Minerals

10 pages, 2344 KiB

Open AccessArticle

Comparing Permeability and Drying Shrinkage of the Concrete Containing Mineral Admixtures under the Equal Strength Grade

by Yufeng Fan, Qiang Zhao and Dengquan Wang

Minerals 2022, 12(11), 1477; https://doi.org/10.3390/min12111477 - 21 Nov 2022

Cited by 1 | Viewed by 1433

Abstract

Fly ash (FA) and ground granulated blast-furnace slag (GGBS) are the most widely used mineral admixtures in engineering. However, their roles in concrete under the equal strength grade, a common comparison method in engineering, were seldom reported. This study investigated the chloride ion [...] Read more.

Fly ash (FA) and ground granulated blast-furnace slag (GGBS) are the most widely used mineral admixtures in engineering. However, their roles in concrete under the equal strength grade, a common comparison method in engineering, were seldom reported. This study investigated the chloride ion permeability and drying shrinkage of concrete samples containing FA or GGBS under an equal strength grade. The samples’ strengths and slumps maintained the same levels by adjusting the water-to-binder ratios and superplasticizer dosages. The results show that both FA and GGBS can promote the resistance to chloride ion penetration and decrease the chloride diffusion coefficients, especially at late ages, due to the hydraulicity of GGBS and pozzolanic activity of FA. Compared with FA, GGBS presents a greater reduction in the concrete permeability due to its higher reactivity. Forty percent replacement levels of FA and GGBS can decrease the penetration level from “high” of plain cement concrete to “moderate” and “low”, respectively. In addition, FA and GGBS can decrease the drying shrinkage of concrete at high replacement levels (30% and 40%). This decrease is more significant in the FA-containing concrete, with the shrinkage decreasing from approximately 400 με to 350 με at a 40% replacement level. The findings can provide scientific guidance for applying FA and GGBS in practical engineering. Full article

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

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11 pages, 4872 KiB

Open AccessArticle

The Electrochemical Response of Chalcopyrite and Galena to Degrading Water Quality

by Nolihle Ndamase, Margreth Tadie and Kirsten Claire Corin

Minerals 2022, 12(11), 1476; https://doi.org/10.3390/min12111476 - 21 Nov 2022

Viewed by 1376

Abstract

Water is used as a liquid medium as well as a means of transportation during mining operations. Flotation, in particular, is a water intensive process where water makes up about 80–85% of the pulp phase. Process water contains organic and inorganic species which [...] Read more.

Water is used as a liquid medium as well as a means of transportation during mining operations. Flotation, in particular, is a water intensive process where water makes up about 80–85% of the pulp phase. Process water contains organic and inorganic species which accumulate as they are recycled. To avoid the treatment costs of removing these contaminants, many mining operations allow the quality of their water to degrade over time. When this water is introduced into flotation circuits, the pulp chemistry is altered. Ionic species that accumulate in recycled process water have been shown by previous studies to be especially deleterious to flotation performance. Such ions include Ca²⁺, Cu²⁺, Mg²⁺, Pb²⁺, SO₄²⁻ and S₂O₃²⁻, amongst others. The flotation sub-process of collector adsorption which is responsible for inducing hydrophobicity on valuable mineral surfaces may be influenced by water chemistry. Accumulating ionic species have been shown to hinder collector adsorption which may reduce recovery of valuable minerals to the concentrate. Consequently, degrading water quality may threaten the economic viability of mining operations that make use of closed water circuits. Electrochemical techniques such as mineral rest potentials can be used to monitor the impact of changing water quality on collector–mineral interactions. Microflotation was used to determine whether mineral floatability was affected by changing water quality. This study therefore aimed to investigate whether electrochemical techniques such as rest potential measurements can be used to predict flotation performance under changing water quality. No definable relationship was found between the rest potential differences and the microflotation initial recoveries, however, rest potential measurements did identify the negative impact that thiosulphate ions may have on flotation processes. Full article

(This article belongs to the Special Issue Recent Developments in Mineral Processing at University of Cape Town)

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18 pages, 2542 KiB

Open AccessFeature PaperArticle

Assessment of Potentially Toxic Element Contamination in the Philippi Peatland, Eastern Macedonia, Greece

by Ioannis Zafeiriou, Dionisios Gasparatos, Ifigeneia Megremi, Dafni Ioannou, Ioannis Massas and Maria Economou-Eliopoulos

Minerals 2022, 12(11), 1475; https://doi.org/10.3390/min12111475 - 21 Nov 2022

Cited by 3 | Viewed by 1577

Abstract

The Philippi peatland is considered the biggest peat deposit in the Balkan Peninsula and one of the deepest in the world. The purpose of this study was to access the impact of eight potentially toxic elements (PTEs), i.e., As, Se, Pb, Cr, Ni, [...] Read more.

The Philippi peatland is considered the biggest peat deposit in the Balkan Peninsula and one of the deepest in the world. The purpose of this study was to access the impact of eight potentially toxic elements (PTEs), i.e., As, Se, Pb, Cr, Ni, Zn, Mn and Cu, on the local environment. PTE content was determined in corn grains and surface soil samples collected from 16 sites in the peatland, and pollution indices were calculated to evaluate the environmental risks. Soil organic matter ranged between 93 and 557 g kg⁻¹ soil, whereas the soil pH was >7, classifying the soils as neutral to slightly alkaline. Mean PTE contents in soil samples were 24.6 mg kg⁻¹ soil for As, 1.68 mg kg⁻¹ soil for Se, 113 mg kg⁻¹ soil for Pb, 32 mg kg⁻¹ soil for Cr, 36.3 mg kg⁻¹ soil for Ni, 141.4 mg kg⁻¹ soil for Zn, 35.5 mg kg⁻¹ soil for Cu and 845 mg kg⁻¹ soil for Mn. In corn grain samples, 0.06 mg kg⁻¹ grain for As, 0.14 mg kg⁻¹ grain for Se, 1.34 mg kg⁻¹ grain for Cr, 0.69 mg kg⁻¹ grain for Ni, 27 for Zn, 8.4 mg kg⁻¹ grain for Cu and 3.2 mg kg⁻¹ grain for Mn were recorded. No Pb was detected in the corn grains. The bioaccumulation factor (BF) was high for Cu, Zn and Se, indicating increased mobility of these elements in the soils and preferential plant uptake. For most soil samples, the geoaccumulation index (Igeo) and single pollution index (PI) showed low to moderate contamination. However, Igeo and PI values of Se in many sampling sites and of Pb and Zn in few were substantially increased, pointing to heavily contaminated soils. According to potential ecological risk (RI), the PTE content in the peat soils of Philippi imposes low to moderate risk on the environment. Full article

(This article belongs to the Special Issue Bio-Geochemistry of Heavy Metals/Metalloids)

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16 pages, 5484 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Magnetic Nanosorbents Based on Bentonite and CoFe₂O₄ Spinel

by Nataliya Khodosova, Lyudmila Novikova, Elena Tomina, Larisa Belchinskaya, Alexander Zhabin, Nikolay Kurkin, Victoria Krupskaya, Olga Zakusina, Tatiana Koroleva, Ekaterina Tyupina, Alexander Vasiliev and Pavel Kazin

Minerals 2022, 12(11), 1474; https://doi.org/10.3390/min12111474 - 21 Nov 2022

Cited by 3 | Viewed by 1717

Abstract

New magnetic nanocomposite sorbents were obtained by doping natural bentonite with nanosized CoFe₂O₄ spinel (10 and 20 wt.%). Nanocrystals of cobalt ferrite were synthesized by a citrate burning method. The structure and physical-chemical properties of the composites were characterized by [...] Read more.

New magnetic nanocomposite sorbents were obtained by doping natural bentonite with nanosized CoFe₂O₄ spinel (10 and 20 wt.%). Nanocrystals of cobalt ferrite were synthesized by a citrate burning method. The structure and physical-chemical properties of the composites were characterized by XRD, XRF, TEM, BET, FTIR and Faraday balance magnetometry. During the formation of nanocomposites, 10–30 nm particles of cobalt ferrite occupied mainly the interparticle space of Fe-aluminosilicate that significantly changed the particle morphology and composite porosity, but at the same time retained the structure of the 2:1 smectite layer. A combination of two functional properties of composites, adsorption and magnetism has been found. The adsorption capacity of magnetic nanosorbents exceeded this parameter for bentonite and spinel. Despite the decrease in the adsorption volume, pore size and specific surface area of the composite material relative to bentonite, the sorption activity of the composite increases by 12%, which indicated the influence of the magnetic component on the sorption process. FTIR data confirmed the mechanism of formaldehyde sorption by the composite sorbent. The production of a magnetic nanosorbent opens up new possibilities for controlling the sorption processes and makes it possible to selectively separate the sorbent from the adsorption medium by the action of a magnetic field. Full article

(This article belongs to the Special Issue Environmental Applications of Chemically Modified Clay Minerals, Volume II)

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22 pages, 2643 KiB

Open AccessArticle

Mineralogical and Sedimentological Characterization of the Clay-Rich Sediments from Ases Cave (Cova Dets Ases, Mallorca, Spain): Origin and Classification

by Ana Entrena, Joan J. Fornós, Luis F. Auqué, Francesc Gràcia and Elisa Laita

Minerals 2022, 12(11), 1473; https://doi.org/10.3390/min12111473 - 21 Nov 2022

Viewed by 1438

Abstract

The Mallorca coastal caves present large amounts of speleothems that have been studied for decades. However, the sedimentary deposits also present in these cases have not been given the same attention. This work is the first study entirely focused on these deposits, specifically [...] Read more.

The Mallorca coastal caves present large amounts of speleothems that have been studied for decades. However, the sedimentary deposits also present in these cases have not been given the same attention. This work is the first study entirely focused on these deposits, specifically the ones found in the Ases cave. These deposits are formed by clay minerals (illitic phases, kaolinite, smectite, and chlorite), calcite and quartz, and minor proportions of dolomite, albite, orthoclase, hematite, and goethite. The grain size and the electron microscopy studies suggested the presence of different sedimentation processes (bedrock degradation, creep or saltation, and suspension) and different origins (authigenic and detrital origins) for the different sediments. Based on these differences, two types of deposits were characterized: autochthonous and allochthonous deposits. The first ones are located on the floor of chambers and corridors in subaqueous zones, indicating the stability of the mixing zone (and therefore the sea level) over time. The second ones appear filling voids on the walls and the ceiling in the terrestrial zone, evidencing the filling of the cavity in the presence of water (during a wet period). These results are very important to complete the understanding of the caves and their evolution and support the relevance of these materials in paleoenvironmental studies. Full article

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

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13 pages, 10431 KiB

Open AccessArticle

The Heat Treatment of Pink Zoisite

by Clemens Schwarzinger

Minerals 2022, 12(11), 1472; https://doi.org/10.3390/min12111472 - 21 Nov 2022

Cited by 1 | Viewed by 2595

Abstract

Natural pink zoisites owe their color to a high concentration of manganese paired with low concentrations of other coloring elements such as vanadium or titanium. Upon conventional heating, such stones typically suffer from the reduction of Mn³⁺ to the colorless Mn²⁺ [...] Read more.

Natural pink zoisites owe their color to a high concentration of manganese paired with low concentrations of other coloring elements such as vanadium or titanium. Upon conventional heating, such stones typically suffer from the reduction of Mn³⁺ to the colorless Mn²⁺ species alongside the destruction of the brownish yellow color that is related to titanium. We have processed manganese containing zoisites under the high pressure of pure oxygen which allowed the manganese to remain oxidized, while the brownish yellow color component was still successfully removed. Depending on the vanadium level, the treated gems show a pink to purplish pink color. Detection of this treatment is not easy as the temperature is too low to result in a change in internal features, but a combination of UV-Vis-NIR spectroscopy and trace element chemistry provided by LA-ICP-MS give evidence of such treatment. Full article

(This article belongs to the Special Issue Gem Characterisation)

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13 pages, 6595 KiB

Open AccessArticle

Correlation between Compressive Strength and Heat of Hydration of Cement Mortars with Siliceous Fly Ash

by Aleksandra Kuryłowicz-Cudowska

Minerals 2022, 12(11), 1471; https://doi.org/10.3390/min12111471 - 20 Nov 2022

Cited by 2 | Viewed by 2045

Abstract

This paper presents the results of calorimetric and strength tests of mortars with ordinary Portland cement and two substitution rates (10 and 20%) of cement by siliceous fly ash. The prepared samples were cured under isothermal conditions at four different temperatures: 23, 33, [...] Read more.

This paper presents the results of calorimetric and strength tests of mortars with ordinary Portland cement and two substitution rates (10 and 20%) of cement by siliceous fly ash. The prepared samples were cured under isothermal conditions at four different temperatures: 23, 33, 43 and 53 °C. Heat of hydration was measured using an isothermal calorimeter dedicated to monitor the hydration process of cementitious composites such as paste, mortar and concrete. Thermal data were recorded continuously for 7 days, while compression tests were performed at 6 h and 1, 2, 5, 7 and 14 days of hardening. The studies proved that the amount of heat released correlates with the early-age strength of 50 mm mortar cubes. In the case of samples cured at 23 and 53 °C, a linear relationship between the heat of hydration and compressive strength was observed. The high value of the coefficient of determination (R²) allows one to estimate the mortar compressive strength after 7 and 14 days based on hydration heat tests conducted at standard temperature (23 °C), regardless of the percentage of siliceous fly ash. The increased curing temperatures do not guarantee a high correlation between compressive strength and the amount of heat released. Full article

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16 pages, 5276 KiB

Open AccessArticle

Minerochemical and Microtextural Study of the Ungrouped Iron Meteorite Oglat Sidi Ali, Eastern Highlands, Morocco, and Geomorphological Characterization of Its Strewnfield

by Hassane Nachit, Abderrahmane Ibhi, Mohamed En-nasiry, Vanni Moggi Cecchi, Giovanni Pratesi, Christopher D. K. Herd and Giorgio S. Senesi

Minerals 2022, 12(11), 1470; https://doi.org/10.3390/min12111470 - 20 Nov 2022

Cited by 2 | Viewed by 2045

Abstract

Fragments of a new iron meteorite were found in and collected from Oglat Sidi Ali, Maatarka region, Morocco, during a series of expeditions in the years 2013–2017. The physical characteristics of recovered fragments feature typical attributes of individual samples of a unique meteorite [...] Read more.

Fragments of a new iron meteorite were found in and collected from Oglat Sidi Ali, Maatarka region, Morocco, during a series of expeditions in the years 2013–2017. The physical characteristics of recovered fragments feature typical attributes of individual samples of a unique meteorite strewnfield that originated from an iron meteorite shower via the fragmentation of a single body that broke up in the lower atmosphere. The total recovered mass of the Oglat Sidi Ali meteorite fragments was estimated to amount to more than 800 kg spread across a NE–SW oriented, 20 km-long and 5 km-wide strewnfield. Geochemical and mineralogical data achieved on Oglat Sidi Ali fragments, as well as the analysis of its microstructures obtained using electron backscattered diffraction (EBSD), suggested it should be classified as an ungrouped iron meteorite. A comparison of this meteorite with other ungrouped iron meteorites, such as NWA 859 and NWA 11010, purchased between 2001 and 2016 in various cities of Northeast Morocco show apparently similar mineralogy, geochemistry and textural features, suggesting a common origin from a single extraterrestrial body. Full article

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

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16 pages, 3411 KiB

Open AccessArticle

Recovery of Uranium, Thorium, and Other Rare Metals from Eudialyte Concentrate by a Binary Extractant Based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and Methyl Trioctylammonium Nitrate

by Alfiya M. Safiulina, Alexey V. Lizunov, Aleksandr A. Semenov, Dmitriy V. Baulin, Vladimir E. Baulin, Aslan Yu. Tsivadze, Sergey M. Aksenov and Ivan G. Tananaev

Minerals 2022, 12(11), 1469; https://doi.org/10.3390/min12111469 - 20 Nov 2022

Cited by 3 | Viewed by 1676

Abstract

Eudialyte-group minerals are of scientific interest as important concentrators of rare elements (mainly Zr and REE) in agpaitic alkaline rocks and a potential source of REE, Zr, Hf, Nb, and Ta for industrial use. Extraction of uranium(VI), thorium(IV), zirconium(IV), hafnium(IV), titanium(IV), [...] Read more.

Eudialyte-group minerals are of scientific interest as important concentrators of rare elements (mainly Zr and REE) in agpaitic alkaline rocks and a potential source of REE, Zr, Hf, Nb, and Ta for industrial use. Extraction of uranium(VI), thorium(IV), zirconium(IV), hafnium(IV), titanium(IV), and scandium(III) by a binary extractant based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyl trioctylammonium nitrate from eudialyte breakdown solutions is studied. Extraction isotherms were obtained and exhaustive extraction was investigated. It is shown that uranium, thorium, hafnium, zirconium, scandium, and titanium are almost completely recovered in two-stage extraction by a mixture of 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyltrioctylammonium nitrate in 1,2-dichloroethane. Quantitative characteristics were compared for uranium(VI), thorium(IV), zirconium(IV), hafnium(IV), titanium(IV), and scandium(III). It was shown that the extraction efficiency of the metals by the binary extractant based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyltrioctylammonium nitrate in 1,2-dichloroethane is much higher in comparison with the commercially available tributyl phosphate. Full article

(This article belongs to the Special Issue Study of the Eudialyte Group Minerals)

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16 pages, 12979 KiB

Open AccessArticle

A Novel Enhanced Total Gradient (ETG) for Interpretation of Magnetic Data

by Korimilli Naga Durga Prasad, Luan Thanh Pham, Anand P. Singh, Ahmed M. Eldosouky, Kamal Abdelrahman, Mohammed S. Fnais and David Gómez-Ortiz

Minerals 2022, 12(11), 1468; https://doi.org/10.3390/min12111468 - 20 Nov 2022

Cited by 9 | Viewed by 2011

Abstract

Edge detection techniques identify the horizontal extents of the underground geological bodies and work well in association with magnetic as well as seismic data. Even though the detected edges might not be a lithological contact, they offer first-hand information regarding various rocks that [...] Read more.

Edge detection techniques identify the horizontal extents of the underground geological bodies and work well in association with magnetic as well as seismic data. Even though the detected edges might not be a lithological contact, they offer first-hand information regarding various rocks that ultimately offers an extra argument for existing tectonics. Most of the edge enhancement techniques depend either on the horizontal gradient or total gradient of the potential fields. As of now, no single edge detection filter performance is best in all conditions. The study proposes a novel edge detection filter called “ETG-Enhanced Total Gradient” that combines the derivatives of the analytic signal (AS) (in the third dimension). The maximum amplitude of the AS is less dependent of the direction of magnetization and is critical in mapping the borders of the buried magnetic sources beneath the Earth. As the ETG filter is based on the total gradient of the field, there is no need to apply reduction to the pole process on the magnetic data. One limitation of the method is that the filter is unable to perform better at the corners where the other conventional methods miserably failed. The filter’s behavior is examined and validated using 2D and 3D synthetic magnetic data. The reliability of the ETG filter is examined by applying it to the magnetic data of the Seattle uplift region, USA. A new structural map of the region is generated by using the proposed ETG filter. The observed peak response of the ETG filter is well correlated with major tectonic features such as the Seattle Fault Zone (SFZ), Hood Canal Fault (HCF), and Dewatto Fault (DF). Full article

(This article belongs to the Special Issue New Concept of Using Geophysical Data in Mineral Exploration, Depth Estimation and Structural Mapping)

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29 pages, 1811 KiB

Open AccessArticle

The Use of Lightweight Penetrometer PANDA for the Compaction Control of Classified Sand Tailings Dams

by Gabriel Villavicencio, Claude Bacconnet, Pamela Valenzuela, Juan Palma, Alex Carpanetti, Gonzalo Suazo, Matías Silva and José García

Minerals 2022, 12(11), 1467; https://doi.org/10.3390/min12111467 - 20 Nov 2022

Cited by 1 | Viewed by 1466

Abstract

Sand tailings dams have historically been the most commonly used technology for tailings storage in Chile. Although engineering advances have resulted in the construction of approximately 250-m-high facilities, some operational challenges still remain, including compaction control. Control is currently performed at a few [...] Read more.

Sand tailings dams have historically been the most commonly used technology for tailings storage in Chile. Although engineering advances have resulted in the construction of approximately 250-m-high facilities, some operational challenges still remain, including compaction control. Control is currently performed at a few control points in a dam embankment, without considering a series of factors that affect its mechanical behavior (e.g.,layer thickness and material variability). Within this context, geostatistics can be applied in combination with low-cost geotechnical tools as an alternative to improve compaction control in tailings storage facilities. In this study, an extensive field investigation was carried out. A total of 91 PANDA penetrometer tests were conducted to monitor the degree of compaction in an experimental classified sand tailings dam. The results were analyzed using stochastic interpolation for ordinary kriging and considering the spatial distribution of the cone resistance and the degree of compaction determined for the dam. The results showed that spatial variability was associated with the material variability of sand tailings and the compaction method used, and deviations from design requirements. The article shows the value of the use of geostatistics in decision-making in the case of classified sand tailings dams. This is mainly due to the fact that it allows optimization of the compaction process used in these tailings dams. Additionally, a useful database is generated to continue deepening studies of physical stability during the useful life of the tailings storage facilities. Full article

(This article belongs to the Special Issue Tailings Dams: Design, Characterization, Monitoring, and Risk Assessment)

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17 pages, 2676 KiB

Open AccessArticle

Valorization Potential of Polish Laterite Leaching Residues through Alkali Activation

by Vasiliki Karmali, Evangelos Petrakis, Georgios Bartzas and Konstantinos Komnitsas

Minerals 2022, 12(11), 1466; https://doi.org/10.3390/min12111466 - 19 Nov 2022

Viewed by 1055

Abstract

In this study, the valorization potential of Polish laterite leaching residues through alkali activation with the use of NaOH and Na₂SiO₃ solutions as activators was investigated. The effect of the main factors, namely the H₂O/Na₂O molar [...] Read more.

In this study, the valorization potential of Polish laterite leaching residues through alkali activation with the use of NaOH and Na₂SiO₃ solutions as activators was investigated. The effect of the main factors, namely the H₂O/Na₂O molar ratio in the activating solution, the curing temperature, and the ageing period on the main properties of the produced alkali activated materials (AAMs) was assessed. The experimental results showed that AAMs with sufficient compressive strength were only produced when the laterite leaching residues were mixed with significant quantities of metakaolin; thus, when the mass ratio of laterite leaching residues and metakaolin was 0.50, after curing at 40 °C for 24 h and ageing for 7 days, the produced AAMs acquired compressive strength that slightly exceeded 25 MPa. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy (SEM–EDS) analysis were used for the characterization of the raw materials and selected AAMs. Furthermore, the structural integrity of the specimens was investigated after immersion in distilled water and acidic solution (1 mol L⁻¹ HCl), or after firing at higher temperatures. Finally, the toxicity of the produced AAMs was assessed with the use of standard leaching tests. Full article

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

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17 pages, 4916 KiB

Open AccessArticle

Seismic Wave Finite-Difference Forward Modeling for Orogenic Gold Deposits

by Yao Pang, Lijun Yan, Yuan Liu, Lin Tang, Rui Zhu and Guofeng Liu

Minerals 2022, 12(11), 1465; https://doi.org/10.3390/min12111465 - 19 Nov 2022

Viewed by 1638

Abstract

The demand for deep prospecting has led to an increase in the enthusiasm for seismic techniques in mineral exploration. Reflection seismology applications in the base metal industry have achieved success. For orogenic gold deposits, however, their applicable conditions remain to be investigated. This [...] Read more.

The demand for deep prospecting has led to an increase in the enthusiasm for seismic techniques in mineral exploration. Reflection seismology applications in the base metal industry have achieved success. For orogenic gold deposits, however, their applicable conditions remain to be investigated. This paper simulated seismic wave propagation based on a finite-difference algorithm with an accuracy of eighth order in space and second order in time to investigate the factors influencing the reflection seismic exploration results. Then, the paper assessed the algorithm’s feasibility for orogenic gold deposits, taking the giant Zaozigou deposit in central China as an example. The forward modeling showed that the petrophysical properties, dimensions, and dip of targets significantly affected the seismic exploration results. In the Zaozigou model, shallowly dipping orebodies were well imaged with precise extension and thickness. Steeply dipping orebodies were recognized but their thickness information was lost. Steeply dipping orebodies at depth were not detectable under a surface configuration. These problems could be effectively solved by increasing the array length and using vertical seismic profiling methods. For small orebodies, multiwave and multicomponent seismic techniques offered more valuable information in terms of mineral exploration. In conclusion, it was possible to locate orogenic gold deposits using the reflection seismology method. Full article

(This article belongs to the Special Issue Understanding Hydrothermal Ore Deposits: Insights from In-situ Analyses)

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21 pages, 6633 KiB

Open AccessArticle

Metallogenesis of Porphyry Copper Deposit Indicated by In Situ Zircon U-Pb-Hf-O and Apatite Sr Isotopes

by Hong Zhang, Fang An, Mingxing Ling, Xiaolin Feng and Weidong Sun

Minerals 2022, 12(11), 1464; https://doi.org/10.3390/min12111464 - 19 Nov 2022

Cited by 1 | Viewed by 1518

Abstract

The origin of the Dexing porphyry Cu deposit is hotly debated. Zircon and apatite are important accessory minerals that record key information of mineralization processes. SHRIMP zircon U-Pb analyses of granodiorite porphyries yield ages of 168.9 ± 1.2 Ma, 168.0 ± 1.0 Ma, [...] Read more.

The origin of the Dexing porphyry Cu deposit is hotly debated. Zircon and apatite are important accessory minerals that record key information of mineralization processes. SHRIMP zircon U-Pb analyses of granodiorite porphyries yield ages of 168.9 ± 1.2 Ma, 168.0 ± 1.0 Ma, and 172.8 ± 1.3 Ma, whereas zircons in the volcanic rocks of the Shuangqiaoshan Group have Neoproterozoic ages of 830 ± 7 Ma, 829 ± 8 Ma, and 899 ± 12 Ma. The porphyry displays zircon in situ δ¹⁸O of mantle values (5.5 ± 0.2‰), low apatite ⁸⁷Sr/⁸⁶Sr ratios (0.7058 ± 0.0005), and high ε_Hf values (5.1 ± 1.5), which are consistent with mantle-derived magmatic rocks. Apatite from the porphyries has relatively high total rare earth elements (REEs) and negative Eu anomalies, with relatively high Cl and As contents. These features are distinctly different from apatite in the Shuangqiaoshan Group, which shows lower total REE, Cl, and As contents but higher F content and positive Eu anomalies. Zircon in porphyries yields a relative high oxygen fugacity of ∆FMQ + 1.5 based on zircon Ce⁴⁺/Ce³⁺. Apatite in porphyries also shows high oxygen fugacity based on its SO₃ and Mn compositions, reaching ∆FMQ + 2, which is different from that of the lower continental crust in general, but similar to subduction-related magmas. In contrast, the oxygen fugacity of the Shuangqiaoshan Group is much lower, suggesting a different origin for its wall rock. Therefore, the Dexing porphyries were not derived from the lower crust but derived from partial melting of the subducting Paleo-Pacific plate. Full article

(This article belongs to the Special Issue Genesis of Porphyry Cu–Mo Deposits: Geochemistry, Mineralogy and Geochronology)

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19 pages, 3905 KiB

Open AccessArticle

A Combined Re-Os and Pt-Os Isotope and HSE Abundance Study of Ru-Os-Ir Alloys from the Kunar and Unga Placer Deposits, the Taimyr Peninsula, Polar Siberia

by Kreshimir N. Malitch, Igor S. Puchtel, Elena A. Belousova and Inna Yu. Badanina

Minerals 2022, 12(11), 1463; https://doi.org/10.3390/min12111463 - 19 Nov 2022

Cited by 2 | Viewed by 1388

Abstract

In order to provide further insights into the origin of Ru-Os-Ir alloys, this study presents new highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundance and ¹⁸⁷Re-¹⁸⁷Os and ¹⁹⁰Pt-¹⁸⁶Os isotope data for detrital grains [...] Read more.

In order to provide further insights into the origin of Ru-Os-Ir alloys, this study presents new highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundance and ¹⁸⁷Re-¹⁸⁷Os and ¹⁹⁰Pt-¹⁸⁶Os isotope data for detrital grains of native Ru-Os-Ir alloys in placer deposits of the Kunar and Unga Rivers, which display a close spatial association with the Kunar dunite–harzburgite complex in the northern part of the Taimyr Peninsula in the Polar Siberia. The study utilized electron microprobe analysis, negative thermal ionization mass-spectrometry (N-TIMS) and laser ablation multiple-collector inductively coupled plasma mass-spectrometry (LA MC-ICP-MS). The primary nature of the Ru-Os-Ir alloys is supported by the occurrence of euhedral inclusions of high-Mg olivine (Fo_92–93) that fall within the compositional range of mantle olivine. The LA MC-ICP-MS data show similar average initial ¹⁸⁷Os/¹⁸⁸Os and γ¹⁸⁷Os(740 Ma) values for PGM assemblages from the Kunar and Unga deposits of 0.1218 ± 0.0010, −0.18 ± 0.85, and 0.1222 ± 0.0025, +0.10 ± 2.1, respectively. These values are identical, within their respective uncertainties, to the initial ¹⁸⁷Os/¹⁸⁸Os value of the Ru-Os-Ir alloy grain measured by N-TIMS (0.1218463 ± 0.0000015, γ¹⁸⁷Os(740 Ma) = −0.1500 ± 0.0012). The combined ¹⁸⁷Re-¹⁸⁷Os isotopic data for all studied grains (γ¹⁸⁷Os(740 Ma) = −0.02 ± 1.6) indicate evolution of the Kunar and Unga mantle sources with a long-term chondritic ¹⁸⁷Re/¹⁸⁸Os ratio of 0.401 ± 0.030. In contrast to the ¹⁸⁷Os/¹⁸⁸Os data, the initial ¹⁸⁶Os/¹⁸⁸Os value of 0.1198409 ± 0.0000012 (µ¹⁸⁶Os(740 Ma) = +34 ± 10) obtained for the same Ru-Os-Ir alloy grain by N-TIMS is suprachondritic and implies evolution of the Kunar and Unga mantle source(s) with a long-term suprachondritic ¹⁹⁰Pt/¹⁸⁸Os ratio of 0.00247 ± 0.00021. This value is ~40% higher than the average chondritic ¹⁹⁰Pt/¹⁸⁸Os ratio of 0.00180 and indicates long-term enrichment of the Kunar source in Pt over Os. Establishing the source of this enrichment requires further investigation. Full article

(This article belongs to the Special Issue Highly Siderophile Elements and Their Isotopes in the Earth’s Mantle)

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26 pages, 3018 KiB

Open AccessReview

A Review on Froth Washing in Flotation

by Tawona Martin Jera and Clayton Bhondayi

Minerals 2022, 12(11), 1462; https://doi.org/10.3390/min12111462 - 19 Nov 2022

Cited by 3 | Viewed by 3025

Abstract

In the attempt to process lower-grade ores, mineral flotation has taken centre stage as the preferred recovery route. However, in many instances, the froth product does not have a high grade due to the entrainment of gangue minerals. Industry has solved this challenge [...] Read more.

In the attempt to process lower-grade ores, mineral flotation has taken centre stage as the preferred recovery route. However, in many instances, the froth product does not have a high grade due to the entrainment of gangue minerals. Industry has solved this challenge by introducing froth washing mechanisms. Clean wash water is introduced into or on top of the froth to reduce the amount of entrained gangue in the final concentrate. This article reviews froth-washing systems in detail and highlights the advantages and disadvantages of each wash-water delivery mechanism. Comments on industrial uptake are provided. The indications are that froth washing improves the grade of the concentrate and influences froth stability and mobility. Other researchers have reported an improvement in recovery—especially of coarse particles—with wash water being added, while others have reported a reduction in recovery, especially with composite particles. Froth washing is generally applied in mechanical flotation cells by washing at the lip. In column flotation cells and Jameson cells, wash water is added to the entire froth surface. The literature also indicates that the wash-water rate, wash-water quality, type of wash-water delivery/ distribution mechanism and the area covered by wash water are critical parameters that dictate the efficacy of the washing system. Further research is necessary on the impact of wash-water quality on the froth phase sub-processes including froth rheology. Full article

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

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16 pages, 6534 KiB

Open AccessArticle

Trace Elements and Pb-O Isotopes of Scheelite: Metallogenic Implications for the Shimensi W-Polymetallic Deposit in South China

by Peng Wang, Ting Liang, HongJun Jiang, XinKui Xiang and Bo Zhong

Minerals 2022, 12(11), 1461; https://doi.org/10.3390/min12111461 - 18 Nov 2022

Viewed by 1406

Abstract

The world-class Shimensi tungsten (W)-polymetallic deposit is located in Jiangnan Orogen, with an estimated reserve of 742.5 kt WO₃ @ 0.195% W, 403.6 kt Cu and 28 kt Mo. In this paper, the trace elements and Pb-O isotopes of scheelite (the main [...] Read more.

The world-class Shimensi tungsten (W)-polymetallic deposit is located in Jiangnan Orogen, with an estimated reserve of 742.5 kt WO₃ @ 0.195% W, 403.6 kt Cu and 28 kt Mo. In this paper, the trace elements and Pb-O isotopes of scheelite (the main ore mineral) are presented to study the ore-forming material source and ore-forming fluid evolution. The results show that the REE distribution in scheelite is mainly controlled by the substitution mechanism of 3Ca²⁺ = 2REE³⁺ + □Ca (where □Ca is the Ca-site vacancy). Oxygen isotope data indicate that the scheelite mineralization occurred under high-temperature oxygen isotope equilibrium conditions, and that the ore-forming fluid has a magmatic–hydrothermal origin. The variation in scheelite Eu anomalies and the wide range of scheelite Y/Ho ratio indicate that the ore-forming fluid evolves from reducing to oxidizing, and the early-stage and late-stage ore-forming fluid may have been relatively rich in F⁻ and HCO₃⁻, respectively. The significant Mo decrease in scheelite from the early to late stage that are opposite to the influence of fO₂ variation may have resulted from the crystallization of molybdenite and Mo-rich scheelite. Lead isotopes of the ore minerals of scheelite, wolframite, molybdenite and chalcopyrite can be divided into three groups, similar to these of feldspars in different granites. Both the Mesozoic porphyritic and fine-grained biotite granites have Pb isotope ratios similar to the ores, which suggests that the former two are the main ore material source. Full article

(This article belongs to the Special Issue Rare Metal Ore Formations and Rare Metal Metallogeny)

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19 pages, 4489 KiB

Open AccessArticle

Dissolution of the Eudialyte-Group Minerals: Experimental Modeling of Natural Processes

by Julia A. Mikhailova, Yakov A. Pakhomovsky, Galina O. Kalashnikova and Sergey M. Aksenov

Minerals 2022, 12(11), 1460; https://doi.org/10.3390/min12111460 - 18 Nov 2022

Cited by 3 | Viewed by 1389

Abstract

Eudialyte-group minerals (EGMs) are typical accessory or rock-forming minerals of the Lovozero peralkaline massif (Kola Peninsula, Russia). The EGM grains in the rocks of the massif are often replaced by an association of various secondary minerals such as lovozerite and wöhlerite group minerals, [...] Read more.

Eudialyte-group minerals (EGMs) are typical accessory or rock-forming minerals of the Lovozero peralkaline massif (Kola Peninsula, Russia). The EGM grains in the rocks of the massif are often replaced by an association of various secondary minerals such as lovozerite and wöhlerite group minerals, as well as terskite, catapleiite, elpidite, gaidonnayite, vlasovite, zircon, and loparite-(Ce). However, EGMs in the Lovozero massif can be not only pseudomorphized, but also partially or completely dissolved. The partial dissolution of eudialyte grains was simulated in three series of experiments, and the results obtained were compared with natural samples. Observations in natural samples and experimental studies have shown that the partial dissolution of eudialyte-group minerals occurs in two stages: (1) loss of sodium and hydration; (2) loss of other cations not included in the zirconosilicate framework. This process proceeds most intensively in acidic hydrothermal solutions and may be responsible for the appearance of new mineral species in the eudialyte group. Full article

(This article belongs to the Special Issue Study of the Eudialyte Group Minerals)

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15 pages, 4978 KiB

Open AccessArticle

Reaction Characteristics of Two Types of Shale with Supercritical CO₂ and Its Potential Impact on Flow-Back Strategies

by Wei Yan, Guangyao Leng, Wenbo Li, Tao Wu, Mustajab Safarov, Jean P. E. Amboulou Ndessabeka and Keyu Meng

Minerals 2022, 12(11), 1459; https://doi.org/10.3390/min12111459 - 18 Nov 2022

Cited by 1 | Viewed by 1649

Abstract

Supercritical carbon dioxide (SC-CO₂) fracturing has been used in developing low permeability and water-sensitive reservoirs in recent years, which is expected to become a new generation of unconventional reservoir fracturing fluid. However, the water-rock interaction characteristics of various lithology shales under [...] Read more.

Supercritical carbon dioxide (SC-CO₂) fracturing has been used in developing low permeability and water-sensitive reservoirs in recent years, which is expected to become a new generation of unconventional reservoir fracturing fluid. However, the water-rock interaction characteristics of various lithology shales under SC-CO₂ circumstance and its influence on fracturing effect still need to be investigated. Two kinds of shale samples from C7 and S1 formations of the Ordos Basin were treated by SC-CO₂ with formation water. The aims of the research are to determine the processes taking place in shale reservoir when considering minerals components transformation, porosity/permeability variation, and micro pore-structure change during the SC-CO₂ fracturing. Static and dynamic SC-CO₂ immersed experiments were conducted and the scanning of electron microscopy (SEM) and X-ray diffraction (XRD) was employed to analyze the surface morphology and newly formed minerals. Helium porosimeter, the ultralow permeability meter, and the CT scanner are employed to record the alternation of physical parameters during SC-CO₂ dynamic injection. The experimental results show that the C7 samples are rich of chlorite and easily reacting with SC-CO₂ saturated formation water to form new minerals, but the S1 samples are insensitive to aqueous SC-CO₂. The minimum value of permeability and porosity of the C7 cores appear at 24h in the long-interval experiment, but in the short-interval dynamic experiment, the minimum values move ahead to 12h. The optimal flowback time for the C7 reservoir is before 12 h or after 24 h. The high-pressure SC-CO₂ flooding pushes the new forming minerals particles to migrate to the outlet side and block the pore throat. For the S1 core results, the porosity and permeability change little in both short and long interval experiments. There is no strict flow-back time requirement for S1 reservoir during SC-CO₂ fracturing. This study is significance for the efficient application of SC-CO₂ in the exploitation of shale oil reservoirs. Full article

(This article belongs to the Special Issue CO₂ Geological Storage: Fluid–Rock Interactions and Geochemical Modeling)

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23 pages, 5782 KiB

Open AccessArticle

Magma Evolution and Constraints on the Graphite Mineralization Hosted by the Huangyangshan Alkaline Granite Suite in the East Junggar of Xinjiang Province: Evidence from In Situ Analyses of Silicate Minerals

by Xinhao Sun, Yunsheng Ren, Jingmou Li, Mengjia Huang, Zhenjun Sun and Zuowu Li

Minerals 2022, 12(11), 1458; https://doi.org/10.3390/min12111458 - 18 Nov 2022

Viewed by 1459

Abstract

The Huangyangshan super-large graphite deposit, located in the East Junggar area of the Xinjiang Province, is hosted in and has closely temporal, spatial, and genetic relationships with the Huangyangshan alkaline granites. There are such silicate minerals as amphibole, biotite, pyroxene, and plagioclase occurring [...] Read more.

The Huangyangshan super-large graphite deposit, located in the East Junggar area of the Xinjiang Province, is hosted in and has closely temporal, spatial, and genetic relationships with the Huangyangshan alkaline granites. There are such silicate minerals as amphibole, biotite, pyroxene, and plagioclase occurring in the graphite-bearing granites. The integration of the electron microprobe analysis (EMPA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) enabled us to reveal the physicochemical conditions and evolution process, as well as the relationship of alkaline magmatism with graphite mineralization. The results show that the amphiboles generally have low Al and high Ti, K, Si, and Fe contents, as well as similar rare-earth elements (REEs) patterns and trace element distribution patterns to granites with significantly negative Eu anomalies. In the analyzed samples, primary biotite belongs to Fe-biotite and has characteristics of high Si and Fe and low Al and Mg contents. In the graphite orbicules, the pyroxene phenocrysts develop multiple zonal structures and are characterized by high Si and low Ca and Fe contents. The dominant plagioclase phenocrysts in the graphite orbicules are oligoclase and andesine, with normal and occasionally oscillatory zoning. The calculated crystallization temperature of the pyroxene, amphibole, and primary biotite in graphite orbicules are 840–1012 °C, 681–761 °C, and 658–720 °C, respectively, corresponding with their crystallization order. The pressure and depth calculation results of the amphibole, representing those of the magmatism, are 157–220 Mpa and 5.95–8.32 km, respectively. Both amphibole and biotite crystallized in a reducing environment with extremely low oxygen fugacity. The elemental compositions of these silicates indicate that the Huangyangshan pluton experienced significant mixing of mafic mantle-derived magma and felsic crust-derived magma. The cores of graphite orbicules were formed in a relatively earlier magmatic stage, while the granites and their dioritic enclaves were formed in a later magmatic stage. During magmatism, the mixing of mantle-derived basic magma had an important influence on the evolution and differentiation of the melts. According to the coexisting sulfides with graphite and compositional difference of amphibole and biotite in the granites and graphite ores, the graphite mineralization might be triggered by a magma mixing process. Full article

(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits)

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15 pages, 4479 KiB

Open AccessArticle

The Rheological Properties and Strength Characteristics of Cemented Paste Backfill with Air-Entraining Agent

by Baogui Yang, Xiaolong Wang, Peng Yin, Chengjin Gu, Xindong Yin, Faguang Yang and Tao Li

Minerals 2022, 12(11), 1457; https://doi.org/10.3390/min12111457 - 18 Nov 2022

Cited by 4 | Viewed by 1005

Abstract

Clogging pipelines is one of the most common and urgent problems in paste backfill mining. The aim of the present study was to solve the problem of pipe blockage in paste backfill mining. In this paper, paste mixed with coal gangue, fly ash, [...] Read more.

Clogging pipelines is one of the most common and urgent problems in paste backfill mining. The aim of the present study was to solve the problem of pipe blockage in paste backfill mining. In this paper, paste mixed with coal gangue, fly ash, cement, and additives is used to investigate the influence of three air-entraining agents (AEAs) (including sodium dodecyl sulfate (SDS), triterpene saponin (SJ), and sodium abietate (SA)) on the flow characteristics and strength characteristics of the paste. A series of relevant tests was conducted on the paste, such as air content experiments, slump and expansion experiments, viscosity and yield stress tests, and the uniaxial compressive strength (UCS) test. The results show that the air content of the paste increases with increasing AEA content, but the increase is limited and reaches a maximum at 0.9 AEA. The slump of the paste increased by up to 10–13 mm, and expansion increased by up to 66–130 mm compared to the paste without AEA. The viscosity of the paste decreased by up to 0.13–0.20 Pa·s, and the yield stress decreased by 81.47%–93.7% of the original. The strength of the paste was also reduced, and after 28 days of curing, the strength was reduced by up to 1–1.2 MPa. Taking into account the strength requirement of 3 MPa for the paste from the Linxi mine, it was considered that the dosage of 0.9 B was a good choice, as it could better change the flowability of the paste and reduce the pipeline transportation resistance and transportation energy consumption. At the same time, the strength was also acceptable. The study in this paper can provide a reference for performance studies of pastes mixed with coal gangue, fly ash, cement, and additives as materials. Full article

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

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38 pages, 14497 KiB

Open AccessArticle

Isomorphism and Mutual Transformations of S-Bearing Components in Feldspathoids with Microporous Structures

by Nikita V. Chukanov, Nadezhda V. Shchipalkina, Roman Yu. Shendrik, Marina F. Vigasina, Vladimir L. Tauson, Sergey V. Lipko, Dmitry A. Varlamov, Vasiliy D. Shcherbakov, Anatoly N. Sapozhnikov, Anatoly V. Kasatkin, Natalia V. Zubkova and Igor V. Pekov

Minerals 2022, 12(11), 1456; https://doi.org/10.3390/min12111456 - 18 Nov 2022

Cited by 6 | Viewed by 1381

Abstract

The isomorphism of S-bearing feldspathoids belonging to the cancrinite, sodalite, tugtupite, vladimirivanovite, bystrite, marinellite and scapolite structure types has been investigated using a multimethodical approach based on infrared, Raman and electron spin resonance (ESR), as well as ultraviolet, visible and near infrared (UV–Vis–near [...] Read more.

The isomorphism of S-bearing feldspathoids belonging to the cancrinite, sodalite, tugtupite, vladimirivanovite, bystrite, marinellite and scapolite structure types has been investigated using a multimethodical approach based on infrared, Raman and electron spin resonance (ESR), as well as ultraviolet, visible and near infrared (UV–Vis–near IR) absorption spectroscopy methods and involving chemical and X-ray diffraction data. Sapozhnikovite Na₈(Al₆Si₆O₂₄)(HS)₂ and sulfite and thiosulfate analogues of cancrinite are synthesized hydrothermally and characterized by means of electron microprobe analyses, powder X-ray diffraction and Raman spectroscopy. The possibility of the incorporation of significant amounts of SO₄²⁻, S₄ and SO₃²⁻ in the crystal structures of cancrisilite, sulfhydrylbystrite and marinellite, respectively, has been established for the first time. Thermal conversions of S-bearing groups in the synthetic sulfite cancrinite and sapozhnikovite analogues as well as natural vladinirivanovite and S₄-bearing haüyne under oxidizing and reducing conditions have been studied using the multimethodical approach. The SO₄²⁻ and S²⁻ anions and the S₃^•– radical anion are the most stable S-bearing species under high-temperature conditions (in the range of 700–800 °C); their ratio in the heated samples is determined by the redox conditions and charge-balance requirement. The HS⁻ and S₅²⁻ anions are stable only under highly reducing conditions. Full article

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

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18 pages, 4836 KiB

Open AccessArticle

Impact of Recycled Process Water on Electrochemical Reactivity of Sulphide Ore

by Benjamin Musuku and Olli Dahl

Minerals 2022, 12(11), 1455; https://doi.org/10.3390/min12111455 - 18 Nov 2022

Cited by 2 | Viewed by 1312

Abstract

The Kevitsa Cu–Ni sequential flotation process is characterised by poor nickel recovery during summer periods (May–September). Evidently, the process water matrix in summer is different from that in other seasons; however, the Cu flotation performance is scarcely affected by the changes in the [...] Read more.

The Kevitsa Cu–Ni sequential flotation process is characterised by poor nickel recovery during summer periods (May–September). Evidently, the process water matrix in summer is different from that in other seasons; however, the Cu flotation performance is scarcely affected by the changes in the water matrix across the seasons. Increasingly different process water quality was generated through a grinding-and-dissolution protocol and its impact on the electrochemical reactivity of sulphide ore was studied. The main objective of this approach was to mimic the increasingly different quality of plant process water emanating from a closed-process water loop. Dissolved oxygen demand tests were conducted on the Kevitsa ore using water of varying quality from dissolution loops. The effect of the temperature and fine grind on the oxidation rates was also investigated. The study was coupled with EDTA metal ion extraction and xanthate adsorption tests. These showed that the number of dissolution loops, which has an impact on water quality, has a direct impact on the rate of oxidation of the ore. A fine grind and high temperature both increase the oxidation rates of the ore. The Kevitsa ore is most reactive in the first 10–20 min after milling. Furthermore, oxidation rates are also driven by the amount of pyrrhotite in the ore, with chalcopyrite being the least reactive, as indicated by the EDTA data. Xanthate adsorption is impacted by the water quality and fine grind. The combined effect of water quality, temperature and fine grind is expected to influence the flotation behaviour of sulphide minerals. The poor nickel recovery of the Kevitsa ore during the summer period is attributable to the unfavourable process water quality, which accelerates the oxidation of the ore during the summer period. Full article

(This article belongs to the Special Issue Water within Minerals Processing, Volume II)

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13 pages, 2612 KiB

Open AccessArticle

Adsorption of Hydrated Pr³⁺ and NH₄⁺/Mg²⁺ Ions onto the (001) Surface of Montmorillonite: A DFT Analysis with Experimental Verification

by Zhiqiang Zou, Lijinhong Huang, Xindong Li, Jie Xu, Xiangrong Zeng, Ronghua Shu, Bin Xiao, Jiacai Ou and Wanfu Huang

Minerals 2022, 12(11), 1454; https://doi.org/10.3390/min12111454 - 18 Nov 2022

Cited by 3 | Viewed by 1269

Abstract

Montmorillonite is a major mineral present in ion-adsorption rare earth ores, and the microscopic adsorption states of rare earth ions on its surface are of a great significance for the efficient exploitation of ion-adsorption rare earth ores. In this article, density functional theory [...] Read more.

Montmorillonite is a major mineral present in ion-adsorption rare earth ores, and the microscopic adsorption states of rare earth ions on its surface are of a great significance for the efficient exploitation of ion-adsorption rare earth ores. In this article, density functional theory calculations were used to investigate the adsorption mechanisms and bonding characteristics of hydrated Pr, Mg and NH₄ ions on the (001) surface of montmorillonite. Pr³⁺ exhibited a directed tendency geometry with Pr(H₂O)₁₀³⁺, which was adsorbed onto montmorillonite by hydrogen bonding with an adsorption energy of −1182 kJ/mol, and one coordinated H₂O ligand was separated from the first hydration layer of Pr. Both hydrated Mg and NH₄ ions were adsorbed onto the montmorillonite surface through hydrogen bonds, and the adsorption energies were −206 and −188 kJ/mol, respectively, indicating that the adsorption stability of the hydrated Mg ion was slightly higher than that of the hydrated NH₄ ion, but both were lower than that of hydrated Pr (−1182 kJ/mol). Hence, higher concentrations of Mg and NH₄ ions than rare earth ions would be necessary in the leaching process of ion-adsorption rare earth ores. Additionally, desorption experiments revealed that the recovery of Pr³⁺ by Mg²⁺ with a concentration of 38 mmol/L is 80%, while it is only 65% with the same concentration of NH₄⁺, and the concentrations of Mg²⁺ and NH₄⁺ were much higher than that of Pr³⁺ in lixivium, which is consistent with the DFT calculations. Full article

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

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32 pages, 6210 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Prospectivity Mapping of Heavy Mineral Ore Deposits Based upon Machine-Learning Algorithms: Columbite-Tantalite Deposits in West- Central Côte d’Ivoire

by Kassi Olivier Shaw, Kalifa Goïta and Mickaël Germain

Minerals 2022, 12(11), 1453; https://doi.org/10.3390/min12111453 - 17 Nov 2022

Viewed by 3192

Abstract

This study aimed to model the prospectivity for placer deposits using geomorphic and landscape parameters. Within a geographic information system (GIS), spatial autocorrelation analysis of 3709 geochemical samples was used to identify prospective and non-prospective targets for columbite-tantalite (Nb-Ta) placer deposits of Hana-Lobo [...] Read more.

This study aimed to model the prospectivity for placer deposits using geomorphic and landscape parameters. Within a geographic information system (GIS), spatial autocorrelation analysis of 3709 geochemical samples was used to identify prospective and non-prospective targets for columbite-tantalite (Nb-Ta) placer deposits of Hana-Lobo (H-L) Geological Complex (West- Central Côte d’Ivoire, West Africa). Based on mineralization system analysis, hydrologic, geomorphologic and landscape parameters were extracted at the locations of the identified targets. Supervised automatic classification approaches were applied, including Random Forest (RF), K-Nearest Neighbors (KNN) and Support Vector Machines (SVM) to find a prospectivity model complex enough to capture the nature of the data. Metrics such as cross-validation accuracy (CVA), Receiver Operating Characteristic (ROC) curves, Area Under Curve (AUC) values and F-score values were used to evaluate the performance and robustness of output models. Results of applying machine-learning algorithms demonstrated that predictions provided by the final RF and KNN models were very close (κ = 0.56 and CVA = 0.69; κ = 0.54 and CVA = 0.68, respectively) and those provided by the SVM models were slightly lower with κ = 0.46 and CVA = 0.63. Independent validation results confirmed the slightly higher performance of both KNN and RF prospectivity models, compared to final SVM. Sensitivity analyses of both KNN and RF prospectivity models for medium and high-grade Nb-Ta deposits show a prediction rate of up to 90%. Full article

(This article belongs to the Special Issue AI-Based GIS for Pinpointing Mineral Deposits)

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17 pages, 2168 KiB

Open AccessArticle

Isolation and Identification of Arsenic Hyper-Tolerant Bacterium with Potential Plant Growth Promoting Properties from Soil

by Debjani Mandal, Mina Aghababaei, Sadhan Kr Das, Santanu Majumder, Debashis Chatterjee and Abhishek Basu

Minerals 2022, 12(11), 1452; https://doi.org/10.3390/min12111452 - 17 Nov 2022

Viewed by 1790

Abstract

The soil and groundwater of the Bhagobangola I block of Murshidabad district, West Bengal, India is severely arsenic-contaminated. A bacterium was isolated from the garden soil of the Mahishasthali village, which could tolerate 36.49 mM arsenic (III), 280.44 mM arsenic (V) and 63 [...] Read more.

The soil and groundwater of the Bhagobangola I block of Murshidabad district, West Bengal, India is severely arsenic-contaminated. A bacterium was isolated from the garden soil of the Mahishasthali village, which could tolerate 36.49 mM arsenic (III), 280.44 mM arsenic (V) and 63 mM chromium (III), which makes it arsenic (III and V) and chromium (III) hyper-tolerant bacterium. The growth pattern of this bacterium does not show much alteration in the presence of 10 mM arsenic (III) and chromium (III), emphasizing its resistance to these heavy metals. Scanning electron microscopic analysis depicted this bacterium to be rod-shaped with a size of ~1.45 µm. 16S rDNA sequencing, followed by subsequent phylogenetic analysis, established the identity of this bacterium as Microbacterium paraoxydans. This bacterium is capable of bioremediation of arsenic and showed 30.8% and 35.2% of bioremediation for 1mM and 22.6%, and 30.5% of bioremediation for 4mM arsenite, over a period of 24 and 48 h, respectively. Microbacterium paraoxydans also exhibits potential plant growth-promoting properties such as nitrogen fixation, phosphate solubilization, indole-3-acetic acid production and production of siderophores. Therefore, the heavy metal resistance, bioremediation potential and plant growth-promoting potential of the bacterium could be utilized not only for reduction in arsenic toxicity in soil and groundwater but also for plant growth promotion. Full article

(This article belongs to the Special Issue Arsenic Pollution: Sources, Modes of Enrichment, Mechanisms of Release, and Mitigation Strategies)

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15 pages, 5367 KiB

Open AccessArticle

Machine Learning Model of Hydrothermal Vein Copper Deposits at Meso-Low Temperatures Based on Visible-Near Infrared Parallel Polarized Reflectance Spectroscopy

by Banglong Pan, Hanming Yu, Hongwei Cheng, Shuhua Du, Shaoru Feng, Ying Shu, Juan Du and Huaming Xie

Minerals 2022, 12(11), 1451; https://doi.org/10.3390/min12111451 - 17 Nov 2022

Cited by 2 | Viewed by 1540

Abstract

The verification efficiency and precision of copper ore grade has a great influence on copper ore mining. At present, the common method for the exploration of reserves often uses chemical analysis and identification, which have high costs, long cycles, and pollution risks but [...] Read more.

The verification efficiency and precision of copper ore grade has a great influence on copper ore mining. At present, the common method for the exploration of reserves often uses chemical analysis and identification, which have high costs, long cycles, and pollution risks but cannot realize the in situ determination of the copper grade. The existing scalar spectrometric techniques generally have limited accuracy. As a vector spectrum, polarization state information is sensitive to mineral particle distribution and composition, which is conducive to high-precision detection. Taking the visible-near infrared parallel polarization reflectance spectrum data and grade data of a copper mine in Xiaoyuan village, Huaining County, Anhui Province, China, as an example, the characteristics of the parallel polarization spectra of the copper mine were analyzed. The spectra were pretreated by first-order derivative transform and wavelet denoising, and the dimensions of wavelet denoising spectra, parallel polarization spectra, and first-order derivative spectra were also reduced by principal component analysis (PCA). Three, four, and eight principal components of the three types of spectra were selected as variables. Four machine learning models, the radial basis function (RBF), support vector machine (SVM), generalized regression neural network (GRNN), and partial least squares regression (PLSR), were selected to establish the PCA parallel polarization reflectance spectrum and copper grade prediction model. The accuracy of the model was evaluated by the determination coefficient (R²) and root mean square error (RMSE). The results show that, for parallel polarization spectra, first-order derivative spectra, and wavelet denoising spectra, the PCA-SVM model has better results, with R² values of 0.911, 0.942, and 0.953 and RMSE values of 0.022, 0.019, and 0.017, respectively. This method can effectively reduce the redundancy of polarized hyperspectral data, has better model prediction ability, and provides a useful exploration for the grade analysis of hydrothermal copper deposits at meso-low temperatures. Full article

(This article belongs to the Special Issue Modeling and Analysis of Mining Area using Remote Sensing and GIS Technology)

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18 pages, 3812 KiB

Open AccessArticle

Genesis of Metal Sulfides and Its Significance on Graphite Mineralization in the Huangyangshan Graphite Deposit, East Junggar, Xinjiang Province, China

by Yunsheng Ren, Jingmou Li, Xinhao Sun, Zuowu Li and Zhenjun Sun

Minerals 2022, 12(11), 1450; https://doi.org/10.3390/min12111450 - 16 Nov 2022

Cited by 3 | Viewed by 1517

Abstract

The Huangyangshan super-large graphite deposit is located in the Qitai area of East Junggar in Xinjiang Province, China. This deposit is well known for its distinguishing properties, including the alkaline granite complex that hosts the graphite ore, the dominantly orbicular structure developed in [...] Read more.

The Huangyangshan super-large graphite deposit is located in the Qitai area of East Junggar in Xinjiang Province, China. This deposit is well known for its distinguishing properties, including the alkaline granite complex that hosts the graphite ore, the dominantly orbicular structure developed in the graphite ore, and the association of graphite with metal sulfides in the orbicular ore. This study aims to determine the genetic relationship between graphite and metal sulfides in order to better understand the graphite mineralization process of the Huangyangshan deposit. The methods applied in the study include X-ray micro-CT scanning and scanning electron microscopy (SEM) analyses of the orbicular graphite ore and in situ inductive laser ablation-coupled plasma mass spectrometry (LA-ICP-MS) trace element analyses of the pyrrhotite and chalcopyrite associated with the graphite. The analytical results show that the graphite ore is composed of crystalline graphite, K-feldspar, albite, quartz, biotite, amphibole, and metal sulfides. The metal sulfides in the orbicular ore include pyrite, pyrrhotite, pentlandite, and chalcopyrite. According to the color, crystalline shape, texture, and occurrence, pyrrhotite can be classified into four types (I, II, III, and IV), and chalcopyrite into two types (I and II), of which types I, II, and III pyrrhotite and type I chalcopyrite have a close genetic relationship with graphite. The granular types (I, II, and III) of pyrrhotite are enriched in Co, Ni, Se, Ge, and Te and are depleted in As, Sb, Ag, and Au; they also have a high value of Co/Ni, indicating that these types of pyrrhotite have a magmatic origin. Low values of Co/Ni suggest that type IV pyrrhotite has a hydrothermal origin. The similar contents of Co and Ni and the values of Co/Ni compared with the chalcopyrite from the magmatic Co–Ni sulfide deposits imply that type I chalcopyrite has a magmatic origin. In summary, the metal sulfides of the Huangyangshan deposit are genetically related to graphite mineralization and formed predominantly by magmatic processes. Full article

(This article belongs to the Special Issue Genesis and Metallogeny of Non-ferrous and Precious Metal Deposits)

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17 pages, 6720 KiB

Open AccessArticle

Black Quartz from the Burano Formation (Val Secchia, Italy): An Unusual Gem

by Franca Caucia, Maurizio Scacchetti, Luigi Marinoni and Mattia Gilio

Minerals 2022, 12(11), 1449; https://doi.org/10.3390/min12111449 - 16 Nov 2022

Cited by 2 | Viewed by 1860

Abstract

The Burano Formation in Val Secchia in the province of Reggio Emilia is rich in black or very dark quartz. The crystals are often pitted by scars, rarely shiny, often opaque, rarely translucent, and about 3 cm long. However, they have a beautiful [...] Read more.

The Burano Formation in Val Secchia in the province of Reggio Emilia is rich in black or very dark quartz. The crystals are often pitted by scars, rarely shiny, often opaque, rarely translucent, and about 3 cm long. However, they have a beautiful color and are generally euhedral and bi-terminate with simple habitus and well developed faces—for these characteristics, they are very sought after by collectors. Micro-Raman analyses showed the quartz contains abundant inclusions of anhydrite and graphite. The inclusions of anhydrite are responsible for the chromatic inhomogeneity, while the black color is linked to the presence of disordered graphite inclusions. LA-ICP-MS analyses did not show a significant presence of chromophore elements. Black quartz formed in the original evaporite deposits of gypsum, which, due to diagenesis and the increase in temperature during deep tectonic burial conditions, lost water of crystallization and subsequently transformed into anhydrite. After the formation of quartz crystals, the Burano Formation was exhumated and rehydrated, resulting in gypsification at conditions close to the surface. The black quartzes of the Burano Formation represent an appreciable gemological material for the development of local craftsmanship, even if the difficulties in reaching the deposit limit their marketing. Full article

(This article belongs to the Special Issue Gem Characterisation)

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23 pages, 4090 KiB

Open AccessArticle

Distribution of Trace Elements in K-Feldspar with Implications for Tracing Ore-Forming Processes in Pegmatites: Examples from the World-Class Kolmozero Lithium Deposit, NW Russia

by Lyudmila Morozova, Dmitry Zozulya, Ekaterina Selivanova, Pavel Serov and Aya Bazai

Minerals 2022, 12(11), 1448; https://doi.org/10.3390/min12111448 - 16 Nov 2022

Viewed by 2496

Abstract

This study utilizes LA-ICP-MS-determined minor and trace element contents of megacrystic blocky K-feldspar to reveal the chemical variability and fractionation degree of albite-spodumene and barren feldspar pegmatites of the Kolmozero lithium deposit in the Kola region, Russia. K-feldspar from albite-spodumene pegmatite is represented [...] Read more.

This study utilizes LA-ICP-MS-determined minor and trace element contents of megacrystic blocky K-feldspar to reveal the chemical variability and fractionation degree of albite-spodumene and barren feldspar pegmatites of the Kolmozero lithium deposit in the Kola region, Russia. K-feldspar from albite-spodumene pegmatite is represented by two generations: early microcline-I and late microcline-II. Rb, Cs, Li, and Tl are the most typical impurity elements in K-feldspar that replace K in its crystal lattice. Microcline-II differs from microcline-I: (i) relatively high contents of Rb (6520 and 4490 ppm, respectively), Cs (146 and 91 ppm), and Li (86 and 68 ppm), Tl (34 and 28 ppm); and (ii) low contents of Ba (13 and 29 ppm), Sr (8 and 24 ppm), and Pb (14 and 26 ppm). K-feldspar from feldspar pegmatites of the Kolmozero pegmatite field differs from those in the Kolmozero Li deposit in (i) low contents of Rb, Cs, Li, Tl, and an orthoclase component; and (ii) high contents of Sr, Ba, Pb, and an albite component. K/Sr, K/Ba, Rb/Ba, and Rb/Sr element ratios increase, while K/Rb, K/Cs, K/Tl, and K/Li element ratios decrease in K-feldspar, from feldspar pegmatites to albite-spodumene pegmatites. These trends reflect different fractionation degrees of pegmatite evolution. The implications of the detected trace element variations in K-feldspar are discussed in respect of tracing the rare element enrichments in pegmatite systems. A model is proposed for the formation of the Kolmozero pegmatites by differentiation from a hypothetical parental granite, rather than by anatexis of the host rock. Full article

(This article belongs to the Special Issue New Economy Minerals)

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Minerals, Volume 12, Issue 11 (November 2022) – 141 articles

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