Minerals

20 pages, 4412 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Gas Barrier Properties of Multilayer Polymer–Clay Nanocomposite Films: A Multiscale Simulation Approach

by Andrey Knizhnik, Pavel Komarov, Boris Potapkin, Denis Shirabaykin, Alexander Sinitsa and Sergey Trepalin

Minerals 2023, 13(9), 1151; https://doi.org/10.3390/min13091151 - 30 Aug 2023

Viewed by 1856

Abstract

The paper discusses the development of a multiscale computational model for predicting the permeability of multilayer protective films consisting of multiple polymeric and hybrid layers containing clay minerals as fillers. The presented approach combines three levels of computation: continuous, full atomic, and quantitative [...] Read more.

The paper discusses the development of a multiscale computational model for predicting the permeability of multilayer protective films consisting of multiple polymeric and hybrid layers containing clay minerals as fillers. The presented approach combines three levels of computation: continuous, full atomic, and quantitative structure–property correlations (QSPR). Oxygen and water are chosen as penetrant molecules. The main predictions are made using the continuum model, which takes into account the real scales of films and nanoparticles. It is shown that reliable predictions of the permeability coefficients can be obtained for oxygen molecules, which is not always possible for water. The latter requires the refinement of existing QSPR methods and interatomic interaction potentials for the atomistic level of calculations. Nevertheless, we show that the maximum effect on permeability reduction from the addition of clay fillers to the hybrid layer can be achieved by using nanoparticles with large aspect ratios and a high degree of orientational order. In addition, the use of the hybrid layer should be combined with the use of polymer layers with minimal oxygen and water permeability. The constructed model can be used to improve the properties of protective coatings for food and drug storage and to regulate the gas permeability of polymeric materials. Full article

(This article belongs to the Special Issue Composites Based on Layered Silicate Minerals: Preparation, Characterization and Applications)

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19 pages, 6402 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Ultrafine Particle Flotation in a Concept Flotation Cell Combining Turbulent Mixing Zone and Deep Froth Fractionation with a Special Focus on the Property Vector of Particles

by Johanna Sygusch, Nora Stefenelli and Martin Rudolph

Minerals 2023, 13(8), 1099; https://doi.org/10.3390/min13081099 - 17 Aug 2023

Cited by 5 | Viewed by 2660

Abstract

Froth flotation faces increasing challenges in separating particles as those become finer and more complex, thus reducing the efficiency of the separation process. A lab flotation apparatus has been designed combining the advantages of agitator-type froth flotation for high turbulences and column flotation [...] Read more.

Froth flotation faces increasing challenges in separating particles as those become finer and more complex, thus reducing the efficiency of the separation process. A lab flotation apparatus has been designed combining the advantages of agitator-type froth flotation for high turbulences and column flotation with a deep froth zone for a fractionating effect, also enabling a study on the effect of different particle property vectors. A model system of ultrafine (<10 µm) particles was used for flotation to study how the separation process is influenced by the ultrafine property vectors of shape and wettability. To evaluate the new apparatus, flotation tests were carried out in a benchmark mechanical flotation cell under comparable conditions. Higher wettabilities result in higher recoveries, but the results show that optimum levels of hydrophobicity vary for different particle shapes. Different behaviours are observed for differently shaped particles, depending on their wettability state. The entrainment of unwanted gangue is reduced with increasing froth depth. While higher recoveries are obtained for the benchmark cell, the newly developed apparatus produces concentrates with higher grades. Our findings contribute to ultrafine flotation techniques and especially our understanding of the complex effect of particle shape in combination with the other property vectors. Full article

(This article belongs to the Special Issue Recent Advances in Flotation Process)

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23 pages, 11364 KiB

Open AccessEditor’s ChoiceArticle

The Behavior of Rare Earth Elements during Green Clay Authigenesis on the Congo Continental Shelf

by Germain Bayon, Pierre Giresse, Hongjin Chen, Marie-Laure Rouget, Bleuenn Gueguen, Gabriel Ribeiro Moizinho, Jean-Alix Barrat and Daniel Beaufort

Minerals 2023, 13(8), 1081; https://doi.org/10.3390/min13081081 - 14 Aug 2023

Cited by 7 | Viewed by 2369

Abstract

Clay mineral authigenesis at continental margins plays an important role in global marine element cycles. However, despite being increasingly used as tracers for both modern and past oceanographic conditions, the behavior of the rare earth elements (REEs) and their isotopes during marine clay [...] Read more.

Clay mineral authigenesis at continental margins plays an important role in global marine element cycles. However, despite being increasingly used as tracers for both modern and past oceanographic conditions, the behavior of the rare earth elements (REEs) and their isotopes during marine clay authigenesis still remains poorly known. In this study, we report on a detailed geochemical investigation of glauconite from the West African continental shelf, near the mouth of the Congo River. Elemental, neodymium, and hafnium isotope analyses were conducted on both acid leachate and separated clay-size fractions of glauconite pellets, in order to investigate the behavior of REE during the formation of authigenic clays. Our data indicate that kaolinite dissolution and subsequent Fe-bearing clay authigenesis act as a net source of REEs to seawater. We show that enhanced glauconitization, as inferred from increasing Fe and K contents, is accompanied by significant decoupling of the REE toward markedly LREE-enriched shale-normalized patterns in neoformed clay separates. Using both Nd and Hf isotopes and SEM observations, we rule out any seawater influence and argue that this shift primarily reflects the progressively overwhelming presence of insoluble nanocrystals of detrital LREE-rich phosphates, which are known to occur in close association with kaolinite in tropical soils. Due to their marked insolubility in surface environments, such nanocrystals can be preserved during kaolinite dissolution and subsequently incorporated into the aggregates of authigenic green clays forming the peloids. Most strikingly, we show that the combined influence of net REE loss (due to kaolinite dissolution) and decoupling (due to subsequent entrapment of inherited LREE-bearing accessory phases into neoformed clay minerals) is accompanied by preferential release of a dissolved REE fraction characterized by seawater-like distribution patterns. These findings reinforce the emerging view that clay mineral dissolution and authigenesis at continental margins possibly play a major role in marine REE cycling. Full article

(This article belongs to the Special Issue Formation and Evolution of Glauconite. New Scale Approach)

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21 pages, 7691 KiB

Open AccessEditor’s ChoiceArticle

Effects of Metasomatism on Granite-Related Mineral Systems: A Boron-Rich Open Greisen System in the Highiş Granitoids (Apuseni Mountains, Romania)

by Andrea Varga, Attila Pozsár, Norbert Zajzon, Boglárka Topa, Zsolt Benkó, Elemér Pál-Molnár and Béla Raucsik

Minerals 2023, 13(8), 1083; https://doi.org/10.3390/min13081083 - 14 Aug 2023

Cited by 2 | Viewed by 3000

Abstract

Greisenization is typically linked with highly fractionated granites and is often associated with hydrothermal vein systems. Late to postmagmatic metasomatic processes involve the enrichment of volatile components such as boron and halogens as well as several metallic elements. The purpose of this study [...] Read more.

Greisenization is typically linked with highly fractionated granites and is often associated with hydrothermal vein systems. Late to postmagmatic metasomatic processes involve the enrichment of volatile components such as boron and halogens as well as several metallic elements. The purpose of this study is to reveal the main metasomatic effects and paragenetic sequences of the related mineralizations in Highiş granitoids, Romania. In a natural outcrop, more than 30 samples were collected from granitoids, felsic veins, and country rocks. We carried out a detailed mineralogical and petrological characterization of carefully selected samples using X-ray powder diffractometry, electron microprobe analysis, and microscopic methods together with K–Ar ages of whole rocks and K-bearing minerals. Several characteristic features of albitization, sericitization, tourmalinization, epidotization, and hematitization were recognized in the studied samples. Crystallization of quartz, K-feldspar, and magnetite represents the first stage during the magmatic-hydrothermal transition. The mineral assemblage of albite, sericite, schorl, and quartz originates from the early and main stages of greisenization. While the subsequent mineral assemblages, which predominantly include dravite, specular hematite, and epidote, are closely related to the late vein-depositing stage. We propose that the study area could belong to a boron-rich open greisen system in the apical portion of Guadalupian A-type granite. Based on a new hypothesis, the previously published Permian crystallization ages (between ~272 Ma and ~259 Ma) could be homogenized and/or partially rejuvenated during the hydrothermal mineralization processes due to uraniferous vein minerals. Additionally, the Highiș granite-related system suffered a Cretaceous thermal overprint (between ~100 Ma and ~96 Ma). The results may help to understand the evolution of highly evolved granite intrusions worldwide and improve our knowledge of the effect of hydrothermal mineralization processes on the emplacement ages. Full article

(This article belongs to the Special Issue Petrogenesis, Geochronology, Mineralization and Geochemistry of Granite Rocks)

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18 pages, 1339 KiB

Open AccessEditor’s ChoiceArticle

Structural and Chemical Diversity and Complexity of Sulfur Minerals

by Vladimir G. Krivovichev, Sergey V. Krivovichev and Galina L. Starova

Minerals 2023, 13(8), 1069; https://doi.org/10.3390/min13081069 - 12 Aug 2023

Cited by 4 | Viewed by 2237

Abstract

The chemical and structural diversity of minerals containing sulfur as an essential mineral-forming element has been analyzed in terms of the concept of mineral systems and the information-based structural and chemical complexity parameters. The study employs data for 1118 sulfur mineral species approved [...] Read more.

The chemical and structural diversity of minerals containing sulfur as an essential mineral-forming element has been analyzed in terms of the concept of mineral systems and the information-based structural and chemical complexity parameters. The study employs data for 1118 sulfur mineral species approved by the International Mineralogical Association. All known sulfur minerals belong to nine mineral systems, with the number of essential components ranging from one to nine. The chemical and structural complexity of S minerals correlate with each other; that is, on average, chemical complexification results in structural complexification. The minerals with S–O bonds (sulfates and sulfites) are more complex than those without S–O bonds (sulfides and sulfosalts). However, the most complex sulfur mineral known so far is incomsartorite, Tl₆Pb₁₄₄As₂₄₆S₅₁₆, a sulfosalt. The complexity-generating mechanism in sulfides and sulfosalts is the complex combination of different modules excised from parent PbS or SnS archetypes with the subsequent formation of superstructures. The drivers for structural complexity in sulfates are more diverse and, in addition to modular construction and superstructures, also include a high hydration state, the presence of polyatomic clusters, and framework complexity. The most complex Martian minerals are most probably halotrichite-group minerals. The chemical and structural complexity increases with the passage of geological time with the formation of the most complex sulfosalts at Lengenbach (Swiss Alps) triggered by life (activity of sulfur-reducing bacteria). Full article

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

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16 pages, 5224 KiB

Open AccessEditor’s ChoiceArticle

Microscopic Pore Structure Characteristics and Fluid Mobility in Tight Reservoirs: A Case Study of the Chang 7 Member in the Western Xin’anbian Area of the Ordos Basin, China

by Qinlian Wei, Huifang Zhang, Yonglin Han, Wenjie Guo and Ling Xiao

Minerals 2023, 13(8), 1063; https://doi.org/10.3390/min13081063 - 11 Aug 2023

Cited by 8 | Viewed by 1495

Abstract

This research addresses the limited understanding of movable fluid occurrence characteristics in the Chang 7 reservoir by employing mercury injection capillary pressure, constant-rate mercury injections, and nuclear magnetic resonance methods. This study investigates the microscopic pore structure characteristics and movable fluids in the [...] Read more.

This research addresses the limited understanding of movable fluid occurrence characteristics in the Chang 7 reservoir by employing mercury injection capillary pressure, constant-rate mercury injections, and nuclear magnetic resonance methods. This study investigates the microscopic pore structure characteristics and movable fluids in the tight reservoir of the western Xin’an region, located in the Ordos Basin. The finding reveals that as permeability decreases, the distribution of the throat radius becomes more concentrated in the low-value area, resulting in a narrow distribution range with high curve peaks. Conversely, with an increasing permeability, the distribution range expands towards the high-value area while the curve peak decreases. This research underscores the significance of the throat radius, especially the main flow throat radius, in constraining the permeability of rock samples. Furthermore, this study highlights a stronger correlation between permeability and movable fluid saturation than porosity. This finding emphasizes the importance of considering movable fluid saturation when assessing reservoir characteristics. Notably, the throat radius plays a crucial role in influencing the occurrence characteristics of movable fluids, with a smaller throat radii posing hindrances to fluid flow in the reservoir. Additionally, the presence of clay minerals in the reservoir leads to pore segmentation and increased fluid flow resistance, ultimately reducing the saturation of movable fluids. I must be understood that these factors are essential for developing and producing reservoirs with similar characteristics. In conclusion, the insights gained from this study hold considerable theoretical value and provide essential references for developing and producing reservoirs with tight characteristics, particularly in the western Xin’an region of the Ordos Basin. Full article

(This article belongs to the Special Issue Mineralogy, Geochemistry, and Sedimentary Geology of Lacustrine Basins)

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16 pages, 2834 KiB

Open AccessEditor’s ChoiceArticle

Heavy Metal Regularity of Carboniferous Weathered Black Shale in Qiziqiao Area, Central Hunan

by Wanghu He, Deqiu Dai, Bozhi Ren, Zhanyu Tang and Yu Qiu

Minerals 2023, 13(8), 1044; https://doi.org/10.3390/min13081044 - 6 Aug 2023

Cited by 5 | Viewed by 1528

Abstract

The Hunan region is a high geological background area of black rock series rich in various metallic elements; accordingly, local heavy metal pollution is severe. Previous studies on black shale have primarily focused on the lower Cambrian strata, while research on Carboniferous black [...] Read more.

The Hunan region is a high geological background area of black rock series rich in various metallic elements; accordingly, local heavy metal pollution is severe. Previous studies on black shale have primarily focused on the lower Cambrian strata, while research on Carboniferous black shale remains scarce. To better explore the activity law of heavy metals during Carboniferous black shale weathering, this study analyzed the elemental components of samples through field observations of outcrops in the Qiziqiao area of central Hunan province, China using inductively coupled plasma mass spectrometry and X-ray fluorescence spectrometry. The results showed that the heavy metal content of black shale under different degrees of weathering varied greatly, with different heavy metals maintaining distinct migration and enrichment rules throughout this process. The heavy metal content in Carboniferous black shale and soils of central Hunan was generally less than that of the regional lower Cambrian black shale and soil; however, the Cd content in the black shale soil was slightly higher than background values, while the Sr content was substantially higher than background values. Heavy metals V, Cr, Co, Ni, Cu, and Pb were not generally leached or released during weathering, and may undergo relative enrichment or secondary enrichment. Comparatively, Zn, Cd, and Ba can be more readily leached and released, and may undergo secondary enrichment. The lithophilic element Sr tended to leach out overall and expressed strong activity, whereas the chemical activities of the high-field-strength elements, Zr and Hf, were relatively stable. During soil formation, all heavy metal elements save Sr were significantly enriched. The enrichment factor analysis of different degrees of weathered black shale reveals that the heavy metals Ba, Hf, and Sr in black shale soil originate from the parent rock. V, Cr, Co, Ni, Cu, Zn, Cd, and Pb are influenced by both natural and anthropogenic factors, with Cd being significantly impacted by human activities. The evaluation of soil heavy metals using the geoaccumulation index method indicates that V, Cr, Co, Ni, Cu, Zn, Zr, Ba, Hf, and Pb are non-polluted, Cd exhibits moderate pollution, and Sr shows moderately heavy pollution. From a geochemical perspective, it can be inferred that heavy metals in black shale soil are likely to be secondarily enriched in clay and iron oxide minerals. Full article

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

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17 pages, 12408 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Composite Collectors for the Flotation of Refractory Alkaline Rock-Type Rare-Earth Ores

by Chunfeng Li, Zhichao Liu, Zhenjiang Liu, Jiajun Liu, Guang Li, Yuhui Tian and Mingliang Zhou

Minerals 2023, 13(8), 1025; https://doi.org/10.3390/min13081025 - 31 Jul 2023

Cited by 3 | Viewed by 1696

Abstract

Alkaline rock-type rare-earth (RE) ores have significant utilisation value. However, the exploitation of such resources faces great challenges owing to the complex mineral and element assemblages. Composite collectors exhibit excellent performances, which may provide solutions to the flotation problem of alkaline rock-type RE [...] Read more.

Alkaline rock-type rare-earth (RE) ores have significant utilisation value. However, the exploitation of such resources faces great challenges owing to the complex mineral and element assemblages. Composite collectors exhibit excellent performances, which may provide solutions to the flotation problem of alkaline rock-type RE ores. Therefore, 16 collectors typically used in RE ores flotation were selected. Flotation tests were performed to identify collectors with high selectivity and collection ability for RE minerals, then nine composite collectors were prepared by combining the satisfactory collectors. The flotation performances of single and composite collectors for RE minerals were examined, and the composite collector FA301 with different carbon chain lengths was identified as the best one. When FA301 was applied in optimal conditions of slurry temperature, grinding size, collector and inhibitor dosage, RE concentrate yield of 6.29%, REO grade of 32.013%, and recovery of 59.02% were achieved. According to the results of the zeta potential, FTIR, and XPS test, the functional groups (dominated by carboxyl groups) in FA301 chemically adsorbed onto the main active sites (La, Ce, Y, etc.) on the surface of RE minerals. The findings can provide scientific basis for the development of efficient collectors to facilitate the exploitation of RE resources. Full article

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

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27 pages, 6974 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Surface Chemistry Tuning Solutions for Flotation of Fine Particles

by Stoyan I. Karakashev, Nikolay A. Grozev, Kristina Mircheva, Seher Ata, Ghislain Bournival, Svetlana Hristova and Orhan Ozdemir

Minerals 2023, 13(7), 957; https://doi.org/10.3390/min13070957 - 18 Jul 2023

Cited by 6 | Viewed by 2428

Abstract

This paper analyses the basic obstacles preventing the fine particles from floating and suggests solutions for the wetting zone between the bubble and the particle during their collision. It has been shown in our recent paper that the basic problem of fine particle [...] Read more.

This paper analyses the basic obstacles preventing the fine particles from floating and suggests solutions for the wetting zone between the bubble and the particle during their collision. It has been shown in our recent paper that the basic problem of fine particle flotation is not the low frequency of collisions with the bubbles, but it consists of the efficiency of these collisions. Moreover, there exists a thermodynamic lower size limit for flotation of fine hydrophobized particles in the sub-micron range, and it is weakly dependent on the size of the bubbles. It was shown that fast flotation with high recovery of fine particles can be achieved by means of: (i) electrostatic attraction between particles and bubbles; (ii) a significant increase in the level of their hydrophobicity; (iii) existence of fine bubbles in the flotation cell. It was shown as well that the drainage of the wetting film between bubbles and particles is unimportant, but the deformation of the bubble by the particle during their clash plays a major role in its rupturing. Electrostatic attraction between bubbles and fine silica particles was achieved with hexylamine. It causes a moderate increase of their hydrophobicity from contact angle = 39.5° ± 2.5° to contact angle = 51.7° ± 7.5° and gave almost 90% recovery within 2 min. Unfortunately, the selectivity of this collector is unsatisfactory if the fine silica particles are mixed with fine magnesite particles. It was shown that even being hydrophilic, the recovery of fine particles can jump to almost 50% if strong electrostatic attraction with the bubbles exists. It was demonstrated as well with the collector hexamethyldisilazane causes significant increase of the hydrophobicity of the fine silica particles (contact angle ≈ 90°) results in skin flotation with 100% recovery when alone and 97% recovery when being mixed with fine magnesite particles (51/49). A new collector significantly increasing the hydrophobicity of magnesite fine particles was tested (disodium dodecyl phosphate) resulting in 89% recovery of fine magnesite particles alone and about 98% recovery in a mixture with fine silica particles. Full article

(This article belongs to the Special Issue Recent Advances in Flotation Process)

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15 pages, 3398 KiB

Open AccessEditor’s ChoiceReview

Dating Amber: Review and Perspective

by Su-Chin Chang, Yuling Li and Daran Zheng

Minerals 2023, 13(7), 948; https://doi.org/10.3390/min13070948 - 15 Jul 2023

Cited by 4 | Viewed by 3339

Abstract

Amber is a fossilized tree resin that ranges in age from the Carboniferous to the Cenozoic. It occurs globally from the Arctic to Antarctica. As the resin petrifies and turns into amber, it can enclose and preserve other materials. Amber with inclusions can [...] Read more.

Amber is a fossilized tree resin that ranges in age from the Carboniferous to the Cenozoic. It occurs globally from the Arctic to Antarctica. As the resin petrifies and turns into amber, it can enclose and preserve other materials. Amber with inclusions can help reconstruct past biodiversity and ecosystems. Some amber contains fossils representing the oldest and most detailed records of critical evolutionary traits or markers. Inclusions can even capture behavioral indicators previously only observed in extant organisms. Evidence of insect pollination of flowering plants and dragonfly mating behavior appears in amber, as does the morphological specialization of insects, indicating sociality and social parasitism. Dating amber deposits can help calibrate evolutionary events and inform reconstructions of past ecosystems. While the direct dating of amber remains impossible, age constraints on most amber deposits are based on correlations or relative dating, methods that come with significant uncertainties. This study discusses two cases using ⁴⁰Ar/³⁹Ar and U–Pb geochronologic methods to constrain the ages of amber deposits in China and the paleo-ecosystems they record. This paper also summarizes how radio-isotopic dating and other techniques combined with the analysis of inclusions in amber can help elucidate biogeography and the dynamic relationship between life and the physical environment. Full article

(This article belongs to the Special Issue Recent Developments in Ar/Ar and U-Th-Pb Geochronology and Its Applications)

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15 pages, 9202 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Response of High Swelling Montmorillonite Clays with Aqueous Polymer

by Guru Prasad Panda, Alireza Bahrami, T. Vamsi Nagaraju and Haytham F. Isleem

Minerals 2023, 13(7), 933; https://doi.org/10.3390/min13070933 - 13 Jul 2023

Cited by 4 | Viewed by 3202

Abstract

Expansive clays containing mineral montmorillonite exhibit swelling and shrinkage due to variations in the moisture content, leading to significant distresses. There has been a growing interest in chemical and polymer additives treated for high swelling montmorillonite clays in recent years. However, limited attention [...] Read more.

Expansive clays containing mineral montmorillonite exhibit swelling and shrinkage due to variations in the moisture content, leading to significant distresses. There has been a growing interest in chemical and polymer additives treated for high swelling montmorillonite clays in recent years. However, limited attention has been paid to the effect of polyacrylamide on the soil’s swelling behavior. Moreover, nontraditional methods of the soil treatment are applied for the rapid stabilization of soil. In this article, polyacrylamide polymer is used as an additive to expansive clays to control the swelling phenomenon. Three different percentages—2.5%, 5%, and 7.5%—of polymer are blended with oven-dried soil to determine Atterberg limits, compaction features, and swelling characteristics. Additionally, electrical impedance measurement is conducted on treated soil samples with different moisture contents. The electrical resistance of soils and polymer-treated soils is measured based on the electrical resistivity correlation of soils. Tests results for soils stabilized with polyacrylamide show that swelling is significantly reduced with increasing the additive content. Moreover, the addition of polymer improves resistivity of soil. Aqueous polyacrylamide can be utilized as an effective stabilization additive to enhance properties of expansive clays. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Utilization of Clay and Clay Composites: Knowledge in Practice)

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20 pages, 4244 KiB

Open AccessEditor’s ChoiceArticle

Geochemical Characteristics of Garnet from Zinc–Copper Ore Bodies in the Changpo–Tongkeng Deposit and Its Geological Significance

by Lei He, Ting Liang, Denghong Wang, Zheng Zhao, Bosheng Liu, Jinggang Gao and Jubiao Cen

Minerals 2023, 13(7), 937; https://doi.org/10.3390/min13070937 - 13 Jul 2023

Cited by 1 | Viewed by 2426

Abstract

The Changpo–Tongkeng tin polymetallic deposit in Dachang, Guangxi, is a world-class, superlarge, polymetallic tin deposit consisting of lower skarn zinc–copper ore bodies and upper tin polymetallic ore bodies. Garnet is the main gangue mineral in the skarn zinc–copper ore bodies and has a [...] Read more.

The Changpo–Tongkeng tin polymetallic deposit in Dachang, Guangxi, is a world-class, superlarge, polymetallic tin deposit consisting of lower skarn zinc–copper ore bodies and upper tin polymetallic ore bodies. Garnet is the main gangue mineral in the skarn zinc–copper ore bodies and has a granular texture. Based on hand specimens and microscopic observations, the existing garnet can be divided into two generations: an early generation (Grt I) and a late generation (Grt II). The results of electron probe microanalysis (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in situ microanalysis show that the contents of SiO₂ and CaO in the garnets from the two generations present limited variations, while the FeO^T and Al₂O₃ contents vary significantly, indicating the grossular–andradite solid solution series (Gro_29–82And_12–69). Compared with Grt I (Gro₇₂And₂₅), Grt II (Gro₃₉And₅₉) is Fe-enriched and oscillatory zoning is developed. The total rare earth element (REE) contents in the two generations of garnet are relatively low, showing light rare earth element (LREE) depletion and heavy rare earth element (HREE) enrichment patterns. Grt II has higher REE content than Grt I and exhibits significant negative Eu anomalies (δEu = 0.18–0.44). The contents and variation characteristics of the major and trace elements in the two generations of garnet suggest that there were variable redox conditions and water/rock ratios in the hydrothermal system during the crystallization process of garnet. In the early stage, skarnization was in a relatively closed and low-oxygen fugacity system, with hydrothermal diffusion metasomatism being dominant, forming homogeneous Grt I lacking well-developed zoning. In the late stage of skarnization, the oxygen fugacity of the ore-forming fluids increased, with infiltration metasomatism being dominant, forming Grt II with well-developed oscillatory zoning. The contents of Sn, As, W, In, and Ge in the garnets are relatively high and increase with the proportion of andradite. Sn in zinc–copper ore bodies mainly exists in the form of isomorphic substitution in garnet, which may be the main reason for the lack of tin ore bodies during the skarn stage. This paper compares the trace element contents in garnets from domestic skarn deposits. The results indicate that the Sn content and δEu in garnet can be used to evaluate the tin-forming potential of skarn deposits. Full article

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21 pages, 4439 KiB

Open AccessEditor’s ChoiceArticle

Geochemistry of the Devonian and Permo-Triassic Black Shales in Peninsular Malaysia: Insights into Provenance, Tectonic Setting, and Source Rock Weathering

by Charles Makoundi, Zakaria Endut and Khin Zaw

Minerals 2023, 13(7), 911; https://doi.org/10.3390/min13070911 - 6 Jul 2023

Cited by 2 | Viewed by 2335

Abstract

Selected Malaysian black shale sequences of the Permo-Triassic and Devonian ages that crop out in the Central Belt were investigated to discuss their chemical composition, provenance, tectonic setting, and weathering history. X-ray fluorescence (XRF) analysis shows that the BRSZ Unit 1 black shale [...] Read more.

Selected Malaysian black shale sequences of the Permo-Triassic and Devonian ages that crop out in the Central Belt were investigated to discuss their chemical composition, provenance, tectonic setting, and weathering history. X-ray fluorescence (XRF) analysis shows that the BRSZ Unit 1 black shale has elevated SiO₂, TiO₂, and K₂O contents compared to the Semantan and Gua Musang black shale. In terms of trace elements, the BRSZ Unit 1 black shale has elevated trace element contents compared to the Semantan and Gua Musang black shales. The BRSZ Unit 1 has the highest V, U, Pb, and Mo contents relative to the other two formations. The Mo content is significant in the BRSZ Unit 1 and is thought to be associated with the elevated total organic carbon (TOC) in the BRSZ Unit 1 black shale. Compared to Post-Archean Australian Shale (PAAS), the BRSZ Unit 1 and Gua Musang black shales are low in Fe₂O₃, MnO, CaO, Na₂O, and P₂O₅. The Semantan black shales are deficient in CaO, K₂O, and P₂O₅ and enriched in MnO. The black shales of BRSZ Unit 1 are enriched in V, Cu, Ga, Rb, Mo, Sn, Pb, and U. Except for Pb (mean: 32.3 ppm), the Gua Musang black shales are largely depleted in trace elements. Similar to the Semantan black shales, all trace element concentrations are largely depleted with the exception of Sc (mean: 22.3 ppm), which is slightly higher. Provenance analysis shows that the BRSZ Unit 1, Semantan, and Gua Musang black shales derived from felsic and intermediate parental source rocks. The BRSZ Unit 1 and Gua Musang black shales indicate a collision setting, whereas the Semantan black shales show affinity to a continental arc setting. The CIA values for all the samples analyzed in this study range between 79.4 and 95.8, indicating an intense chemical weathering in warm and wet paleoclimatic conditions. The average CIW values of samples from the BRSZ Unit 1, Semantan, and Gua Musang are 99.4, 94.5, and 98.6, respectively, implying an intense degree of weathering of the source rocks. Full article

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

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12 pages, 3119 KiB

Open AccessEditor’s ChoiceArticle

Stable Isotope (δ¹⁸O, δD) Composition of Magmatic Fluids Exsolved from an Active Alkaline Magma Chamber—The Case of the AD 79 Magma Chamber of Vesuvius

by Paolo Fulignati and Adrian J. Boyce

Minerals 2023, 13(7), 913; https://doi.org/10.3390/min13070913 - 6 Jul 2023

Viewed by 1830

Abstract

This work documents, for the first time, the calculated oxygen and hydrogen isotope composition of the brines exsolved from the peripheral margin of the active magma alkaline chamber that fed the AD 79 (“Pompei”) eruption of Vesuvius. The exsolved hydrosaline fluids had a [...] Read more.

This work documents, for the first time, the calculated oxygen and hydrogen isotope composition of the brines exsolved from the peripheral margin of the active magma alkaline chamber that fed the AD 79 (“Pompei”) eruption of Vesuvius. The exsolved hydrosaline fluids had a constant δ¹⁸O composition and a variable δD composition, showing a general lowering of δD at nearly constant δ¹⁸O content. We argue that the progressive fluid exsolution at the upper peripheral parts of the AD 79 magma chamber may explain this isotopic path. The modeling of the evolution of the hydrogen isotope composition of water remaining dissolved in the melt, and of the exsolved fluid as a consequence of progressive degassing, would favor multiple fluid-release events from the magmatic reservoir. A schematic model on the pulsed accumulation and release of fluids at the top of the magmatic reservoir prior to the eruption is thus proposed. The assessment of the stable isotope composition of the fluids exsolved from the AD 79 magma chamber of Vesuvius may be particularly relevant for the geochemical surveillance of the volcano as it may help to interpret the isotopic composition of fumarolic gases and its variations. Full article

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

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19 pages, 17677 KiB

Open AccessEditor’s ChoiceArticle

Geochemistry and Geochronology (U-Pb and Lu-Hf) of the Soarinho Alkaline Massif (Brazil): Implications on Mantle versus Crustal Signature of Syenitic Magma

by Daniel Adelino da Silva, Guilherme Loriato Potratz and Mauro Cesar Geraldes

Minerals 2023, 13(7), 904; https://doi.org/10.3390/min13070904 - 3 Jul 2023

Cited by 1 | Viewed by 1489

Abstract

The Soarinho Alkaline Intrusion, southeastern Brazil, makes up part of the Serra do Mar Igneous Province, and it is composed of alkali feldspar syenite, alkali feldspar trachyte, quartz syenite, and monzonite. Geochemical and geochronological analyses of the Soarinho were compared with data from [...] Read more.

The Soarinho Alkaline Intrusion, southeastern Brazil, makes up part of the Serra do Mar Igneous Province, and it is composed of alkali feldspar syenite, alkali feldspar trachyte, quartz syenite, and monzonite. Geochemical and geochronological analyses of the Soarinho were compared with data from its neighbors, Rio Bonito and Tanguá. Zircon U-Pb Laser Ablation ages show that Soarinho is younger than Rio Bonito and Tanguá. Ages obtained from the monzonite (60 ± 2 Ma), alkali feldspar syenite (58 ± 2 Ma), and quartz syenite (58 ± 2 Ma) are indistinguishable within error. One nepheline syenite sample from Tanguá gives an age equal to those of Rio Bonito already published (65 ± 1 Ma). Petrographic and geochemical data show a clear contrast among Soarinho, Rio Bonito, and Tanguá. Lu-Hf isotopic data for the three alkaline intrusions (all negative) point to some similarities in their sources. The data suggest an enriched mantle source for Soarinho; however, an older continental crust contribution cannot be discarded. Full article

(This article belongs to the Special Issue Sm–Nd and Lu–Hf Isotopic Systematics as Tracers of Earth System Processes)

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12 pages, 1607 KiB

Open AccessEditor’s ChoiceArticle

Structural and Thermodynamic Properties of Magnesium-Rich Liquids at Ultrahigh Pressure

by Felipe González-Cataldo and Burkhard Militzer

Minerals 2023, 13(7), 885; https://doi.org/10.3390/min13070885 - 29 Jun 2023

Cited by 2 | Viewed by 1482

Abstract

We explore the structural properties of Mg, MgO, and MgSiO₃ liquids from ab initio computer simulations at conditions that are relevant for the interiors of giant planets, stars, shock compression measurements, and inertial confinement fusion experiments. Using path-integral Monte Carlo and density [...] Read more.

We explore the structural properties of Mg, MgO, and MgSiO₃ liquids from ab initio computer simulations at conditions that are relevant for the interiors of giant planets, stars, shock compression measurements, and inertial confinement fusion experiments. Using path-integral Monte Carlo and density functional theory molecular dynamics, we derive the equation of state of magnesium-rich liquids in the regime of condensed and warm dense matter, with densities ranging from 0.32 to 86.11 g cm⁻³ and temperatures from 20,000 K to 5 × 10⁸ K. We study the electronic structure of magnesium as a function of density and temperature and the correlations of the atomic motion, finding an unexpected local maximum in the pair correlation functions that emerges at high densities which decreases the coordination number of elemental magnesium and reveals a higher packing. This phenomenon is not observed in other magnesium liquids, which maintain a rather constant coordination number. Full article

(This article belongs to the Special Issue First Principles Simulations of Minerals)

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11 pages, 1816 KiB

Open AccessEditor’s ChoiceArticle

Acoustic Sensing of Fresh Feed Disturbances in a Locked-Cycle Laboratory AG/SAG Mill

by Kwaku Boateng Owusu, William Skinner, Christopher Greet and Richmond K. Asamoah

Minerals 2023, 13(7), 868; https://doi.org/10.3390/min13070868 - 27 Jun 2023

Viewed by 1600

Abstract

In a large-scale operation, feed ores are introduced into the AG/SAG mill in a continuous mode at a given flow rate to replace the discharging slurry. Nonetheless, the variations in the feed characteristics, typically hardness and size distribution, could cause sudden disruption to [...] Read more.

In a large-scale operation, feed ores are introduced into the AG/SAG mill in a continuous mode at a given flow rate to replace the discharging slurry. Nonetheless, the variations in the feed characteristics, typically hardness and size distribution, could cause sudden disruption to the mill operation. This would be challenging to detect in practice, owing to the hostile environment of the mill. In this work, an acoustic sensing-based monitoring technique was utilized in a laboratory-scale AG/SAG mill locked-cycle study to keep track of fluctuations caused by feed ore heterogeneity. Analysis of the recorded mill acoustic response using statistical root mean square (RMS) and mill discharge sizes showed that the introduction of fresh feed with varying hardness and size distribution considerably altered the mill product undersize of −150 μm and acoustic emission. Overall, the acoustic sensing technique demonstrated that the AG/SAG mill stability as well as disturbances caused by different feed size fractions and hardness can be monitored using the mill acoustic response, an indication of real-time monitoring and optimisation. Full article

(This article belongs to the Special Issue Recent Developments in Sensors, Machine Learning, Data Analytics, and Process Optimisation in Minerals Processing and Extractive Metallurgy)

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20 pages, 8565 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Three-Dimensional Inversion of Induced Polarization Effects in Airborne Time Domain Electromagnetic Data Using the GEMTIP Model

by Leif H. Cox, Michael S. Zhdanov, Douglas H. Pitcher and Jeremy Niemi

Minerals 2023, 13(6), 779; https://doi.org/10.3390/min13060779 - 7 Jun 2023

Cited by 7 | Viewed by 2478

Abstract

This paper discusses the physical and mathematical principles of the airborne induced polarization (IP) method. The possibility of extracting information about the IP properties of rocks from airborne survey data has become a subject of active research recently. We introduce a method for [...] Read more.

This paper discusses the physical and mathematical principles of the airborne induced polarization (IP) method. The possibility of extracting information about the IP properties of rocks from airborne survey data has become a subject of active research recently. We introduce a method for the joint inversion of the airborne EM data into the electrical conductivity and IP parameters based on the generalized effective-medium theory of induced polarization (GEMTIP). We also present the results of the inversion of the airborne EM data collected over the Echum Project Area, in Northwestern Ontario, Canada, into 3D conductivity and chargeability models. Obtaining IP physical property models from an airborne geophysical survey may result in a paradigm change in mineral exploration by pulling more information and value from airborne EM surveys. Full article

(This article belongs to the Special Issue Feature Papers in Mineral Exploration Methods and Applications 2022)

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21 pages, 8125 KiB

Open AccessEditor’s ChoiceArticle

Agitation Leaching Behavior of Copper–Cobalt Oxide Ores from the Democratic Republic of the Congo

by Chaozhen Zheng, Kaixi Jiang, Zhanmin Cao, Derek O. Northwood, Kristian E. Waters, Haibei Wang, Sanping Liu, Kun’e Zhu and Hao Ma

Minerals 2023, 13(6), 743; https://doi.org/10.3390/min13060743 - 30 May 2023

Cited by 6 | Viewed by 3829

Abstract

Agitation leaching is a promising technology in hydrometallurgy for treating copper–cobalt oxide ores. In this work, the behavior of oxide ores containing around 2.3% Cu and 0.3% Co received from Congo was investigated for varying particle size, acidity, pulp density, temperature, leaching time, [...] Read more.

Agitation leaching is a promising technology in hydrometallurgy for treating copper–cobalt oxide ores. In this work, the behavior of oxide ores containing around 2.3% Cu and 0.3% Co received from Congo was investigated for varying particle size, acidity, pulp density, temperature, leaching time, and reduction potential. XRD, optical microscopy (OM), and ICP-OES methods were used to examine the chemical composition, morphology, and metal content of the samples. The copper and cobalt recovery reached 88.2% and 82.5%, respectively, at room temperature, with a leaching time of 4 h, a pulp density of 33%, an acidity of 178 g/L, and no reductant. The Cu and Co remaining in the leaching residue were found to be in their sulfide forms and coated with dense and fine calcium sulfate. To improve the metal recovery, a combination of flotation and agitation leaching of the flotation tailings method was adopted, after which the Cu and Co recovery reached 96.6% and 86.0%, respectively. Full article

(This article belongs to the Special Issue Surface and Interface Physical Chemistry Applied to Mineral Separation and Element Extraction Processes)

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16 pages, 3473 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Pulp Chemistry Variables for Gaussian Process Prediction of Rougher Copper Recovery

by Bismark Amankwaa-Kyeremeh, Kathy Ehrig, Christopher Greet and Richmond Asamoah

Minerals 2023, 13(6), 731; https://doi.org/10.3390/min13060731 - 27 May 2023

Cited by 3 | Viewed by 1723

Abstract

Insight about the operation of froth flotation through modelling has been in existence since the early 1930s. Irrespective of the numerous industrial models that have been developed over the years, modelling of the metallurgical outputs of froth flotation often do not involve pulp [...] Read more.

Insight about the operation of froth flotation through modelling has been in existence since the early 1930s. Irrespective of the numerous industrial models that have been developed over the years, modelling of the metallurgical outputs of froth flotation often do not involve pulp chemistry variables. As such, this work investigated the influence of pulp chemistry variables (pH, Eh, dissolved oxygen and temperature) on the prediction performance of rougher copper recovery using a Gaussian process regression algorithm. Model performance assessed with linear correlation coefficient (r), root mean square error (RMSE), mean absolute percentage error (MAPE) and scatter index (SI) indicated that pulp chemistry variables are essential in predicting rougher copper recovery, and obtaining r values > 0.98, RMSE values < 0.32, MAPE values < 0.20 and SI values < 0.0034. RNCA feature weights reveal the pulp chemistry relevance in the order dissolved oxygen > pH > Eh > temperature. Full article

(This article belongs to the Special Issue Recent Developments in Sensors, Machine Learning, Data Analytics, and Process Optimisation in Minerals Processing and Extractive Metallurgy)

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33 pages, 34009 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Hydrothermal Alteration in the Nevados de Chillán Geothermal System, Southern Andes: Multidisciplinary Analysis of a Fractured Reservoir

by Diego Morata, Romina Gallardo, Santiago Maza, Gloria Arancibia, Camila López-Contreras, Valentina Mura, Claudia Cannatelli and Martin Reich

Minerals 2023, 13(6), 722; https://doi.org/10.3390/min13060722 - 25 May 2023

Cited by 4 | Viewed by 2949

Abstract

The interplay between a heat source, primary plus secondary permeability, and hydrothermal fluids makes geothermal systems a highly dynamic environment where evolving physico-chemical conditions are recorded in alteration mineralogy. A comprehensive characterization of hydrothermal alteration is therefore essential to decipher the major processes [...] Read more.

The interplay between a heat source, primary plus secondary permeability, and hydrothermal fluids makes geothermal systems a highly dynamic environment where evolving physico-chemical conditions are recorded in alteration mineralogy. A comprehensive characterization of hydrothermal alteration is therefore essential to decipher the major processes associated with geothermal system development. In this study, we defined the hydrothermal mineralogical evolution of the Nevados de Chillán Geothermal System (NChGS), located in the Southern Volcanic Zone (SVZ) of the central Andes, where the regional framework of the system is formed by a direct association with a currently active volcanic complex, a favorable structural control, and vertically inhibited fluid circulation. To characterize the secondary mineralogy present in the NChGS, we integrated optical petrography, Scanning Electron Microscopy (SEM) observations, X-ray Diffraction (XRD) analysis, and microthermometric measurements along a drill core with a depth of 1000 m at the Nieblas-1 well. These mineralogical approaches were combined with a structural field analysis to highlight the relevance of multidisciplinary study in understanding active geothermal systems. The results indicated that the evolution of the system involved four paragenetic stages, with the main processes in each phase being the heating, boiling, and mixing of fluids and re-equilibration to new physico-chemical conditions. Additionally, three hydrothermal zones were recognized: an upper argillic section, an intermediate sub-propylitic zone, and a deep propylitic domain. Sampled thermal springs are characterized by pH values of 2.4–5.9 and high SO₄⁼ concentrations (>290 ppm). These acid-sulfate steam-heated waters suggest the contribution of primary magmatic volatiles to the hydrothermal system. Alunite recorded in the alteration halos of veinlets presents at depths of 170–230 m denote the circulation of acidic fluids at these levels which were favored by reverse faults. These findings indicate that, at this depth range, the condensation of magmatic volatiles into shallow aquifers controls the recharge area of the superficial thermal manifestations. Conversely, deep-seated hydrothermal fluids correspond to near-neutral chloride fluids, with salinities ranging from 0.1 to 6.9 wt.% NaCl eq. The distribution of illite/smectite and chlorite/smectite mixed-layered minerals outline the presence of a significant clay cap, which, in this system, separates the steam-heated domain from the deep hydrothermal realm and restricts fluid circulation to existing permeable channels. Our mineralogical and structural study provides critical data for the interpretation of heat–fluid–rock interaction processes in the NChGS. The interplay between hydrothermal fluids and active faults is also discussed in the context of the complex of geological processes in active geothermal systems along the Chilean Southern Volcanic Zone. Full article

(This article belongs to the Special Issue Fluid Geochemistry and Mineralogy in Volcanic/Hydrothermal Environments)

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12 pages, 6001 KiB

Open AccessEditor’s ChoiceArticle

Study on the Aeromagnetic System between Fixed-Wing UAV and Unmanned Helicopter

by Yong-Zai Xi, Gui-Xiang Liao, Ning Lu, Yong-Bo Li and Shan Wu

Minerals 2023, 13(5), 700; https://doi.org/10.3390/min13050700 - 20 May 2023

Cited by 3 | Viewed by 3278

Abstract

Based on the CH-3 and WH-110A unmanned aerial vehicle (UAV) platforms, we independently developed aeromagnetic systems for fixed-wing UAVs (FUAV) and modified unmanned helicopters (MUH), respectively. These systems overcome key technological challenges in system integration, aeromagnetic compensation, and electromagnetic (EM) compatibility. We conducted [...] Read more.

Based on the CH-3 and WH-110A unmanned aerial vehicle (UAV) platforms, we independently developed aeromagnetic systems for fixed-wing UAVs (FUAV) and modified unmanned helicopters (MUH), respectively. These systems overcome key technological challenges in system integration, aeromagnetic compensation, and electromagnetic (EM) compatibility. We conducted a 1:100,000 aeromagnetic test using both systems in a tidal flat area in Jiangsu province, China. Both systems successfully completed 240 line km measurement lines and collected high-quality data with magnetic compensation accuracies of 0.01428 nT and 0.04690 nT, respectively. The dynamic noise was below 0.14 nT, accounting for 95.72% and 100% of the measurements. These results indicate that both systems offer high measurement accuracy, efficiency, low cost, convenience, and flexibility. We compared the two aeromagnetic systems based on their system parameters, integration modes, magnetic compensation methods and effects, and practical applications. By comprehensively analyzing their characteristics and application fields, we provide guidance for UAV-based aeromagnetic surveys in mineral exploration, basic geological survey and other related fields. And the FUAV and MUH aeromagnetic systems presented in this paper serve as a valuable reference for future research in this area. Full article

(This article belongs to the Special Issue Gravity and Magnetic Methods in Mineral Exploration)

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31 pages, 33833 KiB

Open AccessEditor’s ChoiceArticle

Mineralogy, Geochemistry, and Genesis of Agates from Chihuahua, Northern Mexico

by Maximilian Mrozik, Jens Götze, Yuanming Pan and Robert Möckel

Minerals 2023, 13(5), 687; https://doi.org/10.3390/min13050687 - 18 May 2023

Cited by 4 | Viewed by 3886

Abstract

The present study aimed to investigate the genesis and characteristics of some of the world-famous agate deposits in the state of Chihuahua, Mexico (Rancho Coyamito, Ojo Laguna, Moctezuma, Huevos del Diablo, Agua Nueva). Geochemical and textural studies of host rocks showed that all [...] Read more.

The present study aimed to investigate the genesis and characteristics of some of the world-famous agate deposits in the state of Chihuahua, Mexico (Rancho Coyamito, Ojo Laguna, Moctezuma, Huevos del Diablo, Agua Nueva). Geochemical and textural studies of host rocks showed that all the studied deposits are related to the same rock type within the geological unit of Rancho el Agate andesite, a quartz-free latite that shows clear indications of magma mixing. As a result of their large-scale distribution and various differentiation processes, as well as transport separation, different textures and local chemical differences between rocks of different localities can be observed. These differences have also influenced the properties of SiO₂ mineralization in the rocks. The mixing of near-surface fluids from rock alterations with magmatic hydrothermal solutions led to the accumulation of various elements in the SiO₂ matrix of the agates, which were, on the one hand, mobilized during secondary rock alteration (Fe, U, Ca, K, Al, Si) and, on the other hand, transported with magmatic fluids (Zn, Sb, Si, Zr, Cr). Different generations of chalcedony indicate a multi-stage formation as well as multiple cycles of filling the cavities with fluids. The hydrothermal fluids are presumably related to the residual solutions of a rhyolitic volcanism, which followed the latitic extrusions in the area and probably caused the formation of polymetallic ore deposits in the Chihuahua area. The enrichment of highly immobile elements indicates the involvement of volatile fluids in the agate formation. The vivid colors of the agates are almost exclusively due to various mineral inclusions, which consist mainly of iron compounds. Full article

(This article belongs to the Special Issue Mineralogy, Geochemistry, and Origin of Agate: An Ongoing Challenge)

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14 pages, 5951 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Melting Behaviour under Pressure of Kaolinite Clay: A Nanoscale Study

by Brahim Khalil Benazzouz and Ali Zaoui

Minerals 2023, 13(5), 679; https://doi.org/10.3390/min13050679 - 16 May 2023

Cited by 2 | Viewed by 2182

Abstract

In this study, the curves of variation of melting temperature as a function of pressure were determined for pressures up to 20 GPa using molecular dynamics (MD) calculations. The CLAYFF force field is used for the simulated PT curve of the clay kaolinite [...] Read more.

In this study, the curves of variation of melting temperature as a function of pressure were determined for pressures up to 20 GPa using molecular dynamics (MD) calculations. The CLAYFF force field is used for the simulated PT curve of the clay kaolinite structure. For this purpose, we have adopted the Z-method to determine the melting point (Tm) and superheat limit temperature (TLS) for different densities in kaolinite clay. In addition, various quantities, such as the radial distribution function (RDF), the mean square displacement (MSD), and the diffusion coefficient were evaluated in order to ensure the solid behaviour at the superheat limit temperature and the liquid behaviour at the melting point for the equilibrated structure of kaolinite. Full article

(This article belongs to the Special Issue Feature Papers in Clays and Engineered Mineral Materials)

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34 pages, 31258 KiB

Open AccessEditor’s ChoiceArticle

Mineralogy and Distribution of REE in Oxidised Ores of the Mount Weld Laterite Deposit, Western Australia

by Nigel J. Cook, Cristiana L. Ciobanu, Benjamin P. Wade, Sarah E. Gilbert and Robert Alford

Minerals 2023, 13(5), 656; https://doi.org/10.3390/min13050656 - 10 May 2023

Cited by 13 | Viewed by 5345

Abstract

The Mount Weld rare earth element (REE) deposit, Western Australia, is one of the largest of its type on Earth. Current mining exploits the high-grade weathered goethite-bearing resource that lies above, and which represents the weathering product of a subjacent carbonatite. The mineralogy, [...] Read more.

The Mount Weld rare earth element (REE) deposit, Western Australia, is one of the largest of its type on Earth. Current mining exploits the high-grade weathered goethite-bearing resource that lies above, and which represents the weathering product of a subjacent carbonatite. The mineralogy, petrography, deportment of lanthanides among the different components, and variation in mineral speciation, textures, and chemistry are examined. Microanalysis, involving scanning electron microscope (SEM) imaging, electron probe microanalysis (EPMA) and laser ablation inductively coupled-plasma mass spectrometry (LA-ICP-MS), was conducted on sized fractions of three crushed and ground laterite ore samples from current and planned production, and a representative sample from the underlying carbonatite. High-magnification imaging of particles in laterite samples show that individual REE-bearing phases are fine-grained and extend in size well below the micron-scale. Nanoscale inclusions of REE-phosphates are observed in apatite, Fe-(Mn)-(hydr)oxides, and quartz, among others. These have the appearance, particularly in fluorapatite, of pervasive, ultrafine dusty domains. Apart from the discrete REE minerals and abundant nano- to micron-scale inclusions in gangue, all ore components analysed by LA-ICP-MS contain trace to minor levels of REEs within their structures. This includes apatite, where low levels of REE are confirmed in preserved igneous apatite, but also Fe- and Mn-(hydr)oxides in which concentrations of hundreds, even thousands of ppm are measured. This is significant given that Fe-(Mn)-(hydr)oxides are the most abundant component of the laterite and points to extensive mobility and redistribution of REEs, and especially HREE, during progressive lateritisation. Late-formed minerals, notably tiny grains of cerianite, reflect a shift to oxidising conditions. REE-fluorocarbonates are the main host for REEs in carbonatite and are systematically replaced by hydrated, Ca-bearing REE-phosphates (largely rhabdophane). The latter displays varied compositions but is characteristically enriched in HREE relative to monazite in the same sample. Fine-grained, compositionally heterogeneous rhabdophane is accompanied by minor amounts of other paragenetically late, hydrated phosphates with enhanced MREE/HREE relative to LREE (although still LREE-dominant). Minor, relict xenotime and zircon are significant HREE carriers. Ilmenite and pyrochlore group members contain REE but contribute only negligibly to the overall REE budget. Although the proportions of individual mineral species differ, the chemistry of key ore components are similar in different laterite samples from the current resource. Mineral signatures are, however, subtly different in the lower grade southeastern part of the deposit, including higher concentrations of HREE relative to LREE in monazite, rhabdophane, florencite and Fe-(Mn)-(hydr)oxides. Full article

(This article belongs to the Special Issue Origin, Mobility and Concentration of the Rare Earth Elements in the Crust)

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10 pages, 1625 KiB

Open AccessEditor’s ChoiceArticle

Recovered Fly Ashes as an Anthropogenic Raw Material

by Alicja Uliasz-Bocheńczyk and Eugeniusz Mokrzycki

Minerals 2023, 13(5), 623; https://doi.org/10.3390/min13050623 - 29 Apr 2023

Cited by 3 | Viewed by 1881

Abstract

Poland is a country where the commercial power industry mainly uses coal to produce energy. As a result of energy production processes, by-products of combustion are generated, primarily fly ashes. In Poland, these are mostly obtained from conventional coal combustion boilers. Fly ashes [...] Read more.

Poland is a country where the commercial power industry mainly uses coal to produce energy. As a result of energy production processes, by-products of combustion are generated, primarily fly ashes. In Poland, these are mostly obtained from conventional coal combustion boilers. Fly ashes from coal combustion account for 1.2% of all industrial waste generated in Poland. In addition, fly ashes are produced by fluidized-bed boilers. These are classified as a mixture of fly ashes and solid calcium-based reaction waste from flue-gas desulphurization, and constitute almost 2% of Polish industrial waste. This paper describes the amounts of fly ashes generated in Poland and considers activities related to their recovery and disposal. The high recovery levels of fly ashes (about 90%) and fluidized ashes (about 98%) mean that these waste products can also be considered anthropogenic raw materials. The use of these materials in the cement industry is an example of industrial symbiosis. Such usage benefits not only the economy but also the environment and, therefore, society as a whole. To describe the use of recovered fly ashes in cement plants, the authors use the anthropogenicity index, which characterizes the level of technological advancement and the substitutability of primary raw materials for secondary raw materials. Full article

(This article belongs to the Special Issue Fly Ashes: Characterization, Processing and Utilization)

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19 pages, 14163 KiB

Open AccessEditor’s ChoiceArticle

Petrogenesis of Early Triassic Felsic Volcanic Rocks in the East Kunlun Orogen, Northern Tibet: Implications for the Paleo-Tethyan Tectonic and Crustal Evolution

by Dongdong Yan, Zhiqiang Chu, Zhongyuan Liu, Wei Wang and Fuhao Xiong

Minerals 2023, 13(5), 607; https://doi.org/10.3390/min13050607 - 27 Apr 2023

Cited by 2 | Viewed by 2283

Abstract

The felsic volcanic rocks in orogenic belts are vital probes to understand the tectonic evolution and continental crust growth. Here, we present a comprehensive study on the zircon U–Pb geochronology, whole-rock geochemistry, and zircon Lu-Hf isotopes of Early felsic volcanic rocks from the [...] Read more.

The felsic volcanic rocks in orogenic belts are vital probes to understand the tectonic evolution and continental crust growth. Here, we present a comprehensive study on the zircon U–Pb geochronology, whole-rock geochemistry, and zircon Lu-Hf isotopes of Early felsic volcanic rocks from the Hongshuichuan Formation, East Kunlun Orogen, Northern Tibet, aiming to explore their petrogenesis and implications for the Paleo-Tethyan orogeny and crustal evolution. The studied felsic volcanics comprise rhyolite porphyry and rhyolite, exhibiting coeval zircon U–Pb ages of ca. 247–251 Ma. Rhyolite porphyries show metaluminous to peraluminous nature (A/CNK = 0.88–1.24) with high SiO₂ contents (72.1–78.9 wt%) and moderate Mg^# values (22–40), and they display enrichment of LREE with (La/Yb)_N ratios of 6.02–17.9 and depletion of high field strength elements. In comparison, the rhyolites are strongly peraluminous (A/CNK = 1.09–1.74) with high SiO₂ contents (71.7–74.3 wt%) and high Mg^# values (43–52) and are also enriched in LREE ((La/Yb)_N of 6.65–18.4) and depleted in HFSE (e.g., Nb, Ta, Ti). Combining with their different zircon Lu-Hf isotopes, i.e., enriched isotopes for the rhyolite porphyries (εHf(t) = −7.3 to −3.8) and depleted Hf isotopes for the rhyolites (ɛHf = −0.6 to +3.0), we interpret that the studied rhyolite porphyries and rhyolites were derived by partial melting of Mesoproterozoic metagreywacke sources followed by plagioclase-dominated fractional crystallization, but the latter shows the significant contribution of crust–mantle magma mixing. The mixed mantle-derived magma comes from an enriched lithospheric mantle source that had been metasomatized by subduction-related fluids. Combining with other geological evidence, we propose that the studied Early Triassic felsic volcanic rocks were formed in a subduction arc setting, and the reworking of ancient continental crust with crust–mantle magma mixing is the major mechanism of crustal evolution in the East Kunlun Paleo-Tethyan orogenic belt. Full article

(This article belongs to the Special Issue Tectono-Magmatic Evolution and Metallogeny of Tethyan Orogenic Belts)

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18 pages, 10029 KiB

Open AccessEditor’s ChoiceArticle

Preparation and Properties of Phosphoric Acid-Based Porous Geopolymer with High Magnesium Nickel Slag and Fly Ash

by Xingchun Yang, Yuan Wu, Zhigao Sun, Yufeng Li, Dongsheng Jia, Dongliang Zhang, Dehua Xiong and Mitang Wang

Minerals 2023, 13(4), 564; https://doi.org/10.3390/min13040564 - 17 Apr 2023

Cited by 7 | Viewed by 3167

Abstract

Phosphoric acid-based porous geopolymers were prepared by two different foaming agents (H₂O₂ and Al powder) with phosphoric acid as the activator. High-magnesium nickel slag (HMNS) and fly ash (FA) were the precursor combination. The effects of foaming agent types and [...] Read more.

Phosphoric acid-based porous geopolymers were prepared by two different foaming agents (H₂O₂ and Al powder) with phosphoric acid as the activator. High-magnesium nickel slag (HMNS) and fly ash (FA) were the precursor combination. The effects of foaming agent types and contents on the properties of HMNS-FA-phosphate-based porous geopolymers were investigated in terms of dry density, pore structure, compressive strength, thermal conductivity, and water absorption. The phase was analyzed by x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). It was found that both foaming agents could successfully prepare porous geopolymers, and the compressive strength and dry density of porous geopolymers gradually decreased and the low-thermal conductivity and water absorption gradually increased with the increase in foaming agent content. The foaming agents formed porous structures inside porous geopolymers but did not affect the phases of geopolymerization reactions. This study demonstrates that both foaming agents can be used to prepare HMNS-FA-phosphate-based porous geopolymers for the application of phosphate-activated geopolymers in the direction of refractory materials. Full article

(This article belongs to the Special Issue Metallurgical Solid Waste: Mineralogy, Chemistry and Application/Treatment)

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26 pages, 8815 KiB

Open AccessEditor’s ChoiceArticle

Timing of Transition from Proto- to Paleo-Tethys: Evidence from the Early Devonian Bimodal Volcanics in the North Qaidam Tectonic Belt, Northern Tibetan Plateau

by Mao Wang, Xianzhi Pei, Ruibao Li, Lei Pei, Zuochen Li, Chengjun Liu, Lili Xu and Hao Lin

Minerals 2023, 13(4), 532; https://doi.org/10.3390/min13040532 - 10 Apr 2023

Cited by 3 | Viewed by 2274

Abstract

The transition from the Proto- to the Paleo-Tethys is still a controversial issue. This study reports a new petrology, zircon U–Pb geochronology, and whole-rock geochemistry of volcanic rocks from the Maoniushan Formation in the Nankeke area, northern Qaidam (NQ) of the Tibetan Plateau, [...] Read more.

The transition from the Proto- to the Paleo-Tethys is still a controversial issue. This study reports a new petrology, zircon U–Pb geochronology, and whole-rock geochemistry of volcanic rocks from the Maoniushan Formation in the Nankeke area, northern Qaidam (NQ) of the Tibetan Plateau, to provide new evidence for the transition from the Proto- to the Paleo-Tethys oceans. The volcanic suite consists mainly of rhyolitic crystal lithic tuff lavas and minor basalts. Zircon U–Pb data indicate that the bimodal volcanic rocks were formed during the Early Devonian (ca. 410–409 Ma). Geochemically, the basalts have low contents of SiO₂ (48.92 wt.%–51.19 wt.%) and relatively high contents of MgO (8.94 wt.%–9.99 wt.%), TiO₂ (1.05 wt.%–1.29 wt.%), K₂O (2.35 wt.%–4.17 wt.%), and K₂O/Na₂O ratios (1.04–2.56), showing the characteristics of calc-alkaline basalts. Their rare earth element (REE) patterns and trace element spider diagrams are characterized by enrichments in LREEs (LREE/HREE = 18.31–21.34) and large ion lithophile elements (LILEs; Rb, Th, and K) and depletion in high-field-strength elements (HFSEs; Nb, Ta, P, and Ti), with slight negative Eu anomalies (Eu/Eu* = 0.82–0.86), which are similar to Etendeka continental flood basalts (CFB). These features suggest that the basalts were most likely derived from low degree (1%–5%) partial melting of the asthenospheric mantle, contaminated by small volumes of continental crust. In contrast, the felsic volcanics have high SiO₂ (68.41 wt.%–77.12 wt.%), variable Al₂O₃ (9.56 wt.%–12.62 wt.%), low MgO, and A/CNK ratios mostly between 1.08 and 1.15, defining their peraluminous and medium-K calc-alkaline signatures. Their trace element signatures show enrichments of LREEs and LILEs (e.g., Rb, Th, U, K, and Pb), depletion of HFSEs (e.g., Nb, Ti, Ta, and P), and negative Eu anomalies (Eu/Eu* = 0.22–0.66). These features suggest that the felsic volcanics were derived from partial melting of the middle crust, without interaction with mantle melts. Considering all the previous data and geochemical features, the Maoniushan Formation volcanic rocks in NQ formed in a post-collisional extensional setting associated with asthenospheric mantle upwelling and delamination in the Early Devonian. Together with the regional data, this study proposed that the Proto-Tethys Ocean had closed and evolved to the continental subduction/collision orogeny stage during the Middle to Late Ordovician, evolved to the post-collisional extensional stage in the Early Devonian, and finally formed the Zongwulong Ocean (branches of the Paleo-Tethys Ocean) in the Late Carboniferous, forming the tectonic framework of the Paleo-Tethys Archipelagic Ocean in the northern margin of the Tibetan Plateau. Full article

(This article belongs to the Special Issue Petrology, Geochemistry and Isotopes of Ophiolite and Granites in Kunlun Orogen and Adjacent Area)

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19 pages, 11662 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Fe(III) Biomineralization in the Surface Microlayer of Acid Mine Waters Catalyzed by Neustonic Fe(II)-Oxidizing Microorganisms

by Javier Sánchez-España, Andrey M. Ilin, Iñaki Yusta, Charlotte M. van der Graaf and Irene Sánchez-Andrea

Minerals 2023, 13(4), 508; https://doi.org/10.3390/min13040508 - 1 Apr 2023

Cited by 4 | Viewed by 3242

Abstract

The formation of thin mineral films or encrustations floating on the water surface of low-flow or stagnant zones of acid mine drainage (AMD)-affected streams is probably among the most exotic features that can be found in mining areas. However, most fundamental questions about [...] Read more.

The formation of thin mineral films or encrustations floating on the water surface of low-flow or stagnant zones of acid mine drainage (AMD)-affected streams is probably among the most exotic features that can be found in mining areas. However, most fundamental questions about their origin (biotic vs. abiotic), structure, mineralogy, physical stability and metal-retention capacity remain unanswered. This study aims to reveal the factors promoting their formation and to clarify their composition in detail. With this purpose, the major mineral phases were studied with XRD in surface film samples found in different mine sites of the Iberian Pyrite Belt mining district (SW Spain), and the major oxide and trace metal concentrations were measured with XRF and/or ICP-MS. Fe(III) minerals dominated these formations, with mineralogy controlled by the pH (jarosite at pH~2.0, schwertmannite at pH 2.5–3.5, ferrihydrite at pH > 6.0). Other minerals have also been identified in minor proportions, such as brushite or khademite. These mineral formations show an astounding capacity to concentrate, by orders of magnitude (×10² to ×10⁵), many different trace metals present in the underlying aqueous solutions, either as anionic complexes (e.g., U, Th, As, Cr, V, Sb, P) or as divalent metal cations (e.g., Cu, Zn, Cd, Pb). These floating mineral films are usually formed in Fe(II)-rich acidic waters, so their formation necessarily implies the oxidation of Fe(II) to Fe(III) phases. The potential involvement of Fe(II)-oxidizing microorganisms was investigated through 16S rRNA gene amplicon sequencing of water underneath the Fe(III)-rich floating mineral films. The sequenced reads were dominated by Ferrovum (51.7 ± 0.3%), Acidithiobacillus (18.5 ± 0.9%) and Leptospirillum (3.3 ± 0.1%), three well-known Fe(II)-oxidizing genera. These microorganisms are major contributors to the formation of the ferric mineral films, although other genera most likely also play a role in aspects such as Fe(III) sequestration, nucleation or mineral growth. The floating mineral films found in stagnant acidic mine waters represent hotspots of biosphere/hydrosphere/atmosphere interactions of great value for the study of iron biogeochemistry in redox boundaries. Full article

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

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16 pages, 15588 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Characterization of Alkali Activated Materials Prepared from Continuous Attrition and Ball Milled Fly Ashes

by Jadambaa Temuujin, Batmunkh Davaabal, Ulambayar Rentsennorov, Enkhtur Odbaatar, Dashnyam Enkhbayar, Tserendagva Tsend-Ayush, Sunjidmaa Danzandorj, Claus Henning Ruescher and Kenneth J. D. MacKenzie

Minerals 2023, 13(4), 490; https://doi.org/10.3390/min13040490 - 30 Mar 2023

Cited by 5 | Viewed by 1588

Abstract

Mechanical activation is known to greatly influence the reactivity of fly ashes. In this paper, we report a comparative study of the properties of alkali-activated geopolymer materials prepared using both ball-milled and attrition-milled fly ashes. Ball milling was carried out for 30 min [...] Read more.

Mechanical activation is known to greatly influence the reactivity of fly ashes. In this paper, we report a comparative study of the properties of alkali-activated geopolymer materials prepared using both ball-milled and attrition-milled fly ashes. Ball milling was carried out for 30 min and 60 min while attrition milling was carried out continuously in a high-speed attritor. The surface area of the raw fly ash decreased from 4017 cm²/g to 3999 cm²/g and 3912 cm²/g after ball milling for 30 min and 60 min, respectively. By contrast, the surface area of the continuously attrition-milled fly ash increased to 5545 cm²/g. Fly ash processed by continuous attrition milling showed a 50% particle size reduction to 25–38 μm, whereas fly ash ball-milled for 30 and 60 min was reduced in size by 33.4 and 42.9%. The milled fly ash samples were activated with 8 M NaOH solution and cured at 40 °C for 68 h. After curing, the samples were maintained at room temperature, and their 7-, 14-, and 28-day compressive strengths were measured. The compressive strength of the attrition-milled 28-day geopolymer paste was 24.6 MPa; that of the geopolymers ball-milled for 30 and 60 min was 23.37 MPa and 17.58 MPa, respectively; and that of the unmilled control geopolymer fly-ash-based paste was 17 MPa. The improvement in the mechanical properties is attributed to the increased gel formation resulting from the increased surface area (decreased particle size) in the fly ash glass starting material. Full article

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

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21 pages, 9191 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Soil Contaminated with Hazardous Waste Materials at Rio Tinto Mine (Spain) Is a Persistent Secondary Source of Acid and Heavy Metals to the Environment

by Sandra Fernández-Landero, Juan Carlos Fernández-Caliani, María Inmaculada Giráldez, Emilio Morales, Cinta Barba-Brioso and Isabel González

Minerals 2023, 13(4), 456; https://doi.org/10.3390/min13040456 - 23 Mar 2023

Cited by 9 | Viewed by 3384

Abstract

Mineralogical analysis and laboratory-based leaching tests coupled with speciation modeling were undertaken to quantify the potential for short-term acid generation and the release of trace elements from soils heavily contaminated with mine waste at Rio Tinto. Three different waste materials were considered as [...] Read more.

Mineralogical analysis and laboratory-based leaching tests coupled with speciation modeling were undertaken to quantify the potential for short-term acid generation and the release of trace elements from soils heavily contaminated with mine waste at Rio Tinto. Three different waste materials were considered as case studies: roasted pyrite, copper slags, and leached sulfide ores. The results showed elevated values of net acid generation (up to 663 mmol H⁺/kg), the major pools being potential sulfidic acidity and acidity retained in jarosite. Remarkable contents of As and toxic heavy metals were found especially in the slag-contaminated soil. Copper, Zn, and Pb were the most abundant metals in the acid leach solutions resulting from mine soil-water interaction, with peak values of 55.6 mg L⁻¹, 2.77 mg L⁻¹, and 2.62 mg L⁻¹, respectively. Despite the high total contents of trace elements occurring in soil, the mobile fraction was limited to maximum release values of 12.60% for Cd and 10.27% for Cu, according to the test leaching. Speciation calculations indicated that free metal ions (M²⁺) and sulfate species (MSO₄⁰) accounted for most of the dissolved load. Acid soil drainage is a secondary source of acid and heavy metals in the mine site and, therefore, an effective land reclamation program should ensure that acidity and metal mobility are reduced to environmentally sustainable levels. Full article

(This article belongs to the Special Issue Mobility of Potentially Toxic Elements: Environmental Hazards)

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20 pages, 3154 KiB

Open AccessEditor’s ChoiceReview

Treatment Technology and Research Progress of Residual Xanthate in Mineral Processing Wastewater

by Jiaqiao Yuan, Suqi Li, Zhan Ding, Jie Li, Anmei Yu, Shuming Wen and Shaojun Bai

Minerals 2023, 13(3), 435; https://doi.org/10.3390/min13030435 - 18 Mar 2023

Cited by 28 | Viewed by 4445

Abstract

Xanthate is the most widely used and effective collector in the flotation of sulfide minerals. However, the residual xanthate in flotation wastewater may cause serious environmental pollution and even human health hazards. At present, a variety of treatment technologies have been developed to [...] Read more.

Xanthate is the most widely used and effective collector in the flotation of sulfide minerals. However, the residual xanthate in flotation wastewater may cause serious environmental pollution and even human health hazards. At present, a variety of treatment technologies have been developed to degrade xanthate pollutants in wastewater, with the aim of meeting safe discharge standards. This work reviews the research status of xanthate wastewater treatment technologies in recent years. Treatment technologies are evaluated, including coagulation flocculation, adsorption, microbiological, Fenton, ozone oxidation, and photocatalytic methods. The reaction mechanisms and advantages, as well as disadvantages, of the various treatment technologies are summarized. Future research on the treatment of xanthate wastewater should focus on combined methods, which will be conducive to achieving a high efficiency and low cost, with no secondary pollution, and with the aim of generating further original and innovative technologies. Full article

(This article belongs to the Special Issue Clean Utilization of Nonferrous Metal Resources)

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15 pages, 4047 KiB

Open AccessEditor’s ChoiceArticle

Cementitious Backfill with Partial Replacement of Cu-Rich Mine Tailings by Sand: Rheological, Mechanical and Microstructural Properties

by Nihat Utku Guner, Erol Yilmaz, Muhammet Sari and Tugrul Kasap

Minerals 2023, 13(3), 437; https://doi.org/10.3390/min13030437 - 18 Mar 2023

Cited by 20 | Viewed by 2758

Abstract

The thinning of tailings gradation during ore processing leads to a sizeable fall in the strength of cementitious paste backfill (CPB), increases operational risks, and encourages researchers to use alternative economic products. This study aims to increase the strength performance by improving CPB’s [...] Read more.

The thinning of tailings gradation during ore processing leads to a sizeable fall in the strength of cementitious paste backfill (CPB), increases operational risks, and encourages researchers to use alternative economic products. This study aims to increase the strength performance by improving CPB’s gradation while cutting costs and reducing the sum of the binder employed per unit volume. An evolution of the slump/strength/structural properties of sand-substituted CPBs was explored experimentally. Samples were made with a fixed cement content (7 wt.%), diverse tailings/sand fractions (e.g., 100/0, 90/10, 80/20, 70/30, and 50/50), and diverse solid contents (e.g., 72 and 76 wt.%). After curing for 3–56 days, several experiments, such as slump, uniaxial compressive strength (UCS), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM), were undertaken for the filling samples. The results demonstrate that adding sand to the backfill greatly increases CPB’s strength (up to 99%), but the replacement rate of sand was limited to 30% due to its segregation effect. Microstructural tests reveal that CPB’s void volume decreases as the added amount of sand increases. To sum up, it was concluded that calcareous sand made a major contribution to the filling strength, incorporating the effects of enhancing the fill gradation’s readjustment and reducing the sum of cement being used in the unit volume for CPB manufacturing. Full article

(This article belongs to the Special Issue Solid-Filling Technology in Coal Mining)

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17 pages, 13739 KiB

Open AccessEditor’s ChoiceArticle

Rheological and Strength Properties of Steel-Slag Cemented Paste Backfill: Link to Gypsum Type and Dosage

by Fan Wu, Bolin Xiao and Faguang Yang

Minerals 2023, 13(3), 421; https://doi.org/10.3390/min13030421 - 16 Mar 2023

Cited by 5 | Viewed by 2003

Abstract

This paper aims to study the effects of gypsum type and dosage on the rheological and strength properties of steel-slag cemented paste backfill (SSB-CPB) using fluorogypsum (FG), phosphogypsum (PG), and desulfurization gypsum (DG). Experimental results indicate that the yield stress and the viscosity [...] Read more.

This paper aims to study the effects of gypsum type and dosage on the rheological and strength properties of steel-slag cemented paste backfill (SSB-CPB) using fluorogypsum (FG), phosphogypsum (PG), and desulfurization gypsum (DG). Experimental results indicate that the yield stress and the viscosity of fresh SSB-CPB are the smallest when using FG, followed by PG, and the highest when using DG. The strength of hardened SSB-CPB is the lowest when using PG, regardless of curing time, and is the highest when using DG after 3 and 7 days of curing or FG after 14 and 28 days of curing. With the increase of DG dosage, yield stress and viscosity of fresh CPB increase, while the strength of hardened CPB first increases and then decreases. For the rheological properties, the zeta potential changes the yield stress of fresh SSB-CPB, while the internal particle size and pH affect its viscosity. For the strength property, regardless of the effect of gypsum type or dosage, the changes in the results of microscopic experiments for hardened paste and SSB-CPB are critical indicators that the strength of SSB-CPB varies. When steel slag dosage is 35%, the best gypsum dosage is 24% and gypsum type is DG in the SSB for backfill. The findings of this study contribute to an enhanced understanding of the backfill binder material, which has beneficials of lower greenhouse gas emission, avoidance of natural raw materials excavation, saving environmental taxes, and reducing backfill costs. Full article

(This article belongs to the Special Issue Cemented Mine Waste Backfill: Experiment and Modelling)

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22 pages, 851 KiB

Open AccessEditor’s ChoiceReview

Potential Future Alternative Resources for Rare Earth Elements: Opportunities and Challenges

by Vysetti Balaram

Minerals 2023, 13(3), 425; https://doi.org/10.3390/min13030425 - 16 Mar 2023

Cited by 57 | Viewed by 14840

Abstract

Currently, there is an increasing industrial demand for rare earth elements (REE) as these elements are now integral to the manufacture of many carbon-neutral technologies. The depleting REE ores and increasing mining costs are prompting us to consider alternative sources for these valuable [...] Read more.

Currently, there is an increasing industrial demand for rare earth elements (REE) as these elements are now integral to the manufacture of many carbon-neutral technologies. The depleting REE ores and increasing mining costs are prompting us to consider alternative sources for these valuable metals, particularly from waste streams. Although REE concentrations in most of the alternative resources are lower than current REE ores, some sources including marine sediments, coal ash, and industrial wastes, such as red mud, are emerging as promising with significant concentrations of REE. This review focuses on the alternative resources for REE, such as ocean bottom sediments, continental shelf sediments, river sediments, stream sediments, lake sediments, phosphorite deposits, industrial waste products, such as red mud and phosphogypsum, coal, coal fly ash and related materials, waste rock sources from old and closed mines, acid mine drainage, and recycling of e-waste. Possible future Moon exploration and mining for REE and other valuable minerals are also discussed. It is evident that REE extractions from both primary and secondary ores alone are not adequate to meet the current demand, and sustainable REE recovery from the alternative resources described here is also necessary to meet the growing REE demand. An attempt is made to identify the potential of these alternative resources and sustainability challenges, benefits, and possible environmental hazards to meet the growing challenges of reaching the future REE requirements. Full article

(This article belongs to the Special Issue Rare Earth Elements: Occurrence, Exploration, Alternate Resources, Extraction Techniques, Chemical Characterization and Recycling)

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14 pages, 3295 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

KOH-Based Hydrothermal Synthesis of Iron-Rich Titanate Nanosheets Assembled into 3D Hierarchical Architectures from Natural Ilmenite Mineral Sands

by Karina J. Lagos, Bojan A. Marinkovic, Anja Dosen, Alexis Debut, Karla Vizuete, Victor H. Guerrero, Emilio Pardo and Patricia I. Pontón

Minerals 2023, 13(3), 406; https://doi.org/10.3390/min13030406 - 15 Mar 2023

Cited by 1 | Viewed by 2377

Abstract

The synthesis of titanate nanostructures from low-cost mineral precursors is a topic of continuous interest, considering not only their fundamental aspects but also the benefits of incorporating such nanomaterials in a wide variety of applications. In this work, iron-rich titanate nanosheets were synthesized [...] Read more.

The synthesis of titanate nanostructures from low-cost mineral precursors is a topic of continuous interest, considering not only their fundamental aspects but also the benefits of incorporating such nanomaterials in a wide variety of applications. In this work, iron-rich titanate nanosheets were synthesized from Ecuadorian ilmenite sands (ilmenite–hematite solid solution-IHSS) through an alkaline hydrothermal treatment (AHT) using potassium hydroxide (KOH). The effect of the duration of the KOH-AHT was assessed at 180 °C for 24, 48, 72, and 96 h. The morphology evolution over time and the plausible formation mechanisms of titanate nanostructures were discussed. The most significant morphological transformation was observed after 72 h. At this time interval, the titanate nanostructures were assembled into well-defined 3D hierarchical architectures such as book-block-like arrangements with open channels. Based on X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) analyses, it was determined that these nanostructures correspond to iron-rich layered titanates (Fe/Ti mass ratio of 7.1). Moreover, it was evidenced that the conversion of the precursor into layered nanostructures was not complete, since for all the tested reaction times the presence of remaining IHSS was identified. Our experiments demonstrated that the Ecuadorian ilmenite sands are relatively stable in KOH medium. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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26 pages, 9629 KiB

Open AccessEditor’s ChoiceArticle

Chemical Modification of Lherzolite Xenoliths Due to Interaction with Host Basanite Melt: Evidence from Tumusun Volcano, Baikal Rift Zone

by Marina A. Gornova, Vasiliy A. Belyaev, Anas A. Karimov, Alexander B. Perepelov and Sergei I. Dril

Minerals 2023, 13(3), 403; https://doi.org/10.3390/min13030403 - 14 Mar 2023

Cited by 1 | Viewed by 1702

Abstract

To investigate the process and chemistry of mineral reaction zone formation, we conducted detailed petrographic observations and chemical analysis of rocks and minerals of spinel lherzolite xenoliths from basanites of Tumusun volcano (Baikal Rift Zone). The reaction zones gradually disappear from contact toward [...] Read more.

To investigate the process and chemistry of mineral reaction zone formation, we conducted detailed petrographic observations and chemical analysis of rocks and minerals of spinel lherzolite xenoliths from basanites of Tumusun volcano (Baikal Rift Zone). The reaction zones gradually disappear from contact toward the center of the xenoliths. The influence of basanite melt on major and trace element composition of secondary minerals of reaction zones is notable only at a distance up to 100–200 μm from the contact. At a distance of 0.3–1.0 mm from the contact, the major and trace composition of secondary clinopyroxenes from the orthopyroxene reaction zone indicates their formation from a melt formed by dissolution of orthopyroxene and influenced by the element diffusion from basanite melt. Inside xenoliths, the secondary minerals have Mg# values equal to or higher than Mg# of primary minerals, and secondary clinopyroxenes inherit their depleted or enriched REE pattern from primary pyroxenes. The compositional variations in secondary clinopyroxenes testify melt heterogeneity. Clinopyroxene rims have slightly higher LILE and similar abundances of other trace elements compared to clinopyroxene cores. This is consistent with the model developed from experimental studies: due to the interaction with basanite, incongruent dissolution of orthopyroxene occurs to form a melt which circulates in lherzolite and leads to pyroxenes and spinel dissolution. Diffusion of elements from basanite results in lherzolite enrichment in K, Na, Rb, Ba, La, and Ce, which are incorporated in feldspars and clinopyroxene of reaction zones as well as in feldspar veinlets. Non-dissolved mineral cores are homogenous and similar in major and trace element composition to primary minerals without reaction rims. Full article

(This article belongs to the Special Issue Origin and Evolution of Deep-Seated Melts and Their Interactions with the Lithospheric Mantle)

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29 pages, 13162 KiB

Open AccessEditor’s ChoiceArticle

Diagenesis, Diagenetic Facies and Their Relationship with Reservoir Sweet Spot in Low-Permeability and Tight Sandstone: Jiaxing Area of the Xihu Sag, East China Sea Basin

by Wenguang Wang, Chengyan Lin, Xianguo Zhang, Chunmei Dong, Lihua Ren and Jianli Lin

Minerals 2023, 13(3), 404; https://doi.org/10.3390/min13030404 - 14 Mar 2023

Cited by 3 | Viewed by 2426

Abstract

The optimization of reservoir sweet spots is the key to the efficient exploration and development of low-permeability and tight sandstone gas reservoirs. However, offshore deep, low-permeability and tight sandstone has the characteristics of large burial depth, large diagenesis heterogeneity and prominent importance of [...] Read more.

The optimization of reservoir sweet spots is the key to the efficient exploration and development of low-permeability and tight sandstone gas reservoirs. However, offshore deep, low-permeability and tight sandstone has the characteristics of large burial depth, large diagenesis heterogeneity and prominent importance of diagenetic facies, which make it difficult to predict reservoir sweet spots. This work comprehensively used logging data, core observation, conventional core analysis, thin section, powder particle size analysis, clay X-ray diffraction analysis, cathode luminescence analysis, scanning electron microscopy and energy spectrum analysis and carried out the study of diagenesis, diagenetic facies and reservoir sweet spots of low-permeability and tight sandstone of H3 and H4 (the third and fourth members of Huagang Formation) members in the Jiaxing area of the Xihu Sag. The results show that the H3 and H4 sandstones were divided into five diagenetic facies types, and chlorite-coated facies and dissolution facies were favorable diagenetic facies belts. The H3 member mainly develops chlorite-coated facies, dissolution facies and quartz-cemented facies, whereas the H4 member primarily develops quartz-cemented facies and chlorite-coated facies. The percentages of type I sweet spot, type II₁ sweet spot and type II₂ sweet spot in the H3 reservoir are approximately 21%, 23% and 26%, respectively, whereas the percentages of type I sweet spot, type II₁ sweet spot and type II₂ sweet spot in the H4 reservoir are about 16%, 15% and 16%, respectively. The distribution rules of reservoir sweet spots were investigated. Type I sweet spot was mainly developed in the areas of chlorite-coated facies and dissolution facies of medium sandstone and coarse sandstone in the channel bar and braided channel sedimentary microfacies. Type II sweet spot was primarily distributed in the areas of quartz-cemented facies, chlorite-coated facies and minor dissolution facies of medium sandstone, fine sandstone and sandy conglomerate in the braided channel, subaqueous distributary channel and channel bar sedimentary microfacies. Type III sweet spot was chiefly developed in the areas of tightly compacted facies, calcite-cemented facies and quartz-cemented facies of fine sandstone, siltstone and a small amount of sandy conglomerate in the subaqueous distributary channel sedimentary microfacies. Full article

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15 pages, 12427 KiB

Open AccessEditor’s ChoiceArticle

The Impact of Hydrothermal Fluids on Porosity Enhancement and Hydrocarbon Migration in Qamchuqa Formation, Lower Cretaceous, Kirkuk Oil Company

by Namam M. Salih

Minerals 2023, 13(3), 377; https://doi.org/10.3390/min13030377 - 8 Mar 2023

Cited by 9 | Viewed by 2346

Abstract

The Lower Cretaceous reservoir core samples from the upper part of Qamchuqa Formation, Baba Dome, Kirkuk Oil Company, show evidence for multistage episodes of dolomitization and a complex diagenetic history. Optical microscope reveals muti-phase of diagenesis: an early stage of diagenesis and its [...] Read more.

The Lower Cretaceous reservoir core samples from the upper part of Qamchuqa Formation, Baba Dome, Kirkuk Oil Company, show evidence for multistage episodes of dolomitization and a complex diagenetic history. Optical microscope reveals muti-phase of diagenesis: an early stage of diagenesis and its alteration, later, by evaporated seawater under near-surface setting conditions, followed by different event of dolomitization. The stylolite microstructures postdate anhydrite and early matrix dolomite crystals (DI) and predated the coarse rhombohedral (DII) and saddle dolomite crystals (SD), which were formed under a deep burial realm. High-resolution data from stable isotopes integrated with intensive optical observation, ImageJ software, and litho-log are utilized to establish a qualified methods for mapping a better image of hydrothermal diagenesis under subsurface conditions. These methods revealed different types of dolomites, mostly focused on fractures and void spaces, and the paragenetic sequence shows the complex history of diagenetic carbonate rocks hosted in the limestone of Qamchuqa Formation. The sequence is started from older to younger as follow: Micritization, early anhydrite mineral formation, early dolomite, stylolization, rhombohedral dolomite, and saddle dolomite crystals. The early dolomite phase is usually corroded by hydrocarbon phase, and, geometrically, the hydrocarbon phase is overgrown by the early dolomite. Therefore, the dolomitizing fluids enhanced the porosity system and had positive impact on the hydrocarbon movement. This phase of dolomite and anhydrite formation were associated with the first groups of δ¹⁸OVPDB and δ¹³CVPDB data, a narrow range of oxygen values, and inverse Js of Lohmann curve fits towards the near-surface and shallow diagenetic settings. Detailed optical microscope and supportive data from oxygen-carbon isotopes of saddle dolomite confirm the presence of hot fluids under subsurface condition. The latter data were supported by light δ¹⁸OVPDB and constant heavy δ¹³CVPDB, which indicates a hot fluid possibly circulated in deep burial conditions, and this is channeled along the fracture and pore spaces, consistent with hydrocarbon migration. These pore spaces influenced by leaching were hydrocarbon migrations associated with hot fluids under deep sitting conditions. However, a remarkable part of pristine microfacies of host limestone was preserved. In summary, this study will add a new understanding and insight into the origin, genesis, and timing of these dolomites and their direct connection to hydrocarbon exploration and development in most reservoir oil rocks, which are exposed to hydrothermal fluids. Additionally, the study adds new data on hydrothermal fluids in subsurface conditions, whereas most of the previous reported work has mostly focused on exposed rock. Full article

(This article belongs to the Special Issue Economic Mineral Deposits: A Review)

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19 pages, 26315 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Significance of Secondary Fe-Oxide and Fe-Sulfide Minerals in Upper Peak Ring Suevite from the Chicxulub Impact Structure

by Christina M. Verhagen, Ji-In Jung, Sonia M. Tikoo, Axel Wittmann, David A. Kring, Stefanie Brachfeld, Laying Wu, Dale H. Burns and Sean P. S. Gulick

Minerals 2023, 13(3), 353; https://doi.org/10.3390/min13030353 - 2 Mar 2023

Cited by 2 | Viewed by 3589

Abstract

The suevite (polymict melt rock-bearing breccia) composing the upper peak ring of the Chicxulub impact crater is extremely heterogeneous, containing a combination of relict clasts and secondary minerals. Using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS) and electron probe microanalysis (EPMA), [...] Read more.

The suevite (polymict melt rock-bearing breccia) composing the upper peak ring of the Chicxulub impact crater is extremely heterogeneous, containing a combination of relict clasts and secondary minerals. Using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS) and electron probe microanalysis (EPMA), we investigated the nature and occurrence of primary and secondary Fe-oxide and Fe-sulfide minerals to better understand hydrothermal trends such as mineral precipitation and dissolution, and to document the remobilization of Fe and associated siderophile elements within suevites. Large primary Fe-oxides (~20–100 µm) reveal decomposition and dissolution patterns, forming sub-micrometer to micrometer Fe-oxide phases. Secondary sub-micrometer Fe-oxide crystals are also visibly concentrated within clay. The occurrence of Fe-oxide crystals within clay suggests that these likely formed at temperatures ≤100 °C, near the formation temperature of smectite. The formation of Fe-oxide minerals on clay surfaces is of interest as it may form a micro-setting, where free electrons (from the oxidation of Fe²⁺) and the adsorption of simple organic molecules on the surface of clay could generate reactive conditions favorable to microbial communities. Primary and secondary Fe-sulfide minerals exhibiting a variety of morphologies are present within samples, representing different formation mechanisms. Secondary Fe-sulfide minerals occur within rims of clasts and vesicles and in fractures and voids. Some secondary Fe-sulfide grains are associated with Ni- and Co-rich phases, potentially reflecting the post-impact migration of siderophile elements within the suevite of the Chicxulub crater. Full article

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21 pages, 5294 KiB

Open AccessEditor’s ChoiceArticle

Petrogenesis and Tectonic Implications of the Cryogenian I-Type Granodiorites from Gabgaba Terrane (NE Sudan)

by Mabrouk Sami, Munir M. A. Adam, Xinbiao Lv, El Saeed R. Lasheen, Antoaneta Ene, Hesham M. H. Zakaly, Saad S. Alarifi, Nasser M. Mahdy, Abdel Rahman A. Abdel Rahman, Adil Saeed, Esam S. Farahat, Douaa Fathy and Shehata Ali

Minerals 2023, 13(3), 331; https://doi.org/10.3390/min13030331 - 27 Feb 2023

Cited by 22 | Viewed by 3173

Abstract

The widely distributed granitic intrusions in the Nubian Shield can provide comprehensive data for understanding its crustal evolution. We present new bulk-rock geochemistry and isotopic (zircon U-Pb and Lu-Hf) data from the Haweit granodiorites in the Gabgaba Terrane (NE Sudan). The dated zircons [...] Read more.

The widely distributed granitic intrusions in the Nubian Shield can provide comprehensive data for understanding its crustal evolution. We present new bulk-rock geochemistry and isotopic (zircon U-Pb and Lu-Hf) data from the Haweit granodiorites in the Gabgaba Terrane (NE Sudan). The dated zircons presented a ²⁰⁶Pb/²³⁸U Concordia age of 718.5 ± 2.2 Ma, indicating that they crystallized during the Cryogenian. The granodiorites contain both biotite and amphibole as the main mafic constituents. The samples exhibit metaluminous (A/CNK = 0.84–0.94) and calc-alkaline signatures. Their mineralogical composition and remarkable low P₂O₅, Zr, Ce, and Nb concentrations confirm that they belong to I-type granites. They exhibit subduction-related magma geochemical characters such as enrichment in LILEs and LREEs and depletion in HFSEs and HREEs, with a low (La/Yb)_N ratio (3.0–5.9) and apparent negative Nb anomaly. The positive Hf(t) values (+7.34 to +11.21) and young crustal model age (T_DM^C = 734–985 Ma) indicates a juvenile composition of the granodiorites. The data suggest that the Haweit granodiorites may have formed from partially melting a juvenile low-K mafic source. During subduction, the ascending asthenosphere melts might heat and partially melt the pre-existing lower crust mafic materials to generate the Haweit granodiorites in the middle segment of the Nubian Shield. Full article

(This article belongs to the Special Issue Genesis of Calc-Alkaline Granitic Rocks: Evidence from Petrology and Geochemistry)

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25 pages, 16350 KiB

Open AccessEditor’s ChoiceArticle

Recovery of Copper and Gold from Waste Printed Circuit Boards Using Monosodium Glutamate Supplemented with Hydrogen Peroxide

by Natrawee Khetwunchai, Saengchai Akeprathumchai and Paitip Thiravetyan

Minerals 2023, 13(3), 321; https://doi.org/10.3390/min13030321 - 24 Feb 2023

Cited by 7 | Viewed by 4154

Abstract

This study aimed to recover copper and gold from a waste printed circuit board (WPCB) using monosodium glutamate (MSG) supplemented with a clean oxidizer(s) under 30 °C, 150 rpm, and an initial pH of 7.00. The solder mask of WPCBs needed to be [...] Read more.

This study aimed to recover copper and gold from a waste printed circuit board (WPCB) using monosodium glutamate (MSG) supplemented with a clean oxidizer(s) under 30 °C, 150 rpm, and an initial pH of 7.00. The solder mask of WPCBs needed to be removed before leaching. At the first leaching, 93% of copper was selectively leached from solder–mask–free WPCBs within 3 h using 0.75 M MSG with 0.50% (w/v)

H_{2} O_{2}

. Then, gold (86%) was extracted from the first residue for 3 h by 1 M MSG with 0.25% (w/v)

H_{2} O_{2}

. In the downstream process, 98–100% copper could be directly recovered within 5–6 h from the first leachate by electrowinning (EW). However, gold in the second leachate required separation and purification processes before EW. At 4 h, 98% gold was adsorbed onto the activated carbon. Most impurities were removed from gold-loaded activated carbon by pre-elution using 0.05 M EDTA for 0.5 h without gold release. Afterward, 99% gold was eluted by diluted aqua-regia within an hour. Finally, the gold could be harvested perfectly using EW for 2 h. This complete copper and gold recycling process delivers an innovative concept for hydrometallurgical study and has the potential to develop into a practical industry. Full article

(This article belongs to the Special Issue Thermodynamics, Mechanism and Kinetics of Metallurgical Processes)

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19 pages, 4622 KiB

Open AccessEditor’s ChoiceArticle

Tectonic Background of Carboniferous to Early Permian Sedimentary Rocks in the East Kunlun Orogen: Constraints from Geochemistry and Geochronology

by Xiao Wang, Xianzhi Pei, Ruibao Li, Chengjun Liu, Lei Pei, Zuochen Li, Youxin Chen and Meng Wang

Minerals 2023, 13(3), 312; https://doi.org/10.3390/min13030312 - 23 Feb 2023

Cited by 1 | Viewed by 2766

Abstract

The formation of the East Kunlun Orogen (EKO) was related to the tectonic evolution of the Proto-Tethys and Paleo-Tethys Oceans. However, how the Paleo-Tethys Ocean transited from the Proto-Tethys Ocean, and whether the Paleo-Tethys Ocean subducted northward beneath the East Kunlun–Qaidam Terrane in [...] Read more.

The formation of the East Kunlun Orogen (EKO) was related to the tectonic evolution of the Proto-Tethys and Paleo-Tethys Oceans. However, how the Paleo-Tethys Ocean transited from the Proto-Tethys Ocean, and whether the Paleo-Tethys Ocean subducted northward beneath the East Kunlun–Qaidam Terrane in Carboniferous to Permian times, is still highly debated. Early Carboniferous Halaguole and Late Carboniferous to Early Permian Haoteluowa formations are extensively outcropped in the EKO, north Tibetan Plateau, and have thus recorded key information about the tectonic processes of the Paleo-Tethys Ocean that have implications for the reconstruction of the Northern Paleo-Tethys Ocean (Buqingshan Ocean). Siliciclastic rocks within these formations are collected for petrogeological, geochemical, and detrital zircon U–Pb dating research. Our results show that sandstones from Halaguole and Haoteluowa formations have an average total quartz–feldspar–lithic fragment ratio of Q₆₇F₁₂L₂₁ and Q₅₀F₂₀L₃₀, respectively, indicating relatively high compositional maturity. The geochemical results suggest that the average values of the Chemical Index of Alteration (CIA) are 57.83 and 64.66; together with their angular to subangular morphology, this indicates that their source rocks suffered from weak weathering and the sandstones are the result of proximal deposition. Geochemical features such as the low La/Th, TiO₂, and Ni values suggest that the parental rocks in the provenance area are mainly acidic igneous rocks with minor intermediate igneous and old sedimentary components. The detrital zircon U–Pb age spectrum of these samples is dominated by age peaks at ~405–503 Ma and ~781–999 Ma, with subordinate age peaks at ~1610–2997 Ma and ~1002–1529 Ma, which show tectono–thermal events similar to those of the North Qimatag Belt (NQB), North Kunlun Terrane (NKT), and South Kunlun Terrane (SKT). These features suggest a contribution from the Early Paleozoic magmatic arc and Proterozoic basements in the NQB, NKT, and SKT to the Halaguole and Haoteluowa formations in these areas. In addition, the youngest zircon age of ~440 Ma from these sandstones is greater than the depositional age of Halaguole and Haoteluowa formations, which is a typical basin depositional feature in a passive continental margin. Geochemical tectonic discrimination diagrams, based on a major and trace element Ti/Zr–La/Sc plot, in combination with a detrital zircon age distribution pattern, all suggest a passive continental margin setting. Considering this together with the previous data, we argue that the Paleo-Tethys Ocean did not begin to subduct northward and that there was no oceanic subduction zone in the south EKO during Carboniferous to Early Permian times. Combining this information with that from previous studies suggests that the initial opening of the Paleo-Tethyan Ocean may have occurred before the Early Carboniferous time, and all the branches of the Paleo-Tethys Ocean constituted a complex ocean–continent configuration across parts of what is now Asia during the Early Carboniferous to Early Permian. Full article

(This article belongs to the Special Issue Petrology, Geochemistry and Isotopes of Ophiolite and Granites in Kunlun Orogen and Adjacent Area)

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21 pages, 4470 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Surfactant Intercalation in Li-Al-Based Binary and Ternary Layered Double Hydroxides by the Microwave-Assisted Rapid Ion-Exchange Process and Its Application in Iodine Adsorption

by Dileep Kumar Yadav, Sitharaman Uma and Rajamani Nagarajan

Minerals 2023, 13(3), 303; https://doi.org/10.3390/min13030303 - 21 Feb 2023

Cited by 3 | Viewed by 2168

Abstract

Recognizing the extreme speeds of reactions with microwaves, anionic forms of surfactants (sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS)) have been intercalated successfully by ion-exchange reactions in binary Li-Al and ternary Li-M-Al (M = Mg, Co, Ni, Cu, and Zn) layered double [...] Read more.

Recognizing the extreme speeds of reactions with microwaves, anionic forms of surfactants (sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS)) have been intercalated successfully by ion-exchange reactions in binary Li-Al and ternary Li-M-Al (M = Mg, Co, Ni, Cu, and Zn) layered double hydroxide (LDH) systems with the aid of microwaves. The samples have been characterized extensively. The basal spacings of 28.2 and 30.4 Å have been estimated for Li-Al-DS and Li-Al-DBS LDH samples, respectively, suggesting a perpendicular arrangement of DS⁻ and DBS⁻ anions in the interlayer space. The characteristic vibration bands of both LDH and the surfactant (DS⁻ and DBS⁻) in the FTIR spectra confirmed the binding mode of surfactant molecules within the interlayers. DS⁻-intercalated Li-Al LDH showed lower thermal stability than the DBS⁻-intercalated sample. The nitrate-intercalated Li-M-Al (M = Mg, Co, Ni, Cu, and Zn) LDHs were ion-exchanged with SDS and SDBS to yield DS⁻-and DBS⁻-intercalated systems. The expanded basal spacings and a change in crystallite morphology confirmed the vertical intercalation of DS⁻ and DBS⁻ in Li-M-Al LDHs. ICP-AES and elemental analyses determined the metal contents and the surfactant content. FTIR spectra of intercalated samples confirmed the surfactant’s presence in the interlayer. The presence of Co, Ni, and Cu in Li-M-Al LDHs has been confirmed from UV-visible spectra. The Li-Al-DBS sample adsorbed iodine efficiently from methanol solutions, and the Langmuir model could explain the adsorption data in a better way. The adsorption followed pseudo-second-order kinetics. Full article

(This article belongs to the Section Clays and Engineered Mineral Materials)

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20 pages, 8025 KiB

Open AccessEditor’s ChoiceArticle

Petrogenesis and Geochronology of A₁-Type Rhyolites in the Late Late Triassic of the East Kunlun Orogenic Belt: Constraints on the End of the Paleo-Tethys Orogenic Event

by Zuochen Li, Xianzhi Pei, Lei Pei, Chengjun Liu, Lili Xu, Ruibao Li, Hao Lin, Mao Wang, Shang Ji, Li Qin, Yajie Yang, Meng Wang, Shaowei Zhao and Youxin Chen

Minerals 2023, 13(2), 290; https://doi.org/10.3390/min13020290 - 18 Feb 2023

Cited by 5 | Viewed by 2217

Abstract

The rhyolites which are widely exposed to the northern margin of the East Kunlun orogenic belt were chosen as a research object to discern the post-orogenic tectonic evolution of the East Kunlun orogenic belt and reconstruct the post-collision orogenic processes of the Buqingshan- [...] Read more.

The rhyolites which are widely exposed to the northern margin of the East Kunlun orogenic belt were chosen as a research object to discern the post-orogenic tectonic evolution of the East Kunlun orogenic belt and reconstruct the post-collision orogenic processes of the Buqingshan- A’nyemaqen Ocean. We researched zircon U-Pb ages and geochemistry characteristics of the Late Triassic rhyolites in the eastern segment of the East Kunlun Orogenic Belt in the northern Tibetan Plateau. Zircon U-Pb dating yields coeval ages of 200.4 ± 1.4 Ma and 202.8 ± 1.2 Ma for the Keri rhyolites of the East Kunlun Orogenic Belt, indicating that the volcanic rocks were formed in the Late Triassic Rhaetian–Early Jurassic Hettangian. The Keri rhyolite is a product of the late magmatism of the Elashan Formation volcanic rocks. The rhyolites include rhyolitic brecciated tuff lavas and rhyolitic tuff lavas. The rhyolites are peraluminous and are high-K calc-alkaline, with high contents of SiO₂, K₂O, TFe₂O₃, and low P₂O₅ contents. The A/CNK ratios range from 0.97 to 1.09, indicating that the rhyolites are metaluminous to weakly peraluminous. The chondrite-normalized rare earth element (REE) distribution shows a significant negative Eu anomaly and low total REE concentrations. All samples are depleted in high field strength elements (HFSEs, e.g., Eu, Sr, Ti, and P), heavy rare earth elements (HREEs), and enriched in large ion lithophile elements (LILEs, e.g., Rb, Zr, Nd, Th, and U) and light rare earth elements (LREEs). The Keri rhyolite has the characteristics of A₁-type magmatic rock, formed in an anorogenic environment after the closure of the Paleo-Tethys Ocean, and was the product of late magmatism in the Elashan Formation volcanic rocks. Full article

(This article belongs to the Special Issue Petrology, Geochemistry and Isotopes of Ophiolite and Granites in Kunlun Orogen and Adjacent Area)

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22 pages, 7735 KiB

Open AccessEditor’s ChoiceArticle

Depositional and Diagenetic Controls on Reservoir Quality of Neogene Surma Group from Srikail Gas Field, Bengal Basin, Bangladesh

by Maimuna Akter, M. Julleh Jalalur Rahman, Ming Ma, Delwar Hossain and Farida Khanam

Minerals 2023, 13(2), 283; https://doi.org/10.3390/min13020283 - 17 Feb 2023

Cited by 1 | Viewed by 2869

Abstract

The development of an effective and profitable exploration and production depends heavily on the quality of the reservoir. The primary goal of this study was to evaluate the reservoir quality of the Neogene Surma Group at the Srikail Gas Field, which is situated [...] Read more.

The development of an effective and profitable exploration and production depends heavily on the quality of the reservoir. The primary goal of this study was to evaluate the reservoir quality of the Neogene Surma Group at the Srikail Gas Field, which is situated in the western part of the eastern folded belt of the Bengal Basin, Bangladesh. Wire-line logs, core analysis, petrography, X-Ray diffraction (XRD) and a scanning electron microscope (SEM) were used to understand the depositional and diagenetic controls of the quality of the reservoir. The Surma Group of the Srikail Gas Field was deposited in a delta system with a dominant influence of tide. The subarkosic to sublitharenitic Neogene Surma Group sandstones have primary porosities ranging from 0% to 25.8%, with an average of 21.5%, and the secondary porosity is approximately 7%. The range of log porosity ranges from 15% to 22.2%, while log permeability and core permeability vary from 3.01 to 54.09 mD and 0.1 to 76 mD, respectively. The primary porosity had been destroyed mainly by mechanical and ductile grain compaction. Most of the clay minerals (illite/illite-smectite, chlorite and kaolinite) in sandstone occur as grain coatings, grain lining (rim) and a few occur as pore-filling. This study reveals that the reservoir quality is predominantly controlled by the depositional environment (sediment texture and facies, ductile grain supply, clay content), and diagenetic process (mainly mechanical and ductile grain compaction followed by clay cement). The information gathered from this research will be useful for future petroleum production and for enhancing predictability in order to find new prospects. Full article

(This article belongs to the Special Issue Mineralogical, Petrophysical and Hydromechanical Properties of Reservoirs and Caprocks)

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12 pages, 2577 KiB

Open AccessEditor’s ChoiceArticle

Separation of Valuable Metals in The Recycling of Lithium Batteries via Solvent Extraction

by Yi-Chin Tang, Jian-Zhi Wang and Yun-Hwei Shen

Minerals 2023, 13(2), 285; https://doi.org/10.3390/min13020285 - 17 Feb 2023

Cited by 21 | Viewed by 5060

Abstract

With the development trend and technological progress of lithium batteries, the battery market is booming, which means that the consumption demand for lithium batteries has increased significantly, and, therefore, a large number of discarded lithium batteries will be generated accordingly. Solvent extraction is [...] Read more.

With the development trend and technological progress of lithium batteries, the battery market is booming, which means that the consumption demand for lithium batteries has increased significantly, and, therefore, a large number of discarded lithium batteries will be generated accordingly. Solvent extraction is a promising approach because it is simple. Solvent extraction is low in time consumption and is easy to industrialize. This paper is focused on the selective recovery of cobalt (Co), nickel (Ni), and manganese (Mn) contained in leachate obtained by digesting a cathodic material from spent lithium batteries with hydrochloric acid. After leaching the cathodic material, Mn was selectively extracted from leachate by using solvent extraction with D2EHPA diluted in kerosene in an optimized condition. Afterward, Co was extracted from the Mn-depleted aqueous phase using Cyanex272 diluted in kerosene. Finally, the raffinate obtained via a stripping reaction with H₂SO₄ was used in the Ni extraction experiments. Cyanex272 extractant was employed to separate Ni and Li. The process can recover more than 93% of Mn, 90% of Co, and 90% of Ni. The crucial material recovered in the form of sulfuric acid solutions can be purified and returned to the manufacturer for use. This process proposes a complete recycling method by effectively recovering Mn, Co, and Ni with solvent extraction, to contribute to the supply of raw materials and to reduce tensions related to mineral resources for the production of lithium batteries. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy, Volume II)

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17 pages, 18017 KiB

Open AccessEditor’s ChoiceArticle

Provenance Analysis of Marbles by Combination of Cathodoluminescence Spectroscopy and Electron Microprobe Analyses—Methodological Comments

by Jiří Zachariáš, Aneta Kuchařová and Marek Kotrlý

Minerals 2023, 13(2), 244; https://doi.org/10.3390/min13020244 - 9 Feb 2023

Cited by 1 | Viewed by 2058

Abstract

Various marbles from historic quarries of the Czech Republic were examined by means of cathodoluminescence (CL) spectroscopy (quantitative data) to determine the possible inclusion of the method in marble provenance studies. The methodology used was based on a combination of electron microprobe analysis [...] Read more.

Various marbles from historic quarries of the Czech Republic were examined by means of cathodoluminescence (CL) spectroscopy (quantitative data) to determine the possible inclusion of the method in marble provenance studies. The methodology used was based on a combination of electron microprobe analysis (Ca, Mg, Fe and Mn composition) and CL spectroscopy (intensity) of calcite and dolomite grains of the marbles studied. Several statistical techniques were applied to the CL-spectra to find the most effective way of characterization of the CL-spectra for provenance discrimination. The combination of Mg-admixture of calcite and position of the maximum (i.e., centre) of a single Gaussian curve was revealed to be the most discriminative dependence of the marbles studied. Full article

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

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26 pages, 5469 KiB

Open AccessEditor’s ChoiceArticle

Antarctic Bioconstructional Bryozoans from Terra Nova Bay (Ross Sea): Morphology, Skeletal Structures and Biomineralization

by Chiara Lombardi, Piotr Kuklinski, Edoardo Spirandelli, Giorgio Bruzzone, Giancarlo Raiteri, Andrea Bordone, Claudio Mazzoli, Matthias López Correa, Robert van Geldern, Laurent Plasseraud, Jérôme Thomas and Frédéric Marin

Minerals 2023, 13(2), 246; https://doi.org/10.3390/min13020246 - 9 Feb 2023

Cited by 3 | Viewed by 2778

Abstract

Among Antarctic bryozoans, some species are able to develop calcitic bioconstructions promoting habitat complexity, but the processes leading to biomineral formation are mostly unknown. The present work investigated three Antarctic bryozoans, from morphological to skeletal features, including the organic matrix associated with the [...] Read more.

Among Antarctic bryozoans, some species are able to develop calcitic bioconstructions promoting habitat complexity, but the processes leading to biomineral formation are mostly unknown. The present work investigated three Antarctic bryozoans, from morphological to skeletal features, including the organic matrix associated with the skeleton (SOM). Cellarinella nutti Rogick, 1956 and Reteporella frigida Waters, 1904 were collected in November 2018 from a shallow site (25 m) and Cellarinella njegovanae Rogick, 1956 from a deep site (110 m) at Terra Nova Bay (Ross Sea, Antarctica). Both Cellarinella species showed 5–6 “growth check lines” (gcl) on their laminae. The morphometrical characterization conducted on the growth bands (gb) and zooids, within the band across bands, revealed a variability in length with time (C. nutti: from 4099 µm for gb1 to 1449 µm for gb6; C. njegovanae: from 1974 µm for gb 3 to 7127 µm for gb2). Zooid length varied within gb, from the proximal to the distal part of the bands, but differences also occurred across bands. The shortest zooids (~625 µm) were found at the proximal part and the longest (~ 1190 µm) in the middle part of the gb in C. nutti, whereas in C. njegovanae the shortest zooids (~ 660 µm) were found in the distal part and the longest (~1190 µm) in the proximal part of the gb. Micro-CT analyses indicated the ratio of basal zooidal walls (RbwT gcl/gb) ranged from 3.0 to 4.9 in C. nutti and from 2.3 to 5.9 in C. njegovanae, whereas Reteporella frigida did not form any gcl on either side of the colony. Preliminary characterizations of the SOM for the three species evidenced a mixture of proteins and polysaccharides with properties similar to those of better-known biominerals, in terms of quantity and electrophoretic behavior. In addition, a “lectin fingerprint” has been established for the first time in bryozoans, displaying the presence of chitin or chitin-related saccharides. Understanding the complexity of the processes regulating skeleton formation is a key aspect in comprehending the adaptation of bioconstructional ecosystems and the survival of the associated biodiversity under the future ocean. Full article

(This article belongs to the Special Issue Biomineralization in Marine Environments)

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