which cannot guarantee safety and [...] Read more.

Tunnel faces in underground mines, as the front line of mining, play an important role in both mine safety and mining intelligence. However, the engineering quality of tunnel faces is still evaluated based on visual observations by technicians, which cannot guarantee safety and real-time performance. Therefore, there is an urgent need for a more effective method to detect the quality of tunnel face engineering. In this study, a high-performance and accurate tunnel face segmentation model was developed by applying the YOLOv5-seg computer vision model to an underground mine. By optimizing a classic Chinese underground mine image dataset through Sobel preprocessing and improving the network structure of the YOLOv5-seg model using the SimAM module, good predictive performance was achieved for tunnel face segmentation, with values of 0.97, 0.89, 0.80, and 0.78, respectively, achieved for the pixel accuracy, Dice coefficient, mask intersection over union (IOU), and box IOU on the test set. And the performance of this model outperforms all YOLOv5 models and U-net in the same task of tunnel face segmentation. Model interpretation and visualization further demonstrated the positive effect of the SimAM module on the model, and, finally, the segmentation results were used to evaluate the tunnel face engineering. Overall, this study’s results provide a feasible, safe, and real-time method for accurately segmenting tunnel faces in underground mines and provide a reliable approach for data-driven applications of intelligent technology in mines in the future. Full article

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23 pages, 1069 KiB

Open AccessReview

Towards Circularity in Serbian Mining: Unlocking the Potential of Flotation Tailings and Fly Ash

by Nela Vujović, Vesna Alivojvodić, Dragana Radovanović, Marija Štulović, Miroslav Sokić and Filip Kokalj

Minerals 2025, 15(3), 254; https://doi.org/10.3390/min15030254 - 28 Feb 2025

Abstract

This paper examines sustainable industrial practices in Serbia, particularly in the mining and energy sector, focusing on the potential of flotation tailings and fly ash, as materials with the largest share in disposed waste in Serbia in 2023 (95%). It highlights the environmental [...] Read more.

This paper examines sustainable industrial practices in Serbia, particularly in the mining and energy sector, focusing on the potential of flotation tailings and fly ash, as materials with the largest share in disposed waste in Serbia in 2023 (95%). It highlights the environmental challenges of mining waste and explores innovative approaches to waste management within the circular economy framework. The study analyzes the current state of mining waste in Serbia, particularly in copper mining regions in the east of the country. It discusses the potential for metal recovery from waste and its reuse in various industries. The research also investigates the use of fly ash from thermal power plants as a valuable resource in the construction industry and other sectors. The paper reviews existing initiatives and legislation in Serbia in order to promote sustainable mining practices and waste utilization. By presenting case studies and potential applications, the study demonstrates how implementing circular economy principles in the mining sector can contribute to environmental protection, resource conservation, and economic growth in Serbia. The comprehensive overview of the current state in Serbia provides a solid foundation for establishing a higher degree of circularity in the mining and energy sectors. Full article

(This article belongs to the Special Issue Mineral Processing and Recycling Technologies for Sustainable Future)

31 pages, 8907 KiB

Open AccessArticle

Geologic Characteristics and Age of Beryllium Mineralization in the Jiulong Area, the Southeast Edge of the Western Kunlun–Songpan–Ganzi Rare Metal Metallogenic Belt

by Junliang Hu, Jiayun Zhou, Hongqi Tan, Zhiyao Ni, Zhimin Zhu, Teng Niu and Yingdong Liu

Minerals 2025, 15(3), 253; https://doi.org/10.3390/min15030253 - 28 Feb 2025

Abstract

Rare metals such as lithium and beryllium are strategic mineral resources that play a highly significant role in the national aerospace, defense, and new energy industries. The western Kunlun–Songpan–Ganzi metallogenic belt is an important rare metal metallogenic belt in China that mainly consists [...] Read more.

Rare metals such as lithium and beryllium are strategic mineral resources that play a highly significant role in the national aerospace, defense, and new energy industries. The western Kunlun–Songpan–Ganzi metallogenic belt is an important rare metal metallogenic belt in China that mainly consists of granite–pegmatite-type lithium–beryllium deposits with uncommon beryllium-only deposits. In the Jiulong area on the southeastern edge of this metallogenic belt, several deposits, including the Daqianggou lithium–beryllium, Luomo beryllium, Baitai beryllium, and Shangjigong beryllium deposits, have been identified. Unlike the northern areas of Jiajika, Ke’eryin, Zawulong, and the western regions of Dahongliutan and Bailongshan, this area contains beryllium-only deposits. In this paper, we examine representative beryllium deposits in the Jiulong area, including detailed petrographic observations and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb isotope dating of cassiterite and columbite–tantalite, to define the metallogenic age and summarize the spatiotemporal characteristics of the beryllium mineralization in this area. The research results show that the Daqianggou lithium–beryllium deposit is dominated by spodumene and beryl mineralization, while the Luomo and Baitai beryllium deposits primarily feature beryl mineralization. The dating results indicate that the U-Pb ages of the cassiterite and columbite–tantalite in the Daqianggou lithium–beryllium deposit are 157.3 ± 1.7 Ma and 164.1 ± 0.8 Ma, respectively. For the Luomo beryllium deposit, the U-Pb ages of the cassiterite and columbite–tantalite are 156.1 ± 1.5 Ma and 163.3 ± 0.8 Ma, respectively. For the Baitai beryllium deposit, the U-Pb age of the columbite–tantalite is 188.8 ± 1.1 Ma. Therefore, the Jiulong area experienced two pegmatite-type rare metal metallogenic events: a beryllium–niobium–tantalum–molybdenum event at 197~189 Ma and a lithium–beryllium–niobium–tantalum–rubidium event at 164~156 Ma. Based on the reported metallogenic ages, we suggest that the western Kunlun–Songpan–Ganzi rare metal metallogenic belt experienced three rare metal metallogenic events at 210~200 Ma, 200~180 Ma, and 170~150 Ma. Regarding exploration directions, early Yanshanian beryllium mineralization predominates in the Jiulong area along the southeastern edge of the belt, and deep exploration of the early Yanshanian rare metal mineralization within this belt should be strengthened to facilitate new breakthroughs. Full article

(This article belongs to the Special Issue Metallogenic Regularity and Metallographic Prediction of Strategic Deposits)

15 pages, 11592 KiB

Open AccessArticle

Mapping Bronze Disease Onset by Multispectral Reflectography

by Daniela Porcu, Silvia Innocenti, Jana Striova, Emiliano Carretti and Raffaella Fontana

Minerals 2025, 15(3), 252; https://doi.org/10.3390/min15030252 - 28 Feb 2025

Abstract

The early detection of bronze disease is a significant challenge not only in conservation science but also in various industrial fields that utilize copper alloys (i.e., shipbuilding and construction). Due to the aggressive nature of this corrosion pathway, developing methods for its early [...] Read more.

The early detection of bronze disease is a significant challenge not only in conservation science but also in various industrial fields that utilize copper alloys (i.e., shipbuilding and construction). Due to the aggressive nature of this corrosion pathway, developing methods for its early detection is pivotal. The presence of copper trihydroxychlorides is the main key indicator of the ongoing autocatalytic process. Commonly used for pigment identification, reflectance imaging spectroscopy (RIS) or fiber optics reflectance spectroscopy (FORS) was recently employed for mapping atacamite distribution in extended bronze corrosion patinas. In this work, we detected the onset of bronze disease using visible–near-infrared (VIS-NIR) multispectral reflectography, which allowed for disclosing features that were poorly detectable to the naked eye. The image cube was analyzed using the spectral correlation mapper (SCM) algorithm to map the distribution of copper trihydroxychlorides. FORS and Raman spectroscopy were employed to characterize the patina composition and validate RIS data. A set of bronze samples, representative of Florentine Renaissance workshops, was specifically realized for the present study and artificially aged at different corrosion stages. Full article

(This article belongs to the Special Issue Spectral Behavior of Mineral Pigments, Volume II)

15 pages, 15358 KiB

Open AccessArticle

Comparative Study of Colloidal and Rheological Behaviors of Mixed Palygorskite–Montmorillonite Clays in Freshwater and Seawater

by Jiajun Zhang, Guanzheng Zhuang, Jinrong Chen, Wenxiao Fan, Jixing Fan, Zhuhua Kuang and Dong Liu

Minerals 2025, 15(3), 251; https://doi.org/10.3390/min15030251 - 28 Feb 2025

Abstract

This study systematically investigates the colloidal stability, rheological properties, and filtration behavior of palygorskite–montmorillonite mixed clays in both freshwater and seawater systems. By varying the mass content and dispersion medium (freshwater/seawater), we analyze the colloidal stability, zeta potential, flow curves, viscosity, shear-thinning behavior, [...] Read more.

This study systematically investigates the colloidal stability, rheological properties, and filtration behavior of palygorskite–montmorillonite mixed clays in both freshwater and seawater systems. By varying the mass content and dispersion medium (freshwater/seawater), we analyze the colloidal stability, zeta potential, flow curves, viscosity, shear-thinning behavior, thixotropy, and fluid loss of the dispersions. The results show that palygorskite exhibits good rheological performance in both freshwater and seawater, while montmorillonite performs better in freshwater but suffers a significant decline in seawater. However, palygorskite demonstrates high fluid loss, which is unfavorable for drilling fluid function. Mixed clays can mitigate the limitations of individual clays to some extent, but the specific performance depends on the clay mineral content and dispersion medium. In freshwater, a small amount of montmorillonite improves the viscosity and shear-thinning behavior of the dispersion, with optimal montmorillonite contents of 22% and 38%, respectively. The thixotropy and fluid loss reduction in the mixed clays are positively correlated with montmorillonite content. In seawater, the rheological performance inversely correlates with Mt content due to montmorillonite’s high sensitivity to electrolytes. The addition of Pal enhances the colloidal stability and rheological properties of the mixed clays in seawater. This work provides theoretical insights into the behavior of mixed clays in different media, offering valuable guidance for the design of seawater-based drilling fluids. Full article

(This article belongs to the Collection Clays and Other Industrial Mineral Materials)

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16 pages, 11787 KiB

Open AccessArticle

Genesis of the Xiangluwanzi Gold Deposit, Northeastern China: Insights from Fluid Inclusions and C-H-O Isotopes

by He Yang, Keyong Wang and Bingyang Ye

Minerals 2025, 15(3), 250; https://doi.org/10.3390/min15030250 - 28 Feb 2025

Abstract

The Xiangluwanzi gold deposit, located in the southern Jilin Province of Northeast China, is hosted within the Jurassic Guosong Formation, and surrounded by Archean granitoids. The ore bodies are governed by near-EW and NE-trending faults. Four alteration/mineralization stages have been distinguished: I, pyrite–sericite–quartz; [...] Read more.

The Xiangluwanzi gold deposit, located in the southern Jilin Province of Northeast China, is hosted within the Jurassic Guosong Formation, and surrounded by Archean granitoids. The ore bodies are governed by near-EW and NE-trending faults. Four alteration/mineralization stages have been distinguished: I, pyrite–sericite–quartz; II, gold–pyrite–quartz; III, sphalerite–quartz–carbonate; and IV, quartz–carbonate. Four types of fluid inclusions (FIs) were identified: pure CO₂, CO₂-rich, CO₂-bearing, and NaCl–H₂O fluid inclusions. Stage-I quartz veins contain all FIs, whereas stage II quartz veins host CO₂-rich, CO₂-bearing, and NaCl-H₂O FIs. Only NaCl–H₂O FIs were present in stages-III and -IV quartz veins. The homogenization temperatures of the FIs range, respectively, from 233 to 279, 185–242, 171–217, and 148–170 °C in stages I–IV, having salinities of 2.62–8.54, 2.81–7.58, 4.32–6.58, and 3.37–5.25 wt% NaCl equivalents, respectively. The H (−93.5‰ to −75.9‰) and O (^δ18O_H2O = −5.8‰ to 4.6‰) isotopic compositions suggest magmatic water was gradually diluted by meteoric water. Carbon isotopic values (22.8‰ to −17.8‰) suggest the incorporation of organic carbon from surrounding strata via water–rock interactions. Fluid boiling, fluid mixing, and water–rock interactions are the primary mechanisms driving mineral precipitation. Full article

(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits, 2nd Edition)

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26 pages, 11185 KiB

Open AccessArticle

Crystal Chemistry of Eudialyte Group Minerals from Rouma Island, Los Archipelago, Guinea

by Natale Perchiazzi, Cristiano Ferraris, Daniela Mauro and Pietro Vignola

Minerals 2025, 15(3), 249; https://doi.org/10.3390/min15030249 - 27 Feb 2025

Abstract

We herein present a comprehensive investigation of the eudialyte group minerals from the nepheline syenites of Rouma Island in the Los Archipelago, Conakry region, Guinea. Two distinct mineral phases were identified: an oneillite-like phase, associated with the agpaitic rock suite, and, for the [...] Read more.

We herein present a comprehensive investigation of the eudialyte group minerals from the nepheline syenites of Rouma Island in the Los Archipelago, Conakry region, Guinea. Two distinct mineral phases were identified: an oneillite-like phase, associated with the agpaitic rock suite, and, for the first time in this locality, kentbrooksite, occurring in pegmatites. The oneillite-like phase crystallizes in the trigonal system (space group R3), with unit cell parameters a = 14.1489(2) Å, c = 30.1283(5) Å and an idealized crystal chemical formula of Na₁₅(Mn,REE)₃(Ca,Mn)₃(Fe,Mn)₃Zr₃(Zr,Si,Al,Nb,Ti)₁ (Si₂₅O₇₃)(O,OH,H₂O)₃(OH,Cl,F)₂. Kentbrooksite also exhibits trigonal symmetry (space group R3m), with unit cell parameters a = 14.2037(3) Å c = 30.1507(9) Å and an idealized formula of (Na,REE)₁₅(Ca,Mn)₆(Mn,Fe)₃Zr₃(Nb,Si)₁(Si₂₅O₇₃)(O,OH,H₂O)₃(F,Cl,OH)₂. Compared to the oneillite-like phase, kentbrooksite is markedly enriched in Mn and rare earth elements (REE). This geochemical distinction aligns with the progressive mineralogical evolution of the system, transitioning from the miaskitic to agpaitic suite (oneillite-like phase) and subsequently to pegmatites (kentbrooksite). These findings are consistent with the broader-scale observations regarding the syenite ring structure of the Los Archipelago. Full article

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

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20 pages, 3755 KiB

Open AccessArticle

Tracing the Source of Red Coral in Xinjiang: Evidence from the Western Han Dynasty Shengjindian Site in Turpan

by Yiheng Xian, Lifei Sun, Hao Ai, Jingwen Guo, Yuchen Tan, Francesca Monteith, Zekun Li, Jian Ma and Chun Yu

Minerals 2025, 15(3), 248; https://doi.org/10.3390/min15030248 - 27 Feb 2025

Abstract

This study sheds light on the origin and trade routes of early red coral artifacts found in Xinjiang, primarily dating to the Han and Jin dynasties. The red coral relics examined, excavated from the Shengjindian cemetery of the Western Han Dynasty in Turpan, [...] Read more.

This study sheds light on the origin and trade routes of early red coral artifacts found in Xinjiang, primarily dating to the Han and Jin dynasties. The red coral relics examined, excavated from the Shengjindian cemetery of the Western Han Dynasty in Turpan, offer critical insights into the material’s provenance and its introduction to this pivotal region along the ancient Silk Road. Advanced gemological, mineralogical, and geochemical analyses—utilizing computed tomography (CT), laser Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)—has revealed distinctive features. These include red coloration, a waxy luster, concentric ring structures in cross-section, and calcareous composition, identifying the coral as Sardinian (Corallium rubrum), likely originating from the western Mediterranean region. The findings carry significant archaeological implications. Red coral first appears in the archaeological record in Xinjiang during the Western Han period, facilitated by the thriving Silk Road trade and the expanding influence of Buddhist culture. This study not only confirms the Mediterranean origin of these artifacts but also highlights their integration into the cultural and economic networks of ancient Xinjiang, underscoring the significance of early long-distance trade and cultural exchange. Full article

(This article belongs to the Special Issue Gems Under the Microscope: New Insights into Mineral Structures and Properties)

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23 pages, 24426 KiB

Open AccessArticle

Geometallurgical Characterization of the Arthur River Magnesite Deposit, Northwestern Tasmania for Pathways to Production

by Alfredtina Akua Abrafi Appiah, Julie Hunt, Mohammadbagher Fathi, Owen P. Missen, Wei Hong, Ivan Belousov, Verity Kameniar-Sandery and Mick Wilson

Minerals 2025, 15(3), 247; https://doi.org/10.3390/min15030247 - 27 Feb 2025

Abstract

The Arthur River magnesite deposit is in the northwestern part of Tasmania, Australia, within the Arthur Metamorphic Complex. Physical, mineralogical, and chemical characteristics of the deposit were studied using geological drill core logging and analytical techniques (scanning electron microscopy, portable x-ray fluorescence, and [...] Read more.

The Arthur River magnesite deposit is in the northwestern part of Tasmania, Australia, within the Arthur Metamorphic Complex. Physical, mineralogical, and chemical characteristics of the deposit were studied using geological drill core logging and analytical techniques (scanning electron microscopy, portable x-ray fluorescence, and laser ablation–inductively coupled plasma–mass spectrometry). The results document variations within the ore body, and three ore types have been identified for the potential production of an economic magnesite concentrate separated from associated gangue minerals (dolomite, quartz, and talc and iron bearing minerals such as pyrite and pyrrhotite). The ore types were identified based on a combination of physical, chemical, and mineralogical differences. Type 1 has a relatively high magnesium content and appears in drill core as hard white crystalline magnesite. Type 2 has relatively lower magnesium and higher iron contents than type 1 and occurs visibly as creamy-yellowish soft magnesite. Type 3 ore has the lowest magnesium and the highest iron content of the three ore types and is reddish brown in color. From the characterization studies, potential beneficiation routes for each ore type are suggested along with potential processing challenges. Examples of processing challenges include magnesium present in both magnesite and in dolomite, and the association of magnesite with quartz and talc results in a relatively high silica content. Full article

(This article belongs to the Special Issue Microanalysis Applied to Mineral Deposits)

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26 pages, 5575 KiB

Open AccessArticle

Rheological Properties of Aluminium Oxide Nanoparticle-Modified Cemented Paste Tailings Materials

by Raouf Kaviani and Mamadou Fall

Minerals 2025, 15(3), 246; https://doi.org/10.3390/min15030246 - 27 Feb 2025

Abstract

There is currently no research examining the rheological properties of cementitious paste backfill (CPB) materials containing aluminium oxide nanoparticles (nAlO). Knowing the yield stress and viscosity of CPB containing nAlO is crucial, especially when applying nano-CPB technology in underground mines. The purpose of [...] Read more.

There is currently no research examining the rheological properties of cementitious paste backfill (CPB) materials containing aluminium oxide nanoparticles (nAlO). Knowing the yield stress and viscosity of CPB containing nAlO is crucial, especially when applying nano-CPB technology in underground mines. The purpose of this work is to thoroughly examine how nAlO affects the rheological characteristics of CPB and how those characteristics change over time. Yield stress and viscosity measurements are performed on CPB samples with different compositions (e.g., nAlO content, binder type, and superplasticizer content) at intervals of 0 min, 20 min, 1 h, 2 h, and 4 h. The study also includes measurements of the pH and zeta potential of the materials, microstructural studies (TG/DTG and XRD), and electrical conductivity (EC). The findings show that adding nAlO to CPB significantly changes its rheological properties, which in turn affects flowability. The yield stress and viscosity of CPB samples are greatly increased by the incorporation of nAlO, with the degree of influence varying based on variables including water content, curing duration, and type of binder. Because of the nAlO-induced microstructural changes in the CPB material, the interaction of nAlO and a larger fraction of nAlO, along with an increase in curing time, raises rheological characteristics and decreases paste flowability. The results of EC, DTG, and XRD, which show that binder hydration improves with nAlO dosage, corroborate this. Moreover, as nAlO content increases, the zeta potential decreases in magnitude, resulting in stronger repulsion forces and reduced flowability. However, EC, XRD, and DTG analyses suggest that the addition of 0.125% superplasticizer counteracts the flowability reduction caused by nAlO, as the superplasticizer slows down the cement hydration rate at very early curing stages. Moreover, the increase in the slag percentage from 0% to 50% and 75% of the binder content slightly decreases viscosity but greatly increases yield stress. The study’s fresh perspectives contribute to the advancement of nano-CPB technology and have important ramifications for the practical use of this technology in underground mine backfill operations. Full article

(This article belongs to the Special Issue Mechanical and Rheological Properties of Cemented Tailings Backfill)

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13 pages, 5529 KiB

Open AccessArticle

Effect of Interaction Between Expandable Minerals and Glycerin-Based Fluids on the Occurrence of Accretion

by Ana P. O. Sousa, Mário C. S. Lima, Waleska R. P. Costa, Renalle C. A. M. Nascimento, João M. P. Q. Delgado, Antonio G. B. Lima and Luciana V. Amorim

Minerals 2025, 15(3), 245; https://doi.org/10.3390/min15030245 - 27 Feb 2025

Abstract

Glycerin-based fluids are proposed as a promising alternative to inhibited fluids in the drilling of highly-reactive formations. However, even with the use of these fluids, it is still possible to observe the occurrence of problems related to the balling of drill bits and [...] Read more.

Glycerin-based fluids are proposed as a promising alternative to inhibited fluids in the drilling of highly-reactive formations. However, even with the use of these fluids, it is still possible to observe the occurrence of problems related to the balling of drill bits and drill pipes, such as the agglomeration and accretion of cuttings. This study aims to analyze how the interaction between expandable minerals from reactive formations and glycerin-based drilling fluids affects the stability of oil wells, focusing on the occurrence and extent of the accretion phenomenon. For this purpose, bentonite pellets were characterized regarding their mineralogical composition and plastic behavior. In addition, accretion tests were performed in order to evaluate the interaction between bentonite pellets and glycerin-based drilling fluids containing different types of inhibitors. The results revealed that the pellets were predominantly composed of interstratified illite–smectite (IS) clay minerals and presented highly plastic properties with a high degree of expansion. Furthermore, it was found that the accretion percentages were significant for all the fluids studied, at higher than 58%. Therefore, it was found that using glycerin in drilling fluids did not stabilize expandable minerals in reactive formations, even with different expansion inhibitors, which were ineffective in reducing the rock expansibility. Full article

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

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18 pages, 3764 KiB

Open AccessReview

Sustainable Recovery of Lead from Secondary Waste in Chloride Medium: A Review

by Yeimy Vivar, Lilian Velásquez-Yévenes and Cristian Vargas

Minerals 2025, 15(3), 244; https://doi.org/10.3390/min15030244 - 26 Feb 2025

Abstract

Environmental regulations on lead recycling are becoming increasingly stringent, prompting the search for sustainable alternatives to conventional high-temperature processes. Hydrometallurgical methods in chloride media have emerged as a viable option for recovering lead from mining and urban wastes, including lead anode corrosion residues, [...] Read more.

Environmental regulations on lead recycling are becoming increasingly stringent, prompting the search for sustainable alternatives to conventional high-temperature processes. Hydrometallurgical methods in chloride media have emerged as a viable option for recovering lead from mining and urban wastes, including lead anode corrosion residues, zinc leaching residues, and spent lead–acid batteries. This study reviews the key conditions for lead recovery in chloride media, highlighting the variables that optimize lead dissolution, and the potential challenges associated with these processes. The findings indicate that efficient lead recovery requires high chloride concentrations, with acidity playing a critical role depending on the relative concentrations of lead and sulfate in the solution. When lead and sulfate concentrations are similar, stable lead–chloride complexes form within a pH range of 0 to 6.0. However, at higher sulfate concentrations, the pH range narrows significantly to 0 to 2.0, necessitating a more acidic environment for effective dissolution. Chloride media offer a distinct advantage through the formation of stable lead–chloride complexes, whose stability is influenced by chloride concentration, sulfate concentration, pH, and redox potential. Moreover, this approach provides a sustainable alternative that could integrate seawater into industrial processes, particularly in regions facing water scarcity. Full article

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

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23 pages, 8147 KiB

Open AccessArticle

Thermochronology of the Kalba–Narym Batholith and the Irtysh Shear Zone (Altai Accretion–Collision System): Geodynamic Implications

by Alexey Travin, Mikhail Buslov, Nikolay Murzintsev, Valeriy Korobkin, Pavel Kotler, Sergey V. Khromykh and Viktor D. Zindobriy

Minerals 2025, 15(3), 243; https://doi.org/10.3390/min15030243 - 26 Feb 2025

Abstract

The granitoids of the Kalba–Narym batholith and the Irtysh shear zone (ISZ) are among the main geological features of the late Paleozoic Altai accretion–collision system (AACS) in Eastern Kazakhstan. Traditionally, it is believed that late Paleozoic strike-slip faults played a pivotal role at [...] Read more.

The granitoids of the Kalba–Narym batholith and the Irtysh shear zone (ISZ) are among the main geological features of the late Paleozoic Altai accretion–collision system (AACS) in Eastern Kazakhstan. Traditionally, it is believed that late Paleozoic strike-slip faults played a pivotal role at all stages of the development of the AACS, they were supposed to control deformation, magmatism, and ore deposits. This work is devoted to solving the problem of the tectonic evolution of the AACS based on the reconstruction of the thermal history of granitoids of the Kalba–Narym batholith in connection with the Chechek metamorphic dome structure, which is one of the highly metamorphosed blocks mapped within the ISZ. The new geological and geochronological data presented in this work allowed us to establish the sequence of formation of the Kalba–Narym granitoid batholith and link it with the evolution of the Irtysh shear zone (ISZ). It was revealed that in the late Carboniferous–early Permian (312–289 Ma), during the NE–SW compression, the Irtysh shear zone formed as a gently dipping thrust system into which gabbro of the Surov massif intruded. The combined manifestation of magmatic and tectonic processes caused the formation of tectonic mélange with cataclastic gabbro and metamorphic rocks of the Chechek metamorphic dome structure (312–289 Ma). Compression caused the formation of a cover-thrust structure. The thickening of the crust under the probable thermal action of the Tarim plume led to the formation of the early Permian Kalba–Narym batholith (297–284 Ma) within the Kalba–Narym terrane. Denudation of the orogen occurred before the Early Triassic (280–229 Ma). In this way the sequence of formation of the Kalba–Narym batholith and the ISZ is consistent with the concepts of the stages of plume-lithosphere interaction within the AACS under the influence of the late Carboniferous–early Permian Tarim igneous province, but in the cover-thrust tectonic setting. Full article

(This article belongs to the Special Issue Developments in Geochronology and Dating of Shear Zone Deformation)

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20 pages, 5571 KiB

Open AccessArticle

Utilization of the Finer Particle Fraction of Arsenic-Bearing Excavated Rock Mixed with Iron-Based Adsorbent as Sorption Layer

by Daisuke Ishigami, Takahiko Arima, Satoshi Shinohara, Yutaka Kamijima, Keijirou Ito, Tasuma Suzuki, Keita Nakajima, Walubita Mufalo and Toshifumi Igarashi

Minerals 2025, 15(3), 242; https://doi.org/10.3390/min15030242 - 26 Feb 2025

Abstract

Excavated rocks generated during tunnel construction may pose an environmental hazard due to the release of acidic leachate containing potentially toxic elements (PTEs). Addressing this concern requires strategic countermeasures against mitigating the release of PTEs. This study investigated the efficacy of a novel [...] Read more.

Excavated rocks generated during tunnel construction may pose an environmental hazard due to the release of acidic leachate containing potentially toxic elements (PTEs). Addressing this concern requires strategic countermeasures against mitigating the release of PTEs. This study investigated the efficacy of a novel approach for managing altered excavated rocks that generate acidic leachates with elevated arsenic (As) by utilizing the finer altered rock as a base material for the sorption layer. The proposed method involves classifying the altered excavated rocks into coarse (9.5–37.5 mm) and finer (<9.5 mm) fractions, with the finer fractions incorporated with iron (Fe)-based adsorbent to form a bottom sorption layer for the disposal of coarser rock samples. Leaching behavior and As immobilization efficiency were assessed through shaking, stirring leaching tests, batch sorption tests, and column tests under varying particle size fractions of the rock samples. Results indicate that altered finer rock fractions exhibit increased As leaching under shaking conditions due to enhanced dissolution. The addition of >1% of Fe-based adsorbent to the finer rock in the sorption layer effectively suppressed As leaching concentration, meeting the management criterion of <0.3 mg/L for specially controlled contaminated soils in Japan. Batch sorption tests using the finer rock samples with the Fe-based adsorbent confirmed their efficacy as effective adsorbents. This efficacy was further elucidated in column experiments consisting of the coarse rock samples and fine altered rock samples mixed with the Fe based adsorbent at the bottom as a sorption layer. Results showed that the sorption layer effectively decreased the As leached from the rock layer, utilizing the altered excavated fine rock as a base material in the sorption layer. This approach highlights the potential for repurposing excavated rocks as sorption media, enabling sustainable management strategies for As-contaminated rocks. This study provides an innovative framework for integrating adsorption-based remediation, contributing to sustainable countermeasure strategies for excavated rocks. Full article

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

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