Minerals

18 pages, 7396 KiB

Open AccessArticle

Uranium-Bearing Layers of Sandstone Type Uranium Deposits Identification and Three-Dimensional Reconstruction in the Northern Ordos Basin, North-Central China

by Yulei Tan, Laijun Lu, Chen Yang, Jia Zhao and Yan Ding

Minerals 2023, 13(6), 834; https://doi.org/10.3390/min13060834 - 20 Jun 2023

Cited by 3 | Viewed by 1733

Abstract

Sandstone type uranium is the most valuable and has the most potential for mining among the known uranium deposits. In the process of forming, the hydrolytic migration and enrichment of uranium require special basin sedimentary environment and tectonic background. Therefore, the mineralization process [...] Read more.

Sandstone type uranium is the most valuable and has the most potential for mining among the known uranium deposits. In the process of forming, the hydrolytic migration and enrichment of uranium require special basin sedimentary environment and tectonic background. Therefore, the mineralization process of sandstone type uranium deposits has certain layering characteristics and distribution rules in the underground vertical depth space. It is important to mine the spatial distribution characteristics of vertical uranium-bearing layers, and thus, reconstruct the three-dimensions of uranium orebodies. In this paper, according to the metallogenic law and distribution characteristics of sandstone type uranium in the underground vertical space, a nonlinear uranium-bearing layers identification (NULI) method of sandstone type uranium is proposed by using different types, resolutions and scales of borehole data. Then, the depth of uranium mineralization for the Daying uranium deposit within northern Ordos Basin is identified accurately and the spatial distribution characteristics of the uranium-bearing layer on the exploration line are obtained. Finally, the occurrence mode of the underground uranium orebodies are presented by using three-dimensional reconstruction analysis. It provides a basis for the prediction, exploration and mining of sandstone type uranium deposits within the Ordos Basin. Full article

(This article belongs to the Special Issue Digital Geosciences and Mineral Exploration)

► Show Figures

Figure 1

24 pages, 34695 KiB

Open AccessArticle

Petrology and Age of the Yamaat Uul Mafic Complex, Khangai Mountains, Western Mongolia

by Roman Shelepaev, Maria Shapovalova, Vera Egorova, Yaroslav Shelepov, Tumen-Ulzii Oyunchimeg and Nadezhda Tolstykh

Minerals 2023, 13(6), 833; https://doi.org/10.3390/min13060833 - 20 Jun 2023

Cited by 1 | Viewed by 1404

Abstract

The Yamaat Uul mafic complex with Cu-Ni mineralization is located in the Khangai Mountains of Western Mongolia. We have received new unique data for mafic rocks of the complex: U-Pb dating (SHRIMP II), mineralogy (WDS) and geochemistry (XRF, ICP-MS), Sm-Nd and Rb-Sr isotope [...] Read more.

The Yamaat Uul mafic complex with Cu-Ni mineralization is located in the Khangai Mountains of Western Mongolia. We have received new unique data for mafic rocks of the complex: U-Pb dating (SHRIMP II), mineralogy (WDS) and geochemistry (XRF, ICP-MS), Sm-Nd and Rb-Sr isotope data and sulphur isotopes. The Yamaat Uul mafic complex consists of two intrusions: Intrusion 1 is represented by rocks of plagioclase cumulates and olivine–pyroxene cumulates; Intrusion 2 consists of monzogabbro. Intrusions 1 and 2 are different in composition of minerals such as olivine, plagioclase and biotite. The monzogabbro has higher contents of incompatible elements (REE, K, Ti, P) than rocks of Intrusion 1. Zircon U-Pb dating of the anorthosite and Bt-Am-Ol gabbronorite shows a Late Permian age (255.8 ± 2.9 Ma and 262.6 ± 3.1 Ma, respectively) for the Yamaat Uul mafic complex. All of the rocks of the complex are derived from a unified parental melt due to different amounts of trapped melts in plagioclase and olivine–pyroxene cumulates and without crustal contamination. The Cu-Ni mineralization of the complex has a low degree of evolution of the sulphide melt, similar to PGE-Cu-Ni mafic–ultramafic intrusions of the Khangai Mountains (Nomgon and Oortsog Uul). The Yamaat Uul mafic complex together with other mafic–ultramafic intrusions of the Khangai Mountains is related to the Khangai LIP and can be considered as potential for the PGE-Cu-Ni. The new geological, petrological, geochemical and isotope–geochronological data can later be used to reconstruct the geotectonics of the Khangai Mountains and the Central Asian orogenic belt as a whole. Full article

(This article belongs to the Special Issue Large Igneous Provinces: Research Frontiers)

► Show Figures

Figure 1

13 pages, 2386 KiB

Open AccessArticle

Comparison of Different Radiological Risk Assessment Scenarios at a Coal Ash and Slag Disposal Site

by Ana Getaldić, Marija Surić Mihić, Želimir Veinović, Božena Skoko, Branko Petrinec and Ivica Prlić

Minerals 2023, 13(6), 832; https://doi.org/10.3390/min13060832 - 20 Jun 2023

Cited by 1 | Viewed by 1456

Abstract

Coal fly ash and slag waste residuals from coal combustion are an issue of importance as one of the possible sources of environmental contamination and exposure to NORM. This study compares the results of different radiological risk assessment scenarios targeting terrestrial biota at [...] Read more.

Coal fly ash and slag waste residuals from coal combustion are an issue of importance as one of the possible sources of environmental contamination and exposure to NORM. This study compares the results of different radiological risk assessment scenarios targeting terrestrial biota at a legacy site in Croatia that contains large quantities of coal ash with an enhanced content of radionuclides originating from previous industrial activities. The ERICA assessment tool was used for a risk assessment, which included data from borehole samples with a maximum depth of 6 m and trees as the primary reference organisms. The results of the risk assessments from various depth ranges found the radiological risk to the reference organisms to be negligible, regardless of the depth range, since the screening dose rate of 10 µGyh⁻¹ was not exceeded in any of the assessments. The risk assessment results from all depth ranges show higher total dose rate predictions when the tool’s default CR values are used, compared to the site-specific ones, which is in agreement with previous studies on the application of the ERICA tool. A comparison of results from different spatial radiological risk assessments showed that sample depth does not affect the estimated total dose rate to biota. Full article

(This article belongs to the Special Issue Radionuclides and Radiation Exposure in Mine Sites)

► Show Figures

Figure 1

18 pages, 5098 KiB

Open AccessArticle

Investigation of Hydrated Dy(III) and MgSO₄ Leaching Agent Ion Adsorption on (001) Surface of Montmorillonite: A Study Using Density Functional Theory

by Lijinhong Huang, Zhiqiang Zou, Shaomin Liu, Lihong Liu, Wengang Xiao, Yantao Qian, Shafiq Alam and Wanfu Huang

Minerals 2023, 13(6), 831; https://doi.org/10.3390/min13060831 - 20 Jun 2023

Viewed by 1351

Abstract

Kaolinite is one of the principal rare earth element (REE) ion-adsorption clays that hosts a wide range of elements, including Dy(III) as a representative example. Ammonium sulfate is a typical salt used to leach REEs. Due to the carbon dioxide emissions which occur [...] Read more.

Kaolinite is one of the principal rare earth element (REE) ion-adsorption clays that hosts a wide range of elements, including Dy(III) as a representative example. Ammonium sulfate is a typical salt used to leach REEs. Due to the carbon dioxide emissions which occur during ammonia production, it is urgently necessary to develop low environmental pollution leaching agents that can replace (NH₄)₂SO₄. MgSO₄ is regarded as the most promising eco-friendly leaching agent. Herein, the first-principles plane-wave pseudopotential method based on the density functional theory (DFT) was used to investigate the stable adsorption structures of Dy(III) and its hydrated ions, MgSO₄ leaching agent ions and the corresponding hydrated ions on the surface of kaolinite, which revealed the adsorption mechanism of Dy(III), Mg(II), and SO₄²⁻ on the silico–oxygen plane and the aluminum–hydroxyl plane of kaolinite. Based on the research results of the steric hindrance effect of Dy(III) on the silico–oxygen plane and the aluminum–hydroxyl plane of kaolinite, the adsorption of Dy(H₂O)₁₀³⁺ was more stable on the silico–oxygen plane. It was easier to leach out Dy(III) with MgSO₄, while SO₄²⁻ tended to interact with the rare earth ions in an aqueous solution. The results provide theoretical guidance for efficient rare earth extraction and obtaining novel efficient leaching agents. Full article

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

► Show Figures

Figure 1

19 pages, 3016 KiB

Open AccessArticle

Trace Element Composition of Pyrite from Selected Black Shale and Chert Exposures in the Central Belt of Peninsular Malaysia: Implications for Mineral Exploration

by Charles Makoundi, Khin Zaw, Zakaria Endut and Hareyani Zabidi

Minerals 2023, 13(6), 829; https://doi.org/10.3390/min13060829 - 20 Jun 2023

Viewed by 1729

Abstract

Sedimentary and hydrothermal pyrites contained in selected Malaysian black shale and cherts have been analysed using laser ablation inductively coupled plasma (LA ICP-MS) and electron probe microanalysis (EPMA) at the University of Tasmania, Australia. This study shows that gold is concentrated in sedimentary [...] Read more.

Sedimentary and hydrothermal pyrites contained in selected Malaysian black shale and cherts have been analysed using laser ablation inductively coupled plasma (LA ICP-MS) and electron probe microanalysis (EPMA) at the University of Tasmania, Australia. This study shows that gold is concentrated in sedimentary and hydrothermal pyrite in the Middle Permian to Late Triassic black shales and Devonian cherts. According to LA ICP-MS analysis, gold contents in pyrite varied from 0.5 to 0.8 ppm Au in the Permo-Triassic black shale and between 0.2 and 0.8 ppm Au in the Devonian cherts. The lowest level of gold (0.3 ppm Au) was observed in the Permo-Triassic black shale that crops out at the Selinsing gold mine. In the Permo-Triassic period, the selenium contents display one peak (average range: 63.4–103.4 ppm Se) that is far from any gold deposit and one lowest point (average: 5.3 ppm Se) at the Selinsing gold deposit. In the Devonian period, the selenium content in sedimentary pyrite shows a peak (72.6–243.8 ppm Se) in the cherts. EPMA and LA ICP-MS data show consistent Se content variation in the Devonian and Permo-Triassic periods. Using selenium as a proxy for atmospheric oxygenation, the lowest level of Se content in the Permo-Triassic period is believed to decrease atmospheric oxygenation, as recorded in sedimentary pyrite found in black shale from the Selinsing gold deposit. The two peaks of selenium contents are interpreted as periods of increased atmospheric oxygenation. From an exploration perspective, the concentration of gold in sedimentary pyrites makes them sources for gold in the central sedimentary basin of Peninsular Malaysia. Therefore, the two maximum levels of Se and gold content during Permo-Triassic and Devonian times correspond to two stratigraphic levels of potential for orogenic gold mineralisation in the district. The EPMA data show significant values of Co over Ni in pyrite from the Gua Musang, Semantan, and Karak formation black shales, indicating a volcanic contribution of Co during the formation of sedimentary pyrite. Based on the current study’s findings, gold exploration should not be restricted to areas in and around the Selinsing gold mine, Buffalo Reef, Penjom mine, Tersang mine, and Bukit Koman mine but can be extended to BRSZ Units 1 and 2, Gua Musang, and Karak formations in the central belt of Peninsular Malaysia. Full article

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

► Show Figures

Graphical abstract

24 pages, 10349 KiB

Open AccessArticle

Prediction of Ore Production in a Limestone Underground Mine by Combining Machine Learning and Discrete Event Simulation Techniques

by Sebeom Park, Dahee Jung and Yosoon Choi

Minerals 2023, 13(6), 830; https://doi.org/10.3390/min13060830 - 19 Jun 2023

Cited by 4 | Viewed by 1730

Abstract

This study proposes a novel approach for enhancing the productivity of mining haulage systems by developing a hybrid model that combines machine learning (ML) and discrete event simulation (DES) techniques to predict ore production. This study utilized time data collected from a limestone [...] Read more.

This study proposes a novel approach for enhancing the productivity of mining haulage systems by developing a hybrid model that combines machine learning (ML) and discrete event simulation (DES) techniques to predict ore production. This study utilized time data collected from a limestone underground mine using tablet computers and Bluetooth beacons for 15 weeks. The collected data were used to train an ML model to predict truck cycle time, and the support vector regression with particle swarm optimization (PSO–SVM) model demonstrated the best performance. The PSO–SVM model accurately predicted cycle time with a mean absolute error (MAE) of 2.79 min, mean squared error (MSE) of 14.29 min², root mean square error (RMSE) of 3.79 min, and coefficient of determination (R²) of 0.68. The output of the ML model was linked to the DES model to predict ore production for each truck, section, and time period. Verification of the DES model demonstrated its ability to accurately simulate the haulage system in the study area by comparing production logs with the simulation results. This study’s novel approach offers a new method for predicting ore production and determining the optimal equipment combination for each workplace, thus enhancing productivity in mining haulage systems. Full article

(This article belongs to the Special Issue Applications of Unmanned Aerial Vehicle and Artificial Intelligence Technologies in Mining from Exploration to Reclamation, Volume II)

► Show Figures

Figure 1

25 pages, 2212 KiB

Open AccessReview

Bioleaching of Metals from E-Waste Using Microorganisms: A Review

by Adegoke Isiaka Adetunji, Paul Johan Oberholster and Mariana Erasmus

Minerals 2023, 13(6), 828; https://doi.org/10.3390/min13060828 - 18 Jun 2023

Cited by 24 | Viewed by 11558

Abstract

The rapid and improper disposal of electronic waste (e-waste) has become an issue of great concern, resulting in serious threats to the environment and public health. In addition, e-waste is heterogenous in nature, consisting of a variety of valuable metals in large quantities, [...] Read more.

The rapid and improper disposal of electronic waste (e-waste) has become an issue of great concern, resulting in serious threats to the environment and public health. In addition, e-waste is heterogenous in nature, consisting of a variety of valuable metals in large quantities, hence the need for the development of a promising technology to ameliorate environmental hazards associated with the indiscriminate dumping of e-waste, and for the recovery of metal components present in waste materials, thus promoting e-waste management and reuse. Various physico-chemical techniques including hydrometallurgy and pyrometallurgy have been employed in the past for the mobilization of metals from e-waste. However, these approaches have proven to be inept due to high operational costs linked to the consumption of huge amounts of chemicals and energy, together with high metal loss and the release of secondary byproducts. An alternative method to avert the above-mentioned limitations is the adoption of microorganisms (bioleaching) as an efficient, cost-effective, eco-friendly, and sustainable technology for the solubilization of metals from e-waste. Metal recovery from e-waste is influenced by microbiological, physico-chemical, and mineralogical parameters. This review, therefore, provides insights into strategies or pathways used by microorganisms for the recovery of metals from e-waste. Full article

(This article belongs to the Special Issue Metal Recovery from Printed Circuit Boards)

► Show Figures

Figure 1

20 pages, 28672 KiB

Open AccessFeature PaperArticle

Recurring Patterns of Sea Level Changes within a Palynological-Based Sequence Stratigraphy Framework of the Middle Jurassic Organic Matter-Rich Khatatba Formation, Egypt

by Ahmed Mansour, Sameh S. Tahoun, Aya Raafat, Mohamed S. Ahmed and Thomas Gentzis

Minerals 2023, 13(6), 827; https://doi.org/10.3390/min13060827 - 18 Jun 2023

Cited by 2 | Viewed by 1452

Abstract

The Middle Jurassic was a time of marginal to shallow shelf settings dominated by organic matter-rich deposition in northern Egypt, southern Tethys. Paleoenvironmental and sequence stratigraphic reconstructions are of paramount significance for a better understanding of basin history and related reservoirs and source [...] Read more.

The Middle Jurassic was a time of marginal to shallow shelf settings dominated by organic matter-rich deposition in northern Egypt, southern Tethys. Paleoenvironmental and sequence stratigraphic reconstructions are of paramount significance for a better understanding of basin history and related reservoirs and source rock units. For this purpose, a detailed palynomorph and palynofacies analysis of the Middle Jurassic Khatatba Formation in the Dahab-Mireir Basin, north Western Desert, was conducted. A moderately to well-preserved, moderately diverse palynomorph assemblage of spores, pollen, and dinoflagellate cysts is identified. Marker dinoflagellate cysts, including Dichadogonyaulax sellwoodii, Escharisphaeridia pocokii, Gonyaulacysta adecta, Korystocysta gochtii, Pareodinia ceratophora, and Wanaea acollaris, defined a Bajocian to Callovian age. Palynofacies analysis of the Khatatba Formation revealed two assemblages, whereby PFA-1 is the most abundant in the study well and is comprised mainly of terrestrial phytoclasts deposited nearby fluvio-deltaic sources. The infrequently reported PFA-2 consists of moderate abundances of phytoclasts and AOM, deposited in an inner shelf environment. A more reliable paleoenvironmental interpretation was indicated based on three palynomorph assemblages. The spore-dominated assemblage indicated deposition in a deltaic environment, while the mixed palynomorph assemblage revealed fluvio-deltaic to marginal shallow marine conditions. The microplankton-dominated assemblage is represented by minor samples and reflects an offshore inner shelf condition. Furthermore, the Middle Jurassic relative sea level was reconstructed based on the quantitative variations in the terrestrial/marine (T:M) ratios and abundances of spores, pollen, and dinoflagellate cysts. This led to the subdivide of the Khatatba Formation into thirteen third-order transgressive-regressive sequences, which can be correlated with the global Jurassic short-term sea level changes. Active tectonics and accelerated drifting of the Eurasian Plate during the Middle Jurassic are suggested to control basin uplift/subsidence and, therefore, recurring patterns of relative sea level change. Full article

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

► Show Figures

Figure 1

35 pages, 39306 KiB

Open AccessArticle

Impact of DEMs for Improvement Sentinel 2 Lithological Mapping Utilizing Support Vector Machine: A Case Study of Mineralized Fe-Ti-Rich Gabbroic Rocks from the South Eastern Desert of Egypt

by Ali Shebl, Hatem M. El-Desoky, Ahmed M. Abdel-Rahman, Wael Fahmy, Hamada El-Awny, Anas El-Sherif, Mahmoud M. El-Rahmany and Árpád Csámer

Minerals 2023, 13(6), 826; https://doi.org/10.3390/min13060826 - 18 Jun 2023

Cited by 5 | Viewed by 2269

Abstract

Fused remote sensing datasets have greatly contributed to enhancing lithological targets and providing significant information for mineral exploration. For instance, multispectral datasets can discriminate rock units through their unique spectral signatures. Digital Elevation Models (DEMs) could be an effective tool boosting lithological discrimination [...] Read more.

Fused remote sensing datasets have greatly contributed to enhancing lithological targets and providing significant information for mineral exploration. For instance, multispectral datasets can discriminate rock units through their unique spectral signatures. Digital Elevation Models (DEMs) could be an effective tool boosting lithological discrimination based mainly on their topographic variations. Consequently, the current study applied the power of the support vector machine (SVM) algorithm and the integrated Phased Array L-type band Synthetic Aperture Radar (PALSAR) DEM and multispectral Sentinel 2 data to: 1—Create an updated lithological map of a poorly mapped arid terrain (Khashir-Ras El-Kharit district, Eastern Desert of Egypt), and 2—Compare and assess the distribution of ferrogabbros with the aim of improving the localization of these rock bodies and investigating their mineral content. Our results enhanced the lithological mapping and revealed a better generalization of mineralized ferrogabbros when the input was a fused DEM with Sentinel 2 compared to the salt and pepper effect observed when adopting the Sentinel 2 solely as the input data. Additionally, the current research strongly recommends detailed exploration programs for Fe-Ti oxide ores within the gabbroic rocks delineated through the resultant thematic map. The ferrogabbros were subjected to a comprehensive analysis involving whole rock geochemistry, XRD, EDX, and light-reflecting investigations, which revealed the existence of magnetite, titanomagnetite, and hematite. The titanomagnetite crystals display subhedral morphology and exhibit fine- to medium-grained surfaces with irregular shapes. X-ray diffraction (XRD) analysis revealed the presence of magnetite and hematite in the concentrated Fe-Ti oxides. Additionally, the whole rock geochemistry highlighted the origin of the ferrogabbros and their proposed tectonic setting as an alkaline to calc-alkaline magma type that developed in a continental arc setting. Full article

(This article belongs to the Special Issue Mineralogy and Geochemistry of Mafic-Ultramafic Assemblages and Associated Ore Deposits)

► Show Figures

Figure 1

12 pages, 2960 KiB

Open AccessArticle

Mechanism of Modified Ether Amine Agents in Petalite and Quartz Flotation Systems under Weak Alkaline Conditions

by Jianhang Zhou, Yong Chen, Wenjuan Li, Yongsheng Song, Weiguang Xu, Kaiguo Li and Yong Zhang

Minerals 2023, 13(6), 825; https://doi.org/10.3390/min13060825 - 18 Jun 2023

Cited by 4 | Viewed by 1929

Abstract

To investigate the flotation separation behavior of petalite and quartz, various methods were employed in this study. These included micro-flotation experiments, a contact angle analysis, zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) to explore the separation mechanism [...] Read more.

To investigate the flotation separation behavior of petalite and quartz, various methods were employed in this study. These included micro-flotation experiments, a contact angle analysis, zeta potential analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) to explore the separation mechanism of a modified ether amine reagent (L0-503) for petalite and quartz under weakly alkaline conditions. The micro-flotation test results indicated that the modified ether amine collector had a higher collecting ability for quartz than for petalite, with a maximum recovery rate of 93.2% for quartz and a recovery rate consistently below 14% for petalite in the presence of L0-503. This indicates that the modified ether amine reagent can be used as a reverse flotation agent for separating petalite and quartz. The separation mechanism results showed that the modified ether amine reagent had a significantly higher adsorption capacity for quartz than for petalite due to a strong reaction between the quartz and the secondary amine (-NH=) on the modified ether amine collector. Additionally, the electrostatic force and hydrogen bonding between the reagent and quartz further enhanced the adsorption, while no reaction occurred between the reagent and petalite. Full article

(This article belongs to the Special Issue Flotation Chemistry of Oxidized Ore)

► Show Figures

Figure 1

20 pages, 13006 KiB

Open AccessArticle

Characteristics and Geological Significance of High-Frequency Cycles in Salinized Lake Basins: The Paleogene Kumugeliemu Group in the Xinhe Area, Northern Tarim Basin

by Yanru Yang, Jingchun Tian, Xiang Zhang, Yingxu Li, Yue Zhang and Qiaoyi Xia

Minerals 2023, 13(6), 824; https://doi.org/10.3390/min13060824 - 16 Jun 2023

Viewed by 1311

Abstract

Salinized lake basins have distinctive sedimentary response characteristics, similar to marine shallow-water carbonate platforms. High-frequency cycles can also be used to reveal more sedimentological information, such as relative lake-level fluctuations, lithofacies sequence combinations, and paleogeographic evolution. In this article, a comprehensive study on [...] Read more.

Salinized lake basins have distinctive sedimentary response characteristics, similar to marine shallow-water carbonate platforms. High-frequency cycles can also be used to reveal more sedimentological information, such as relative lake-level fluctuations, lithofacies sequence combinations, and paleogeographic evolution. In this article, a comprehensive study on the stratigraphic shelf delineation and high-frequency cycles of the Paleozoic Kumugeliemu Group in Xinhe area, northern Tarim Basin, was performed using drilling cores, logging curves, and seismic analyses. As a result of the study, the following data were obtained: the three sets of marker beds in the Kumugeliemu Group in the study area could be divided into a bottom sandstone component (E_1-2 km¹), a lower gypsum mudstone component (E_1-2 km²), a salt rock component (E_1-2 km³), and an upper gypsum mudstone component (E_1-2 km⁴) by petrology vertical overlay combination and isochronous tracking correlation, which constituted two third-order cycles (ESQ₁, ESQ₂). They were further divided into seven fourth-order cycles (Esq1–Esq7). Due to the droughty and saline lacustrine depositional system background, the internal rock fabric changed frequently and showed a periodic vertical overlay pattern. Stratified gypsum salt, gypsum mud (sand) rock, and gypsum rock were used as the cycle interface. A single cycle was mainly characterized by an upward shallower depositional sequence of rapid lake transgression followed by a slow lake regression, composed of massive sandstone–lamellar mudstone–lime dolomite–gypsum rock, massive sandstone–lamellar mudstone–gypsum rock (gypsum salt), massive sandstone–massive gypsum mud (sand) rock–gypsum rock, and other cycle structure types. The complete sedimentary cycle was superposed by a single cycle and compared by the inter-well thickness difference, indicating that the study area had a paleogeomorphology pattern of “West-Low–East-High”. The thickness of the cycles decreased gradually from bottom to top vertically, and five sedimentary stages were determined, i.e., freshwater, brackish, brackish water, salt lake, and semi-saltwater, reflecting the evolutionary process of increasing salinity, lake basin filling, and gradual salinization and shrinkage. Full article

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

► Show Figures

Figure 1

15 pages, 2145 KiB

Open AccessArticle

Long-Term Leaching Behavior and Geochemical Modeling of Cement Solidified Incineration Fly Ash Containing Waste Tires and Wood Biomass

by Jose Rodolfo Santiago, Tomoo Sekito and Yutaka Dote

Minerals 2023, 13(6), 823; https://doi.org/10.3390/min13060823 - 16 Jun 2023

Cited by 2 | Viewed by 1595

Abstract

Waste incineration is a widely used treatment method, and sustainable approaches are required to properly recycle large volumes of incineration ash to reduce environmental impacts and landfill space consumption. Studies have focused on the potential of recycling incineration ash as a replacement for [...] Read more.

Waste incineration is a widely used treatment method, and sustainable approaches are required to properly recycle large volumes of incineration ash to reduce environmental impacts and landfill space consumption. Studies have focused on the potential of recycling incineration ash as a replacement for natural aggregates in civil engineering applications, such as road construction. However, industrial waste incineration ash, such as waste tire incineration ash, contains hazardous heavy metals, such as lead and zinc that pose potential environmental threats. Moreover, few studies have investigated the leachability of these hazardous metals after long-term natural aging. This study investigates the long-term evolution of leachate chemistry, mineralogical transformation, and heavy metal fixation performance of a recycled roadbed material using ash from industrial waste incineration of waste tires and biomass (SFA). Additionally, field samples from a five-year pilot test site utilizing SFA were also examined. Regulatory leaching tests showed that the concentrations of Cd, Pb, As, T-Cr, and Ni were all below permissible limits even after five years of utilization. Long-term column leaching experiment results indicated that, compared to the total content of the SFA material, the leaching ratios of Pb, T-Cr, Cu, and Zn were 27%, 12%, 5%, and 0.1%, respectively. The SFA pH-stat leaching test results demonstrated that the mass release of the total content of heavy metals was relatively minimal, even under acidic pH conditions (pH < 4). Finally, profiles of pH and major ions in leachate from the column leaching experiment were simulated using HYDRUS HP1, implementing a dual-porosity modeling approach. In conclusion, despite containing hazardous heavy metals, SFA exhibits significantly low leaching rates over a long-term period. Full article

(This article belongs to the Special Issue Ashes: Characterisation, Recovery and Utilization)

► Show Figures

Graphical abstract

20 pages, 4545 KiB

Open AccessArticle

Crystal Chemistry, Thermal and Radiation-Induced Conversions and Indicatory Significance of S-Bearing Groups in Balliranoite

by Nikita V. Chukanov, Anatoly N. Sapozhnikov, Roman Yu. Shendrik, Natalia V. Zubkova, Marina F. Vigasina, Nadezhda V. Potekhina, Dmitry A. Ksenofontov and Igor V. Pekov

Minerals 2023, 13(6), 822; https://doi.org/10.3390/min13060822 - 16 Jun 2023

Cited by 2 | Viewed by 1165

Abstract

Crystal-chemical features of a sulfide-bearing variety of the cancrinite-group mineral balliranoite from the Tuluyskoe lapis lazuli deposit, Baikal Lake area, Siberia, Russia, have been investigated using a multimethodic approach based on infrared (IR), Raman, and electron spin resonance (ESR), as well as ultraviolet, [...] Read more.

Crystal-chemical features of a sulfide-bearing variety of the cancrinite-group mineral balliranoite from the Tuluyskoe lapis lazuli deposit, Baikal Lake area, Siberia, Russia, have been investigated using a multimethodic approach based on infrared (IR), Raman, and electron spin resonance (ESR), as well as ultraviolet, visible and near infrared (UV–Vis–near IR) absorption spectroscopy methods, luminescence spectroscopy, electron microprobe analysis, selective sorption of CO₂ and H₂O from annealing products, and single-crystal X-ray structure analysis. Holotype balliranoite and its sulfate analogue, davyne, were studied for comparison. The crystal-chemical formula of the studied sample from Tultuyskoe is Na_5.4K_0.1Ca_2.4(Si₆Al₆O₂₄)Cl₂[(CO₃)_0.7(SO₄)_0.18S*_0.95Cl_0.1(H₂O)_0.16], where the content of the wide zeolite channel is given in square brackets; S* is total sulfide sulfur occurring as disordered S₂^●−, cis- and trans-S₄, S₅²⁻, minor S₃^●−, and HS⁻ groups. The presence of S₅²⁻ and HS⁻ groups, the absence of CO₂ molecules, and the association with pyrrhotite and Fe-free pargasite indicate that the studied sample crystallized under highly reducing, low-temperature conditions, unlike holotype balliranoite whose formation was related to the Somma-Vesuvius volcanic complex, Italy. Irradiation of balliranoite from Tultuyskoe with X-rays results in the transformations of polysulfide groups other than S₃^●− into S₃^●− in accordance with the scheme: S₅²⁻ → S₂^●− + S₃^●−; 3S₂^●− → 2S₃^●− + e⁻; S₄ + S₂^●− + e⁻ → 2S₃^●−; S₄ + S₂^●− + e⁻ → 2S₃^●−; S₄ + S₅²⁻ + e⁻ → 3S₃^●− (e⁻ = electron). Full article

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

► Show Figures

Figure 1

18 pages, 13063 KiB

Open AccessArticle

Petrogenesis and Geodynamic Significance of the Early Triassic Nanpo Adakitic Pluton of the Luang Prabang-Loei Tectonic Belt (Northwestern Laos) in the East Tethys Domain: Constraints from Zircon U-Pb-Hf Isotope Analyses and Whole-Rock Geochemistry

by Hui Li, Jie Gan, Zhengwei He, Yu Gan, Bin Wang, Yong Li and Wei Jiang

Minerals 2023, 13(6), 821; https://doi.org/10.3390/min13060821 - 16 Jun 2023

Cited by 2 | Viewed by 1599

Abstract

Adakites are magmatic rocks with specific geochemical characteristics and specific dynamics that provide important clues to understanding the magmatic-tectonic evolution of orogenic belts. We studied the Early Triassic Nanpo adakitic pluton of the Luang Prabang-Loei tectonic belt in the Eastern Tethys domain (Laos [...] Read more.

Adakites are magmatic rocks with specific geochemical characteristics and specific dynamics that provide important clues to understanding the magmatic-tectonic evolution of orogenic belts. We studied the Early Triassic Nanpo adakitic pluton of the Luang Prabang-Loei tectonic belt in the Eastern Tethys domain (Laos Sarakan) using detailed petrological, zircon U-Pb chronological, whole-rock geochemical, and zircon Lu-Hf isotope studies to constrain their petrogenesis. The rocks are predominantly diorites and granodiorites with Early Triassic zircon U-Pb emplacement ages ranging from 247.9 ± 1.0 to 249.0 ± 2.4 Ma. Moderate SiO₂ (56.26–65.95 wt%) and Na₂O (3.24–5.00 wt%) contents, with Na₂O/K₂O values between 1.76 and 2.51 and A/CNK values between 0.81 and 0.94, indicate that the rocks belong to the metaluminous calc-alkaline rock series. The high Sr content (590–918 ppm), low Y (6.30–11.89 ppm) and Yb (1.99–3.44 ppm) contents, intermediate Mg# (42–50) values, and high Sr/Y and (La/Yb) _N ratios (Sr/Y = 24–41, (La/Yb) _N = 6.84–13.8) are typical for adakites. Zircon Hf isotope analysis shows a significant variation in the εHf(t) values (6.7–12.0), with a mean value of 9.4 and a T_DM2 of 512–845 Ma. Geochemical evidence indicates that the Nanpo adakitic rock was formed by the partial melting of the thickened lower crust in the plate-breaking environment and has an important contribution to the underplated mantle-derived magma. We propose that the Early Triassic adakites in the Luang Prabang-Loei tectonic belt formed during the transition from subduction to a continental collision, and the mixing of crust- and mantle-derived magmas is the main mechanism for the growth of continental crust in the Paleo-Tethys orogenic belt of southeastern Asia. Full article

(This article belongs to the Special Issue Petrogenesis, Magmatism and Geodynamics of Orogenic Belts)

► Show Figures

Figure 1

17 pages, 11932 KiB

Open AccessArticle

Feasibility of High-Density and Non-Segregable Niobium Ore Tailings

by Renata Monteiro Furtado, Arthur Pinto Chaves, Francisco Gregianin Testa and Priscila Tavares de Paula

Minerals 2023, 13(6), 820; https://doi.org/10.3390/min13060820 - 16 Jun 2023

Viewed by 1185

Abstract

Tailings disposal in the form of diluted slurries has a tendency for particle size segregation, where coarse particles settle near the discharge point, and finer particles are carried by the water flux to more distant regions. This causes a loss of reservoir capacity [...] Read more.

Tailings disposal in the form of diluted slurries has a tendency for particle size segregation, where coarse particles settle near the discharge point, and finer particles are carried by the water flux to more distant regions. This causes a loss of reservoir capacity due to voids between the coarser particles and increased water content in the deposit. This work aimed to evaluate the feasibility of reaching non-segregable high-density slurries with fine tailings from the niobium oreflotation process and measure its disposal parameters. The innovation is to achieve increased solids percentage in the settled deposit and to avoid particle size segregation along the slurry path with niobium tailings. The study involved physical, chemical, and mineralogical characterization and semi-pilot thickening tests to produce enough volume of underflow with different bed heights and solids flux rates. Slump, rheology, and flume tests were performed to evaluate underflow disposal characteristics. The results indicated that the thickener bed height did not significantly influence the underflow solids content, yield stress, or slump. The solids flux rate, on the other side, had a greater influence—the higher it was, the lower the solids content, yield stress, and disposal angle, along with a higher slump. In flume tests, a high density of non-segregable tailings slurry was achieved with 1.96 t/m³, corresponding to an underflow with 66.8% solids, 43.9 Pa of yield stress with 0.5 (t/h)/m², and 0.5 m of bed height. Full article

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

► Show Figures

Figure 1

11 pages, 6394 KiB

Open AccessArticle

Cu-Ag-Au Microspherules in Igneous Rocks: Morphology, Composition, Diagnostic Criteria and Possible Origin

by Nikolai Berdnikov, Pavel Kepezhinskas, Valeria Krutikova, Nadezhda Kozhemyako and Natalia Konovalova

Minerals 2023, 13(6), 819; https://doi.org/10.3390/min13060819 - 16 Jun 2023

Cited by 3 | Viewed by 1404

Abstract

Igneous rocks from the Russian Far East contain Cu-Ag-Au microspherules with distinct exterior and interior structures, compositions and assemblages of Cu-rich micro-inclusions. Natural microspherules are compared in this study with technogenic Cu-Ag-Au microspherules, which are experimentally produced and extracted from gold scrap jewelry. [...] Read more.

Igneous rocks from the Russian Far East contain Cu-Ag-Au microspherules with distinct exterior and interior structures, compositions and assemblages of Cu-rich micro-inclusions. Natural microspherules are compared in this study with technogenic Cu-Ag-Au microspherules, which are experimentally produced and extracted from gold scrap jewelry. The following set of diagnostic criteria are considered to distinguish natural from technogenic microspherules on a genetic basis as follows: (1) compacted-related features versus cellular appearance of the exterior; (2) lack of exsolution- or crystallization-related features in natural and domain-type internal structure in technogenic microspherules; (3) absence of spherical copper-oxide inclusions along with meniscus-type textural boundaries in technogenic mcirospherules; (4) pure copper-oxide composition of inclusions versus the common presence of Fe, Ni, Zn, Cu and Na in natural microspherules. The diagnostic characteristics of natural Cu-Ag-Au microspherules suggest extremely fast cooling rates during their formation, which is possible during violent explosive volcanic eruptions or injection of partially molten, pulverized metal alloys into shallow intra-crustal cavities and fault-related tectonic gashes. Full article

► Show Figures

Figure 1

3 pages, 203 KiB

Open AccessEditorial

Editorial for the Special Issue “Petrology and Mineralogy of Pegmatite Deposits”

by Axel Müller and Encarnación Roda-Robles

Minerals 2023, 13(6), 818; https://doi.org/10.3390/min13060818 - 15 Jun 2023

Viewed by 1350

Abstract

This Special Issue of Minerals, section Mineral Deposits, on the topic of “Petrology and Mineralogy of Pegmatite Deposits”, was inspired by the currently growing scientific and economic interest in pegmatites [...] Full article

(This article belongs to the Special Issue Petrology and Mineralogy of Pegmatite Deposits)

23 pages, 4378 KiB

Open AccessFeature PaperReview

Nanoclay-Reinforced Nanocomposite Nanofibers—Fundamentals and State-of-the-Art Developments

by Ayesha Kausar, Ishaq Ahmad, O. Aldaghri, Khalid H. Ibnaouf and M. H. Eisa

Minerals 2023, 13(6), 817; https://doi.org/10.3390/min13060817 - 15 Jun 2023

Cited by 3 | Viewed by 2805

Abstract

Nanoclays are layered mineral silicates, i.e., layered silicate nanosheets. Nanoclays such as montmorillonite, bentonite, kaolinite, etc., have been used as reinforcements in the nanofibers. Numerous polymers have been used to fabricate the nanofibers, including poly(vinylidene fluoride), poly(vinyl alcohol), polycaprolactone, nylon, polyurethane, poly(ethylene oxide), [...] Read more.

Nanoclays are layered mineral silicates, i.e., layered silicate nanosheets. Nanoclays such as montmorillonite, bentonite, kaolinite, etc., have been used as reinforcements in the nanofibers. Numerous polymers have been used to fabricate the nanofibers, including poly(vinylidene fluoride), poly(vinyl alcohol), polycaprolactone, nylon, polyurethane, poly(ethylene oxide), and others. To develop better compatibility with polymers, nanoclays have been organo-modified prior to reinforcement in the nanofiber matrices. This state-of-the-art review highlights the fundamentals, design, fabrication, and characteristics of the polymer/nanoclay nanofibers. The nanoclay filled nanocomposite nanofibers have been fabricated using electrospinning and other fiber processing techniques. The electrospinning technique has been preferred to form the nanoclay-filled nanofibers, owing to the better control of processing parameters and resulting nanofiber properties. The electrospun polymer/nanoclay nanofibers usually have fine nanoparticle dispersions, microstructures, smooth textures, and narrow diameters. The physical properties of the designed nanofibers depend upon the processing technology used, solvent, solution/melt concentration, flow rate, spinning speed, voltage, and other process parameters. Hence, this review attempts to assess a literature-driven consequence of embedding nanoclays in the polymeric nanofibers in a broad context of the application of these fibrous materials. Conclusively, to design the polymer/nanoclay nanofibers, montmorillonite nanoclay has been observed as a nanofiller in most of the studies, and, similarly, the electrospinning technique was preferred as a fabrication technique. Almost all the physical properties of the nanofibers studied revealed dependences upon the choice of the polymer matrix for nanofiber formation as well as the nanoclay contents, modification, and dispersion state. Accordingly, the nylon/nanoclay nanofibers have been investigated for nanofiller dispersion, mechanical properties, and thermal profiles. The antibacterial properties were among the prominent features of the poly(vinyl alcohol)/nanoclay nanofibers. The poly(vinylidene fluoride)/nanoclay systems were explored for the microstructure, crystallinity, and piezoelectric properties. The polycaprolactone/nanoclay nanofibers having fine microstructure were capable of forming tissue engineering scaffolds. The drug delivery and sound absorption properties were noticeable for the polyurethane/nanoclay nanofiber systems. Moreover, the poly(lactic acid)/nanoclay nanofibers were found to have prominent biodegradability and low gas permeability features. The resulting polymer/nanoclay nanocomposite nanofiber systems found potential for the technical applications of sensors, packaging, tissue engineering, and wound healing. However, thorough research efforts have been found to be desirable to find the worth of polymer/nanoclay nanofibers in several concealed technological sectors of energy, electronics, aerospace, automotives, and biomedical fields. Full article

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

► Show Figures

Graphical abstract

14 pages, 2789 KiB

Open AccessArticle

The Sulfur Isotopic Characteristics of Evaporites in the Yarkand Basin of Xinjiang Province in the Paleocene and Its Paleoenvironmental Evolution

by Yidong Liu, Aihua Zeng, Wenjun Chen and Yangtong Cao

Minerals 2023, 13(6), 816; https://doi.org/10.3390/min13060816 - 15 Jun 2023

Cited by 2 | Viewed by 1355

Abstract

The Yarkand Basin, located in the southwest of the Tarim Basin, is a northeastern part of the eastern Paratethys ocean in the Paleocene, and a significant amount of evaporites, with gypsum, anhydrite, and halite as the main types, were developed in this area. [...] Read more.

The Yarkand Basin, located in the southwest of the Tarim Basin, is a northeastern part of the eastern Paratethys ocean in the Paleocene, and a significant amount of evaporites, with gypsum, anhydrite, and halite as the main types, were developed in this area. These evaporites record the sedimentary environment at that time. A study was conducted on the sulfur isotopic composition of gypsum in the Paleocene of the Yarkand Basin to explore the origin of the evaporites and interpret the sedimentary environment. The experimentally measured sulfur isotope δ³⁴S_CDT values of 187 gypsum samples ranged from 6.69‰ to 25.92‰ with an average value of 18.64‰. The overall trend of the Paleocene gypsum sulfur isotopic curve is consistent with the global seawater sulfur isotopic curve, which shows a decreasing trend. In the early and middle Paleocene, the curve shows four stages of sulfur isotope increase, indicating that the sedimentary environment during that time was mainly influenced by bacterial reduction and a relatively open sedimentary environment, while the late period shows a decreasing trend, suggesting that the late period may be primarily influenced by terrigenous freshwater. In addition, the sulfur isotope value has the characteristics of decreasing from northwest to southeast of the basin, which may indicate that the sedimentary environment of Paleocene evaporites in the Yarkand Basin may also be related to paleotopography and distance from the estuary, resulting in differences in sedimentary environments. The mainly original sulfur isotope values of the Paleocene evaporites in the Yarkand Basin should be in the range of 18‰–20‰, which is a supplement to the Paleocene global paleoseawater and is of great significance for the reconstruction of the marine transgressive–regressive cycle and sulfur isotopic composition of the eastern Paratethys ocean during this period. Full article

(This article belongs to the Special Issue Mineralogy, Petrology and Geochemistry of Evaporites, Volume II)

► Show Figures

Figure 1

18 pages, 2569 KiB

Open AccessFeature PaperArticle

Industrial Ceramics: From Waste to New Resources for Eco-Sustainable Building Materials

by Maura Fugazzotto, Paolo Mazzoleni, Isabella Lancellotti, Rachel Camerini, Pamela Ferrari, Maria Rosaria Tiné, Irene Centauro, Teresa Salvatici and Germana Barone

Minerals 2023, 13(6), 815; https://doi.org/10.3390/min13060815 - 15 Jun 2023

Cited by 5 | Viewed by 2788

Abstract

Today, the need to dispose of a huge amount of ceramic industrial waste represents an important problem for production plants. Contextually, it is increasingly difficult to retrieve new mineral resources for the realization of building materials. Reusing ceramic industrial waste as precursors for [...] Read more.

Today, the need to dispose of a huge amount of ceramic industrial waste represents an important problem for production plants. Contextually, it is increasingly difficult to retrieve new mineral resources for the realization of building materials. Reusing ceramic industrial waste as precursors for building blocks/binders, exploiting their aluminosilicate composition for an alkaline activation process, could solve the problem. This chemical process facilitates the consolidation of new binders/blocks without thermal treatments and with less CO₂ emissions if compared with traditional cements/ceramics. The alkali-activated materials (AAMs) are today thought as the materials of the future, eco-sustainable and technically advanced. In this study, six different kind of industrial ceramic waste are compared in their chemical and mineralogical composition, together with their thermal behaviour, reactivity in an alkaline environment and surface area characteristics, with the aim of converting them from waste into new resources. Preliminary tests of AAM synthesis by using 80%–100% of ceramic waste as a precursor show promising results. Workability, porosity and mechanical strengths in particular are measured, showing as, notwithstanding the presence of carbonate components, consolidated materials are obtained, with similar results. The main factors which affect the characteristics of the synthetized AAMs are the precursors’ granulometry, curing temperature and the proportions of the activating solutions. Full article

(This article belongs to the Special Issue Sustainable Mining as the Key for the Ecological Transition: Current Trends and Future Perspectives)

► Show Figures

Figure 1

20 pages, 3540 KiB

Open AccessFeature PaperArticle

Investigating the Relationship between Growth Rate, Shell Morphology, and Trace Element Composition of the Pacific Littleneck Clam (Leukoma staminea): Implications for Paleoclimate Reconstructions

by Hannah L. Kempf, David A. Gold and Sandra J. Carlson

Minerals 2023, 13(6), 814; https://doi.org/10.3390/min13060814 - 14 Jun 2023

Cited by 1 | Viewed by 2316

Abstract

Due to their robust preservation and widespread nature, marine bivalve shells are increasingly used as informative, high-resolution records of past environmental conditions. Unfortunately, few studies have investigated variability amongst individuals in a genetic cohort and throughout their ontogeny. We measured several morphological properties [...] Read more.

Due to their robust preservation and widespread nature, marine bivalve shells are increasingly used as informative, high-resolution records of past environmental conditions. Unfortunately, few studies have investigated variability amongst individuals in a genetic cohort and throughout their ontogeny. We measured several morphological properties and the element patterning of 200-day-old juvenile Leukoma staminea (Conrad, 1837) grown in identical conditions from the same reproductive cohort. We hypothesized that slower shell growth would correspond to the reduced incorporation of trace/minor elements (Sr, Mg, and S) in the aragonite lattice, as has been documented in other biomineralizing marine invertebrates. Microprobe analyses of adult shells revealed higher levels of S, Sr, and Mg in the dark, slower-growing growth lines compared to the light, faster-growing increments, particularly in the inner shell layer, thus refuting our hypothesis. Moreover, elemental count variation within single adult shells generally tracked changes in shell microstructure (i.e., higher counts in prismatic microstructures) and growth line patterns, and these differences are detectable on a micrometer scale. Juvenile shells of different sizes showed variation in S, Sr, and Mg counts as well, but it was unclear whether the variability closely tracked changes in microstructure, body size, and/or growth line patterns. In all individuals, regardless of life stage, the outermost shell layer showed higher Sr and S count values, and these elements closely mirrored each other within individual shells. The results presented herein represent the first in-depth description of the shell mineralogy, microstructure, body size variability, and geochemical properties of modern L. staminea, a common eastern Pacific, shallow, infaunal bivalve, allowing for the rigorous evaluation of L. staminea shells as recorders of past environmental and biological change. Significant intraspecific variation in the young body size, growth band patterning, and elemental composition of individuals of the same age and genetic stock complicates the use of size alone as a proxy for age in historical studies. Additionally, elemental composition shifted from high to low values (for example, Sr ranging from ~190 to 100 counts) at a very fine (micrometer) scale within single shells, as evidenced by visible correlations between microstructure and elemental composition. While young L. staminea shells are likely not useful as archives of (paleo)environmental conditions, adult L. staminea shells are likely suitable if micrometer-scale variability in shell structure and chemistry is accounted for. Full article

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

► Show Figures

Figure 1

32 pages, 12161 KiB

Open AccessArticle

The Current State of Research on Secondary Quartzites of the Northern Segment of the Jungar-Balkhash Folded System and Their Au Mineralization (Central Kazakhstan)

by Eleonora Y. Seitmuratova, Vera S. Goryaeva, Farida F. Saidasheva, Yalkunzhan K. Arshamov, Refat T. Baratov, Diyas O. Dautbekov, Nurgali S. Shadiyev, Moldir A. Mashrapova, Ansagan Dauletuly and Tauassar K. Karimbekov

Minerals 2023, 13(6), 813; https://doi.org/10.3390/min13060813 - 14 Jun 2023

Cited by 1 | Viewed by 1587

Abstract

In this paper, we outline a study conducted on altered rocks in Central Kazakhstan, in particular, focusing on secondary quartzites. The study reveals a connection between copper-porphyry deposits in Central Kazakhstan and secondary quartzites. Recent research has unveiled gold mineralization in various secondary [...] Read more.

In this paper, we outline a study conducted on altered rocks in Central Kazakhstan, in particular, focusing on secondary quartzites. The study reveals a connection between copper-porphyry deposits in Central Kazakhstan and secondary quartzites. Recent research has unveiled gold mineralization in various secondary quartzite massifs, which has spurred further investigations in the region. Over the past three decades, extensive studies have been conducted that have demonstrated similarities among the gold deposits in this area and epithermal gold-silver deposits in volcanic-plutonic arcs around the world. By identifying patterns in the distribution of gold mineralization and developing regional exploration criteria, researchers have comprehensively assessed 48 secondary quartzite massifs and have prioritized promising areas for further exploration. Valuable findings have emerged from detailed examinations of the Akgirek and Birlestik massifs, which have involved drilling exploration wells up to a depth of 250 m. These investigations have shed light on the depth distribution of metasomatites and their association with gold mineralization. Consequently, these findings strengthen our belief in the significant potential for gold mineralization in the secondary quartzites of the Jungar-Balkhash folded system. Full article

(This article belongs to the Special Issue Mineral, Fluid, and Melt Inclusions—Analysis, Interpretation, and Application, Volume II)

► Show Figures

Figure 1

19 pages, 3203 KiB

Open AccessArticle

Controlling Factors of Meteoric Diagenesis in Karst Reservoirs: An Example from the Majiagou Formation, Ordos Basin, China

by Jiaqi Yang, Juntao Zhang, Zhiliang He, Macro Brandano and Chongyang Wu

Minerals 2023, 13(6), 812; https://doi.org/10.3390/min13060812 - 14 Jun 2023

Cited by 1 | Viewed by 1300

Abstract

Karst reservoirs have always been a key field of oil and gas exploration. However, quantifying the process of meteoric transformation remains a persistent challenge that limits the accuracy of reservoir quality prediction. To explore the controlling factors of meteoric cementation on karst reservoirs, [...] Read more.

Karst reservoirs have always been a key field of oil and gas exploration. However, quantifying the process of meteoric transformation remains a persistent challenge that limits the accuracy of reservoir quality prediction. To explore the controlling factors of meteoric cementation on karst reservoirs, the Majiagou Formation of the Ordos Basin in China was selected as an example. The petrology; carbon, oxygen, and strontium isotopes; and in situ major, trace, and rare earth elements were used, types and origins of calcite cements were analyzed in detail. The results revealed five types of calcite cements (Cal-1~Cal-5), four types of cathodoluminescence (CL) intensities (dull, dull red, deep red, and bright red luminescence), and six types of rare earth element patterns (Pattern-1~Pattern-6). These five types of calcite cements developed in three periods. Cal-1 (transition CL) and Cal-2 (dull CL) were precipitated during the Early Pennsylvanian period, the meteoric freshwater was clean; Cal-3 (transition CL) and Cal-4 (bright red CL) were precipitated at the end of the Late Carboniferous period, the fluids had strong dissolution ability and were polluted by terrigenous debris; Cal-5 (transition CL) was deposited during the burial period, the fluid was pure pore water or groundwater. The control of the cement on the reservoir during the burial period was much weaker than that of meteoric cements. Therefore, explorations of karst reservoirs should be focused on weak cementation during the epigenetic period. Full article

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

► Show Figures

Figure 1

14 pages, 7237 KiB

Open AccessArticle

Deciphering the Color Origin of Pink Conch Pearl Using Nondestructive Spectroscopies and DFT Calculations

by Chaoyang Chen, Jing Yu, Xu Ye and Andy H. Shen

Minerals 2023, 13(6), 811; https://doi.org/10.3390/min13060811 - 14 Jun 2023

Cited by 1 | Viewed by 1563

Abstract

Conch pearl is a calcareous concretion produced by the Queen conch mollusk and is of extremely high economic value. Its attractive pink color has remained a mystery for hundreds of years. This difficulty limits the development of cultivation and preservation technology of conch [...] Read more.

Conch pearl is a calcareous concretion produced by the Queen conch mollusk and is of extremely high economic value. Its attractive pink color has remained a mystery for hundreds of years. This difficulty limits the development of cultivation and preservation technology of conch pearl. Due to its super-high value, it is generally impossible to use destructive chemical analysis methods. Here, various nondestructive spectroscopic analysis methods and theoretical calculations were used to reveal the color origin of pink conch pearl. The experimental Raman and UV-Vis spectroscopies were used to characterize the color and pigments. We further discuss the pigments in conch pearl by comparing the Raman spectral characteristics and pigments of the red coral. Based on the characteristics of the experimental spectra, we speculate that the carotenoids color the conch pearl. The theoretical Raman and UV-Vis spectra of all-trans polyene and carotenoids were simulated using DFT calculations. According to the results, we proposed that the pigments in pink conch pearl are polyenes containing 11 shortened C–C bonds with multiplicities > 1.5, which may be demethylated carotenoids. Full article

(This article belongs to the Special Issue Gemstone Analysis by Spectroscopy and Microscopy, Volume II)

► Show Figures

Figure 1

16 pages, 10181 KiB

Open AccessArticle

Origin of the Yinshan Pb-Zn-Ag Deposit in the Edong District Section of the Middle–Lower Yangtze River Metallogenic Belt: Insights from In-Situ Sulfur Isotopes

by Dengfei Duan, Haobo Jia and Yue Wu

Minerals 2023, 13(6), 810; https://doi.org/10.3390/min13060810 - 14 Jun 2023

Cited by 1 | Viewed by 1186

Abstract

The investigation into the enigmatic origin of Pb-Zn mineralization within the Middle-Lower Yangtze River Metallogenic Belt has long been marred by a paucity of prior studies. Seeking to alleviate this dearth of knowledge, our study meticulously scrutinizes the Yinshan Pb-Zn-Ag deposit nestled within [...] Read more.

The investigation into the enigmatic origin of Pb-Zn mineralization within the Middle-Lower Yangtze River Metallogenic Belt has long been marred by a paucity of prior studies. Seeking to alleviate this dearth of knowledge, our study meticulously scrutinizes the Yinshan Pb-Zn-Ag deposit nestled within the Edong district of the belt, endeavoring to cast an illuminating spotlight upon its enigmatic genesis. We identify two distinct epochs: (1) the pre-mineralization pyrite epoch (Epoch I) mainly characterized by colloform and massive pyrite, and (2) the hydrothermal mineralization epoch (Epoch II) which can be further divided into three stages: pyrite-arsenopyrite (stage 1), galena-sphalerite (stage 2), and vein pyrite (stage 3). We conduct in-situ sulfur isotope analyses on sulfide minerals from both epochs, revealing δ³⁴S values ranging from −0.5 to 4.8‰ for Epoch I and varying from 2.2–4.9‰ (stage 1), 1.1–3.0‰, 4.2–7.1‰ (stage 2), and 2.1–3.8‰ (stage 3) for Epoch II. Integrating our sulfur isotope data with the geological characteristics of the deposit, we infer that Pb-Zn mineralization was related to a granite of ~130 Ma age. Additionally, our study suggests the possibility of coexisting Mo mineralization beneath the Pb-Zn mineralization. Our findings contribute to a better understanding of the origin of Pb-Zn mineralization in the Middle-Lower Yangtze River Metallogenic Belt. Full article

(This article belongs to the Special Issue Genesis and Evolution of Pb-Zn-Ag Polymetallic Deposits)

► Show Figures

Figure 1

35 pages, 7929 KiB

Open AccessReview

An Overview of Currently Applied Ferrochrome Production Processes and Their Waste Management Practices

by Stephanus P. du Preez, Tristan P. M. van Kaam, Eli Ringdalen, Merete Tangstad, Kazuki Morita, Dmitri G. Bessarabov, Pieter G. van Zyl and Johan P. Beukes

Minerals 2023, 13(6), 809; https://doi.org/10.3390/min13060809 - 13 Jun 2023

Cited by 8 | Viewed by 8383

Abstract

Ferrochrome (FeCr) is the main source of virgin chromium (Cr) units used in modern-day chromium (Cr) containing alloys. The vast majority of produced Cr is used during the production of stainless steel, which owes its corrosion resistance mainly to the presence of Cr. [...] Read more.

Ferrochrome (FeCr) is the main source of virgin chromium (Cr) units used in modern-day chromium (Cr) containing alloys. The vast majority of produced Cr is used during the production of stainless steel, which owes its corrosion resistance mainly to the presence of Cr. In turn, stainless steel is mainly produced from Cr-containing scrap metal and FeCr, which is a relatively crude alloy between iron (Fe) and Cr. The production of FeCr is an energy and material-intensive process, and a relatively wide variety of by-products, typically classified as waste materials by the FeCr industry, are created during FeCr production. The type and extent of waste generation are dictated by the smelting route used and the management practices thereof employed by a specific smelter. In some cases, waste management of hazardous and non-hazardous materials may be classified as insufficient. Hazardous materials, such as hexavalent Cr, i.e., Cr(VI), -containing wastes, are only partially mitigated. Additionally, energy-containing wastes, such as carbon monoxide (CO)-rich off-gas, are typically discarded, and energy-invested materials, such as fine oxidative sintered chromite, are either stockpiled or sold as ordinary chromite. In cases where low-value containing wastes are generated, such as rejects from ore beneficiation processes, consistent and efficient processes are either difficult to employ or the return on investment of such processes is not economically viable. More so, the development of less carbon (C)-intensive (e.g., partial replacement of C reductants) and low-temperature pellet curing processes are currently not considered by the South African FeCr smelting industry. The reasoning for this is mainly due to increased operation costs (if improved waste management were to be implemented/higher cost reductants were used) and a lack of research initiatives. These reasons result in the stagnation of technologies. From an environmental point of view, smelting industries are pressured to reduce C emissions. An attractive approach for removing oxygen from the target metal oxides, and the mitigation of gaseous C, is by using hydrogen as a reductant. By doing so, water vapor is the only by-product. It is however expected that stable metal oxides, such as the Cr-oxide present in chromite, will be significantly more resistive to gaseous hydrogen-based reduction when compared to Fe-oxides. In this review, the various processes currently used by the South African FeCr industry are summarized in detail, and the waste materials per process step are identified. The limitations of current waste management regimes and possible alternative routes are discussed where applicable. Various management regimes are identified that could be improved, i.e., by utilizing the energy associated with CO-rich off-gas combustion, employing a low-temperature alternative chromite pelletization process, and considering the potential of hydrogen as a chromite reductant. These identified regimes are discussed in further detail, and alterative processes/approaches to waste management are proposed. Full article

(This article belongs to the Special Issue Ferrochrome Waste Management—Addressing Current Gaps for Energy and Material Consumption, Carbon Release, and Waste Beneficiation)

► Show Figures

Figure 1

17 pages, 2107 KiB

Open AccessArticle

Using Machine Learning to Evaluate Coal Geochemical Data with Respect to Dynamic Failures

by David R. Hanson and Heather E. Lawson

Minerals 2023, 13(6), 808; https://doi.org/10.3390/min13060808 - 13 Jun 2023

Cited by 1 | Viewed by 1451

Abstract

Dynamic failure events have occurred in the underground coal mining industry since its inception. Recent NIOSH research has identified geochemical markers that correlate with in situ reportable dynamic event occurrence, although the causes behind this correlative relationship remain unclear. In this study, NIOSH [...] Read more.

Dynamic failure events have occurred in the underground coal mining industry since its inception. Recent NIOSH research has identified geochemical markers that correlate with in situ reportable dynamic event occurrence, although the causes behind this correlative relationship remain unclear. In this study, NIOSH researchers conducted machine learning analysis to examine whether a model could be constructed to assess the probability of dynamic failure occurrence based on geochemical and petrographic data. Linear regression, random forest, dimensionality reduction, and cluster analyses were applied to a catalog of dynamic failure and control data from the Pennsylvania Coal Sample Databank, cross-referenced with accident data from the Mine Safety and Health Administration (MSHA). Analyses determined that 7 of the 18 geochemical parameters that were examined had the biggest impact on model performance. Classifications based on logistic regression and random forest models attained precision values of 85.7% and 96.7%, respectively. Dimensionality reduction was used to explore patterns and groupings in the data and to search for relationships between compositional parameters. Cluster analyses were performed to determine if an algorithm could find clusters with given class memberships and to what extent misclassifications of dynamic failure status occurred. Cluster analysis using a hierarchal clustering algorithm after dimensionality reduction resulted in four clusters, with one relatively distinct dynamic failure cluster, and three clusters mostly consisting of control group members but with a small number of dynamic failure members. Full article

(This article belongs to the Special Issue Rock Mechanics and Geochemistry in Mining Engineering)

► Show Figures

Figure 1

28 pages, 23715 KiB

Open AccessArticle

Testing Tectonostratigraphic Hypotheses of the Blountian Phase of the Taconic Orogeny in the Southern Appalachians through an Integrated Geochronological and Sedimentological Study of Ordovician K-Bentonites and Quartz Arenites

by Achim D. Herrmann, John T. Haynes, Richard Robinet, Peter D. Clift and Keith E. Goggin

Minerals 2023, 13(6), 807; https://doi.org/10.3390/min13060807 - 13 Jun 2023

Viewed by 1751

Abstract

The tectonic setting of the southernmost part of the eastern margin of Laurentia during the Blountian tectophase (~472–452 Ma) of the Ordovician Taconic Orogeny remains unresolved. Tephras produced by explosive volcanism during this early phase of the orogeny are now K-bentonites, and in [...] Read more.

The tectonic setting of the southernmost part of the eastern margin of Laurentia during the Blountian tectophase (~472–452 Ma) of the Ordovician Taconic Orogeny remains unresolved. Tephras produced by explosive volcanism during this early phase of the orogeny are now K-bentonites, and in many locations, they are interbedded with mature to supermature quartz arenites. We conducted U-Pb analyses of detrital zircons from the sandstones, and of zoned magmatic zircons from the K-bentonites, to constrain the tectonostratigraphic setting with more precision. We also used geochemical fingerprinting of apatite phenocrysts to correlate the K-bentonites in these sandstones along the tectonic front, and we then integrated these results with a depositional systems study of the quartz arenites to further constrain and test competing models of the regional tectonomagmatic setting during that time. The general dearth of detrital zircons that have ages contemporaneous with the volcanic activity, coupled with the predominantly Precambrian ages of the zircons in these Lower Paleozoic quartz arenites that otherwise lack volcaniclastic components—such as detrital VRFs or a muddy matrix derived from an eroding volcanic arc—suggests that magmatic zircons from the tephra layers entered the depositional system only occasionally, and that the volcanic centers were separated geographically from where these quartzose sands were being deposited. Our findings support a tectonostratigraphic and tectonomagmatic model analogous to a combination of select modern settings in the western Pacific and Indonesia, specifically (1) New Guinea, where mature quartz arenites occur in the Cenozoic foreland succession, and (2) Sumatra, where the enormous Toba caldera formed in association with subduction beneath the Cretaceous-aged continental crust of Sumatra. Full article

(This article belongs to the Special Issue LA-ICP-MS and LIBS Applied to Minerals)

► Show Figures

Figure 1

20 pages, 2060 KiB

Open AccessArticle

Optimization of Soil-Sludge Mixtures by Compaction for Potential Use in Mine Site Reclamation

by Mamert Mbonimpa, Élysée Tshibangu Ngabu, Tikou Belem, Ousseynou Kanteye and Abdelkabir Maqsoud

Minerals 2023, 13(6), 806; https://doi.org/10.3390/min13060806 - 13 Jun 2023

Viewed by 1278

Abstract

Studies have indicated the potential of mixtures of silty soil and sludge produced by active treatment of acid mine drainage for use in covers with capillary barrier effects for mine site reclamation. Very high water contents of sludge in the settling pond could [...] Read more.

Studies have indicated the potential of mixtures of silty soil and sludge produced by active treatment of acid mine drainage for use in covers with capillary barrier effects for mine site reclamation. Very high water contents of sludge in the settling pond could negatively affect the required hydrogeotechnical properties of soil sludge mixtures with high sludge contents. The challenge is then to determine the optimum wet sludge content of soil-sludge mixtures with air entry values (AEV) and/or saturated hydraulic conductivity (k_sat) required for use in mine site reclamation covers. This paper presents a method to determine the optimum wet sludge content β_opt for obtaining the maximum dry density of compacted soil-sludge mixtures. Two types of soil (S1 and S2) and two types of sludge (A and W) were tested. It was observed that β_opt can be determined when the initial water content of the soil used in the mixture is lower than the optimum water content determined from the Proctor curve of the soil alone (10 wt% and 6 wt% for soils S1 and S2, respectively) and that β_opt does not change with increasing initial soil water content. Optimum wet sludge contents found were low (≈15 wt% and ≈7 wt% for mixtures containing soils S1 and S2, respectively) for the test conditions, indicting a limited quantity of reusable sludge in the mixtures. For all mixtures, the water content corresponding to β_opt was close to the optimum water content of the soil alone. Results of soil water retention and saturated hydraulic conductivity (k_sat) tests conducted on selected optimized mixtures indicated that the mixtures based on soils S1 and S2 have air entry values higher than 20 kPa and would be suitable for use in the moisture retention layer of covers with capillary barrier effects, while soil S2 and the derived mixtures exhibited k_sat < 10⁻⁷ cm/s and would be potential materials for the low permeability layer in low saturated hydraulic conductivity covers. Full article

(This article belongs to the Special Issue Reutilization and Valorization of Mine Waste, Volume II)

► Show Figures

Figure 1

26 pages, 13742 KiB

Open AccessArticle

Geochemical Characteristics and Metallogenic Significance of the X03 Vein Tourmaline in the Jiajika Rare Metal Deposit, West Sichuan

by Yan Qin, Yang Li, Chenghui Wang, Lijun Liu, Kejun Hou and Qian Wang

Minerals 2023, 13(6), 805; https://doi.org/10.3390/min13060805 - 13 Jun 2023

Cited by 3 | Viewed by 1817

Abstract

The Jiajika rare metal deposit contains the largest area of granitic pegmatite-type rare metal deposits in China. The X03 vein is an immense rare metal deposit dominated by lithium, which was found in the deposit in recent years. The contact metamorphic belt of [...] Read more.

The Jiajika rare metal deposit contains the largest area of granitic pegmatite-type rare metal deposits in China. The X03 vein is an immense rare metal deposit dominated by lithium, which was found in the deposit in recent years. The contact metamorphic belt of tourmalinization and petrochemistry is widely developed in its wall rocks, and the altered rocks formed contain Li and other rare metal mineralization. In this paper, the tourmaline found in the different rocks of the Jiajika X03 vein is divided into four types: two-mica quartz schist (Tur-Ⅰ), tourmaline hornfels (Tur-Ⅱ), tourmaline-bearing granite pegmatite (Tur-Ⅲ) and spodumene-bearing granite pegmatite (Tur-Ⅳ); their in situ major element, trace element and boron isotope data are systematically studied. The results show that all tourmalines in the Jiajika X03 vein deposit belong to the alkali group, and are schorl–Oxy/Fluor–schorl, dravite–Hydroxy-dravite and foitite–Oxy foitite solid solutions, among which Tur-Ⅰ are dravite, Tur-Ⅱ are foitite of hydrothermal origin and Tur-Ⅲ and Tur-Ⅳ are schorl of magmatic origin. The boron isotope values show that the boron involved the formation process of tourmaline mainly originates from the Majingzi S-type granite, and the boron isotope variations in tourmaline are controlled by melt fluid and Rayleigh fractionation. Moreover, there is a clear correlation between the B isotope value of tourmaline and the Li, Mn, Zn, Mg, and V contents, showing that these contents in tourmaline are good indicators of the mineralization type of pegmatite. Full article

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

► Show Figures

Figure 1

Journal Menu

Journal Browser

Minerals, Volume 13, Issue 6 (June 2023) – 125 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI