Minerals

28 pages, 9060 KiB

Open AccessArticle

First U-Pb (CA-ID-TIMS) Dating of the Uppermost Permian Coal Interval in the Minusinsk Coal Basin (Siberia, Russia) Using Zircon Grains from Volcanic Ashfalls

by Vladimir V. Silantiev, Sergey I. Arbuzov, Marion Tichomirowa, Alexandra Käßner, Alsu Kh. Izmailova, Sergey S. Ilenok, Bulat R. Soktoev, Nouria G. Nurgalieva, Yaroslav M. Gutak, Anastasia S. Felker, Lyubov G. Porokhovnichenko, Nikolai A. Eliseev, Veronika V. Zharinova, Evgenia M. Nurieva and Milyausha N. Urazaeva

Minerals 2024, 14(10), 982; https://doi.org/10.3390/min14100982 (registering DOI) - 29 Sep 2024

Abstract

This study presents the first U-Pb (CA-ID-TIMS) radioisotopic dating of zircon grains extracted from tonsteins within the uppermost Permian coal interval of the Minusinsk Coal Basin (Siberia, Russia). Petrographic, structural, and mineralogical analyses confirm the volcanic ash origin of the tonsteins. The parent [...] Read more.

This study presents the first U-Pb (CA-ID-TIMS) radioisotopic dating of zircon grains extracted from tonsteins within the uppermost Permian coal interval of the Minusinsk Coal Basin (Siberia, Russia). Petrographic, structural, and mineralogical analyses confirm the volcanic ash origin of the tonsteins. The parent pyroclastic materials are identified as rhyolite–pantellerite for tonstein I-22 and dacite–rhyodacite for tonstein I-12. Morphological analysis of zircon crystals, along with cathodoluminescence and melt inclusion studies, confirms their volcanic origin and crystallisation temperatures of 700–900 °C. New radioisotopic dates of 261.4 ± 0.7 Ma and 261.3 ± 0.4 Ma clarify the age of the Izykh Formation, enabling its direct correlation with the Capitanian Stage of the International Chronostratigraphic Chart. The results emphasise the possible discontinuity of the coal-bearing succession of Siberian palaeocontinent and highlight the potential for further stratigraphic refinement through continued radioisotopic dating of tonsteins. Full article

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

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17 pages, 14653 KiB

Open AccessArticle

New Insights on the Understanding of Sulfur-Containing Coal Flotation Desulfurization

by Gan Cheng, Yulong Li, Yijun Cao, Xin Wang, Enze Li, Yanxia Guo and Ee Von Lau

Minerals 2024, 14(10), 981; https://doi.org/10.3390/min14100981 (registering DOI) - 29 Sep 2024

Abstract

The clean and efficient utilization of coal is a promising way to achieve carbon neutrality. Coking coal is a scarce resource and an important raw material in the steel industry. However, the presence of pyrite sulfur affects its clean utilization. Nonetheless, this pyrite [...] Read more.

The clean and efficient utilization of coal is a promising way to achieve carbon neutrality. Coking coal is a scarce resource and an important raw material in the steel industry. However, the presence of pyrite sulfur affects its clean utilization. Nonetheless, this pyrite could be removed using depressants during flotation. Commonly used organic depressants (sodium lignosulfonate (SL), calcium lignosulfonate (CL), and pyrogallol (PY)) and inorganic depressants (calcium oxide (CaO) and calcium hypochlorite (Ca(ClO)₂)) were chosen in this study. Their inhibition mechanism was discussed using FTIR, XPS, and molecular dynamics (MD) methods. The desulfurization ability of organic depressants was shown to be better than inorganic ones. Among the organic depressants, PY proved to be advantageous in terms of low dosage. Physical adsorption was identified as the main interaction form of SL, CL, and PY onto the surface of pyrite, as evidenced from FTIR and XPS analyses. Similarly, MD simulation results showed that hydrogen bonds played a proactive role in the interactions between PY and pyrite. The diffusion coefficient of water molecules on the pyrite surface was also observed to decrease when organic depressants were present, indicating an increase in the hydrophilicity of pyrite. This research is of great significance to utilize sulfur-containing coal and minerals. Full article

(This article belongs to the Special Issue Coal Processing and Utilization)

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14 pages, 6608 KiB

Open AccessArticle

Carbonate Nanoparticles Formed by Water–Rock Reactions in Groundwater: Implication of Carbonate Rock Weathering in Carbonate Aquifers

by Gang Tao, Rui Liu, Peng Zhang, Yaqin Wang, Lei Zuo and Xiaoheng Zhang

Minerals 2024, 14(10), 980; https://doi.org/10.3390/min14100980 (registering DOI) - 28 Sep 2024

Abstract

Carbonate rocks are highly reactive and exhibit higher ratios of chemical weathering compared to most other rock types. A chemo-mechanical mechanism, which is particularly effective in groundwater due to higher ion concentrations, is common in fine-grained carbonates at the nanoscale. As a result, [...] Read more.

Carbonate rocks are highly reactive and exhibit higher ratios of chemical weathering compared to most other rock types. A chemo-mechanical mechanism, which is particularly effective in groundwater due to higher ion concentrations, is common in fine-grained carbonates at the nanoscale. As a result, the weathering of carbonate aquifers produces a substantial number of carbonate nanoparticles (CNPs). In this study, we utilized high-resolution transmission electron microscopy (HRTEM) to analyze CNPs formed by water–rock reactions in two types of groundwater from Shandong Province, China. Our findings reveal a significant presence of naturally occurring CNPs in groundwater. The HRTEM results show that CNPs display spherical, cubic, hexagonal, and irregular shapes, with some forming aggregates. Energy-dispersive spectrometry indicates that most nanoparticles contain O, C, Ca, and Fe, with some also containing Si, Mg, S, Sr, and Cl. Selected area electron diffraction (SAED) patterns show that CNPs are mainly amorphous, with some crystalline forms. The diverse shapes and complex compositions of these CNPs suggest that they are not man-made but formed through the weathering of carbonate minerals via chemo-mechanical mechanisms. This discovery provides new insights into carbonate mineral evolution and mineralization during weathering. Given their widespread presence, CNPs in groundwater could represent the transportation of elements in the form of particles. Full article

(This article belongs to the Special Issue Mineral Evolution and Mineralization during Weathering)

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13 pages, 7542 KiB

Open AccessArticle

Peak Height Comparison K-Ar Method Applied to Zao Volcano Bomb Samples Younger than ca. 35 ka

by Mirai Takebe, Keiko Sato, Hidenori Kumagai, Naoyoshi Iwata and Masao Ban

Minerals 2024, 14(10), 979; https://doi.org/10.3390/min14100979 (registering DOI) - 28 Sep 2024

Abstract

The peak height comparison K-Ar dating method was applied to very young (younger than ca. 35 ka) vesiculated bombs from three pyroclastic units (Komakusadaira Pyroclastics, Kattadake Pyroclastics, and Umanose Agglutinate) from Zao Volcano in northeast Japan. Because the ³⁸Ar/³⁶Ar ratios [...] Read more.

The peak height comparison K-Ar dating method was applied to very young (younger than ca. 35 ka) vesiculated bombs from three pyroclastic units (Komakusadaira Pyroclastics, Kattadake Pyroclastics, and Umanose Agglutinate) from Zao Volcano in northeast Japan. Because the ³⁸Ar/³⁶Ar ratios differed from 0.187, the mass fractionation was corrected for all measurement data. The obtained K-Ar ages are 30.0 ± 32.2 ka (no. 1-1, weakly vesiculated), 37.4 ± 64.8 ka, and 33.0 ± 58.0 ka (nos. 2-1, 2-2, weakly vesiculated) for the samples from Komakusadaira Pyroclastics; 12.6 ± 46.7 ka (no. 3-1, highly vesiculated) for a sample from Kattadake Pyroclastics; and 5.3 ± 44.9 ka, 5.7 ± 14.3 ka (no. 4-1, 4-2, weakly vesiculated), and 17.3 ± 79.3 ka (no. 5-1, moderately vesiculated) for the samples from Umanose Agglutinate on a 1σ error basis. For all cases, the obtained ages’ errors exceed 100%, with none involved within the error range. Therefore, the following age value upper limits are considered statistically significant: no. 1-1 is ≤94.4 ka, 2-1 is ≤167.0 ka, 2-2 is ≤149.0 ka, 3-1 is ≤106.0 ka, 4-1 is ≤95.1 ka, 4-2 is ≤34.3 ka, and 5-1 is ≤175.9 ka, considering 2σ errors. The obtained ages are generally consistent with those previously estimated using ¹⁴C dating. Full article

(This article belongs to the Special Issue Challenges and Future Trends in K–Ar (⁴⁰Ar/³⁹Ar) Geochronology, 2nd Edition)

15 pages, 5972 KiB

Open AccessArticle

Enrichment Mechanism of Polymetallic Elements at the Base of the Niutitang Formation in Southeast Chongqing

by Guozhi Wang, Can Zhang, Dayong Liu, Linfei Qiu, Ziying Li and Ping’an Peng

Minerals 2024, 14(10), 978; https://doi.org/10.3390/min14100978 (registering DOI) - 28 Sep 2024

Abstract

Polymetallic enrichment layers are commonly found at the base of the Lower Cambrian and extensively distributed across the Upper Yangtze Platform, yet their genetic models remain controversial. This study systematically collected samples from a typical section in the southeastern Chongqing region for mineral, [...] Read more.

Polymetallic enrichment layers are commonly found at the base of the Lower Cambrian and extensively distributed across the Upper Yangtze Platform, yet their genetic models remain controversial. This study systematically collected samples from a typical section in the southeastern Chongqing region for mineral, organic, and inorganic analyses. It investigates the relationship between the abundance of various trace metal elements and organic matter at the base of the Niutitang Formation, as well as the vertical distribution characteristics of organic carbon isotopes and organic matter features. The results indicate that the Niutitang Formation shale exhibits a distinct three-part structure from bottom to top. Various metal elements are enriched in the lower interval, showing a close correlation between the abundance of polymetallic elements and the carbon isotopes of shale organic matter. The middle interval contains the highest TOC value and the lowest Ti/Al ratio, while the upper interval shows a significant decrease in organic matter abundance, with a clear positive correlation between the excess silicon content and Ti/Al ratio. Additionally, the mixing effect of deep-sea upwelling is the primary control on the formation of polymetallic enrichment layers in the lower interval, followed by the adsorption of organic matter under anoxic conditions. The sedimentary environment of the upper interval of the Niutitang Formation trends toward oxidation, with paleoclimate shifting toward colder and drier conditions, exhibiting aeolian sedimentary features that are unfavorable for the enrichment of trace metal elements. Consequently, upwelling is a key factor in the enrichment and mineralization of trace metal elements at the base of the Lower Cambrian in the Upper Yangtze region. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Geological Materials)

24 pages, 10729 KiB

Open AccessArticle

Performance of Geopolymer Insulation Bricks Synthesized from Industrial Waste

by Kamilia A. M. El Naggar, Mahmoud M. Abd El-Razik, Mohammed Kuku, Mohammad Arishi, Ibrahim M. Maafa, Ayman Yousef and Eman M. Abdel Hamid

Minerals 2024, 14(10), 977; https://doi.org/10.3390/min14100977 (registering DOI) - 28 Sep 2024

Abstract

In the current work, aluminum dross from the aluminum industry and fired-clay brick waste (Homra) were combined with alkaline activators (Na₂SiO₃/NaOH) with varying molarities of NaOH to create insulating geopolymer bricks. An alkaline activator with an (S/L) ratio of [...] Read more.

In the current work, aluminum dross from the aluminum industry and fired-clay brick waste (Homra) were combined with alkaline activators (Na₂SiO₃/NaOH) with varying molarities of NaOH to create insulating geopolymer bricks. An alkaline activator with an (S/L) ratio of 3/1 was combined with Homra to replace it partly. The mixture was then molded into 50 × 50 × 50 mm³ stainless steel molds. Water absorption, compressive strength, bulk density, and apparent porosity of the produced geopolymer were measured at various curing durations and NaOH molarities. The findings showed that adding more aluminum dross waste replacement leads to a decrease in bulk density and compressive strength and an increase in the creation of pores that improve the produced bricks’ ability to insulate against heat. Using 8 M of NaOH after 28 days, the findings revealed that 3% aluminum dross waste replacement has a compressive strength of about 8.6 MPa, water absorption of 14.6%, bulk density of 1.307 g/cm³, and thermal conductivity of 0.32 W/m·K. The Egyptian standard, ASTM C62, satisfies these outcomes. Using DesignBuilder energy simulation software version 6.1.06, the constructed insulating brick under ideal circumstances was utilized to calculate its contribution performance in energy consumption. The annual energy consumption was reduced by about 21% compared to traditional hollow cement bricks. Full article

(This article belongs to the Special Issue Geopolymers: Synthesis, Characterization and Application)

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22 pages, 3196 KiB

Open AccessArticle

The Role of Hypergenic and Technogenic Processes in Contamination the Ecosphere

by Valentina Zvereva and Konstantin Frolov

Minerals 2024, 14(10), 976; https://doi.org/10.3390/min14100976 - 27 Sep 2024

Abstract

Mining in the Russian Far East has been developing for more than 100 years, resulting in the formation of mining technogenic systems that negatively affect all components of the environment. The purpose of this paper is to develop and present an ecological and [...] Read more.

Mining in the Russian Far East has been developing for more than 100 years, resulting in the formation of mining technogenic systems that negatively affect all components of the environment. The purpose of this paper is to develop and present an ecological and geochemical model of supergene processes in tinsulfide and polymetallic ore mining systems. This paper presents, for the first time, the results of long-term field observations (more than 50 years): studies of numerous secondary minerals (more than 80) identified in mine workings and tailings, their natural associations, as well as the sequence, zonality, and stages of mineral formation as well as the characteristics of hydrochemical samples of river waters, contaminated by acid mine drainage (30 years of observations). Experimental modeling of sulfide oxidation was carried out under laboratory conditions (electrochemical method) and using Selektor software, which made it possible to study the process of acid mine drainage formation and to show the metal ions and ionic complexes composition, to establish Eh-pH parameters of crystallization for 52 secondary minerals, associations of primary and secondary minerals. The influence of water components on the formation of slurry and drainage in different time periods (dry, heavy rainfall, and snowmelt) is shown, and their mixing at the geochemical barrier “acid mine drainage—surface natural waters” is described. Experimental results are verified with numerous in-situ observations and mineralogical studies. The work allowed for the presentation of an environmental–geochemical model of ecosphere pollution, which describes not only the negative impact of sulfide-bearing systems of Russian Far East mining districts but locations all over the world. Full article

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

34 pages, 22660 KiB

Open AccessArticle

Source Rock Evaluation and Hydrocarbon Expulsion Characteristics of Effective Source Rocks in the Fushan Depression, Beibuwan Basin, China

by Xirong Wang, Fujie Jiang, Xiaowei Zheng, Di Chen, Zhenguo Qi, Yilin Liu, Jing Guo and Yuqi Zhang

Minerals 2024, 14(10), 975; https://doi.org/10.3390/min14100975 (registering DOI) - 27 Sep 2024

Abstract

This study presents an integrated approach using organic geochemistry and incident-light organic petrographic microscopy techniques to characterize the kerogen type, hydrocarbon potential, thermal maturity, and effective depositional environment of the Eocene Liushagang Formation intervals in the western Huangtong Sag, eastern Bailian Sag, central [...] Read more.

This study presents an integrated approach using organic geochemistry and incident-light organic petrographic microscopy techniques to characterize the kerogen type, hydrocarbon potential, thermal maturity, and effective depositional environment of the Eocene Liushagang Formation intervals in the western Huangtong Sag, eastern Bailian Sag, central Huachang Sub-uplift, and Southern Slope Zone area in the Fushan Depression, Beibuwan Basin. The results show that the hydrocarbon potential of these organic-rich lacustrine shale areas is mainly dependent on the depositional environment and the present-day burial depth of sediments. Oscillations and transitions between (i) rocks with dominant allochthonous organic matter (including primary/reworked vitrinite and inertinite macerals and terrestrial debris particles) representing a large influence of continental sediments (e.g., source supply direction) and (ii) rocks with dominant autochthonous organic matter (e.g., alginite) indicate a distal and stable lacustrine basin depositional environment. The source rock thickness ranges from 40.1 to 387.4 m. The average TOC of the Liushagang Formation in the Fushan Sag is between 0.98% and 2.00%, with the highest organic matter abundance being in the first and second sections of the Liushagang Formation, presenting as high-quality source rocks. The organic matter is predominantly Type II₁ and Type II₂. The highest vitrinite reflectance (1.14%) is in the Huangtong and Bailian Sags. The source rocks of the second section of the Liushagang Formation are primary hydrocarbon generators, contributing 55.11% of the total generation. Hydrocarbon sequestration peaks at %Ro 0.80%, with a maximum efficiency of 97.7%. The cumulative hydrocarbon generation of the Liushagang Formation is 134.10 × 10⁸ tons, with 50.52 × 10⁸ tons having been expelled and 83.58 × 10⁸ tons remaining. E₂L_2X and E₂L_2S have maximum hydrocarbon displacement intensities of 184.22 × 10⁴ t/km² and 45.39 × 10⁴ t/km², respectively, with cumulative displacements of 52.99 × 10⁸ tons and 15.58 × 10⁸ tons. The oil and gas accumulation system is highly prospective, showing significant exploration potential. Full article

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

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14 pages, 4287 KiB

Open AccessArticle

Parametrization of Geopolymer Compressive Strength Obtained from Metakaolin Properties

by Madeleing Taborda-Barraza, Luis U. D. Tambara, Jr., Carlos M. Vieira, Afonso R. Garcez de Azevedo and Philippe J. P. Gleize

Minerals 2024, 14(10), 974; https://doi.org/10.3390/min14100974 - 27 Sep 2024

Abstract

In the search for alternative cementitious materials, the alkali activation of aluminosilicates has been found to be a mechanically effective binder. Among precursors, metakaolin is most frequently used, with a primary source, kaolin, distributed globally in varying compositions. This variability may indicate potential [...] Read more.

In the search for alternative cementitious materials, the alkali activation of aluminosilicates has been found to be a mechanically effective binder. Among precursors, metakaolin is most frequently used, with a primary source, kaolin, distributed globally in varying compositions. This variability may indicate potential compositional limitations for the large-scale production of such binders. Thus, four types of commercial calcined clays, activated under identical conditions, were evaluated, and their physicochemical characteristics were correlated with the mechanical properties of the resulting binder. Different characterization methods were used for the raw material and for each alkali-activated system. Anhydrous metakaolin was assessed through particle size distribution, specific surface area, zeta potential, vitreous phases, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), amorphism, and pozzolanic activity. The pastes were evaluated in the fresh state through apparent activation energy progression and isothermal conduction calorimetry, and in the hardened state through compressive strength and dilatometry. Compressive strength values ranged from 7 to 42 MPa. From these results, a mathematical model was developed to estimate mechanical performance based on key variables, specifically amorphism, the pozzolanic index, and the silica-to-alumina ratio. This model allows for performance predictions without the need to prepare additional pastes. Interestingly, it was found that while some systems displayed low initial reactivity, their relative reactivity over time increased more significantly than those with higher early-stage reactivity, suggesting their potential for reconsideration in long-term applications. Full article

(This article belongs to the Special Issue Geopolymers: Synthesis, Characterization and Application)

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16 pages, 2103 KiB

Open AccessArticle

A Novel Surface Passivation Method of Pyrite within Rocks in Underwater Environments to Mitigate Acid Mine Drainage at Its Source

by Lijun Fan, Tiancheng Han, Xianxing Huang, Yixuan Yang, Tao Zhu, Weiwei Zhai, Daoyong Zhang and Xiangliang Pan

Minerals 2024, 14(10), 973; https://doi.org/10.3390/min14100973 - 27 Sep 2024

Abstract

Mitigating acid mine drainage (AMD) at its source, specifically within rocks containing pyrite in underwater environments, poses a significant environmental challenge worldwide. Existing passivation techniques are primarily designed for open-air conditions, involving direct contact with coating materials at a solid–liquid interface, making them [...] Read more.

Mitigating acid mine drainage (AMD) at its source, specifically within rocks containing pyrite in underwater environments, poses a significant environmental challenge worldwide. Existing passivation techniques are primarily designed for open-air conditions, involving direct contact with coating materials at a solid–liquid interface, making them ineffective beneath a water barrier. In this study, we introduce a novel passivation method inspired by the design of underwater bio-adhesives. Tannic acid (TA) combined with polyethylene glycol (PEG) was employed to form a hydrophobic film directly on the pyrite surface, overcoming water resistance and addressing the limitations of current techniques. Electrochemical experiments and chemical leaching experiments were conducted to evaluate the oxidation resistance of the passivating films. TA–PEG-coated pyrite exhibited a lower oxidation rate and a higher static contact angle of 126.2°, achieving suppression efficiencies of 71.6% for total Fe release and 68.1% for total S release. A comprehensive characterization approach, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), was employed to investigate the passivation mechanism. The results of this study may provide new insights into the preparation of simpler and greener passivating agents to suppress pyrite oxidation at its source in underwater environments. Full article

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

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14 pages, 5900 KiB

Open AccessArticle

Improved Quartz Flotation at Low Temperature by Amino Acid Lauryl Lysine as a Novel Green Collector

by Fei Wu, Shaohang Cao, Wanzhong Yin, Yafeng Fu, Chao Li and Yijun Cao

Minerals 2024, 14(10), 972; https://doi.org/10.3390/min14100972 - 27 Sep 2024

Abstract

A new type of amino acid surfactant, lauroyl lysine (LL), is used as a green collector for the low-temperature flotation of quartz. The micro-flotation test results indicate that, under flotation conditions of 10–40 °C, pH = 11.0, 20 mg/L CaCl₂, and [...] Read more.

A new type of amino acid surfactant, lauroyl lysine (LL), is used as a green collector for the low-temperature flotation of quartz. The micro-flotation test results indicate that, under flotation conditions of 10–40 °C, pH = 11.0, 20 mg/L CaCl₂, and 60 mg/L LL, the highest recovery of quartz by LL could reach up to 97.08%. The temperature at which flotation occurs little impacts LL collection efficiency. In contrast, sodium oleate (NaOL) gives inferior performance to LL at all tested temperatures. The adsorption measurement and SEM-EDS results confirm that a quantity of LL is absorbed onto the quartz surface at low temperatures. Investigations into the interaction between the reagents and mineral surfaces are conducted using X-ray photoelectron spectroscopy (XPS) analysis, zeta potential measurements, and Fourier transform infrared (FT-IR) spectra. Findings indicate that LL is adsorbed onto the quartz surface through hydrogen bonds and intense chemisorption. Additionally, the amide groups in the LL molecular structure increase the solubility of the collector at low temperatures, and simultaneously, the amide bond can form an intermolecular hydrogen bond between O and H, which is conducive to quartz flotation. Full article

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

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25 pages, 8944 KiB

Open AccessArticle

Paleoenvironmental Reconstruction and Hydrocarbon Potential of the Westphalian-A Kozlu Formation Hard Coal in the Zonguldak Basin: Insights from Organic Geochemistry and Petrology

by Neslihan Ünal-Kartal and Selin Karadirek

Minerals 2024, 14(10), 971; https://doi.org/10.3390/min14100971 - 26 Sep 2024

Abstract

The Zonguldak coal basin is the area with the most important hard coal reserves in Turkey. This study focuses on coal samples extracted from three seams of the Kozlu Formation, specifically from the Kozlu underground mine, to assess the coals’ organic geochemical and [...] Read more.

The Zonguldak coal basin is the area with the most important hard coal reserves in Turkey. This study focuses on coal samples extracted from three seams of the Kozlu Formation, specifically from the Kozlu underground mine, to assess the coals’ organic geochemical and petrographic properties. Analytical methods, including TOC-pyrolysis, biomarker analysis, and maceral distribution studies, were employed. Based on these analyses, the paleoenvironmental conditions and hydrocarbon generation potential of the coals were evaluated. The results reveal that the coals, characterized by high TOC, high HI, and low OI, contain type II–III kerogen. These findings, coupled with the high QI and low BI values, suggest the presence of oil–gas prone source rocks. Elevated Tmax (457–466 °C) and Rr (0.89%–1.17%) values indicate a maturity level ranging from mature to overmature stages. High GI and GWI values suggest a significant degree of gelification and wet conditions during formation. The high Pr/Ph (1–6.58), C₃₁R/C₃₀ hopane (<0.25), and low DBT/P (0.27–0.50) ratios show that the Acılık seam was formed in a lacustrine environment under anoxic–suboxic conditions, whereas the Büyük and Domuzcu seams were formed in a fluvial/deltaic environment under oxic conditions. The findings of this study suggest that the paleovegetation in coal-forming environments consisted of aquatic and herbaceous plants. Full article

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19 pages, 11777 KiB

Open AccessArticle

Optimization of Feature Selection in Mineral Prospectivity Using Ensemble Learning

by Hong Zhang, Miao Xie, Shiyao Dan, Meilin Li, Yunhe Li, Die Yang and Yuanxi Wang

Minerals 2024, 14(10), 970; https://doi.org/10.3390/min14100970 - 26 Sep 2024

Abstract

In recent years, machine learning (ML) has been extensively used for the quantitative prediction of mineral resources. However, the accuracy of prediction models is often influenced by data quality, feature selection, and algorithm limitations. This research investigates the benefits of data-driven feature optimization [...] Read more.

In recent years, machine learning (ML) has been extensively used for the quantitative prediction of mineral resources. However, the accuracy of prediction models is often influenced by data quality, feature selection, and algorithm limitations. This research investigates the benefits of data-driven feature optimization techniques in enhancing model accuracy. Using the Lhasa region in Tibet as the study area, this research applies ensemble learning methods, such as random forest and gradient boosting tree techniques, to optimize 43 feature variables encompassing geology, geochemistry, and geophysics. The optimized feature variables are then input into a support vector machine (SVM) model to generate a prospectivity map. The performance characteristics of the SVM, RF_SVM, and GBDT_SVM models are evaluated using ROC curves. The results indicate that the feature-optimized GBDT_SVM model achieves superior classification accuracy and prediction effectiveness, demonstrating that feature optimization is a necessary step for mineral prospectivity mapping, as it can significantly improve the performance of mineral prospectivity prediction. Full article

(This article belongs to the Special Issue Application of Big Data Mining, Machine Learning and Artificial Intelligence in Geoscience, 2nd Edition)

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21 pages, 10350 KiB

Open AccessArticle

Opal Synthesis: Toward Geologically Relevant Conditions

by Simon Gouzy, Benjamin Rondeau, Vassilissa Vinogradoff, Boris Chauviré, Marie-Vanessa Coulet, Olivier Grauby, Hélène Terrisse and John Carter

Minerals 2024, 14(10), 969; https://doi.org/10.3390/min14100969 - 26 Sep 2024

Abstract

Natural opal is a widespread mineral formed by the aqueous alteration of silicate rocks. It occurs as a mixture of silica nano-to-micro-structures (e.g., nanograins, spheres) and silica hydrogel cement, with variations in the proportions of these components leading to significant differences in the [...] Read more.

Natural opal is a widespread mineral formed by the aqueous alteration of silicate rocks. It occurs as a mixture of silica nano-to-micro-structures (e.g., nanograins, spheres) and silica hydrogel cement, with variations in the proportions of these components leading to significant differences in the physico-chemical properties of opals. However, the detailed process of their formation in nature and the influence of the mixing ratio are not fully understood, as opal has not been yet synthesized under geologically relevant conditions. This study aims to develop a method of opal synthesis in conditions close to continental weathering conditions (<50 °C, ambient pressure) using relevant chemicals that could be employed to gain insight into the processes that give rise to opal on Earth and Mars. Our synthesis method enabled us to synthesize opal-A with different mixing ratios, of which four were then studied to determine the effect on the material’s properties. Changes in the proportion of the hydrogel cement affect the porosity and the total water content, as well as the proportion of “water” species (H₂O and OH). Moreover, the synthetic opal obtained with a 1:1 ratio shows the closest similarity to natural opal-AG. Finally, our results support the hypothesized multistage process for opal formation in nature. Full article

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

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17 pages, 7229 KiB

Open AccessArticle

Study of Hydrometallurgical Treatment of Metal-Bearing Material from Environmental Burdens Containing Iron, Chromium, Nickel, and Cobalt

by Martina Laubertová, Oksana Velgosova, Martin Sisol and Tomáš Vindt

Minerals 2024, 14(10), 968; https://doi.org/10.3390/min14100968 - 25 Sep 2024

Abstract

In Slovakia, around 200 environmental burdens that contain a significant amount of usable raw materials were created by the extraction of ores or the dumping of industrial waste. In this research, the hydrometallurgical metal recovery method from a metal-bearing environmental landfill in Sereď [...] Read more.

In Slovakia, around 200 environmental burdens that contain a significant amount of usable raw materials were created by the extraction of ores or the dumping of industrial waste. In this research, the hydrometallurgical metal recovery method from a metal-bearing environmental landfill in Sereď was investigated. The analysis of a representative sample of waste obtained from this landfill proved the presence of significant amounts of metals (43.45% Fe; 1.3% Cr; 0.09% Co, and 0.23% Ni). A thermodynamic study of the metals’ (Fe, Cr, Ni, and Co) leaching probability confirmed the possibility of metal extraction in an acidic environment. Subsequently, the effect of the most important factors on the leaching process (stirring intensity, temperature, liquid-to-solid phase ratio, and acid concentration) was experimentally tested. The analysis of the results determined the optimal leaching conditions. The extraction of 90.35% Fe and 59.62% Cr was ensured at a stirring intensity of 400 rpm, a leaching temperature of 80 °C, a liquid-to-solid phase ratio of 40, and a H₂SO₄ concentration of 3 mol/dm³. Various techniques, including SEM, EDX, XRD, Eh-pH diagrams, and AAS analysis, were used to analyze samples and products after leaching. The possibility of precipitating metals/compounds from the leachate to obtain a marketable product was theoretically proposed and proven. Full article

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

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15 pages, 2709 KiB

Open AccessArticle

Trace Element Geochemical Characteristics of Plants and Their Role in Indicating Concealed Ore Bodies outside the Shizhuyuan W–Sn Polymetallic Deposit, Southern Hunan Province, China

by Le Ouyang, Kaixuan Tan, Yongmei Li, Zhenzhong Liu, Hao Zhou, Chunguang Li, Yanshi Xie and Shili Han

Minerals 2024, 14(10), 967; https://doi.org/10.3390/min14100967 - 25 Sep 2024

Abstract

To explore the potential of plant trace elements as indicators in the search for concealed deposits within the W–Sn polymetallic mining area of Shizhuyuan, Hunan Province, this study focused on the geochemical characterization of 21 trace elements, including Ag, As, B, Bi, Cd, [...] Read more.

To explore the potential of plant trace elements as indicators in the search for concealed deposits within the W–Sn polymetallic mining area of Shizhuyuan, Hunan Province, this study focused on the geochemical characterization of 21 trace elements, including Ag, As, B, Bi, Cd, Mo, Ni, Pb, and U, in the stem and leaf tissues of three predominant plants in the area. A total of 126 plant samples were collected, covering an area of about 10 km², and analyzed using ICP-MS. The best indicator plants and sampling sites were selected using multiple indicators, including the biological absorption coefficient (X_BAC), the enrichment coefficient (K_NJ), and the contrast coefficient (K_CD). The results showed that plant leaf tissues represent the most effective sampling components for phyto-geochemical surveys in this region. Dicranopteris dichotoma exhibited markedly pronounced geochemical anomalies of Ag (0.137 µg/g), As (86.12 µg/g), Mo (0.963 µg/g), Pb (15.4 µg/g), Sb (2.03 µg/g), and Se (0.547 µg/g) and demonstrated superior absorption capabilities for Ni, Sn, Sb, Pb, and Bi in the soil, with X_BAC values of 12.0, 54.2, 23.3, 2.9, and 83.9, respectively. R-type cluster analysis and factor analysis identified four distinct mineralization element combinations: (1) Sn–As, (2) Ag–Cu–Mo, (3) Pb, and (4) Bi–Sb–Se. Consequently, D. dichotoma is a viable indicator plant for the phyto-geochemical detection of concealed Ag, Bi, Mo, Pb, Sb, Se, and Sn mineralization in mining areas. The results demonstrate that using phyto-geochemical methods for mineral prospecting is feasible and has significant application value in the Shizhuyuan mining area, which is characterized by dense vegetation and complex geological conditions. Full article

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

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18 pages, 3488 KiB

Open AccessArticle

Adsorption of Ciprofloxacin and Lidocaine by Non-Fibrous Raw Mg-Clays: The Role of Composition and Texture

by Maria Eugenia Roca-Jalil, Telma Musso, Vanina Rodriguez-Ameijide, Micaela Sanchez, Andrea Maggio, Miria Teresita Baschini, Gisela Pettinari, Luis Villa, Manuel Pozo and Alejandro Pérez-Abad

Minerals 2024, 14(10), 966; https://doi.org/10.3390/min14100966 - 25 Sep 2024

Abstract

This study evaluated non-fibrous Mg-clays as potential adsorbents of emerging contaminants (ECs) from water. The materials were characterized, and their textural and structural properties were related to their ability to remove two model EC molecules: ciprofloxacin (CPX) and lidocaine (LID). The results showed [...] Read more.

This study evaluated non-fibrous Mg-clays as potential adsorbents of emerging contaminants (ECs) from water. The materials were characterized, and their textural and structural properties were related to their ability to remove two model EC molecules: ciprofloxacin (CPX) and lidocaine (LID). The results showed that Ad-6 and Ad-7 are mixed-layer kerolite/stevensite, while Ad-5 and Ad-8 are mainly composed of smectite minerals like stevensite and saponite, respectively. Ad-8 exhibited the highest CPX-adsorption capacity (0.91 mmol·g⁻¹ clay), likely due to its saponite content. Mixed-layer materials also performed well, with Ad-6 and Ad-7 achieving an adsorption capacity of 0.8 and 0.55 mmol·g⁻¹ clay, respectively. Adsorption studies suggested that CPX is adsorbed through ion exchange in materials with high smectite content (Ad-8 and Ad-5), while interstratified materials showed enhanced retention due to kerolite presence, which improves their porous structures. Similar findings were observed for LID, indicating a cationic-exchange mechanism for LID adsorption in all the materials and suggesting that the molecular size of the EC could regulate the removal capacity of these materials. This work showed that the studied Mg-clays could be effectively used for the removal of pharmaceutical pollutants, expanding their commercial possibilities. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Geological Materials)

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20 pages, 6163 KiB

Open AccessReview

Review on the Challenges of Magnesium Removal in Nickel Sulfide Ore Flotation and Advances in Serpentinite Depressor

by Fengxiang Yin, Chengxu Zhang, Yao Yu, Chenyang Lv, Zhengbo Gao, Bingang Lu, Xiaohui Su, Chunhua Luo, Xiangan Peng, Belinda McFadzean and Jian Cao

Minerals 2024, 14(10), 965; https://doi.org/10.3390/min14100965 - 25 Sep 2024

Abstract

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in [...] Read more.

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in sulfide nickel ores, particularly serpentine, pose significant challenges to the flotation of nickel sulfide ores. The presence of magnesium silicate gangue leads to a series of issues, including increased energy consumption in subsequent smelting processes, accelerated equipment wastage, and increased SO₂ emissions, which severely impact the comprehensive utilization of nickel resources in sulfide nickel ores. In this regard, flotation depressants are the most direct and effective method to reduce adverse influences caused by magnesium silicate gangue in the flotation of nickel sulfide ore concentrate. Based on the characteristics of the typical magnesium-containing nickel sulfide ore, this review illustrates the difficulties of the depression of magnesium silicate gangue during the flotation of nickel sulfide ore and gives an overview of the common depressants from six aspects (chelation depressants, dispersion depressants, flocculation depressants, depressants for grinding, depressants for slurry adjustment and combination depressants). Each section summarizes the relevant depression mechanisms and analyzes the advantages and disadvantages of various reagents, providing a reference for designing depressants specifically targeting serpentine. Full article

(This article belongs to the Special Issue Selected Papers from the 7th International Conference of Young Scholars in Mineral Processing)

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14 pages, 3886 KiB

Open AccessArticle

Study on the Rheological and Thixotropic Properties of Fiber-Reinforced Cemented Paste Backfill Containing Blast Furnace Slag

by Xulin Zhao, Haijun Wang, Guanghua Luo, Kewei Dai, Qinghua Hu, Junchao Jin, Yang Liu, Baowen Liu, Yonggang Miao, Kunlei Zhu, Jianbo Liu, Hai Zhang, Lianhe Wu, Jianming Wu, Yueming Lu, Wei Wang and Dingchao Lv

Minerals 2024, 14(10), 964; https://doi.org/10.3390/min14100964 - 24 Sep 2024

Abstract

To investigate the mechanism of polypropylene fiber (PPF) on the rheological and thixotropic properties of cemented paste backfill containing mineral admixtures, the concept of water film thickness (WFT) was introduced. The packing density of the tailings-binder-PPF (TBP) system was measured in dry and [...] Read more.

To investigate the mechanism of polypropylene fiber (PPF) on the rheological and thixotropic properties of cemented paste backfill containing mineral admixtures, the concept of water film thickness (WFT) was introduced. The packing density of the tailings-binder-PPF (TBP) system was measured in dry and wet conditions and the WFT was calculated accordingly. Additionally, the rheological parameters (yield stress, thixotropy, etc.) of the fiber-reinforced cemented paste backfill (FRCPB) were quantified. The results demonstrate that the wet packing test is a more appropriate method for measuring the packing density of the TBP system. The PPF length has a slight adverse effect on the packing density, and the packing density initially increases and then decreases with the PPF content. The reasons can be attributed to the filling effect and wedge effect of the fibers, respectively. In addition to the packing density, the thixotropy of FRCPB is also affected by the interaction of fibers. WFT is a crucial factor affecting the yield stress of FRCPB, with which it exhibits a strong linear relationship. The study identified that the optimum PPF content for enhancing the rheological and thixotropic properties of CPB is 0.2%, with a fiber length of 9 mm, balancing flowability and stability for practical application in mining backfill operations. These insights can guide the optimization of CPB mixtures, enhancing their flowability and stability during placement in mined-out spaces. By improving the fill quality and reducing the risk of blockage during backfill operations, the results offer practical benefits in increasing the safety and efficiency of underground mining activities. Full article

(This article belongs to the Special Issue Metallurgy Waste Used for Backfilling Materials)

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