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Minerals, Volume 13, Issue 3 (March 2023) – 155 articles

Cover Story (view full-size image): Opal is a unique natural material composed of silica (from amorphous to poorly crystalline) that could contain up to 18%wt water. In addition to its geological interest in tracing the water–rocks interaction on the telluric surface, its microstructure may display patches of spectral color that have fascinated humans since antiquity. However, its use for jewelry has been tarnished by its potential to crack over time. As the reader can see in this cover, opal naturally exposed to the atmosphere may crack, preventing its reliable use. In the paper published in this issue, we present novel data and theoretical knowledge to understand and maybe prevent the cracking of opal. View this paper
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16 pages, 3452 KiB  
Article
Stabilization of Aeolian Sand for Pavement Subbase Applications Using Alkali-Activated Fly Ash and Slag
by Likang Bai, Zhenjia Yang, Yang Wu, Mohadeseh Anbarlouie and Zhu Pan
Minerals 2023, 13(3), 453; https://doi.org/10.3390/min13030453 - 22 Mar 2023
Cited by 1 | Viewed by 1841
Abstract
Using local materials to construct building elements as well as transport road facilities, including highways, intercity roads, and roads, in remote areas is a top topic of scholarly research all over the world. The main reason for that is the fact that these [...] Read more.
Using local materials to construct building elements as well as transport road facilities, including highways, intercity roads, and roads, in remote areas is a top topic of scholarly research all over the world. The main reason for that is the fact that these kinds of materials not only ease the intensity of material transportation but are also cost-efficient. In desert areas, aeolian sand is a commonly used local material and it has been investigated in unbound and cement-stabilized pavement base/subbase applications. However, the production of cement is associated with a high carbon footprint, leading this research to seek alternative low-carbon binders. This research investigated the strength properties and the carbon footprint of fly ash (FA) and a ground-granulated blast-furnace slag (S)-based geopolymer-stabilized aeolian sand. Setting time, compressive strength, California bearing ratio (CBR), and temperature shrinkage measurements of the stabilized aeolian sand were carried out in this research. The maximum strength of the stabilized aeolian sand was found at the optimal ratio of Si/Al ratio of 2.5 and Na/Al ratio of 1.0. The compressive strength increased as the geopolymer stabilizer content increased. A stabilizer content ranging between 8% and 20% is recommended in practice. The carbon footprint of the geopolymer-stabilized aeolian sand was lower than that of cement-stabilized aeolian sand. This tendency became more evident in the samples with higher strength, indicating the effectiveness of geopolymer as an alternative green soil stabilizer to traditional Portland cement. Full article
(This article belongs to the Special Issue Alkali-Activated Binders)
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19 pages, 7612 KiB  
Article
Extraction of Iron and Alumina from Red Mud with a Non-Harmful Magnetization Sintering Process
by Rui Chen, Lin Shi, Haoyong Huang and Jie Yuan
Minerals 2023, 13(3), 452; https://doi.org/10.3390/min13030452 - 22 Mar 2023
Cited by 4 | Viewed by 2756
Abstract
Red mud, which could cause numerous problems to the environment, is a hazardous waste generated from the alumina smelting industry. In general, the storage and harmless utilization of red mud are hard to implement due to its fine particle size and high alkalinity. [...] Read more.
Red mud, which could cause numerous problems to the environment, is a hazardous waste generated from the alumina smelting industry. In general, the storage and harmless utilization of red mud are hard to implement due to its fine particle size and high alkalinity. This study put forward a novel process to separate iron (MgFe2O4) and alumina (Al2O3) in red mud by a magnetization sintering method. The magnesium oxide was added to transform the nonmagnetic Fe2O3 into magnetic MgFe2O4 to achieve physical separation of iron-bearing minerals, and the alumina-bearing minerals were converted into dissoluble NaAlO2 minerals in a one-step reaction. The atmospheric pressure leaching process was adopted in this study for alumina resource recovery. To achieve clean alumina production, the silicate in the leaching solution was removed by adding the slightly soluble CaSO4, and the entire process becomes clean and harmless. The feasibility of the process was verified by thermodynamic analysis, and a series of experiments were performed to detect the optimum MgO/(Fe2O3 + MgO) ratio and the calcining and leaching conditions. The morphological and mineralogical characteristics of modified red mud, leaching red mud, and magnetic separation product were studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS). It was observed that under the optimal conditions with MgO/(Fe2O3 + MgO) of 14.89% to recover iron and aluminum, the corresponding recovery rates were 67.54% and 73.01% respectively, and the iron grade was 30.46%. The EDS results showed that the obtained Mg/Fe ratio of the magnetic separation product was 0.4677–0.528, which is slightly different from that of the standard MgFe2O4 at 0.5. This new method can promote the development of comprehensive utilization of red mud and iron production. Full article
(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)
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20 pages, 4025 KiB  
Article
The Genetic Link between Iron-Oxide–Apatite and Porphyry Cu–Au Mineralization: Insight from the Biotite–Pyroxene–Zircon Study of the Nihe Fe Deposit and the Shaxi Cu–Au Deposit in the Lower Yangtze Valley, SE China
by Yi Li, Ke-Zhang Qin, Guo-Xue Song, Yu Fan, Fang-Yue Wang and Le Wang
Minerals 2023, 13(3), 451; https://doi.org/10.3390/min13030451 - 22 Mar 2023
Cited by 2 | Viewed by 1511
Abstract
Different ore deposit types may evolve from a common magmatic-hydrothermal system. Establishing a genetic link between different deposit types in an ore cluster can not only deepen the understanding of the magmatic-hydrothermal mineralization process but can also guide exploration. Both the Nihe iron-oxide–apatite [...] Read more.
Different ore deposit types may evolve from a common magmatic-hydrothermal system. Establishing a genetic link between different deposit types in an ore cluster can not only deepen the understanding of the magmatic-hydrothermal mineralization process but can also guide exploration. Both the Nihe iron-oxide–apatite (IOA) deposit and the Shaxi porphyry Cu–Au deposit in the Lower Yangtze Valley, Anhui, Southeast China, formed in the Luzong Cretaceous volcanic basin at ~130 Ma. We examined a temporal–spatial and potential genetic link between these deposits based on stratigraphic lithofacies sections, biotite and clinopyroxene mineralogical chemistry, zircon chronology, Hf isotopes, and trace elements. Stratigraphy, petrology, mineralogical chemistry, and available fluid inclusion results support that the emplacement depth of the Nihe ore-related porphyry is shallower than that of the Shaxi porphyry. The magmatic zircon and hydrothermal zircon from Nihe provided U–Pb ages of 130.6 ± 0.7 Ma and 130.7 ± 0.7 Ma, respectively. The magmatic zircon U–Pb age (130.0 ± 0.8 Ma) of Shaxi overlaps with its molybdenite Re–Os age (130.0 ± 1.0 Ma). The agreement between the mineralization and porphyry emplacement ages of Nihe and Shaxi indicates a temporal coincidence and supports a possible genetic link between the two deposits, considering their close spatial relationship (in the same ore district, 15 km). The zircon Hf isotopes and trace elements support the evolution of both deposits from an enriched lithospheric mantle, although the Shaxi deposit may have experienced contamination of the Jiangnan-type basement. Both deposits lie above the fayalite-magnetite-quartz buffer, but the Nihe magmatic zircons are of lower temperature and less oxidized than that of Shaxi. The much higher Eu/Eu* and Yb/Dy values of zircons from Shaxi are likely caused by the suppression of early plagioclase crystallization and the prevalence of amphibole fractionation, thus indicating more hydrous content of the Shaxi ore-related magma. Additionally, the Shaxi ore-related porphyry has higher zircon Hf concentrations, suggesting that the porphyry Cu–Au deposit has experienced a greater degree of magma fractionation. Our study highlights that the Nihe IOA deposit and the Shaxi porphyry Cu–Au deposit have a common magma source, while different extent of crust contamination, magma oxidation state, hydrous content, and degree of magma fractionation collectively result in the two distinct ore deposits. This possible genetic link suggests a great potential of porphyry Cu–Au-PGE mineralization in the Middle–Lower Yangtze River metallogenetic belt, especially in the deep part of the IOA district in the Luzong Cretaceous volcanic basin. Full article
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24 pages, 8788 KiB  
Article
In Situ LA-ICP-MS of Zoned Garnets from the Huanggang Skarn Iron–Tin Polymetallic Deposit, Southeastern Mongolia, Northern China
by Wei Mei, Banxiao Ruan and Hongyu Liu
Minerals 2023, 13(3), 450; https://doi.org/10.3390/min13030450 - 22 Mar 2023
Cited by 1 | Viewed by 1911
Abstract
The Huanggang deposit is the most important and largest skarn Fe–Sn polymetallic deposit in the Southern Great Xing’an Range of Northeast China. Cassiterite, magnetite, and other metal minerals are related to the garnets within skarn systems. The zoned garnets from various skarn stages [...] Read more.
The Huanggang deposit is the most important and largest skarn Fe–Sn polymetallic deposit in the Southern Great Xing’an Range of Northeast China. Cassiterite, magnetite, and other metal minerals are related to the garnets within skarn systems. The zoned garnets from various skarn stages are able to record numerous geological and mineralizing processes including variations in physicochemical conditions and hydrothermal fluid evolution. In this contribution, we present the mineralogy, systematic major, trace, and rare earth element (REE) concentrations of zoned garnets from the Huanggang Fe–Sn polymetallic skarn deposit. The in situ analytical results of garnets in the prograde skarn stage from andradite core (Grt I) to grossular rim (Grt II) reveal that core sections were formed from a fluid that was generally LREE-rich, with relatively high ∑REE, high LREE/HREE ratios, and weak negative Eu anomalies, whereas rim sections were crystallized from a fluid that was typically HREE-rich, with relatively low ∑REE, low LREE/HREE ratios, and obviously negative Eu anomalies. The garnets of the retrograde skarn stage from Fe3+-rich andradite core (Grt III) to andradite rim (Grt IV) demonstrate that the core sections have a flat trend with high ∑REE and obvious negative Eu anomalies, whereas rim sections were formed from a fluid with relatively low ∑REE, HREE-rich and obviously negative Eu anomalies. The garnets from the prograde skarn stage principally display relatively lower U and higher Y and F concentrations than those from the retrograde skarn stage. Based on optical and textural characteristics, REE patterns, Eu anomalies, and trace element variations in zoned garnets, it can be shown that, during skarn formation, Huanggang hydrothermal fluids shifted from near-neutral pH, oxidizing conditions, and high W/R ratios with relatively low LREE/HREE ratios characteristics to acidic, reducing conditions, and low W/R ratios with relatively high LREE/HREE ratios characteristics. We infer that variations in fluid compositions and physicochemical conditions may exert major control on formation and evolution of garnets and skarn hydrothermal fluids. Full article
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15 pages, 2449 KiB  
Article
Geochemical Records of the Late Glacial and Holocene Paleoenvironmental Changes from the Lake Kaskadnoe-1 Sediments (East Sayan Mountains, South Siberia)
by Elena V. Bezrukova, Alena A. Amosova and Victor M. Chubarov
Minerals 2023, 13(3), 449; https://doi.org/10.3390/min13030449 - 22 Mar 2023
Cited by 3 | Viewed by 1507
Abstract
Long-term and continuous lake sedimentary records offer enormous potential for interpreting paleoenvironmental histories and for understanding how terrestrial environments might respond to current global warming conditions. However, sedimentary records that contain the Late Glacial and Holocene epochs are scarce in deep continental high-mountain [...] Read more.
Long-term and continuous lake sedimentary records offer enormous potential for interpreting paleoenvironmental histories and for understanding how terrestrial environments might respond to current global warming conditions. However, sedimentary records that contain the Late Glacial and Holocene epochs are scarce in deep continental high-mountain regions. A 150 cm sediment core was obtained from Lake Kaskadnoe-1 in the East Sayan Mountains (South Siberia, Russia, 2080 m above sea level), containing a unique record of the last 13,200 calibrated years (cal yr). Chronological control was obtained by AMS 14C dating. Here, we show the first detailed X-ray fluorescence (XRF) geochemical record, with the goal of broadening our knowledge of the paleoenvironmental history of the East Sayan Mountains in the past. The determination of major compounds and trace elements (Sr, Zr) was performed from each centimeter of the Lake Kaskadnoe-1 sediment core. The inorganic geochemistry indicates significant variations in elemental composition between two major lithological units of the sediment core: the Late Glacial dense grey silty clay (150–144 cm), and the upper interval (0–143 cm) mostly consisted of dark biogenic-terrigenous silt, accumulated during the Holocene. The Late Glacial sediments accumulated 13,200–12,800 cal yr BP are characterized by high values of CIA, Mg/Al, K/Al, and Mn/Fe, and are depleted in Si/Al, Fe/Al, and Ca/Al. During the Younger Dryas cold episode, LOI enrichment was probably caused by the presence of less oxic conditions, as seen in lower Mn/Fe values, due to a longer period of lake ice-cover. The Early Holocene (12,000–7500 cal yr BP) is associated with a decreasing trend of mineral matter with fluvial transport to Lake Kaskadnoe-1 (low K/Al, Mg/Al) and stronger chemical weathering in the lake basin. The increase in Ti/Al, K/Al and CIA values over the last 7500 years suggests an increase in the terrigenous input into the lake. Low LOI values can be possibly explained by the presence of less dense vegetation cover in the basin. In summary, our data indicate that the geochemical indices and selected elemental ratios mirror the sedimentation conditions that were triggered by environmental and climate changes during the Late Glacial and Holocene. Full article
(This article belongs to the Special Issue Environment and Geochemistry of Sediments)
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15 pages, 14012 KiB  
Article
Cracking and Microstructure Transition of Iron Ore Containing Goethite in Fe-C Melt Based on the HIsmelt Process
by Guilin Wang, Jianliang Zhang, Zhengjian Liu, Yubo Tan and Yaozu Wang
Minerals 2023, 13(3), 448; https://doi.org/10.3390/min13030448 - 22 Mar 2023
Cited by 2 | Viewed by 2233
Abstract
The phenomenon of cracking and deterioration of iron ore particles is a widespread scientific problem in the field of mineral processing and metallurgy. In this paper, the thermal decomposition properties of iron ore were investigated by a non-isothermal method using thermogravimetric equipment, and [...] Read more.
The phenomenon of cracking and deterioration of iron ore particles is a widespread scientific problem in the field of mineral processing and metallurgy. In this paper, the thermal decomposition properties of iron ore were investigated by a non-isothermal method using thermogravimetric equipment, and the crack evolution behavior of iron ore within Fe-C melt was investigated experimentally, by scanning electron microscopy and Micro-CT. The results show that the start decomposition temperature of #2 iron ore is 292.7 °C, which is 37.3 °C higher compared to that of #1 iron ore, because of its smaller pores and the difficulty of water vapor diffusion. The initial decomposition of iron ore is the decomposition goethite to form water vapor, and as heat transfer continues, hematite particles break into smaller particles and decompose to form Fe3O4. During the smelting reduction process, the Crack index (CI) of #1 iron ore was 5.50% at 4 s, and the CI index increased to 23.54% when time was extended to 16 s, and the internal evolved from locally interconnected holes to cracked structure. The iron ore maintains a relatively intact form during reduction within the Fe-C melt, and interfacial reduction reaction is dominant in the later stage. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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19 pages, 48291 KiB  
Article
Petrogenesis of the Ore-Related Intrusions of the Aikengdelesite Mo (–Cu) and Halongxiuma Mo Deposits: Implication for Geodynamic Evolution and Mineralization in the East Kunlun Orogen, Northwest China
by Qinglin Xu, Yonggang Sun, Guangzhou Mao, Wei Xin and Yanqian Yang
Minerals 2023, 13(3), 447; https://doi.org/10.3390/min13030447 - 22 Mar 2023
Cited by 1 | Viewed by 1632
Abstract
The East Kunlun Orogenic Belt (EKOB) is the most important Triassic polymetallic metallogenic belt in China. A study about the petrogenesis of the ore-related intrusions is of great significance to the geodynamic evolution of orogenic belts. In this study, analysis of U–Pb zircon [...] Read more.
The East Kunlun Orogenic Belt (EKOB) is the most important Triassic polymetallic metallogenic belt in China. A study about the petrogenesis of the ore-related intrusions is of great significance to the geodynamic evolution of orogenic belts. In this study, analysis of U–Pb zircon dating, whole-rock major and trace element compositions, and zircon Hf isotopes for the granitoids hosting the Aikengdelesite Mo (–Cu) and Halongxiuma Mo deposits in the EKOB are studied to determine their chronology and petrogenesis. Zircon date results show that the Aikengdelesite granite porphyry and the Halongxiuma granodiorite porphyry formed at 244.2 ± 1.7 Ma and 230.0 ± 1.0 Ma respectively. All samples of the Aikengdelesite granite porphyry and the Halongxiuma granodiorite porphyry which have high SiO2 and K2O contents, and low MgO and Cr, belong to the high-K calc-alkaline series. The Aikengdelesite granite porphyry samples show I-type geochemical affinities, whereas the Halongxiuma granodiorite porphyry samples are A-type granitoids. They all show negative zircon εHf(t) values (−7.4 to −3.3 and −3.7 to −2.5). We suggest that the Aikengdelesite granite porphyry may have been derived from the lower continental crust. While the Halongxiuma granodiorite porphyry could have formed by partial melting of basic lower crustal materials. By combining the results of this study with previous data, two magmatic and mineralization peak periods (278–237 Ma and 230–210 Ma) were observed in the Paleo-Tethys of the EKOB. Porphyry–skarn deposits occurring in the first episode were formed in the setting of an active continental margin related to the Paleo-Tethys Ocean plate subduction (e.g., Aikengdelesite porphyry deposit), while deposits occurring in the second episode were formed in a post-collisional setting (e.g., Halongxiuma porphyry deposit). Full article
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23 pages, 9503 KiB  
Article
Reconstruction of the Magma Transport Patterns in the Permian-Triassic Siberian Traps from the Northwestern Siberian Platform on the Basis of Anisotropy of Magnetic Susceptibility Data
by Anton Latyshev, Victor Radko, Roman Veselovskiy, Anna Fetisova, Nadezhda Krivolutskaya and Sofia Fursova
Minerals 2023, 13(3), 446; https://doi.org/10.3390/min13030446 - 21 Mar 2023
Cited by 2 | Viewed by 1448
Abstract
Patterns of magma transport during the emplacement of Large Igneous Provinces (LIPs) are extremely important for the understanding of their formation. The Permian-Triassic Siberian Traps LIP is considered to be one of the largest in the Phanerozoic; however, mechanisms of magma transfer within [...] Read more.
Patterns of magma transport during the emplacement of Large Igneous Provinces (LIPs) are extremely important for the understanding of their formation. The Permian-Triassic Siberian Traps LIP is considered to be one of the largest in the Phanerozoic; however, mechanisms of magma transfer within and under the crust are still poorly studied. This problem is vital for the reconstruction of the dynamics of magmatic activity and eruption styles, ascertaining the position of magmatic centers and feeding zones, and conception of ore deposits genesis. Here, we present the detailed results of anisotropy of magnetic susceptibility measurements for lava flows and intrusions from the Noril’sk and Kulumbe regions (the northwestern Siberian platform). We reconstructed patterns of magma flow based on the magnetic fabric analysis of more than 100 sites. Distribution of the magnetic lineation in the studied intrusions and flows points out that the lateral magma flow of NW-SE directions was predominant. Our results support the idea of a magma-controlling role of Noril’sk-Kharaelakh and Imangda-Letninskiy regional fault zones. Furthermore, the reconstructed geometry of magma transport in intrusions is contrasting with that in the Angara-Taseeva depression (the southern part of the LIP) due to the presence of the long-lived mobile zones in the northwestern Siberian platform. Full article
(This article belongs to the Special Issue Large Igneous Provinces: Research Frontiers)
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12 pages, 5121 KiB  
Article
The Surface Structure Change of Columbite-(Fe) Dissolution in H2SO4
by Xiao Guo, Dan Wang and Qiuju Li
Minerals 2023, 13(3), 445; https://doi.org/10.3390/min13030445 - 21 Mar 2023
Cited by 2 | Viewed by 1363
Abstract
The mineral surface structure and ions’ interaction were of significant interest to understanding mineral dissolution and reaction. In this study, X-ray photoemission spectroscopy combined with ICP emission spectrometer was used to investigate the influence of the leaching reaction conditions of 8 M dilute [...] Read more.
The mineral surface structure and ions’ interaction were of significant interest to understanding mineral dissolution and reaction. In this study, X-ray photoemission spectroscopy combined with ICP emission spectrometer was used to investigate the influence of the leaching reaction conditions of 8 M dilute sulfuric acid and 12 M concentrated sulfuric acid on the surface chemical composition, chemical (valence) state and ion distribution of Columbite-(Fe) (FeNb2O6). The binding energy of the cations (Fe, Nb) bonding with different anions (O2−, SO42−) and the ratio of Fe3+/Fe2+ oxidation–reduction provided direct understanding of Fe and Nb releasing from the mineral surface during leaching. The results showed that the binding energy of the Nb5+-O bond was much smaller than that of Nb5+-SO4, and the binding energy decreased in sequence as Nb5+-O < Fe2+-O < Fe3+-O and increased in sequence as Fe3+-SO4 < Fe2+-SO4 < Nb5+-SO4. The mineral surface reaction during the leaching could be expressed with the formula: Fe-O + H2SO4 → Fe-SO4 + H2O, Nb-O + H2SO4 → Nb-SO4 + H2O. The results also revealed that Nb dissolution from Columbite-(Fe) occurred more easily compared to Fe. Nb dissolution from the mineral was owed to the content of H+ in solution, and increasing the H+ concentration could promote the dissolution. For Fe dissolution from the mineral, the oxidation potential could play an effective role in enhancement dissolution. Full article
(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)
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13 pages, 3402 KiB  
Article
Effect of MgO/Al2O3 on Viscosity and Thermodynamic Properties of High-Titanium Slag Containing Chlorine
by Qinyu Cheng, Zhaohui Zhang, Xiangdong Xing, Jianlu Zheng and Yuan She
Minerals 2023, 13(3), 444; https://doi.org/10.3390/min13030444 - 21 Mar 2023
Cited by 2 | Viewed by 1570
Abstract
In order to study the effect of the change of MgO/Al2O3 on the viscosity and thermodynamic properties of the chlorinated blast-furnace slag, the CaO-SiO2-MgO-Al2O3-TiO2-CaCl2 slag system was taken as the research [...] Read more.
In order to study the effect of the change of MgO/Al2O3 on the viscosity and thermodynamic properties of the chlorinated blast-furnace slag, the CaO-SiO2-MgO-Al2O3-TiO2-CaCl2 slag system was taken as the research object, and the viscosity change rule of the chlorinated high-titanium slag was studied by using the rotating cylinder method. The thermal stability of the chlorinated high-titanium slag was quantitatively analyzed by calculating the extreme heat release rate (EHRS) of the chlorinated high-titanium slag. At the same time, the qualitative and quantitative analysis of the high-titanium slag containing chlorine was carried out by combining FTIR and Raman spectroscopy, and the mechanism of the influence of MgO/Al2O3 on the viscous flow characteristics of the high-titanium slag containing chlorine was revealed. The results show that when the alkalinity (R2) of the fixed slag is 1.15, when MgO/Al2O3 is in the range of 0.40–0.66, the viscosity of the high-titanium slag containing chlorine presents a significant decreasing trend with the gradual increase of MgO/Al2O3, and the viscous flow activation energy of the slag decreases from 98.75kJ · mol−1 to 95.21kJ · mol−1. The heat capacity and enthalpy change of slag decrease with the increase of MgO/Al2O3, but the change rule of slag extreme heat release is opposite to that of heat capacity and enthalpy change. When MgO/Al2O3 increases, the slag extreme heat release increases from 13.413 kJ to 15.172 kJ. The content of simple structural units Q0 and Q1 of silicate tetrahedron in the slag gradually increases, the content of complex structural units Q2 and Q3 gradually decreases, and the average amount of non-bridging oxygen decreases from 1.94 to 1.79, indicating that Al2O3 acts as a network maker in the internal network structure of the slag. The increase of MgO/Al2O3 destroys the complex silicate tetrahedron structure in the slag, reducing the degree of polymerization of the slag silicate network. In addition, the transmissivity of [SiO4]4− tetrahedron, [AlO4]4− tetrahedron and T-O-T bond bending vibration band in the slag shows a decreasing trend. Within the scope of the experiment, the increase of MgO/Al2O3 can effectively improve the fluidity of the chlorine-containing blast-furnace slag and improve the thermal stability of the chlorine-containing blast-furnace slag. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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32 pages, 9894 KiB  
Article
Phonolite-Carbonatite Liquid Immiscibility at 3–6 GPa
by Anton V. Arefiev, Anton Shatskiy, Altyna Bekhtenova and Konstantin D. Litasov
Minerals 2023, 13(3), 443; https://doi.org/10.3390/min13030443 - 20 Mar 2023
Cited by 1 | Viewed by 1385
Abstract
Liquid immiscibility plays an important role in the formation of carbonatites and associated alkaline Si-undersaturated magmas. Experiments in the sodium carbonate-aluminosilicate systems suggest that the carbonate-silicate miscibility gap is limited by crustal and shallow mantle pressures (up to 2.5 GPa). Unlike in the [...] Read more.
Liquid immiscibility plays an important role in the formation of carbonatites and associated alkaline Si-undersaturated magmas. Experiments in the sodium carbonate-aluminosilicate systems suggest that the carbonate-silicate miscibility gap is limited by crustal and shallow mantle pressures (up to 2.5 GPa). Unlike in the potassium-rich carbonate-aluminosilicate systems, the carbonate-silicate miscibility gap was established at pressures of 3.5–6 GPa. It is therefore interesting to elucidate the immiscibility range under intermediate pressures, corresponding to 100–200 km depths. Here we conducted experiments over 3–6 GPa and 1050–1500 °C in the systems corresponding to immiscible melts obtained by partial melting of carbonated pelite (DG2) at 6 GPa and 1200 °C. We found that partial melting begins with the alkali-rich carbonatite melt, while immiscible phonolite melt appears over 1050–1200 °C at 3 GPa, 1200 °C at 4.5 GPa, and 1200–1500 °C at 6 GPa. As pressure decreases from 6 to 3 GPa, Na becomes less compatible, and the concentration of the jadeite component in clinopyroxene decreases by a factor of 1.5–6. As a result, the compositions of the immiscible phonolite and carbonatite melts evolve from ultrapotassic (K2O/Na2O weight ratio = 10–14) resembling silicic and carbonatitic micro-inclusions in diamonds from kimberlites and placers worldwide to moderately potassic (K2O/Na2O = 1–2), which may correspond to phonolitic and associated carbonatitic melts of the spinel facies of the shallow mantle. Full article
(This article belongs to the Special Issue Sulphate and Carbonate Minerals)
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20 pages, 13799 KiB  
Article
Magnesite as a Sorbent in Fluid Combustion Conditions—Role of Magnesium in SO2 Sorption Process
by Elżbieta Hycnar, Magdalena Sęk and Tadeusz Ratajczak
Minerals 2023, 13(3), 442; https://doi.org/10.3390/min13030442 - 20 Mar 2023
Viewed by 1132
Abstract
This article presents the results of research on magnesites from the Polish deposits of Szklary, Wiry and Braszowice as SO2 sorbents under the conditions of fluidized bed combustion technology. In practice, magnesites are not used as SO2 sorbents, and the role [...] Read more.
This article presents the results of research on magnesites from the Polish deposits of Szklary, Wiry and Braszowice as SO2 sorbents under the conditions of fluidized bed combustion technology. In practice, magnesites are not used as SO2 sorbents, and the role of magnesium in the desulfurization process under the conditions of fluidized bed combustion technology is evaluated differently among researchers. The literature data question the participation of magnesium in the process of SO2 capture from flue gas and prove its high reactivity. Similarly, previous studies referred to the problem of the stability of magnesium-containing desulfurization products under high temperature conditions. This paper analyzes the SO2 binding process and determines the parameters of the sorbent responsible for the efficiency of magnesite sorption. It was shown that MgO, formed as a result of thermal dissociation of magnesite, actively participates in the SO2 binding reaction to form magnesium sulfate phases (MgSO4 and CaMg2(SO4)3) stable in the temperature conditions of fluidized bed boilers. The problem of differentiated reactivity of magnesium-containing sorbents should be associated with the porosity of the sorbents. If the secondary surface of the sorbent is developed based on micropores and smaller mesopores (below 0.1 µm), the sorbent will be characterized by low sorption activity. It was shown that the SO2 binding process is then limited only to the outer part of the sorbent grains. This results in the formation of a massive, SO2-impermeable desulfurization-product layer on the sorbent grain surface. In real conditions, where the reactions of CaCO3 thermal dissociation and SO2 sorption occur almost simultaneously, the inside of the sorbent grains may remain undissociated. The results of experimental research allowed us to trace the dynamics of the SO2 binding process in relation to real conditions prevailing in fluidized bed boilers. Full article
(This article belongs to the Special Issue Sulphate and Carbonate Minerals)
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13 pages, 10664 KiB  
Article
Triassic Appinite from the Qinling Orogen (Central China): Hydrous Melting of Depleted Mantle Wedge in Post-Collision Stage
by Hang Liu, Hujun Gong, Fenhong Luo, Yaqin Zhang and Ben Dang
Minerals 2023, 13(3), 441; https://doi.org/10.3390/min13030441 - 20 Mar 2023
Cited by 1 | Viewed by 1454
Abstract
Mantle wedge melting and the formation of hydrous mafic melts in collision orogenic belts have great significance for crustal melting and the related granitic magmatism, which can provide key messages about the crustal–mantle interaction in the convergent margin. This paper reported Late-Triassic appinite [...] Read more.
Mantle wedge melting and the formation of hydrous mafic melts in collision orogenic belts have great significance for crustal melting and the related granitic magmatism, which can provide key messages about the crustal–mantle interaction in the convergent margin. This paper reported Late-Triassic appinite (212 ± 2 Ma), which is closely associated with Late-Triassic granites. The large euhedral hornblende crystals in the appinite indicate a water-rich feature. This appinite displays low SiO2 (46.55% to 50.44%) contents, high MgO (7.62 to 10.76%) and Cr and Ni contents, with high Mg# values of 61 to 75. It also displays insignificant Eu anomalies (Eu*/Eu = 0.91 to 0.93), high Sr (596 to 676 ppm) contents and moderate Sr/Y (34 to 40) ratios; these features are similar to those of Sanukite formed by the hydrous melting of the mantle wedge. Its depleted zircon Lu-Hf isotopic composition (εHf(t) = +0.97 to +18.21) indicates a depleted mantle source. Zircons in the appinite display extremely high Ti-in zircon temperatures (>1000 °C) and high oxygen fugacity, indicating a high-temperature hydrous condition. In combination with its typical arc-like trace element geochemistry (depletion in Nb, Ta and Ti), it is proposed that this appinite represents hydrous mafic melts that derived from the melting of the depleted sub-arc mantle wedge. The occurrence of this appinite has great significance for the further understanding of Triassic granitic magmatism and potential magmatic metal ore deposits in the Qinling orogenic belt. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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16 pages, 5301 KiB  
Article
Automated and Quantitative Mineralogy Applied to Chromite Ore Characterization and Beneficiation
by Mark I. Pownceby, David A. McCallum and Warren J. Bruckard
Minerals 2023, 13(3), 440; https://doi.org/10.3390/min13030440 - 20 Mar 2023
Cited by 4 | Viewed by 2143
Abstract
A characterization study of chromite ore from South Africa was conducted using bulk assays, X-ray diffraction, optical, scanning electron microscopy (SEM), automated electron probe microanalysis (EPMA) and quantitative evaluation of mineral by scanning electron microscopy (QEMSCAN) mineralogical techniques, and quantitative EPMA. The aim [...] Read more.
A characterization study of chromite ore from South Africa was conducted using bulk assays, X-ray diffraction, optical, scanning electron microscopy (SEM), automated electron probe microanalysis (EPMA) and quantitative evaluation of mineral by scanning electron microscopy (QEMSCAN) mineralogical techniques, and quantitative EPMA. The aim was to identify all major gangue impurities, the degree of chromite liberation, and possible beneficiation options. The bulk material assayed 40.5% Cr2O3 with the major impurities being Al2O3 (13.2%), MgO (12.1%), and SiO2 (7.5%). Quantitative mineral phase analysis showed that the sample mineralogy was dominated by a chrome-rich spinel phase with an average chemical composition (in wt.%) of: Cr2O3—47.8; FeO—26.0; Al2O3—15.4; and MgO—11.0. Contaminant phases included siliceous minerals enstatite, anorthite-rich plagioclase (bytownite), Cr-rich diopside (containing 1–2 wt.% Cr2O3), and phlogopite mica. QEMSCAN analysis of sized fractions indicated that (a) most silicate gangue species were in the +850 μm fractions, (b) the chrome-rich spinel in all fractions was >80% liberated, and (c) the most common mineral association for chromite was with enstatite. Based on the results, upgrading test work demonstrated that stage crushing followed by wet gravity concentration produced a chemical–metallurgical-grade ‘chromite’ product containing >46% Cr2O3 and <1% SiO2. Full article
(This article belongs to the Special Issue Automated and Quantitative Analysis of Minerals)
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26 pages, 2287 KiB  
Review
Review of Polymetallic Mineralization in the Sila and Serre Massifs (Calabria, Southern Italy)
by Rosa Anna Fregola, Antonio Ciccolella, Vincenzo Festa, Giovanni Ruggieri, Emanuela Schingaro, Fabrizio Tursi and Gennaro Ventruti
Minerals 2023, 13(3), 439; https://doi.org/10.3390/min13030439 - 19 Mar 2023
Viewed by 2388
Abstract
We provide an updated overview of the known mineral deposits from the Sila and Serre Massifs in Calabria, contributing to setting their genesis within a complex geologic history, starting from the late-Carboniferous. We summarize the mineralization reported in the literature, with a critical [...] Read more.
We provide an updated overview of the known mineral deposits from the Sila and Serre Massifs in Calabria, contributing to setting their genesis within a complex geologic history, starting from the late-Carboniferous. We summarize the mineralization reported in the literature, with a critical review of the host tectonic units, by taking into account the upgrades in the knowledge of these areas. We also set them in updated geological maps and in stratigraphic columns, highlighting the crustal levels to which they pertain. Despite the geologic and minerogenetic similarities potentially existing with late- to post-Variscan mineral deposits from other regions (e.g., Sardinia and French Central Massif), the scientific literature on the Calabria mineralization is out-of-date and not exhaustive. Moreover, these ore deposits were likely considered not economically attractive enough to stimulate new scientific studies. However, in our opinion, such studies are needed to resolve the main open questions, which rely on deciphering the origin and age of mineralization. Finally, research for critical elements hosted by the Sila and Serre mineralization (e.g., In, Ge and Ga in sphalerites) is a possible interesting new perspective. Full article
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16 pages, 2617 KiB  
Article
Coal-Based Activated Carbon via Microwave-Assisted ZnCl2 Activation for Methyl Violet 2B Dye Removal: Optimization, Desirability Function, and Adsorption Mechanism
by Salis A. Musa, Ahmed Saud Abdulhameed, Siti Nor Atika Baharin, Zeid A. ALOthman, Lee D. Wilson and Ali H. Jawad
Minerals 2023, 13(3), 438; https://doi.org/10.3390/min13030438 - 19 Mar 2023
Cited by 15 | Viewed by 1947
Abstract
In this work, activated carbon (referred to as MCAC) was produced by microwave radiation assisted ZnCl2 activation using Malaysian coal (MC) as a precursor. The Brunauer–Emmett–Teller findings indicate that the MCAC has a relatively large surface area (798.18 m2/g) and [...] Read more.
In this work, activated carbon (referred to as MCAC) was produced by microwave radiation assisted ZnCl2 activation using Malaysian coal (MC) as a precursor. The Brunauer–Emmett–Teller findings indicate that the MCAC has a relatively large surface area (798.18 m2/g) and a mesoporous structure (average pore diameter of 3.67 nm). The removal of Methylene Violet (MV 2B) a cationic dye model, was employed to investigate the adsorption properties of MCAC. A numerical desirability function in the Box–Behnken design (BBD) was employed to optimize the independent crucial adsorption variables as follows: A: MCAC dose (0.02–0.1 g); B: pH (4–10); and C: time (5–25 min). The results of equilibrium and dynamic adsorption showed that the adsorption of MV 2B followed Freundlich and pseudo-second order models, respectively. The maximum amount of MV 2B dye that the MCAC could adsorb (qmax) was 134.1 mg/g. Electrostatic interactions, π-π stacking, H-bonding, and pore diffusion contribute to the adsorption of MV 2B dye onto the MCAC surface. This study demonstrates the potential to utilize MC as a low-cost precursor for the efficient synthesis of MAC and its utility for the removal of pollutants. Full article
(This article belongs to the Special Issue Characterization, Processing and Utilization of Coal)
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15 pages, 4047 KiB  
Article
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 16 | Viewed by 2015
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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16 pages, 2056 KiB  
Article
Mechanisms Governing 90Sr Removal and Remobilisation in a VLLW Surface Disposal Concept
by Mallory S. Ho, Gianni F. Vettese, Paula H. Keto, Suvi P. Lamminmäki, Minna Vikman, Emmi Myllykylä, Kathy Dardenne and Gareth T. W. Law
Minerals 2023, 13(3), 436; https://doi.org/10.3390/min13030436 - 18 Mar 2023
Cited by 1 | Viewed by 1703
Abstract
Flow-through columns were used to assess potential long-term trends in 90Sr biogeochemistry and transport in a Finnish near-surface very low-level waste (VLLW) repository concept. Experiments simulated the effects of water intrusion and flow through the repository barrier and backfill materials, examining impacts [...] Read more.
Flow-through columns were used to assess potential long-term trends in 90Sr biogeochemistry and transport in a Finnish near-surface very low-level waste (VLLW) repository concept. Experiments simulated the effects of water intrusion and flow through the repository barrier and backfill materials, examining impacts on 90Sr migration. Artificial rainwater containing 2.0 mg/L stable Sr (as a proxy for 90Sr) was pumped through column systems that had varying compositions from a matrix of rock flour (backfill material), bentonite (backfill/sealing material), and carbon steel (waste encapsulation material), for 295 days. Effluent geochemistry was monitored throughout. Sr retention behaviour in all column systems was broadly similar. Sr removal from influent rainwater was marked (~95% removed) at the beginning of the experiments, and this degree of removal was maintained for 20 days. Thereafter, Sr concentrations in the effluents began to rise, reaching ~2 mg/L by 295 days. Further, 56%–67% of added Sr was retained in the repository materials over the 295-day reaction period. Analysis of the effluents indicated that colloids did not form; as such, Sr output was likely to be aqueous Sr2+. Upon completion of the experiment, solid-associated Sr distribution and speciation in the columns were assessed through column sectioning and post-mortem analyses, which encompassed the following: total acid digests, sequential extractions, and XAS analysis. The total acid digests and sequential extractions showed that Sr was evenly distributed throughout the columns and that the majority (68%–87%) of solid-associated Sr was in the exchangeable fraction (MgCl2). This suggested that a major part of the solid-phase Sr was weakly bound to the column materials via outer-sphere sorption. Interestingly, a smaller amount of Sr (7%–23%) could only be extracted by aqua regia, suggesting that a proportion of Sr may bind more strongly to the barrier materials. XAS analysis of select samples confirmed that the dominant Sr phase was sorbed to the rock flour and bentonite, but not corroded carbon steel. Columns were also subject to remobilisation experiments using artificial rain- and seawater without added Sr. While rainwater remobilised Sr slowly, high-ionic strength seawater remobilised Sr at much higher rates in the systems containing bentonite. Interestingly, Sr was well retained in the rock flour-only system following rain and seawater intrusion. Overall, the results indicate that the column materials provide reactive surfaces for Sr removal should it be released from waste packages; however, the backfill and barrier materials have limited retention capacity, and the dominant sorption interaction is relatively weak. The safety case for the shallow disposal of radioactive waste should consider the possibility of seawater intrusion and that the bentonite-bound Sr was significantly more susceptible to remobilisation following seawater, despite retaining slightly more Sr during sorption experiments. Full article
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20 pages, 3154 KiB  
Review
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 18 | Viewed by 3097
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, 3463 KiB  
Article
Effect of Mining Height on Shield Resistance in Shallow Buried Longwall Panel
by Chuang Liu, Hani S. Mitri and Huamin Li
Minerals 2023, 13(3), 434; https://doi.org/10.3390/min13030434 - 18 Mar 2023
Viewed by 1164
Abstract
Based on the field conditions of Huojitu Coal Mine of Shendong coal field in Northern China, eight dynamic numerical models are developed to examine the interaction between the shield and surrounding rock of the longwall panel. The models take into consideration the actual [...] Read more.
Based on the field conditions of Huojitu Coal Mine of Shendong coal field in Northern China, eight dynamic numerical models are developed to examine the interaction between the shield and surrounding rock of the longwall panel. The models take into consideration the actual mining process and are developed to simulate the change in the working resistance of the shield for the same shallow burial but with different mining height conditions, ranging from 2.5 to 7 m. The results show that the average shield resistance during the basic roof initial and periodic weighting is 7 to 20 times the weight load of the mining height under the same shallow stratum conditions. By means of dimensional analysis, a relation between mining height and shield resistance in longwall panels is derived theoretically and is fitted by using the shield resistance data under different mining heights monitored in the numerical simulations. This work has led to a new method for the selection of shield support in shallow coal seams. Full article
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17 pages, 3831 KiB  
Article
A Toxicological Study of the Respirable Coal Mine Dust: Assessment of Different Dust Sources within the Same Mine
by Milton Das, Vanessa Salinas, Jason LeBoeuf, Rifat Khan, Quiteria Jacquez, Alexandra Camacho, Mark Hovingh, Katherine Zychowski, Mohammad Rezaee, Pedram Roghanchi and Gayan Rubasinghege
Minerals 2023, 13(3), 433; https://doi.org/10.3390/min13030433 - 18 Mar 2023
Cited by 2 | Viewed by 1730
Abstract
Respirable coal mine dust (RCMD) exposure is one of the utmost health hazards to the mining community causing various health issues, including coal worker pneumoconiosis (CWP). Considering multiple potential sources of RCMD having different physicochemical properties within the same mine suggests a wide [...] Read more.
Respirable coal mine dust (RCMD) exposure is one of the utmost health hazards to the mining community causing various health issues, including coal worker pneumoconiosis (CWP). Considering multiple potential sources of RCMD having different physicochemical properties within the same mine suggests a wide range of health impacts that have not yet been studied extensively. In this work, we investigate the toxicity of lab-created RCMD based on different sources: coal seam, rock dust, host floor, and host roof collected from the same mine. Comparative samples obtained from several mines situated in various geographic locations were also assessed. This work quantifies metal leaching in simulated lung fluids and correlates dissolution with in vitro immune responses. Here, dissolution experiments were conducted using two simulated lung fluids; Gamble solution (GS) and artificial lysosomal fluid (ALF). In vitro studies were performed using a lung epithelial cell line (A549) to investigate their immune responses and cell viability. Si and Al are the most dissolved metals, among several other trace metals, such as Fe, Sr, Ba, Pb, etc. RCMD from the coal seam and the rock dust showed the least metal leaching, while the floor and roof samples dissolved the most. Results from in vitro studies showed a prominent effect on cell viability for floor and roof dust samples suggesting high toxicity. Full article
(This article belongs to the Special Issue Dust (Urban and Industrial) Medical Mineralogy and Geochemistry)
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14 pages, 10940 KiB  
Article
The Geochemical Characteristics of Source Rock and Oil in the Fukang Sag, Junggar Basin, NW China
by Bocai Li, Youjun Tang, Zhonghong Chen, Yifeng Wang, Daxiang He, Kai Yan and Lin Chen
Minerals 2023, 13(3), 432; https://doi.org/10.3390/min13030432 - 17 Mar 2023
Cited by 1 | Viewed by 1577
Abstract
The Fukang Sag in the Junggar Basin is the main exploration block. However, the origin and source of crude oil are still controversial, which seriously affects the well locating and exploration in this area. In the present work, 30 source rocks and 21 [...] Read more.
The Fukang Sag in the Junggar Basin is the main exploration block. However, the origin and source of crude oil are still controversial, which seriously affects the well locating and exploration in this area. In the present work, 30 source rocks and 21 crude oils were collected for geochemical analysis to clarify the source of the organic matter, the sedimentary environment, and the evolution degree. Among them, the source rocks of the Pingdiquan Formation are type II1 organic matter with good quality, the source rocks of the Badaowan Formation are type II2-III organic matter with fair–good quality, and the source rocks of the Xishanyao Formation are type II2 organic matter with fair quality. All source rocks are in the mature stage. The results of the biomarker compounds show that the lacustrine mudstone of the Xishanyao Formation and the coal-measure mudstone of the Badaowan Formation were deposited in reducing environments. The former was mainly from lower aquatic organisms, and the latter was from terrestrial higher plants. The mudstone of the Pingdiquan Formation was formed in a weakly oxidizing–weakly reducing depositional environment, and its parent material was of mixed origin. Based on the results of the biomarker compounds and carbon isotopes, the crude oils were divided into three categories. The Family I crude oil has the characteristics of low maturity, low salinity, and more input of low-level aquatic organisms, and the carbon isotope has a good affinity with the lacustrine mudstone of the Xishanyao Formation. The Family II crude oil shows medium maturity, low salinity, mainly higher plant input, and heavy carbon isotope, mainly derived from the Badaowan Formation coal-measure mudstone. The Family III crude oil is characterized by high maturity, high salinity, mixed parent materials, and light carbon isotope and originates from the mudstone of the Pingdiquan Formation. The results provide a reference for oil and gas exploration and development in the eastern area of the Junggar Basin; the future research will focus on well areas with high maturity near the Fukang fault zone. Full article
(This article belongs to the Special Issue Geochemical Characterization of Source Rocks in Oil and Gas Fields)
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23 pages, 6860 KiB  
Article
Multi-Objective Scheduling Strategy of Mine Transportation Robot Based on Three-Dimensional Loading Constraint
by Xuanxuan Yan, Guorong Wang, Kuosheng Jiang, Ziming Kou, Kaisong Wang and Lixiang Zhang
Minerals 2023, 13(3), 431; https://doi.org/10.3390/min13030431 - 17 Mar 2023
Cited by 1 | Viewed by 1461
Abstract
In an attempt to solve the problems of the low intelligent distribution degree and high working intensity of auxiliary transportation systems in underground coal mines, an intelligent distribution strategy of materials in the whole mine is put forward. Firstly, combined with the characteristics [...] Read more.
In an attempt to solve the problems of the low intelligent distribution degree and high working intensity of auxiliary transportation systems in underground coal mines, an intelligent distribution strategy of materials in the whole mine is put forward. Firstly, combined with the characteristics of materials and standard containers, a three-dimensional loading model is established with the goal of maximizing the space utilization of standard containers, and a three-dimensional space segmentation heuristic algorithm is used to solve the material loading scheme. Then, the multi-objective optimization model of distribution parameters is established with the goal of the shortest delivery distance, the shortest delay time, and the fewest number of delivery vehicles, and the dual-layer genetic algorithm is used to solve the distribution scheme. Finally, the spatiotemporal conversion coefficient is designed to solve the task list by hierarchical clustering, and the solution time is reduced by 30%. The results show that the dual-layer genetic algorithm based on hierarchical clustering has good adaptability in complex material scheduling scenarios. Full article
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21 pages, 10515 KiB  
Article
Study on the Characteristics of Damaged Sandstone in the Longshan Grottoes Using Water Chemistry and Freeze–Thaw Cycling
by Bo Sun, Xingyue Li, Kai Cui, Ningbo Peng, Jie Hong, Rui Chen and Chen Jia
Minerals 2023, 13(3), 430; https://doi.org/10.3390/min13030430 - 17 Mar 2023
Cited by 8 | Viewed by 1552
Abstract
Sandstone from the Longshan Grottoes in Taiyuan, China, was the research object of this paper. The sandstone samples were soaked in distilled water, Na2SO4 solution, and NaCl solution and subjected to freeze–thaw testing. Sandstone specimens were treated with 0, 5, [...] Read more.
Sandstone from the Longshan Grottoes in Taiyuan, China, was the research object of this paper. The sandstone samples were soaked in distilled water, Na2SO4 solution, and NaCl solution and subjected to freeze–thaw testing. Sandstone specimens were treated with 0, 5, 10, 15, 20, 25, and 30 freeze–thaw cycles. The mass ratio, P-wave velocity, surface hardness, uniaxial compressive strength, and other physical-mechanical features of rock samples were measured after different numbers of cycles. The results of mercury injection, scanning electron microscopy, and X-ray diffraction were combined to explore the damage mechanisms and characteristics of the rock samples under the combined action of chemicals and freeze–thaw cycles. It was found that the damage degree of sandstone increased logarithmically with the number of cycles, with Na2SO4 solution causing the most damage. Damage variables D of the samples soaked in distilled water, Na2SO4 solution, and NaCl solution after 30 freeze–thaw cycles were 3.89%, 6.51%, and 4.74%, respectively. The difference in damage between the solutions is caused by the combination of frost heave, dissolution, and salt crystallization, and the damage process generally occurs from the inside and the outside and is manifested as an increase in the number of macropores and the appearance of new pores. Freezing–thawing and salt action are important causes of the powdering and detachment of sandstone in the Longshan Grottoes. Full article
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8 pages, 1601 KiB  
Review
Single Crystal Growth of Synthetic Sulfide- and Phosphide-Based Minerals for Physical Measurements
by Paul C. Canfield and Tyler J. Slade
Minerals 2023, 13(3), 429; https://doi.org/10.3390/min13030429 - 17 Mar 2023
Viewed by 1584
Abstract
In this work, we review recent advances in the use of high-temperature solution growth that allow for the growth of single crystalline samples of synthetic minerals. We outline how low-melting binary or ternary solutions are attractive solvents for solution growth and provide examples [...] Read more.
In this work, we review recent advances in the use of high-temperature solution growth that allow for the growth of single crystalline samples of synthetic minerals. We outline how low-melting binary or ternary solutions are attractive solvents for solution growth and provide examples of the growth of bismuthinite (Bi2S3), galena (PbS) and parkerite (Ni3Bi2S2). We then focus on the Rh-S, Pd-S and Ni-P phase spaces to discuss how the low-melting regions near transition metal-main group eutectic compositions make excellent solvents for crystal growth of several binary and ternary minerals containing both high melting and volatile elements as well as for the discovery of new materials. We end by discussing the growth of synthetic canfieldite (Ag8SnS6) and argyrodite (Ag8GeS6) from Ag2S–Sn-S-based solutions. Full article
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21 pages, 8479 KiB  
Article
Triaxial Test Study on Energy Evolution of Marble after Thermal Cycle
by Qi Wu, Bowen Li and Xuehai Jiang
Minerals 2023, 13(3), 428; https://doi.org/10.3390/min13030428 - 17 Mar 2023
Cited by 1 | Viewed by 1276
Abstract
With the increasing requirements for the exploitation of underground resources, the subject of the physical and mechanical properties of rocks under high temperature and pressure needs to be studied urgently. In order to analyze the mechanical and energy characteristics of rocks under different [...] Read more.
With the increasing requirements for the exploitation of underground resources, the subject of the physical and mechanical properties of rocks under high temperature and pressure needs to be studied urgently. In order to analyze the mechanical and energy characteristics of rocks under different thermal damages and confining pressures (c), a triaxial compression test is performed on 35 marble samples. The effects of thermal damage and high pressure are simulated with different thermal cycles and confining pressures. The results show that as the number of thermal cycles increases, the peak strain of marble gradually rises, but the peak stress and the elastic modulus (E) decrease by a degree, reaching 11.19‰, 39.53 MPa, 4.79 GPa, while there is no confining pressure applied at eight thermal cycles. At this point, the failure mode gradually changes from brittle fracture to plastic failure. When confining pressure rises, peak stress, peak strain, and elastic modulus all show an upward trend, reaching a maximum of 189.45 MPa, 13.39‰, 35.41 GPa, while the sample is undamaged at 30 MPa confining pressure. Moreover, peak stress increases linearly with confining pressure increase. The increased rate of the peak value of the total absorbed energy, elastic strain energy, and dissipated energy all show a convex trend. The dissipated energy gradually increases with the axial strain (ε1) during the rock loading process. The elastic strain energy has an energy storage limit, but the rock fails when the value exceeds the limit. The limit increases first and then decreases with the number of thermal cycles. These results can provide important engineering references for mining underground resources. Full article
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12 pages, 2956 KiB  
Article
The Immobility of Uranium (U) in Metamorphic Fluids Explained by the Predominance of Aqueous U(IV)
by Min Zhang, Richen Zhong, Chang Yu and Hao Cui
Minerals 2023, 13(3), 427; https://doi.org/10.3390/min13030427 - 17 Mar 2023
Viewed by 1428
Abstract
The solubility of uranium (U) in hydrothermal fluid is thought to be controlled by oxidation. In general, uranium is mainly transported as U(VI) in oxidized fluid, but precipitated as U(IV) in reduced fluid. However, many geological observations indicate that metamorphic fluids, which are [...] Read more.
The solubility of uranium (U) in hydrothermal fluid is thought to be controlled by oxidation. In general, uranium is mainly transported as U(VI) in oxidized fluid, but precipitated as U(IV) in reduced fluid. However, many geological observations indicate that metamorphic fluids, which are buffered by metamorphic rocks with oxidized protoliths such as oxidized pelite or altered marine basalt, are not enriched in U. To explore the reason of the low solubility of U in metamorphic fluids, we simulated the hydrous speciation and solubility of U in fluids that are in equilibrium with rocks. The simulations were conducted at pressure–temperature (P-T) conditions of greenschist and amphibolite facies metamorphism. The results show that U is mainly dissolved as U(IV), instead of U(VI), in metamorphic fluids. The solubility of U remains at a low level of ~10−12 molal, and is not significantly influenced by metamorphic temperature, pressure, and fluid salinity. This result is consistent with geological observations and, thus, can explain the low-U nature of natural metamorphic fluids. The simulation also shows high solubility of U(VI) (1.3 × 10−7 molal) in oxidized pelite-buffered fluids at low temperature (<250 °C), consistent with the geological fact that U can be mobilized by low-temperature geofluids. Full article
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18 pages, 7947 KiB  
Article
Thermobarometry of the Rajmahal Continental Flood Basalts and Their Primary Magmas: Implications for the Magmatic Plumbing System
by Nilanjan Chatterjee and Naresh C. Ghose
Minerals 2023, 13(3), 426; https://doi.org/10.3390/min13030426 - 17 Mar 2023
Viewed by 1633
Abstract
The Late Aptian Rajmahal Traps originated through Kerguelen-Plume-related volcanism at the eastern margin of the Indian Shield. Clinopyroxene and whole-rock thermobarometry reveals that the Rajmahal magmas crystallized at P-T conditions of ≤~5 kbar/~1100–1200 °C. These pressures correspond to upper crustal depths (≤~19 km). [...] Read more.
The Late Aptian Rajmahal Traps originated through Kerguelen-Plume-related volcanism at the eastern margin of the Indian Shield. Clinopyroxene and whole-rock thermobarometry reveals that the Rajmahal magmas crystallized at P-T conditions of ≤~5 kbar/~1100–1200 °C. These pressures correspond to upper crustal depths (≤~19 km). Modeling shows that the Rajmahal primary magmas were last in equilibrium with mantle at P-T conditions of ~9 kbar/~1280 °C. The corresponding depths (~33 km) are consistent with gravity data that indicate a high-density layer at lower crustal depths below an upwarped Moho. Thus, the high-density layer probably represents anomalous mantle. It is likely that the mantle-derived magmas accumulated below the upwarped Moho and were subsequently transported via trans-crustal faults/fractures to the upper crust where they evolved by fractional crystallization in small staging chambers before eruption. In the lower part of the Rajmahal plumbing system, buoyant melts from the Kerguelen Plume may have moved laterally and upward along the base of the lithosphere to accumulate and erode the eastern Indian lithospheric root. The Rajmahal plumbing system was probably shaped by tectonic forces related to the breakup of Gondwana. Full article
(This article belongs to the Special Issue Large Igneous Provinces: Research Frontiers)
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22 pages, 851 KiB  
Review
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 33 | Viewed by 9922
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
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16 pages, 4563 KiB  
Article
A New Approach to the Grinding Kinetics of Magnetite Ore Based on the Population Balance Model
by Chengfang Yuan, Caibin Wu, Xin Fang, Ningning Liao, Jiaqi Tong and Yuqing Li
Minerals 2023, 13(3), 424; https://doi.org/10.3390/min13030424 - 16 Mar 2023
Viewed by 1355
Abstract
A new approach to batch grinding kinetics was established based on the conventional population balance model, with magnetite as the experimental object. The distribution function commonly used in the population balance model is a sum of two power functions, i.e., [...] Read more.
A new approach to batch grinding kinetics was established based on the conventional population balance model, with magnetite as the experimental object. The distribution function commonly used in the population balance model is a sum of two power functions, i.e., Bi1=φ(xi1x1+1φ(xi1x1)β. Based on the new finding that the cumulative mass fraction coarser than the size class of the discharge is consistent with the first-order grinding kinetic, the gi function of the new approach is only a single power function, i.e., =+k1xia, which will greatly reduce the parameter error and make the fit more accurate. The maximum error between simulation calculations and the actual experiment using the two methods did not exceed 1%, indicating that both models can accurately predict the fracture characteristics of magnetite. Because the new approach has fewer derived parameters, it addresses the conventional population balance model’s problems of large computational effort and poor fitting accuracy, making it more applicable to the study of the impact of parameters on the grinding status, with a simpler process and higher accuracy. In addition, this new method is applicable to minerals other than magnetite. Further research is required to verify its applicability to wide size ranges and continuous grinding. Full article
(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation, Volume II)
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