Minerals

23 pages, 7937 KiB

Open AccessArticle

Contribution of Triassic Tectonomagmatic Activity to the Mineralization of Liziyuan Orogenic Gold Deposits, West Qinling Orogenic Belt, China

by Shuo Wang, Zhanjin Liu, Yunhua Liu, Nan Deng, Benzhao Yang and Le Tan

Minerals 2023, 13(1), 130; https://doi.org/10.3390/min13010130 - 16 Jan 2023

Cited by 7 | Viewed by 2236

Abstract

The Western Qinling orogenic belt (WQOB) is one of the most important prospective gold districts in China, with widely distributed Indosinian intermediate–acidic intrusions. The Liziyuan Au deposit is a representative orogenic deposit in the northern WQOB, hosting several sections spatially associated with igneous [...] Read more.

The Western Qinling orogenic belt (WQOB) is one of the most important prospective gold districts in China, with widely distributed Indosinian intermediate–acidic intrusions. The Liziyuan Au deposit is a representative orogenic deposit in the northern WQOB, hosting several sections spatially associated with igneous rocks. The Au deposit is hosted by meta-sedimentary volcanic rocks of the Cambrian–Ordovician Liziyuan Group and the Tianzishan monzogranite. Two periods, including five stages of mineralization, are recognized in this area: an early metamorphic mineralization period (PI), including quartz–pyrite (Stage I) and banded quartz–polymetallic sulfide (Stage II) veins, and a later magmatic mineralization period (PII) including quartz–K-feldspar–pyrite–molybdenite veins (Stage III), quartz–polymetallic sulfide–chlorite ± calcite veinlets and stockwork (Stage IV), and late calcite–quartz veinlets (Stage V). Geochronological studies indicate a SHRIMP zircon U-Pb age of 236.1 Ma for the Tianzishan monzogranite, and our published ages of ore-bearing diorite porphyrite of the Suishizi section and granite porphyry of the Jiancaowan section being 213 and 212 Ma, respectively. Pyrites formed in association with PI and PII mineralization have well-defined Rb–Sr ages of 220 ± 7.5, 205.8 ± 8.7, and 199 ± 15 Ma, with close temporospatial coupling between mineralization and magmatism. The δ¹⁸O and δD values of fluid inclusions in Stage IV auriferous quartz veins range from −0.03‰ to +5.24‰ and −93‰ to −75‰, respectively, suggesting that mineralizing fluid was likely of magmatic origin. Three distinct ranges of δ³⁴S values are identified in the studied sections (i.e., 7.04‰–9.12‰, −4.95‰ to −2.44‰, and 0.10‰–3.08‰), indicating a source containing multiple sulfur isotopes derived from magmatic and metamorphic fluids. The Liziyuan Au deposit is thus likely an orogenic deposit closely related to magmatism. Geochemical characteristics indicate that Tianzishan monzogranite is adakitic and was derived from thickened lower crust during Triassic orogenesis. The ore-bearing diorite porphyrite and granite porphyry formed in a post-collision extensional setting. Together with previous geological and geochemical data, our results indicate that the Liziyuan orogenic Au deposit was formed by early collisional–compressional metamorphism and late post-collision extensional magmatic fluids related to the evolution of the WQOB. 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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20 pages, 5522 KiB

Open AccessFeature PaperReview

Rare Earth Element Deposits in Mongolia

by Jaroslav Dostal and Ochir Gerel

Minerals 2023, 13(1), 129; https://doi.org/10.3390/min13010129 - 16 Jan 2023

Cited by 4 | Viewed by 8104

Abstract

In Mongolia, rare earth element (REE) mineralization of economic significance is related either to the Mesozoic carbonatites or to the Paleozoic peralkaline granitoid rocks. Carbonatites occur as part of alkaline silicate-carbonatite complexes, which are composed mainly of nepheline syenites and equivalent volcanic rocks. [...] Read more.

In Mongolia, rare earth element (REE) mineralization of economic significance is related either to the Mesozoic carbonatites or to the Paleozoic peralkaline granitoid rocks. Carbonatites occur as part of alkaline silicate-carbonatite complexes, which are composed mainly of nepheline syenites and equivalent volcanic rocks. The complexes were emplaced in the Gobi-Tien Shan rift zone in southern Mongolia where carbonatites usually form dikes, plugs or intruded into brecciated rocks. In mineralized carbonatites, REE occur mainly as fluorocarbonates (bastnäsite, synchysite, parisite) and apatite. Apatite is also present in the carbonatite-hosted apatite-magnetite (mostly altered to hematite) bodies. Alkaline silicate rocks and carbonatites show common geochemical features such as enrichment of light REE but relative depletion of Ti, Zr, Nb, Ta and Hf and similar Sr and Nd isotopic characteristics suggesting the involvement of the heterogeneous lithospheric mantle in the formation of both carbonatites and associated silicate rocks. Hydrothermal fluids of magmatic origin played an important role in the genesis of the carbonatite-hosted REE deposits. The REE mineralization associated with peralkaline felsic rocks (peralkaline granites, syenites and pegmatites) mainly occurs in Mongolian Altai in northwestern Mongolia. The mineralization is largely hosted in accessory minerals (mainly elpidite, monazite, xenotime, fluorocarbonates), which can reach percentage levels in mineralized zones. These rocks are the results of protracted fractional crystallization of the magma that led to an enrichment of REE, especially in the late stages of magma evolution. The primary magmatic mineralization was overprinted (remobilized and enriched) by late magmatic to hydrothermal fluids. The mineralization associated with peralkaline granitic rocks also contains significant concentrations of Zr, Nb, Th and U. There are promising occurrences of both types of rare earth mineralization in Mongolia and at present, three of them have already established significant economic potential. They are mineralization related to Mesozoic Mushgai Khudag and Khotgor carbonatites in southern Mongolia and to the Devonian Khalzan Buregtei peralkaline granites in northwestern Mongolia. Full article

(This article belongs to the Special Issue Editorial Board Members’ Collection Series: "Critical and Strategic Minerals")

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19 pages, 6252 KiB

Open AccessArticle

Advanced Simulation of Quartz Flotation Using Micro-Nanobubbles by Hybrid Serving of Historical Data (HD) and Deep Learning (DL) Methods

by Sabereh Nazari, Alireza Gholami, Hamid Khoshdast, Jinlong Li, Yaqun He and Ahmad Hassanzadeh

Minerals 2023, 13(1), 128; https://doi.org/10.3390/min13010128 - 16 Jan 2023

Cited by 6 | Viewed by 2453

Abstract

The present study investigates the optimization and advanced simulation of the flotation process of coarse particles (–425 + 106) using micro-nanobubbles (MNBs). For this purpose, flotation experiments in the presence and absence of MNBs were performed on coarse quartz particles, and the results [...] Read more.

The present study investigates the optimization and advanced simulation of the flotation process of coarse particles (–425 + 106) using micro-nanobubbles (MNBs). For this purpose, flotation experiments in the presence and absence of MNBs were performed on coarse quartz particles, and the results were statistically analyzed. Methyl isobutyl carbinol (MIBC) was employed as a frother for generating MNBs through hydrodynamic cavitation. The significance of the operating variables, including impeller speed, air flow rate, together with the bubble size, and particle size on the flotation recovery was assessed using historical data (HD) design and analysis of variance (ANOVA). The correlation between the flotation parameters and process response in the presence and absence of MNBs was modeled using hybrid convolutional neural networks (CNNs) and recurrent neural networks (RNNs) as the deep learning (DL) frameworks to automatically extract features from input data using a CNN as the base layer. The ANOVA results indicated that all variables affect process responses statistically and meaningfully. Significant interactions were found between air flow rate and particle size as well as impeller speed and MNB size. It was found that a CNN-RNN model could finally be used to model the process based on the intelligent simulation results. Based on Pearson correlation coefficients (PCCs), it was evident that particle size had a strong linear relationship with recovery. However, Shapley additive explanations (SHAP) was considerably more accurate in predicting relationships than Pearson correlations, even though the model outputs agreed well. Full article

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14 pages, 1420 KiB

Open AccessArticle

Controls on Lithium Incorporation and Isotopic Fractionation in Large Benthic Foraminifera

by Laurie M. Charrieau, Claire Rollion-Bard, Anja Terbrueggen, David J. Wilson, Philip A. E. Pogge von Strandmann, Sambuddha Misra and Jelle Bijma

Minerals 2023, 13(1), 127; https://doi.org/10.3390/min13010127 - 15 Jan 2023

Cited by 4 | Viewed by 2263

Abstract

The lithium (Li) isotopic composition of carbonates is considered to be a reliable archive of past seawater Li isotopic compositions, which are useful as a tracer of silicate weathering. However, δ⁷Li values have been shown to be dependent on either pH [...] Read more.

The lithium (Li) isotopic composition of carbonates is considered to be a reliable archive of past seawater Li isotopic compositions, which are useful as a tracer of silicate weathering. However, δ⁷Li values have been shown to be dependent on either pH or DIC in two studies using similar species of large, benthic foraminifera from the genus Amphistegina. To resolve this issue, we conducted culture experiments on Amphistegina lessonii in decoupled pH–DIC conditions, under two different light treatments, and with normal or Li-enriched seawater. The δ⁷Li values and Li/Ca ratios in the foraminifera tests were analysed by ion microprobe and LA-ICP-MS, respectively. No links between either the pH or DIC and δ⁷Li or Li/Ca values were observed for any of the treatments, and growth rates also did not seem to influence the Li incorporation or isotopic fractionation, contrary to observations from inorganic carbonate-precipitation experiments. Overall, these findings appear to support the use of Li isotopes in large benthic foraminifera to reconstruct past seawater chemistry and to infer changes in chemical weathering during carbon-cycle perturbations. Full article

(This article belongs to the Special Issue Biomineralization of Organisms Used as Environmental Proxy Archives)

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Graphical abstract

30 pages, 15637 KiB

Open AccessArticle

Volcano–Plutonic Complex of the Tumrok Range (Eastern Kamchatka): An Example of the Ural-Alaskan Type Intrusion and Related Volcanic Series

by Ivan F. Chayka, Nikolay I. Baykov, Vadim S. Kamenetsky, Anton V. Kutyrev, Evgenii V. Pushkarev, Adam Abersteiner and Vasily D. Shcherbakov

Minerals 2023, 13(1), 126; https://doi.org/10.3390/min13010126 - 15 Jan 2023

Cited by 4 | Viewed by 2833

Abstract

Zoned plutons, composed of dunites, pyroxenites, and gabbroic rocks, have been referred to as the Ural-Alaskan type complexes (UA-complexes) and occur in numerous paleo-arc settings worldwide. Many of these complexes are source rocks for economic placers of platinum-group metals. Thus, it is important [...] Read more.

Zoned plutons, composed of dunites, pyroxenites, and gabbroic rocks, have been referred to as the Ural-Alaskan type complexes (UA-complexes) and occur in numerous paleo-arc settings worldwide. Many of these complexes are source rocks for economic placers of platinum-group metals. Thus, it is important to understand how UA-complexes form and the origin and behavior of platinum-group elements (PGEs). It is widely assumed that the UA-complexes result from differentiation of supra-subduction high-Ca high-Mg sub-alkaline magmas. However, there is a lack of direct evidence for the existence and differentiation of such magmas, mainly because cases of UA-complexes being spatially and temporally linked to co-genetic volcanics are unknown. We studied an UA-complex from the Tumrok range (Eastern Kamchatka) where a dunite-clinopyroxenite-gabbro assemblage is spatially and temporary related to high-Ca volcanics (i.e., picrites and basalts). Based on the mineral and chemical composition of the rocks, mineral chemistry, and composition of melt inclusions hosted within rock-forming minerals, we conclude that the intrusive assemblage and the volcanics are co-genetic and share the same parental magma of ankaramitic composition. Furthermore, the compositions of the plutonic rocks are typical of UA-complexes worldwide. Finally, the rocks studied exhibit a full differentiation sequence from olivine-only liquidus in picrites and dunites to eutectic crystallization of diopside or hornblende, plagioclase, and K-Na feldspar in plagio-wehrlites and gabbroic rocks. All these results make the considered volcano–plutonic complex a promising case for petrological studies and modelling of UA-complex formation. Full article

(This article belongs to the Special Issue Precious Metals vs. Base Metals: Nature and Experiment)

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9 pages, 1162 KiB

Open AccessOpinion

Trace Elements in Dental Enamel Can Be a Potential Factor of Advanced Tooth Wear

by Elzbieta Zamojda, Karolina Orywal, Barbara Mroczko and Teresa Sierpinska

Minerals 2023, 13(1), 125; https://doi.org/10.3390/min13010125 - 15 Jan 2023

Cited by 2 | Viewed by 2673

Abstract

Enamel is the outermost layer of the tooth and has no ability to regenerate after tooth eruption. Its mineral composition is likely to be responsible for the enamel resistance to any agents that appear in oral cavity. The objective of this study was [...] Read more.

Enamel is the outermost layer of the tooth and has no ability to regenerate after tooth eruption. Its mineral composition is likely to be responsible for the enamel resistance to any agents that appear in oral cavity. The objective of this study was to compare the content of Ca, Mg, Zn and Cu in specific layers of healthy and worn tooth enamel. Three groups of dental enamel samples were analyzed. The amounts of Ca, Mg and Zn in the enamel bioptates were established using atomic absorption spectroscopy after an acid biopsy technique had been applied. The concentration of Cu was established using an electrothermic method with an AA spectrometer. The analysis was carried out using parametric tests (the Pearson’s linear correlation coefficient and the t-test for the correlation coefficient). Results: A statistically significant difference was confirmed between the mean amount of zinc in severely worn dentition and all the layers in vitro and in vivo. Strong positive relationships between magnesium and zinc contents were shown at some depths. A significant difference was registered between the amount of copper in the severely worn dentitions compared to the superficial layer of the healthy teeth in vitro and in vivo. Conclusion: It appears that zinc metabolism may play an important role in enamel formation and may influence enamel’s resistance to wear after tooth eruption. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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16 pages, 6165 KiB

Open AccessArticle

Deciphering Alterations of Rodent Bones through In Vitro Digestion: An Avenue to Understand Pre-Diagenetic Agents?

by Christiane Denys, Denné N. Reed and Yannicke Dauphin

Minerals 2023, 13(1), 124; https://doi.org/10.3390/min13010124 - 14 Jan 2023

Viewed by 1935

Abstract

Recent taphonomic studies have shown that avian predators such as owls are responsible for most small-mammal fossil accumulations, and that predators cause bone loss and breakage as well as modification to the surface of bones that are preserved. However, the specific physiochemical alterations [...] Read more.

Recent taphonomic studies have shown that avian predators such as owls are responsible for most small-mammal fossil accumulations, and that predators cause bone loss and breakage as well as modification to the surface of bones that are preserved. However, the specific physiochemical alterations and the alterations of bone microstructures that predators induce remain poorly understood. In order to better separate and characterize the effects of bone digestion by owls, we performed an experimental study to simulate digestion by a predator. We put fresh rodent long bones into various solutions to simulate the digestive effects of predators. We first tested an acid solution, followed by other solutions containing key enzymes such as trypsin, lipase, and trypsin + lipase. Next, we compared the results of the simulated digestion experiments with partly digested long bones recovered from Tyto alba and Bubo bubo pellets. We observed that acid action alone did not reproduce the modifications observed on bones from owl pellets, while the enzymatic activity (notably trypsin and trypsin + lipase) produced modifications most similar to those observed on the bones from the owl pellets. These results open a promising field of future experimentation to better understand the early diagenetic modification induced in small mammal bones by digestion, which can improve our ability to recognize the role of nocturnal predators in fossil accumulations. Full article

(This article belongs to the Special Issue Feature Papers in Biomineralization and Biominerals)

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21 pages, 14314 KiB

Open AccessArticle

Investigation into the Gaseous SO₂ Attack on Sandstone in the Yungang Grottoes

by Yue Zhang, Cheng Cao, Houmeng Du, Jizhong Huang, Xiuwei Guo, Qingyang Luo and Jianguang Ren

Minerals 2023, 13(1), 123; https://doi.org/10.3390/min13010123 - 13 Jan 2023

Cited by 6 | Viewed by 2391

Abstract

The Yungang Grottoes, with over 1500 years of history, have been subjected to air pollution since the last century. Field investigations have indicated that acid gases, particularly sulfur dioxide (SO₂), have accumulated on the surface of the sculptures and caused various [...] Read more.

The Yungang Grottoes, with over 1500 years of history, have been subjected to air pollution since the last century. Field investigations have indicated that acid gases, particularly sulfur dioxide (SO₂), have accumulated on the surface of the sculptures and caused various types of decay that reduce their artistic value. To shed new light on the gas–stone interaction process, artificially accelerated weathering was performed on local sandstone in the laboratory. In a specially developed test device, fresh specimens were exposed to gaseous SO₂ under different relative humidity and temperature conditions. The physical, mineralogical, and chemical changes of Yungang sandstone were evaluated conjointly using destructive and non-destructive methods. The results show that after weathering, the luminosity of all specimens changed, with a slight alteration in hue toward yellow. The weight increased to various degrees during the aging cycles, which depended on both the accumulation of matter and the detachment of particles. Higher relative humidity and cyclic temperature fluctuations favored the dissolution of carbonates and the hydrolysis of feldspar in sandstone. The concentration of ions, especially dissolved Ca²⁺ and SO₄²⁻, increased considerably over time in the near-surface region of the specimens. A trace of newly formed gypsum was detected in some specimens at the end of the test. Knowing the synergistic impact of different climatic variables will make it possible to identify the mechanisms of the deterioration of sandstone in complex environments. Full article

(This article belongs to the Special Issue Natural and Artificial Building Stones: Insights from Petrophysical Properties and Consolidation Procedures)

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19 pages, 9021 KiB

Open AccessArticle

Occurrence Relationship between Sodium and Maceral Groups in Subbituminous Coal: A Case Study on Zhundong Coal and Shenfu Coal

by Xin He, Wenfeng Wang, Yitao Yang, Changchun Zhou, Jingfeng He, Piaopiao Duan and Qingfeng Lu

Minerals 2023, 13(1), 122; https://doi.org/10.3390/min13010122 - 13 Jan 2023

Cited by 6 | Viewed by 1728

Abstract

The occurrence characteristics of sodium and its potential relationship with macerals in Zhundong coal, as well as in Shenfu coal with average sodium levels, are investigated in this study. A new five-step sequential extraction method was first conducted for determination. The occurrence status [...] Read more.

The occurrence characteristics of sodium and its potential relationship with macerals in Zhundong coal, as well as in Shenfu coal with average sodium levels, are investigated in this study. A new five-step sequential extraction method was first conducted for determination. The occurrence status of sodium and its related macerals in samples was determined by microscope and SEM–EDS (scanning electron microscope–energy dispersive X-ray spectroscopy). Soluble sodium salts (H₂O-Na) make up the primary proportion of sodium in Zhundong coal, at approximately 50%, while various sodium species are distributed in Shenfu coal with nonobvious differences. Inertinite contains more sodium than vitrinite does in both coals, and the highest enrichment degree of sodium was discovered in inertinite from Zhundong coal, which presented primarily as NaCl crystals (H₂O-Na) in fusinite cells, with a local weight percentage of over 15%. More specifically, H₂O-Na and insoluble Na both tend to enrich in fusinite. Additionally, it is found that maceral-rich products can be gathered using triboelectrostatic separation, and a portion of sodium can thus be removed from the coal by removing inertinite. This study may provide new insights and references regarding sodium removal from Zhundong coal. Full article

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

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20 pages, 7546 KiB

Open AccessArticle

Metal Source and Fluid Evolution in Xiaojiashan Gold Deposit in Northeastern Hunan, China: Implications of Rare Earth Elements, Fluid Inclusions, and Pyrite S Isotopic Compositions

by Dongzhuang Hou, Shu Lin, Lang Liu, Chao Huan, Huafu Qiu and Bingbing Tu

Minerals 2023, 13(1), 121; https://doi.org/10.3390/min13010121 - 13 Jan 2023

Viewed by 1901

Abstract

The material source and the evolution of ore-forming hydrothermal fluids of Xiaojiashan gold deposits remain controversial. We carried out a mineralogical characteristics analysis, trace elements analysis, sulfur isotope composition analysis, and fluid inclusion microthermometry in order to explore the ore-forming sources, conditions, and [...] Read more.

The material source and the evolution of ore-forming hydrothermal fluids of Xiaojiashan gold deposits remain controversial. We carried out a mineralogical characteristics analysis, trace elements analysis, sulfur isotope composition analysis, and fluid inclusion microthermometry in order to explore the ore-forming sources, conditions, and process of this deposit. Gold mineralization can be divided into three stages: the quartz-pyrite stage, the quartz-polymetallic sulfide stage, and the quartz-ankerite stage. This gold deposit was probably formed under the following conditions: temperature of 122–343 °C and salinity of 0.8–11.4 wt% (NaCl). It was inferred that the ore-forming hydrothermal fluids were early metamorphic–hydrothermal (Stage I) and late magmatic–hydrothermal (Stages II and III), and were characterized by medium–low temperature and medium–low salinity based on fluid inclusion microthermometry and S isotope composition. The temperature and salinity of the ore-forming fluid decreased during mineralization, which was caused by the involvement of groundwater. The chondrite-normalized trace element patterns of the gold ores are similar to the host rocks of the Lengjiaxi Formation, indicating that the ore-forming materials were sourced from the Lengjiaxi Formation. The S isotopes indicated that the magmatic components also provided the ore-forming materials during Stages II and III. Full article

(This article belongs to the Special Issue Critical Metals on Land and in the Ocean)

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18 pages, 6203 KiB

Open AccessArticle

Insights into Alpine-Karst-Type Tufa Deposits in Geological Environmental Records: A Case Study of the Calcareous Tufa Profile of the Jiuzhaigou Natural Reserve on the Eastern Margin of the Tibetan Plateau

by Congcong Lv, Xueqin Zhao, Yaoxi Jiang, Heyan Zhu, Hongmin Zhang, Fudong Wang, Qiongfang Li and Keli Hou

Minerals 2023, 13(1), 120; https://doi.org/10.3390/min13010120 - 13 Jan 2023

Cited by 2 | Viewed by 2033

Abstract

To study the geological environmental records of alpine-karst-type tufa deposits in the eastern margin of the Tibetan Plateau, the calcareous tufa profile exposed by the “8.8” Jiuzhaigou earthquake was taken as the research object and combined with a field geological investigation. Further, the [...] Read more.

To study the geological environmental records of alpine-karst-type tufa deposits in the eastern margin of the Tibetan Plateau, the calcareous tufa profile exposed by the “8.8” Jiuzhaigou earthquake was taken as the research object and combined with a field geological investigation. Further, the petrography, sedimentology, chronology, and elemental geochemistry of the calcareous tufa were studied and analyzed. The results show the following. (1) The Sparkling Lake calcareous tufa profile was deposited under the background of a warm and humid climate during the Holocene. The growth pattern follows a bottom-to-top deposition. (2) At 750 ± 30–300 ± 30 aB.P., the calcareous tufa layers were gray-black as a whole, and the changes in mineral composition and elemental geochemistry indicate a fluctuating upward trend for temperature and precipitation during this period. (3) The formation of two sets of black peat layers in the upper part of the tufa calcareous profile is due to the synergistic action of multiple factors caused by strong tectonic activity. In conclusion, the deposition mechanism of the calcareous tufa in Jiuzhaigou was controlled by paleoclimate hydrology and glaciation for a long time, while strong tectonic activity over a short period of time considerably changed the color, structure, element content, and mineral composition of the calcareous tufa. Full article

(This article belongs to the Special Issue Geochemistry of Travertines and Calcareous Tufas)

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16 pages, 9068 KiB

Open AccessArticle

Study on Mechanical Properties of Ring Sandstone Specimen under Temperature and Water Coupling Dynamic Compression

by Qi Ping, Qi Gao and Shiwei Wu

Minerals 2023, 13(1), 119; https://doi.org/10.3390/min13010119 - 12 Jan 2023

Cited by 2 | Viewed by 2127

Abstract

The excavation of hard rock roadways in coal mines is often in the environment of underground water and high ground temperature, and it is easy to be affected by the dynamic load, which leads to roadway destruction and increases the difficulty of roadway [...] Read more.

The excavation of hard rock roadways in coal mines is often in the environment of underground water and high ground temperature, and it is easy to be affected by the dynamic load, which leads to roadway destruction and increases the difficulty of roadway support. The ring sandstone specimens with different inner diameters (0~25 mm) were treated with temperature and water coupled, and the dynamic compression test was produced by the Hopkinson pressure rod device (SHPB). The experimental results indicate that the coupling effect of temperature and water reduces the dynamic performance of sandstone specimens. XRD test results showed that the composition of sandstone specimens did not change before and after warm water coupling, and no new substances were found. Dynamic properties of ring sandstone specimens with different inner diameters weaken with the increase in inner diameters. With the increasing inner diameter of ring sandstone specimens, the energy dissipation per unit volume increases the dynamic compressive strength decreases, and the degree of breakage increases. Fracture morphology, average strain rate, and dynamic peak strain of ring sandstone specimens increase with inner diameter. Full article

(This article belongs to the Topic New Trends in Rock Materials Mechanics and Engineering Geology)

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19 pages, 8558 KiB

Open AccessArticle

Research on Roof Load Transfer by Passing Coal Pillar of Working Face in Shallow Buried Closely Multiple-Seam

by Yanpeng He, Qingxiang Huang, Yehao Wei and Junwu Du

Minerals 2023, 13(1), 118; https://doi.org/10.3390/min13010118 - 12 Jan 2023

Cited by 7 | Viewed by 1475

Abstract

The dynamic load effect of supports is mainly caused by the movement of the roof structure and the load transfer of overburden. In view of the practice issue that the phenomenon of strong ground pressure is easy to happen, when the working face [...] Read more.

The dynamic load effect of supports is mainly caused by the movement of the roof structure and the load transfer of overburden. In view of the practice issue that the phenomenon of strong ground pressure is easy to happen, when the working face of the lower coal seam passes the inclined coal pillar in shallow buried closely multiple-seam, it will lead to supprot damaged. This paper takes the mining of over-inclined coal pillars in the 22410 working face of the Bulianta Coal Mine as the background, based on the research method combining the field measurement, physical simulation experiment, and numerical calculation, the evolution law of the front abutment pressure (FAP) and roof weighting in mining under the inclined coal pillar is analyzed, and the mechanism of the stress transfer of the inclined coal pillar and the dynamic load of the support is revealed. The research shows that the concentrated stress of the coal pillar is jointly borne by the front coal wall of the working face and the interburden structure above the support. The vertical stress transmitted from the coal pillar to the floor acts on the key blocks of the interburden of the lower coal seam, which causes strong pressure and dynamic load effect, such as roof structure cut-off. The periodic breaking of the key stratum of the interburden leads to the development height and range of the cracks increasing stepwise. The partition characteristics of the mutual transformation of the interburden stress, the FAP, and the working resistance (WR) by passing the coal pillar stage are revealed, which is divided into three stages and four regions. With the working face passing through the inclined coal pillar, the influence area of the concentrated stress of the coal pillar is reduced, and the peak stress of the coal pillar is gradually transferred to the outside of the coal pillar. When the working face is 5 m away from the coal pillar, the peak of FAP and WR reaches the maximum values, the roof is cutting along the peak stress line, and the working face has a strong weighting phenomenon. The research results are consistent with the field measurement results, providing a reference for the mining of working faces under similar conditions. Full article

(This article belongs to the Special Issue Green Mining of Coal Mine in China)

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18 pages, 6260 KiB

Open AccessArticle

Modified Tributary Area and Pressure Arch Theories for Mine Pillar Stress Estimation in Mountainous Areas

by Yang Yu, Jin Ma, Shenen Chen, Kazhong Deng, Bingqian Chen, Fenfen Hua and Jianrong Kang

Minerals 2023, 13(1), 117; https://doi.org/10.3390/min13010117 - 12 Jan 2023

Cited by 1 | Viewed by 2188

Abstract

This paper describes a parametric study using discrete element modeling (DEM) of partial mining in a mountain terrain with in situ pillars for overburden support. For room and pillar mining or strip pillar mining, the accurate estimation of pillar stress is essential to [...] Read more.

This paper describes a parametric study using discrete element modeling (DEM) of partial mining in a mountain terrain with in situ pillars for overburden support. For room and pillar mining or strip pillar mining, the accurate estimation of pillar stress is essential to ensure pillar stability and mine safety. Classical mine design methods such as the tributary area theory (TAT) and the pressure arch theory (PAT) are commonly used to calculate the pillar stress for mines under a relatively flat terrain. However, mine sites with uneven terrains can result in nonuniform stress distributions in the mine system and the classical methods may underestimate the pillar stresses by several times. In this paper, 1200 DEM mine models with terrains that include either a single slope or a valley, have been constructed. Through rigorous numerical modeling, the effects of several design parameters are identified: The influence factors, influence range, and mechanism of the concentrated pillar stresses computed from the models indicate that the shape of an extended pressure arch (EPA) can dictate the accuracy of the TAT and PAT methods. Based on the EPA estimation, a pillar stress estimation method is proposed for the design of mines in mountainous terrains. This paper updated the method of terrain-induced pillar stress concentrations with an improved EPA theory, and the gap between PAT and TAT theories is addressed by further discussion on their relationship and applicability. Full article

(This article belongs to the Special Issue Mechanical Behavior and Fracture Characteristics of Rock in Deep Underground Engineering)

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11 pages, 6441 KiB

Open AccessArticle

Gold Extraction from a Refractory Sulfide Concentrate by Simultaneous Pressure Leaching/Oxidation

by Juan Carlos Soto-Uribe, Jesus Leobardo Valenzuela-Garcia, Maria Mercedes Salazar-Campoy, Jose Refugio Parga-Torres, Guillermo Tiburcio-Munive, Martin Antonio Encinas-Romero and Victor Manuel Vazquez-Vazquez

Minerals 2023, 13(1), 116; https://doi.org/10.3390/min13010116 - 12 Jan 2023

Cited by 4 | Viewed by 4977

Abstract

Most gold deposits occur associated with sulphides like pyrite and arsenopyrite; thus, precious metal dissolution is possible by oxidizing auriferous sulfide concentrate using simultaneous pressure oxidation and cyanidation. The effectiveness of this process of extraction can be influenced by the temperature, cyanide (NaCN) [...] Read more.

Most gold deposits occur associated with sulphides like pyrite and arsenopyrite; thus, precious metal dissolution is possible by oxidizing auriferous sulfide concentrate using simultaneous pressure oxidation and cyanidation. The effectiveness of this process of extraction can be influenced by the temperature, cyanide (NaCN) concentration, and oxygen pressure. In this study, we conducted experiments to characterize the effects on gold extraction of ores using a range of sodium cyanide concentrations (1–8 g/L), temperatures (40–75 °C), and oxygen pressures (0.5–1.1 MPa). Characterization of the ores showed that pyrite and quartz were the main minerals present in the concentrate. The best results in terms of the highest extraction of Au were obtained with an oxygen pressure of 0.5 MPa, 6 g/L sodium cyanide, and a temperature of 75 °C, along with a constant stirring speed of 600 rpm. These conditions allowed for approximately 95% gold extraction in 90 min. Full article

(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)

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21 pages, 10681 KiB

Open AccessArticle

Corona-Type Textures in Ultrabasic Complexes of the Serpentinite Belt, Kola Peninsula, Russia

by Andrei Y. Barkov, Andrey A. Nikiforov, Robert F. Martin and Vladimir N. Korolyuk

Minerals 2023, 13(1), 115; https://doi.org/10.3390/min13010115 - 11 Jan 2023

Cited by 3 | Viewed by 2494

Abstract

For the first time, corona-type textures are described in ultrabasic rocks in three complexes of the Serpentinite Belt on the Kola Peninsula in the northeastern Fennoscandian Shield. Three variants of the corona texture formed at different stages during the crystallization of a komatiitic, [...] Read more.

For the first time, corona-type textures are described in ultrabasic rocks in three complexes of the Serpentinite Belt on the Kola Peninsula in the northeastern Fennoscandian Shield. Three variants of the corona texture formed at different stages during the crystallization of a komatiitic, Al-undepleted melt emplaced in a subvolcanic setting. The first type crystallized at an early stage (Mg# Ol = 87) in a fine-grained harzburgite of the Chapesvara-I sill, with the following order in the corona: Ol → Opx → Cpx → Pl → Amp (aluminous sodic-calcic). The second type displays the sequence Opx → Cpx → Amp → Pl → Qz, which is observed in the orthopyroxenite zone in the Lotmvara-I sill. The third type involves a symplectitic corona in a plagioclase-bearing orthopyroxenite in the Lyavaraka complex, in which the inferred order is: Cpx → Amp (aluminous hornblende) + symplectitic Qz, formed in direct contact with grains of Pl. The corona-type textures occur in fresh rocks and are not related to regional metamorphism. They likely formed as consequences of two important factors: (1) rapid cooling, leading to unsteady conditions of crystallization in a shallow setting; and (2) an intrinsic enrichment in H₂O and other volatiles in the parental magma, giving rise to fluid-saturated environments at advanced stages of crystallization. This was followed by a deuteric deposition of Amp rims as a result of the accumulation of H₂O and reaction of H₂O-bearing fluid with early grains of pyroxene and late plagioclase. The likely existence of a close relationship is suggested by the drusites of the Belomorian complex, which are coeval. In addition, unusual occurrences of lamellar inclusions of phlogopite and Al₂SiO₅ are documented, hosted by interstitial grains of plagioclase in the orthopyroxenite zone of the Lotmvara-I sill. These are attributed to crystallization from late portions of remaining melt enriched in Al, K, Na, H₂O, and Cl, which is indicated by the recorded occurrence of chlorapatite in this association. Thus, our findings indicate the presence and abundance of intrinsic volatiles, Cl, F, CO₂, and especially magmatic H₂O, which were important to lower the liquidus, decrease the density and viscosity of the highly magnesian melt of Al-undepleted komatiite, thus enabling its transport from the mantle to a shallow level in the crust. Full article

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

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14 pages, 2963 KiB

Open AccessArticle

Trace Element Composition of Molybdenite: Deposit Type Discrimination and Limitations

by Mao Tan, Xiaowen Huang, Yumiao Meng and Houmingrui Tan

Minerals 2023, 13(1), 114; https://doi.org/10.3390/min13010114 - 11 Jan 2023

Cited by 5 | Viewed by 2527

Abstract

Molybdenite is a common sulfide hosting many trace elements. Trace elements in molybdenite from individual deposits have been widely used to constrain the source and conditions of ore-forming fluids. However, the relationship between the trace element composition of molybdenite and deposit types has [...] Read more.

Molybdenite is a common sulfide hosting many trace elements. Trace elements in molybdenite from individual deposits have been widely used to constrain the source and conditions of ore-forming fluids. However, the relationship between the trace element composition of molybdenite and deposit types has not been well investigated from a large dataset. Here, simple statistics and partial least squares–discriminant analysis (PLS-DA) were used to determine whether different types of deposits can be distinguished by trace elements in molybdenite and what factors control the variations in trace element composition based on published laser ablation ICP–MS data. Molybdenite from porphyry deposits is separated from that from quartz veins, greisen Sn–W, granite vein Mo, and granodiorite Mo deposits. The former is characterized by relatively high Re, Cu, Ag, Se, Pb, Bi, and Te contents, whereas the latter has higher Ni, Co, Sn, Sb and W contents. Molybdenite from the quartz vein Au ± W deposits (Au-dominated), and porphyry Cu–Au–Mo (moderate Au) are separated from other deposits without gold due to positive correlations with Au, Sb, Te, Pb, and Bi for the former. Assemblages of Au–Sb–Te–Pb–Bi in molybdenite are thus useful to discriminate as to whether deposits contain gold and the degree of gold mineralization. Higher oxygen fugacity is responsible for the relative enrichment of W in molybdenite from greisen Sn–W deposits, whereas lower oxygen fugacity results in the relative enrichment of Re in molybdenite from porphyry Cu ± Mo ± Au and Mo ± Cu ± Au deposits. There are some limitations to using molybdenite as an indicator mineral because of the complex occurrences of elements in molybdenite, large compositional variations within a specific deposit type, and an imbalanced dataset. To develop molybdenite as an indicator mineral tool, further work should be carried out to overcome these limitations. This study provides an attempt to classify deposit types using molybdenite trace elements and has important implications for ore genesis research and mineral exploration. Full article

(This article belongs to the Special Issue Magmatic-Hydrothermal Fe Deposits and Affiliated Critical Metals)

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19 pages, 3127 KiB

Open AccessArticle

Comparison of Handheld and Echelle Spectrometer to Assess Copper in Ores by Means of Laser-Induced Breakdown Spectroscopy (LIBS)

by Pia Brinkmann, Nicole Köllner, Sven Merk, Toralf Beitz, Uwe Altenberger and Hans-Gerd Löhmannsröben

Minerals 2023, 13(1), 113; https://doi.org/10.3390/min13010113 - 11 Jan 2023

Cited by 4 | Viewed by 2541

Abstract

Its properties make copper one of the world’s most important functional metals. Numerous megatrends are increasing the demand for copper. This requires the prospection and exploration of new deposits, as well as the monitoring of copper quality in the various production steps. A [...] Read more.

Its properties make copper one of the world’s most important functional metals. Numerous megatrends are increasing the demand for copper. This requires the prospection and exploration of new deposits, as well as the monitoring of copper quality in the various production steps. A promising technique to perform these tasks is Laser Induced Breakdown Spectroscopy (LIBS). Its unique feature, among others, is the ability to measure on site without sample collection and preparation. In this work, copper-bearing minerals from two different deposits are studied. The first set of field samples come from a volcanogenic massive sulfide (VMS) deposit, the second part from a stratiform sedimentary copper (SSC) deposit. Different approaches are used to analyze the data. First, univariate regression (UVR) is used. However, due to the strong influence of matrix effects, this is not suitable for the quantitative analysis of copper grades. Second, the multivariate method of partial least squares regression (PLSR) is used, which is more suitable for quantification. In addition, the effects of the surrounding matrices on the LIBS data are characterized by principal component analysis (PCA), alternative regression methods to PLSR are tested and the PLSR calibration is validated using field samples. Full article

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3 pages, 180 KiB

Open AccessEditorial

Editorial for Special Issue “Environmental Geochemistry in the Mining Environment”

by Benoît Plante, Thomas Pabst and David Wilson

Minerals 2023, 13(1), 112; https://doi.org/10.3390/min13010112 - 11 Jan 2023

Viewed by 1822

Abstract

The demand for minerals has never been so high and is expected to increase in the coming decades [...] Full article

(This article belongs to the Special Issue Environmental Geochemistry in the Mining Environment)

22 pages, 7042 KiB

Open AccessArticle

New Mineral Occurrences in Massive Sulfide Deposits from Mănăilă, Eastern Carpathians, Romania

by Gheorghe Damian, Andrei Ionuț Apopei, Andrei Buzatu, Andreea Elena Maftei and Floarea Damian

Minerals 2023, 13(1), 111; https://doi.org/10.3390/min13010111 - 10 Jan 2023

Viewed by 2224

Abstract

The massive sulfide deposits (VMS) from Mănăilă are associated with the metamorphic formations of the Tulgheș Lithogroup from the Bucovinian Nappes of the Crystalline-Mesozoic Zone in the Eastern Carpathians, Romania. The following types of ore were identified: pyrite-polymetallic, pyrite copper, compact and precompact [...] Read more.

The massive sulfide deposits (VMS) from Mănăilă are associated with the metamorphic formations of the Tulgheș Lithogroup from the Bucovinian Nappes of the Crystalline-Mesozoic Zone in the Eastern Carpathians, Romania. The following types of ore were identified: pyrite-polymetallic, pyrite copper, compact and precompact copper, and quartz-precompact copper. The polymetallic mineralization consists of pyrite, chalcopyrite, sphalerite, galena, and subordinately arsenopyrite and tennantite. The copper, especially the quartz-copper mineralizations, have a distinct mineralogical composition compared to the other metamorphosed mineralizations of the Tulgheș Lithogroup. These types of deposits from Mănăilă contain large amounts of bornite and chalcocite along with chalcopyrite. Tennantite is abundant and has up to a 3.57 wt.% of bismuth. Wittichenite was identified for the first time in the metamorphic mineralizations and mawsonite was identified as the first occurrence in Romania. An unnamed mineral with the formula:

{(C u, F e)}_{11} (P b, A g) S_{7}

was also identified, belonging to the sulfides group. The compact and precompact pyrite-rich ores, located in sericite ± quartzite schists and covered by rhyolitic metatuffs, are of hydrothermal-sedimentary type metamorphosed in the greenschist facies. The source of the quartz-copper mineralization would be the retromorphic or metasomatic hydrothermal solutions that circulated through major fractures. Full article

(This article belongs to the Special Issue Sulfide Mineralogy and Geochemistry)

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9 pages, 735 KiB

Open AccessArticle

Tracking Amorphous Calcium Carbonate Crystallization Products with Far-Infrared Spectroscopy

by Boyang Gao and Kristin M. Poduska

Minerals 2023, 13(1), 110; https://doi.org/10.3390/min13010110 - 10 Jan 2023

Cited by 2 | Viewed by 2427

Abstract

We prepared solution-precipitated amorphous calcium carbonate by two similar methods and tracked structural changes over time as they crystallized. By cross-referencing mid-range infrared (400–4000 cm⁻¹) with far-infrared (100–400 cm⁻¹) spectral features, and by comparing with powder X-ray diffraction data [...] Read more.

We prepared solution-precipitated amorphous calcium carbonate by two similar methods and tracked structural changes over time as they crystallized. By cross-referencing mid-range infrared (400–4000 cm⁻¹) with far-infrared (100–400 cm⁻¹) spectral features, and by comparing with powder X-ray diffraction data for the aged crystallized products, we provide guidelines for—and potential limitations of—using far-infrared spectroscopy to assess multi-phase Mg-containing calcium carbonate samples that include amorphous or poorly crystallized components. Full article

(This article belongs to the Special Issue Sulphate and Carbonate Minerals)

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13 pages, 3858 KiB

Open AccessArticle

Crystal-Chemical and Spectroscopic Study of Gem Sphalerite from Banská Štiavnica, Slovakia

by Peter Bačík, Jana Fridrichová, Olena Rybnikova, Ján Štubňa, Ľudmila Illášová, Radek Škoda, Tomáš Vaculovič, Zuzana Pulišová and Peter Sečkár

Minerals 2023, 13(1), 109; https://doi.org/10.3390/min13010109 - 10 Jan 2023

Viewed by 2708

Abstract

A complex crystal-chemical investigation based on spectroscopic methods, Electron MicroProbe Analysis (EMPA), and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was made on sphalerite samples from the Terézia and Rozália veins in the Banská Štiavnica ore district. The yellow (sample A) and [...] Read more.

A complex crystal-chemical investigation based on spectroscopic methods, Electron MicroProbe Analysis (EMPA), and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was made on sphalerite samples from the Terézia and Rozália veins in the Banská Štiavnica ore district. The yellow (sample A) and olive-green sphalerite (C) are in association only with quartz; orange sphalerite (B) is associated with quartz and chalcopyrite; and black sphalerite (D) is associated with galena, chalcopyrite, quartz, and baryte. EMPA revealed that Cd and Fe are substituting for Zn with variable proportions; the Cd/Fe ratio decreases from 2.82–2.85 in the A sample to 0.42 in the D sample. LA-ICP-MS showed that, except Cd and Fe, only Mn has content above 20; Co and Cu vary between 2 and 17 ppm. The optical absorption spectra exhibit absorption between 644 and 740 nm with three smaller humps at 669–671, 698–702, and 732–743 nm, and weaker absorption bands at 858–894 nm in the NIR region, which can be all assigned to crystal-field transitions of Fe²⁺. The absorption edge starts at about 600 nm to the UV region. Minimal absorption is in the yellow-red part of the visible spectrum giving rise to yellowish-orange and orange-red colors. Absorption in the red region for olive-green sphalerite is more pronounced, explaining the shift to greenish hues. In black sphalerite, the absorption pattern is similar to the olive-green sphalerite, but the bands in the 644 to 740 nm region are less defined. The black color could be caused by slightly higher concentrations of Fe, the smaller size of individual crystals in the aggregate reducing macroscopic transparency, and/or the presence of submicroscopic inclusions. Full article

(This article belongs to the Special Issue Gem Deposits: Mineralogical and Gemological Aspects)

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16 pages, 4394 KiB

Open AccessArticle

Study on Characteristics of Compression Deformation and Post-Peak Stress Rebound for Solid Waste Cemented Body

by Xinyuan Zhao, Ke Yang, Xiang He, Zhen Wei, Jiqiang Zhang and Xiang Yu

Minerals 2023, 13(1), 108; https://doi.org/10.3390/min13010108 - 10 Jan 2023

Cited by 8 | Viewed by 1676

Abstract

Most of the previous studies focused on the mechanical characteristics before the stress peak of solid waste cemented backfill, but in the compression process of a solid waste cemented body, the phenomenon of post-peak stress rebound often occurs. Through the uniaxial compression experiment [...] Read more.

Most of the previous studies focused on the mechanical characteristics before the stress peak of solid waste cemented backfill, but in the compression process of a solid waste cemented body, the phenomenon of post-peak stress rebound often occurs. Through the uniaxial compression experiment of a solid waste cemented body composed of coal gangue, fly ash, desulfurization gypsum, gasification slag, and furnace bottom slag, this paper analyzed the compression deformation characteristics of a solid waste cemented body with different mix proportions before and after the stress peak, established the stress–strain curve model of rebound stress in the rising and descending section after the stress peak, and revealed the reasons for the rebound stress and secondary unloading of the cemented body after the stress peak. The results showed that the maximum rebound stress accounts for 40%–80% of the compressive strength, and the changes in the two are positively correlated. The stress–strain curve model is a cubic function in the post-peak stress rising section and a quadratic rational function in the descending section. With the increase in the maximum compressive strength of the cemented body, its maximum rebound stress also increases, but its corresponding compressive strain generally shows a downward trend. There is a positive correlation between the rebound stress increment and strain increment of the cemented body. The change in the supporting structure and the evolution of the failure form of the cemented body before and after the maximum rebound stress indicate that the compression failure of the residual supporting structure caused by the main crack is the main reason for the rebound of the stress after the peak value of the cemented body to the complete unloading. Full article

(This article belongs to the Topic Green Low-Carbon Technology for Metalliferous Minerals)

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20 pages, 3585 KiB

Open AccessArticle

The Characteristics, Enrichment, and Migration Mechanism of Cadmium in Phosphate Rock and Phosphogypsum of the Qingping Phosphate Deposit, Southwest China

by Chengjie Zou, Zeming Shi, Yulong Yang, Junji Zhang, Yun Hou and Na Zhang

Minerals 2023, 13(1), 107; https://doi.org/10.3390/min13010107 - 9 Jan 2023

Cited by 5 | Viewed by 2519

Abstract

Sedimentary phosphate rocks are characteristically rich in organic matter, and contain sulfides and a high concentration of trace elements, including cadmium (Cd), which is harmful to the human body. The mining of phosphate rock and phosphogypsum at Qingping has expanded the release of [...] Read more.

Sedimentary phosphate rocks are characteristically rich in organic matter, and contain sulfides and a high concentration of trace elements, including cadmium (Cd), which is harmful to the human body. The mining of phosphate rock and phosphogypsum at Qingping has expanded the release of Cd into groundwater and farmland soil. To prevent and control Cd pollution it is critical to reveal the carrier mineral phase(s) and migration mechanism of Cd and other elements in phosphate rock and phosphogypsum. The elemental and mineral composition of bulk samples were analysed by XRF, ICP-MS, and XRD, respectively. The results showed that from phosphate rock to phosphogypsum, the main constituent elements changed from CaO (49.43%) and P₂O₅ (36.63%) to CaO (33.65%) and SO₃ (>34%), and the main mineral changed from fluorapatite to gypsum. Among all the elements, the element transfer factor (ETF) of P₂O₅, F, Co, U, Cd, and other elements was low; the ETF (Cd) was only 10.85%, and only a small amount of Cd entered the acidic phosphogypsum during the production process. Raman spectroscopy analysis revealed two types of apatite: the brown–black apatite with organic matter (type 1) and the yellow–light brown apatite without organic matter (type 2). LA-ICP-MS analysis showed that the Cd element content in type 2 was lower, while the organic matter and Cd element content in type 1 were higher, suggesting that Cd may be controlled by organic matter, and the relationship with apatite is not apparent. Electron probe analysis and XRD semiquantitative results show that the content of Cd in pyrite is higher (511 ppm), which is significantly higher than that of bulk rock. In addition, pyrite is rich in Co, As, Ni, Zn, and other elements. The content of Cd in phosphate ore shows a good correlation with that of pyrite. Cd in Qingping phosphate rock is mainly controlled by organic matter and pyrite, and only a small amount of Cd is transferred to phosphogypsum. Reducing the environment leads to the enrichment of Cd in phosphate rock. Full article

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

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19 pages, 4254 KiB

Open AccessArticle

Biosorption of Aqueous Pb(II), Co(II), Cd(II) and Ni(II) Ions from Sungun Copper Mine Wastewater by Chrysopogon zizanioides Root Powder

by Saba Madadgar, Faramarz Doulati Ardejani, Zohreh Boroumand, Hossein Sadeghpour, Reza Taherdangkoo and Christoph Butscher

Minerals 2023, 13(1), 106; https://doi.org/10.3390/min13010106 - 9 Jan 2023

Cited by 9 | Viewed by 2931

Abstract

In this study, a plant-based adsorbent was used in order to remove lead, nickel, cobalt and cadmium metals from a wastewater sample collected from Sungun mine real wastewater. The biosorbent was one of the most abundant native plants of the Sungun region, named [...] Read more.

In this study, a plant-based adsorbent was used in order to remove lead, nickel, cobalt and cadmium metals from a wastewater sample collected from Sungun mine real wastewater. The biosorbent was one of the most abundant native plants of the Sungun region, named Chrysopogon zizanioides (C. zizanioides). The root powder of C. zizanioides was used in order to remove heavy metals from the wastewater sample. The biosorbent was characterized by FTIR, SEM, HR-TEM, EDS, BET and ZPC analyses. The effect of pH, initial metals concentrations, contact time and temperature on the biosorption process were accurately investigated. The metal concentrations were significantly reduced to lower concentrations after the biosorption process, which indicated that the C. zizanioides root powder removal efficiency was more than 95% for the metals from the wastewater sample, with maximum adsorption capacities of 31.78, 21.52, 26.69 and 27.81 mg/g, for Pb(II), Co(II), Cd(II) and Ni(II) ions, respectively. Furthermore, the adsorption kinetic results showed that the pseudo-second-order kinetic model correlated with the experimental data well, with correlation coefficient values of 1 for all metals. Isotherm studies illustrated that the Freundlich and Dubinin-Radushkevich (D-R) isotherm models could describe the obtained equilibrium data well. Moreover, from the D-R model, it was found that the biosorption type was physical. The thermodynamic studies demonstrated that the metals’ biosorption was an exothermic and spontaneous process. Moreover, the reusability of the biosorbent to be used in several successive cycles, and also the percentage of recovery of adsorbed metals from the biosorbent, was investigated. Altogether, being simple and cost-effective and having a high adsorption rate, fast kinetics, easy separation and high reusability prove that C. zizanioides root powder shows significant performance for the removal of heavy metals from waste effluents. Full article

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23 pages, 11895 KiB

Open AccessArticle

Behaviors of Silicon, Aluminum and Iron and Kinetics of Silicon from the Roasted Clinker of Silver Tailings in Water–Acid Leaching Process

by Jie Chang, Aifang Pan, Yuzhao Ma, Yue Sun and Shentao Hu

Minerals 2023, 13(1), 105; https://doi.org/10.3390/min13010105 - 9 Jan 2023

Cited by 3 | Viewed by 2028

Abstract

In order to achieve efficient resource utilization of metal tailings, taking the roasted clinker of silver tailings (RCST) as the object, the dissolution behaviors of Si, Al and Fe in the water–acid two-stage leaching process and the water leaching kinetics of Si were [...] Read more.

In order to achieve efficient resource utilization of metal tailings, taking the roasted clinker of silver tailings (RCST) as the object, the dissolution behaviors of Si, Al and Fe in the water–acid two-stage leaching process and the water leaching kinetics of Si were investigated in this study. Single-factor experiments were performed to investigate the effects of the leaching parameters; the XRF, XRD and SEM-EDS methods were used to characterize the leaching residues with different leaching times, and the leaching kinetics models of Si were established. The results demonstrate that, in the water leaching stage, the sodium silicate and a small part of the structurally unstable sodium aluminosilicate in RCST are dissolved, while the nepheline, most of the sodium aluminosilicate and the mixed materials containing iron enter the water leaching residue. The first 5 min of water leaching is controlled by both interfacial transfer and diffusion across the product layer, with an apparent activation energy of 22.36 kJ/mol, and the dissolution reaction during 5–15 min is controlled by the unsteady diffusion of the liquid film, with an apparent activation energy of 14.22 kJ/mol. The structure of the materials in the clinker is completely destroyed, and a great number of fissures and pores are produced by the continued dissolving action of the water. Thus, in the acid leaching stage, the amorphous Si-, Al- and Fe-containing substances in the water leaching residue are rapidly dissolved in the sulfuric acid solution at a lower temperature. Full article

(This article belongs to the Special Issue Synthesis, Properties and Applications of Metallurgical Waste-Modified Materials in Construction Industry)

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17 pages, 2158 KiB

Open AccessArticle

Shortwave UV Blue Luminescence of Some Minerals and Gems Due to Titanate Groups

by Maxence Vigier, Emmanuel Fritsch, Théo Cavignac, Camille Latouche and Stéphane Jobic

Minerals 2023, 13(1), 104; https://doi.org/10.3390/min13010104 - 9 Jan 2023

Cited by 7 | Viewed by 5657

Abstract

This article reviews blue shortwave-excited luminescence (BSL) in natural minerals and synthetic materials. It also describes in detail the emission of seven minerals and gems displaying BSL, as well as three references in which BSL is caused by titanate groups (TiO₆): [...] Read more.

This article reviews blue shortwave-excited luminescence (BSL) in natural minerals and synthetic materials. It also describes in detail the emission of seven minerals and gems displaying BSL, as well as three references in which BSL is caused by titanate groups (TiO₆): benitoite, Ti-doped synthetic sapphire and spinel. Emission (under 254 nm shortwave excitation) and excitation spectra are provided, and fluorescence decay times are measured. It is proposed that BSL in beryl (morganite), dumortierite, hydrozincite, pezzotaite, tourmaline (elbaite), some silicates glasses, and synthetic opals is due to titanate groups present at a concentration of 20 ppmw Ti or above. They all share a broad emission with a maximum between 420 and 480 nm (2.95 to 2.58 eV) (thus perceived as blue), and an excitation spectrum peaking in the short-wave range, between 230 and 290 nm (5.39 to 4.27 eV). Furthermore, their luminescence decay time is about 20 microseconds (from 2 to 40). These three parameters are consistent with a titanate emission, and to our knowledge, no other activator. Full article

(This article belongs to the Special Issue Gem Characterisation)

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18 pages, 12916 KiB

Open AccessEditor’s ChoiceArticle

Ensemble Tree Model for Long-Term Rockburst Prediction in Incomplete Datasets

by Huanxin Liu, Guoyan Zhao, Peng Xiao and Yantian Yin

Minerals 2023, 13(1), 103; https://doi.org/10.3390/min13010103 - 9 Jan 2023

Cited by 5 | Viewed by 1917

Abstract

The occurrence of rockburst can seriously impact the construction and production of deep underground engineering. To prevent rockburst, machine learning (ML) models have been widely employed to predict rockburst based on some related variables. However, due to the costs and complicated geological conditions, [...] Read more.

The occurrence of rockburst can seriously impact the construction and production of deep underground engineering. To prevent rockburst, machine learning (ML) models have been widely employed to predict rockburst based on some related variables. However, due to the costs and complicated geological conditions, complete datasets to evaluate rockburst cannot always be obtained in rock engineering. To fill this limitation, this study proposed an ensemble tree model suitable for incomplete datasets, i.e., the histogram gradient boosting tree (HGBT), to build intelligent models for rockburst prediction. Three hundred fourteen rockburst cases were employed to develop the HGBT model. The hunger game search (HGS) algorithm was implemented to optimize the HGBT model. The established HGBT model had an excellent testing performance (accuracy of 88.9%). An incomplete database with missing values was applied to compare the performances of HGBT and other ML models (random forest, artificial neural network, and so on). HGBT received an accuracy of 78.8% in the incomplete database, and its capacity was better than that of other ML models. Additionally, the importance of input variables in the HGBT model was analyzed. Finally, the feasibility of the HGBT model was validated by rockburst cases from Sanshandao Gold Mine, China. Full article

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15 pages, 3269 KiB

Open AccessArticle

Structural Features of Oxyapatite

by Natalia V. Bulina, Leon A. Avakyan, Svetlana V. Makarova, Igor B. Orehov and Vladimir S. Bystrov

Minerals 2023, 13(1), 102; https://doi.org/10.3390/min13010102 - 9 Jan 2023

Cited by 10 | Viewed by 2268

Abstract

One of the most widely known representatives of the apatite family is hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂. This mineral is a part of the human dental and bone tissues, and, therefore, is widely used in medicine. Less known [...] Read more.

One of the most widely known representatives of the apatite family is hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂. This mineral is a part of the human dental and bone tissues, and, therefore, is widely used in medicine. Less known is oxyapatite, Ca₁₀(PO₄)₆O, which has the same biocompatibility as hydroxyapatite. In this work, it is shown that oxyapatite can be obtained by heating hydroxyapatite powder at 1000 °C in vacuum. IR and NMR spectroscopy proved the absence of the hydroxyl groups in the apatite obtained. In the IR spectrum, the presence of new absorption bands of phosphate groups, indicating a symmetry disorder, was observed. Density functional theory modeling confirmed lowering of symmetry for the oxyapatite structure. Modeling the IR spectrum of oxyapatite made it possible to identify the experimentally observed new absorption bands. According to the modeling, the presence of a vacancy in a hydroxyl channel of the apatite structure lowered the symmetry. Powder X-ray diffraction data confirmed that full dehydroxylation of hydroxyapatite led to a decrease in symmetry to triclinic phase. Comparison of the formation energies showed that formation of the hydroxyapatite phase was more preferable than that of oxyapatite, which explains apatite’s tendency to rehydroxylation. It was shown that the solubility of oxyapatite in water was comparable to that of hydroxyapatite. Full article

(This article belongs to the Special Issue Recent Advances of Hydroxyapatite and Its Applications, Volume II)

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22 pages, 6543 KiB

Open AccessArticle

Petrogenesis of the Helong Granites in Southern Jiangxi Province, China: Constraints from Geochemistry and In Situ Analyses of Zircon U–Pb–Hf Isotopes

by Xinxing Liu, Weixin Shi, Juan Zhang, Xiaoyan Zhang, Junfeng Yang and Wei Li

Minerals 2023, 13(1), 101; https://doi.org/10.3390/min13010101 - 9 Jan 2023

Cited by 1 | Viewed by 1816

Abstract

The Jinzhuping and Changkeng granites are related to the Helong W–Sn ore field in southern Jiangxi Province, China. Three different phases can be found in the Jinzhuping pluton, and their LA-ICP-MS zircon U–Pb ages are 155.2 ± 0.68 Ma, 154.0 ± 0.56 Ma, [...] Read more.

The Jinzhuping and Changkeng granites are related to the Helong W–Sn ore field in southern Jiangxi Province, China. Three different phases can be found in the Jinzhuping pluton, and their LA-ICP-MS zircon U–Pb ages are 155.2 ± 0.68 Ma, 154.0 ± 0.56 Ma, and 153.4 ± 0.99 Ma, respectively, indicating two types of granitic rocks. All granites in the Helong ore field have similar geochemical characteristics, they have high contents of SiO₂ (73.99 wt.%–77.68 wt.%), and total alkali (7.56 wt.%–8.76 wt.%) and are weakly to strongly peraluminous. They are slightly enriched in HREE and depleted in Eu, Ba, Sr, P, and Ti. Zircon εHf(t) values of the Jinzhuping three granites are from −14.4 to −10.4, from −15.3 to −11.4, and from −18.1 to −10.5, and the Hf TDM model ages range from 1.83 to 2.06 Ga, from 1.89 to 2.14 Ga, and from 1.83 to 2.31 Ga, respectively. Whole-rock geochemistry and Hf isotope analysis indicate that the Helong granites experienced a high degree of differentiation and evolution derived by partial melting of the Late Paleoproterozoic crustal materials, and they formed in a backarc caused by low-angle subduction of the Paleopacific plate. Full article

(This article belongs to the Special Issue Petrology, Mineralogy, Geochemistry and Geochronology of Granites)

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Minerals, Volume 13, Issue 1 (January 2023) – 130 articles

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