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Passive Structural Control on Skarn Mineralization Localization: A Case Study from the Variscan Rosas Shear Zone (SW Sardinia, Italy)
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Fabrication of Hydrotalcite-like Copper Hydroxyl Salts as a Photocatalyst and Adsorbent for Hexavalent Chromium Removal
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Evaluating the Application of Rock Breakage without Explosives in Underground Construction—A Critical Review of Chemical Demolition Agents
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Enhanced Flotation Recovery of Fine Molybdenite Particles Using a Coal Tar-Based Collector
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Origin of the Coloured Karst Fills in the Neogene Extensional System of NE Iberia (Spain)
Journal Description
Minerals
Minerals
is an international, peer-reviewed, open access journal of natural mineral systems, mineral resources, mining, and mineral processing. Minerals is published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), GeoRef, CaPlus / SciFinder, Inspec, Astrophysics Data System, AGRIS, and many other databases.
- Journal Rank: JCR - Q2 (Mineralogy) / CiteScore - Q2 (Geology)
- Rapid Publication: manuscripts are peer-reviewed and a first decision provided to authors approximately 15.9 days after submission; acceptance to publication is undertaken in 3.1 days (median values for papers published in this journal in the second half of 2021).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Mining
Impact Factor:
2.644 (2020)
;
5-Year Impact Factor:
2.737 (2020)
Latest Articles
A Kinetic Monte Carlo Approach to Model Barite Dissolution: The Role of Reactive Site Geometry
Minerals 2022, 12(5), 639; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050639 - 18 May 2022
Abstract
Barite (Ba[SO4]) is one of the promising candidates for sequestration of radioactive waste. Barite can incorporate radium (Ra) and form ideal solid solutions, i.e., (Ba,Ra)[SO4]. Together with isostructural celestite (Sr[SO4]), ternary solid solutions, (Ba,Sr,Ra)[SO4], may
[...] Read more.
Barite (Ba[SO4]) is one of the promising candidates for sequestration of radioactive waste. Barite can incorporate radium (Ra) and form ideal solid solutions, i.e., (Ba,Ra)[SO4]. Together with isostructural celestite (Sr[SO4]), ternary solid solutions, (Ba,Sr,Ra)[SO4], may exist in natural conditions. Our fundamental understanding of the dissolution kinetics of isostructural sulfates is critically important for a better risk assessment of nuclear waste repositories utilizing this mineral for sequestration. So far, the barite-water interface has been studied with experimental methods and atomistic computer simulations. The direct connection between the molecular scale details of the interface structure and experimental observations at the microscopic scale is not yet well understood. Here, we began to investigate this connection by using a kinetic Monte Carlo approach to simulate the barite dissolution process. We constructed a microkinetic model for the dissolution process and identified the reactive sites. Identification of these sites is important for an improved understanding of the dissolution, adsorption, and crystal growth mechanisms at the barite–water interface. We parameterized the molecular detachment rates by using the experimentally observed etch pit morphologies and atomic step velocities. Our parameterization attempts demonstrated that local lattice coordination is not sufficient to differentiate between the kinetically important sites and estimate their detachment rates. We suggest that the water structure and dynamics at identified sites should substantially influence the detachment rates. However, it will require more work to improve the parameterization of the model by means of Molecular Dynamics and ab initio calculations.
Full article
(This article belongs to the Special Issue Ion Adsorption at Mineral–Water Interfaces)
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A Feasibility Study of CSEM in Geological Advance Forecast with Horizontal Casing Well
Minerals 2022, 12(5), 638; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050638 - 18 May 2022
Abstract
With the rapid exploitation of deep mines by digging new tunnels, the advance forecast of water inrush has become increasingly important. The land-based controlled source electromagnetic method (CSEM) is commonly used to detect water-bearing structures. To increase its sensitivity, we propose a new
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With the rapid exploitation of deep mines by digging new tunnels, the advance forecast of water inrush has become increasingly important. The land-based controlled source electromagnetic method (CSEM) is commonly used to detect water-bearing structures. To increase its sensitivity, we propose a new measuring configuration for CSEM by placing EM sensors in an underground steel-cased well. The numerical modeling is conducted by COMSOL to overcome the difficulties of investigating the feasibility of the measuring configuration. The current distribution and electromagnetic field along an in-seam horizontal casing are investigated based on a synthesis three-layered model. The results illustrate that the casing can be treated as antennas that enhance the electric fields at large depths. The water-bearing structures can be observed by a magnetic field (with a perpendicularly horizontal electric dipole (HED) source) rather than an electric field (with a parallelly HED source). Numerical simulations demonstrate that the proposed method is a feasible and effective technique for the detection of water-bearing structures during deep mineral exploration.
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(This article belongs to the Special Issue Electromagnetic Exploration: Theory, Methods and Applications)
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Chemical Composition and Strontium Isotope Characteristics of Scheelite from the Doranasai Gold Deposit, NW China: Implications for Ore Genesis
Minerals 2022, 12(5), 637; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050637 - 18 May 2022
Abstract
Scheelite, as a common accessory mineral found in hydrothermal deposits, is an indicator that allows the study of the ore-forming hydrothermal process and the tracing of fluid sources. The Doranasai gold deposit is a large-sized orogenic gold deposit in the South Altai, and
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Scheelite, as a common accessory mineral found in hydrothermal deposits, is an indicator that allows the study of the ore-forming hydrothermal process and the tracing of fluid sources. The Doranasai gold deposit is a large-sized orogenic gold deposit in the South Altai, and orebodies occur as veins in the Devonian Tuokesalei Formation and Permian albite granite dykes. The ores are quartz veins and altered tectonites (rocks). Here, scheelite can be observed in the early-stage milky quartz veins, the middle-stage smoky quartz-polymetallic sulfide veins, and the altered albite granite dykes. In this study, the scheelites of these three types were carefully investigated in terms of texture, element, and isotope geochemistry to understand their ore-forming processes and fluid sources. The results showed that all types of scheelite were rich in Sr and poor in Mo, indicating that their ore-forming fluids had no genetic relation to magmatic–hydrothermal activities. The scheelites were characterized by the enrichment of medium rare earth element (MREE) and positive Eu anomaly in the chondrite-standardized REE patterns. This indicated the REE differentiation between scheelite and fluid, i.e., REE3+ and Na+ were in the form of valence compensation, preferentially replacing Ca2+ and selectively entering the scheelite lattice. The trace element composition of scheelite showed that the ore-forming fluid system was relatively closed, mesothermal, Na-rich, and reductive. The Sr isotope ratio of the scheelite (0.704819–0.70860, average 0.706372) was higher than that of the ore-bearing albite granite dyke (0.704654–0.704735), indicating that the Tuokesalei Formation is the main source for the fluids forming the Doranasai deposit.
Full article
(This article belongs to the Special Issue Mineral Resources in North China Craton)
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Alkali Recovery of Bauxite Residue by Calcification
Minerals 2022, 12(5), 636; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050636 - 17 May 2022
Abstract
Bauxite residue (red mud) generated during alumina production is a highly alkaline solid waste. The red mud is mainly stored on land, but it can cause harm to the surrounding environment and human health. The transformation of red mud into soil is a
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Bauxite residue (red mud) generated during alumina production is a highly alkaline solid waste. The red mud is mainly stored on land, but it can cause harm to the surrounding environment and human health. The transformation of red mud into soil is a feasible method for the large-scale disposal of red mud, but alkali removal is the key process that controls the transformation of red mud into soil. In this study, the calcification dealkalization of red mud with a small particle size was carried out below 100 °C. The results show that the sodium in red mud is predominately distributed in small particles, mainly because the lattice alkali and alkali present between the crystals are exposed to the surface of red mud particles by ball milling. The dealkalization process was controlled by the internal diffusion of the shrinking-core model (SCM), and the apparent activation energy was 23.55 kJ/mol. The dealkalization rate and the Na2O content of dealkalized red mud reached 92.44% and 0.61%, respectively. The dealkalization rate increased with increasing reaction time, reactant concentration, and leaching temperature, and this result was consistent with the results of the kinetic study. In addition, calcification enhances the flocculation of particles, so the filtration performance of red mud improved.
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(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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CO2-Water-Rock Interactions in Carbonate Formations at the Tazhong Uplift, Tarim Basin, China
Minerals 2022, 12(5), 635; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050635 - 17 May 2022
Abstract
The effects of CO2-water-rock interactions on the injectivity and safety of CO2 geological storage have drawn wide attention. The geochemical reaction mechanisms in carbonate formations after CO2 injection are still controversial. To better understand the transformation of injected CO
[...] Read more.
The effects of CO2-water-rock interactions on the injectivity and safety of CO2 geological storage have drawn wide attention. The geochemical reaction mechanisms in carbonate formations after CO2 injection are still controversial. To better understand the transformation of injected CO2 in carbonates and the involved geochemical reactions, we first conducted autoclave experiments reproducing the in-situ conditions of the Lianglitage Formation, Yingshan Formation, and Qiulitage Formation at the Tazhong Uplift in the Tarim Basin. We then established a batch model using TOUGHREACT-ECO2H, validated with the experimental results, to simulate the long-term CO2-water-rock interactions. It was found that the initial mineral compositions and water chemistry have important effects on the CO2-water-rock interactions in carbonate formations. The experiment results show that the dissolution of calcite and dolomite dominates in the early reaction period. However, we still observed some secondary minerals, such as ankerite, montmorillonite, calcite, and dolomite. The CO2-water-rock reactions can be more dramatic when the contents of calcite and dolomite in carbonates are closer. Moreover, the long-term simulation results show that calcite, magnesite, and hematite are the main formed secondary minerals, whereas dolomite is the major dissolved mineral. This study is helpful for a better understanding of the CO2 mineral trapping mechanism in carbonate formations.
Full article
(This article belongs to the Special Issue Challenges of Groundwater Quality Degradation in the Past Decades: Clues From Water–Minerals Interaction)
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Assessment of Operational Effectiveness of Innovative Circuit for Production of Crushed Regular Aggregates in Particle Size Fraction 8–16 mm
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, , , , and
Minerals 2022, 12(5), 634; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050634 - 17 May 2022
Abstract
The purpose of this paper is to analyze a modern and unique technological system producing common aggregates at the Imielin Dolomite Mine. The installation was built on the basis of inventions of AGH UST and consists of an impact crusher, innovative screens WSR
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The purpose of this paper is to analyze a modern and unique technological system producing common aggregates at the Imielin Dolomite Mine. The installation was built on the basis of inventions of AGH UST and consists of an impact crusher, innovative screens WSR and WSL, light fraction separator SEL and hard fraction separator SET, low-pressure hydrocyclone NHC and infrastructure. The study was carried out on the crusher and screen on the example of production of aggregates with grain size 8–16 mm from dolomite, granite, limestone, sandstone, and gravel. The results showed that cubic aggregates with a low content of irregular grains of less than 1% can be produced in this technological system.
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(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)
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Geochemical and Geochronological Constraints of Permian-Triassic Magmatism on Oceanic Subduction and Continental Collision during the Eastern Paleo-Tethyan Evolution
Minerals 2022, 12(5), 633; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050633 - 17 May 2022
Abstract
The Jinshajiang–Ailaoshan–Song Ma orogenic belt (JASB), as a vital segment of the eastern Paleo-Tethyan tectonic zone, is one of the most important zones in which to study the Paleo-Tethyan tectonic evolution. We have undertaken an integrated geochronological, petrological, and geochemical study of mafic
[...] Read more.
The Jinshajiang–Ailaoshan–Song Ma orogenic belt (JASB), as a vital segment of the eastern Paleo-Tethyan tectonic zone, is one of the most important zones in which to study the Paleo-Tethyan tectonic evolution. We have undertaken an integrated geochronological, petrological, and geochemical study of mafic rocks from the JASB to reveal the subduction and closure processes of the eastern Paleo-Tethyan Ocean during the Permian to Triassic. In conjunction with previous magmatic and metamorphic records in the JASB, three important tectonic stages are identified: (1) Early Permian to Early Triassic (ca. 288–248 Ma). Most of the Early Permian to Early Triassic mafic rocks have normal mid-ocean ridge basalt (N-MORB)- or enriched MORB (E-MORB)-like rare earth elements (REE) and trace element-normalized patterns with positive εNd(t) and εHf(t) values and negative Nb and Ta anomalies. Their La/Nb ratios and εNd(t) values show that approximately 3%–15% of slab-derived fluid accounts for the generation of these rocks. These characteristics suggest that the mafic rocks formed in an arc/back-arc basin setting at this stage. Additionally, the Early Permian mafic rocks are mainly exposed in the Jomda–Weixi–Yaxuanqiao–Truong Son magmatic rock belt (JYTB) on the western side of the JASB, indicating that the westward subduction of the Jinshajiang–Ailaoshan–Song Ma Paleo-Tethys Ocean (JASO) began in the Early Permian. Middle Permian mafic rocks are exposed in the Ailaoshan-Day Nui Con Voi metamorphic complex belt and the JYTB on both sides of the JASB. We propose that the bipolar subduction of the JASO occurred in the Middle Permian and ended in the Early Triassic. (2) Middle Triassic (ca. 248–237 Ma). The mafic rocks at this stage have LREE- and LILE-enriched patterns, negative Nb and Ta anomalies and negative εNd(t) values. Their variable εHf(t), εNd(t) values and La/Nb ratios show that these mafic rocks were highly affected by crustal material (ca. 16%). Considering the Middle Triassic high-pressure (HP) metamorphism and massive Al-enriched felsic magmatism in the JASB, these rocks may have formed in a collisional setting between the South China Block (SCB) and the North Qiangtang–Simao–Indochina Block (QSIB) during the Middle Triassic. (3) Late Triassic (ca. 235–202 Ma). The mafic rocks at this stage have negative εNd(t) and εHf(t) values and show terrestrial array characteristics. The εNd(t) values and La/Nb ratios show that approximately 30% of crustal components account for the generation of these rocks. Combined with the contemporaneous bimodal magma and metamorphism during the Late Triassic, we suggest that these rocks may have formed in a postcollisional extensional setting associated with magma diapir.
Full article
(This article belongs to the Special Issue Tectono-Magmatic Evolution and Metallogeny of Tethyan Orogenic Belts)
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The Effect of the Concentration of Copper Ions on the Unfrozen Water Content in Bentonites Measured with the Use of DSC Method
by
and
Minerals 2022, 12(5), 632; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050632 - 17 May 2022
Abstract
Studies on changes of unfrozen water content in calcium bentonite from Slovakia, with various concentrations of copper ions, were carried out using the method of differential scanning calorimetry (DSC). In this study, the influence of molar concentration of copper(II) chloride solution (1 M,
[...] Read more.
Studies on changes of unfrozen water content in calcium bentonite from Slovakia, with various concentrations of copper ions, were carried out using the method of differential scanning calorimetry (DSC). In this study, the influence of molar concentration of copper(II) chloride solution (1 M, 0.5 M, 0.25 M, 0.1 M), used to saturate clay, was analyzed, as well as the impact of copper ions contained in bentonite and how the copper concentration affects to changes of unfrozen water content versus temperature. The results suggest that new mineral phases originate in bentonite saturated with highly concentrated solutions due to the reaction with copper(II) chloride solutions. These minerals, identified based on XRD and SEM-EDS (X-ray Diffraction and Scanning Electron Microscopy with Energy Dispersive Spectroscopy) studies, are from the atacamite group. ANOVA (Analysis of Variance) has shown a statistically significant relationship between the unfrozen water content and the molar concentration of the solution used to saturate bentonite and between the unfrozen water content and the content of copper ions in the bentonite. The analysis of multiple regression has shown that the change of unfrozen water content in copper bentonites is related to the temperature change, specific surface, and the concentration of copper ions in the clay. An empirical equation was developed to estimate the content of unfrozen water at a given negative temperature in Cu-bentonites, in which the specific surface and copper ions concentration in the bentonite are the main parameters.
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(This article belongs to the Special Issue Application of Clays and Clay Minerals to Prevent Contamination)
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Iron Ore Sinter Macro- and Micro-Structures, and Their Relationships to Breakage Characteristics
Minerals 2022, 12(5), 631; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050631 - 16 May 2022
Abstract
A systematic analysis of industrial iron ore sinter product and associated sinter returns was undertaken. The samples were characterised through identification of the major macro- and micro-structural types present in these materials. Examination of the breakage surfaces of the particles indicates a strong
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A systematic analysis of industrial iron ore sinter product and associated sinter returns was undertaken. The samples were characterised through identification of the major macro- and micro-structural types present in these materials. Examination of the breakage surfaces of the particles indicates a strong correlation between mechanical sinter strength and sinter microstructure. Preferential breakage was observed to occur in sinter materials having high porosity and those microstructures consisting of isolated hematite grains in a glass matrix. The bulk of the sinter product consisted of material with a microstructure of magnetite and silico-ferrite of calcium and aluminium (SFCA). The phases formed and the reaction sequences responsible for the formation of the principal microstructure types are explained by the non-equilibrium solidification of melts in the “Fe2O3”-Al2O3-CaO-SiO2 system.
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(This article belongs to the Special Issue Mineralogy of Iron Ore Sinters, Volume II)
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A Methodology to Determine the Potential for Particulate Ore Sorting Based on Intrinsic Particle Properties
by
and
Minerals 2022, 12(5), 630; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050630 - 16 May 2022
Abstract
Sensor-based particulate ore sorting is a pre-concentration technique that sorts particles based on measurable physical properties, resulting in reduced energy consumption by removing waste prior to grinding. This study presents an integrated methodology to determine the potential for ore sorting based on intrinsic
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Sensor-based particulate ore sorting is a pre-concentration technique that sorts particles based on measurable physical properties, resulting in reduced energy consumption by removing waste prior to grinding. This study presents an integrated methodology to determine the potential for ore sorting based on intrinsic particle properties. The methodology first considers the intrinsic sortability based on perfect separation. Only intrinsically sortable ore is further assessed by determining the sensor-based sortability. The methodology is demonstrated using a case study based on a typical copper porphyry comminution circuit. The sorting duty identified for the case study was the removal of low-grade waste material from the pebble crusher stream at a suitable Cu cut-off grade. It was found that the ore had the potential to be sorted based on the intrinsic and ideal laboratory sensor sortability results but showed no potential to be sorted using industrial-scale sensors. The ideal laboratory XRF sensor results showed that around 40% of mass could be rejected as waste at copper recoveries above 80%. An economic analysis of the sortability tests showed that, at optimum separation conditions, the intrinsic, ideal sensor and industrial sensor sortability would result in an additional annual profit of ~$30 million, $21 million and $−7 million (loss), respectively.
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(This article belongs to the Special Issue Recent Developments in Mineral Processing at University of Cape Town)
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Hyperspectral and Geochemical Analysis of Chlorites at the Gongchangling High-Grade Magnetite Deposit, NE China: Implications for Alteration Processes
Minerals 2022, 12(5), 629; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050629 - 15 May 2022
Abstract
The Gongchangling deposit is a representative banded iron formation (BIF) in China, in which developed several high-grade magnetite ores. The surrounding alteration rocks recorded the genesis information of the high-grade ores. However, the study related to alteration processes remains poor. In this study,
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The Gongchangling deposit is a representative banded iron formation (BIF) in China, in which developed several high-grade magnetite ores. The surrounding alteration rocks recorded the genesis information of the high-grade ores. However, the study related to alteration processes remains poor. In this study, we investigate the sub-types and formation temperature of chlorite using hyperspectral imaging and electronic probe microanalysis (EPMA), and deciphered the elemental migration trend during alteration processes by whole-rock geochemistry. The chlorites in the alteration rocks were divided into three sub-types according to the spectral features of the Fe-OH band near 2250 nm. The range of wavelength position is approximately 2250–2255 nm for chlorite-I, 2255–2260 nm for chlorite-II, and 2260–2265 nm for chlorite-III. The variation in Mg# is 0.32–0.44 in chlorite-I, 0.20–0.34 in chlorite-II, and 0.15–0.23 in chlorite-III, which is consistent with the range of wavelength position. The hydrothermal alteration resulted in the enrichment of iron and the depletion of silicon. The results shed new light on the recognition of chlorite sub-types and deciphered the hydrothermal alteration processes of high-grade magnetite ores, which proposed an effective method for mineralogical mapping.
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(This article belongs to the Special Issue Mapping of Rocks and Minerals Using Hyperspectral Remote Sensing)
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On the Morphology and Geochemistry of Hydrothermal Crypto- and Microcrystalline Zircon Aggregates in a Peralkaline Granite
Minerals 2022, 12(5), 628; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050628 - 14 May 2022
Abstract
Singular crypto- and microcrystalline hydrothermal zircon aggregates occur in peralkaline granites from the Corupá Pluton of “A-type” granites and syenites in Graciosa Province, Southern Brazil, and are herein characterized for their morphological, textural and geochemical (major, minor and trace elements, and Lu-Hf isotopes)
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Singular crypto- and microcrystalline hydrothermal zircon aggregates occur in peralkaline granites from the Corupá Pluton of “A-type” granites and syenites in Graciosa Province, Southern Brazil, and are herein characterized for their morphological, textural and geochemical (major, minor and trace elements, and Lu-Hf isotopes) properties. The aggregates were found to present a variety of habits, such as dendritic, oolitic, botryoidal and spherulitic, and they are associated with typical hydrothermal minerals (alkali-feldspars, quartz, fluorite, epidote-group minerals, phyllosilicates and Fe oxides) in micro-fractures and small miarolitic cavities in the host rock. They precipitated directly from a hydrothermal fluid and, compared to magmatic zircon crystals from the host, were found to contain relatively high abundances of the “non-formula” elements (e.g., Fe, Al, and Ca) and HFSEs (High-Field-Strength Elements), particularly the L- and MREEs (Light and Medium Rare Earth Elements), features most typical of hydrothermal zircon, as well as high Th/U ratios, whereas the Lu-Hf isotopic signatures were found to be similar. The formation of the zircon aggregates and the associated epidote-groups minerals was probably due to the interaction between an orthomagmatic, F-bearing, aqueous fluid transporting the HFSEs with the host-rock and/or with an external meteoritic fluid from the country rocks. The preservation of an amorphous-like Zr-silicate compound and crypto-to-microcrystalline zircon varieties is arguably related to the inefficient fluid flux and/or elemental diffusion in a low-temperature oxidizing environment.
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(This article belongs to the Special Issue Minerals of Alkaline Igneous Rocks: Chemical and Isotopic Features as Tracers of Magmatic Processes)
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Another Potentially Hazardous Zeolite from Northern Italy: Fibrous Mordenite
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, , , , , , and
Minerals 2022, 12(5), 627; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050627 - 14 May 2022
Abstract
This study explored morphological, mineralogical, and physicochemical features of suspected toxic mordenite fibers from Northern Italy. All the mordenite samples (FAS1, GC1, SP1) show similar structural and chemical character, are Na-rich (Na > Ca > K), and the Al content decrease reflects the
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This study explored morphological, mineralogical, and physicochemical features of suspected toxic mordenite fibers from Northern Italy. All the mordenite samples (FAS1, GC1, SP1) show similar structural and chemical character, are Na-rich (Na > Ca > K), and the Al content decrease reflects the unit cell volumes in the series: FAS1 > SP1 > GC1. The aerodynamic diameter (Dae) values of the mordenite fibers are 1.19 μm for the GC1 sample, 2.69 μm for FAS1, and 3.91 μm for SP1. All the studied mordenite samples are characterized by “respirable” fibers despite the size differences, which could reach the deeper parts of the lungs. For this reason, fibrous mordenite could represent a potential health hazard and then need to be handled with attention, but further toxicity studies are needed.
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(This article belongs to the Special Issue Elongated Mineral Particles and Health)
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Fibrous Ferrierite from Northern Italy: Mineralogical Characterization, Surface Properties, and Assessment of Potential Toxicity
by
, , , , , , , , and
Minerals 2022, 12(5), 626; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050626 - 14 May 2022
Abstract
Nowadays, fibrous minerals pose as significant health hazards to humans, and exposure to these fibers can lead to the development of severe pulmonary diseases. This work investigated the morphology, crystal structure, chemistry, and surface activity of fibrous ferrierite recently found in northern Italy
[...] Read more.
Nowadays, fibrous minerals pose as significant health hazards to humans, and exposure to these fibers can lead to the development of severe pulmonary diseases. This work investigated the morphology, crystal structure, chemistry, and surface activity of fibrous ferrierite recently found in northern Italy through an integrated approach using scanning electron microscopy–energy dispersive spectroscopy, electron microprobe, inductively coupled plasma atomic emission spectrometry, X-ray powder diffraction, and electron paramagnetic resonance. Our results show that a notable amount of ferrierite fibers are breathable (average length ~22 µm, average diameter 0.9 µm, diameter-length ratio >> 1:3) and able to reach the alveolar space (average Dae value 2.5 μm). The prevailing extra-framework cations are in the Mg > (Ca ≈ K) relationship, R is from 0.81 to 0.83, and the Si/Al ratio is high (4.2–4.8). The <T-O> bond distances suggest the occurrence of some degree of Si,Al ordering, with Al showing a site-specific occupation preference T1 > T2 > T3 > T4. Ferrierite fibers show high amounts of adsorbed EPR probes, suggesting a high ability to adsorb and interact with related chemicals. According to these results, fibrous ferrierite can be considered a potential health hazard, and a precautionary approach should be applied when this material is handled. Future in vitro and in vivo tests are necessary to provide further experimental confirmation of the outcome of this work.
Full article
(This article belongs to the Special Issue Elongated Mineral Particles and Health)
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Suitability of Clinker Replacement by a Calcined Common Clay in Self-Consolidating Mortar—Impact on Rheology and Early Age Properties
Minerals 2022, 12(5), 625; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050625 - 14 May 2022
Abstract
The use of a high amount of calcined clays as cement replacement presents a great challenge in designing self-consolidating concrete. This current attempt evaluates the influence of cement replacement with up to 40 vol.% by a calcined common clay (CC), dominated by 2:1
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The use of a high amount of calcined clays as cement replacement presents a great challenge in designing self-consolidating concrete. This current attempt evaluates the influence of cement replacement with up to 40 vol.% by a calcined common clay (CC), dominated by 2:1 phyllosilicates in combination with a fixed limestone powder (LP) content on fresh and hardened properties of self-consolidating mortar (SC-M). The fresh properties of SC-M were investigated by mini-slump flow, V-funnel and rotational viscometer measurements. Setting and hardening behavior were observed via dynamic modulus of elasticity and plastic shrinkage. Hydration mechanisms were determined by isothermal calorimetry and thermal analysis. Hardened properties of SC-M were evaluated using compressive strength tests and mercury intrusion porosimetry (MIP). The results revealed a decreased rate of deformability in SC-M when cement is substituted increasingly by CC and a rising superplasticizer (SP) demand, but indicated an improved stability of SC-M even at a higher dosage of SP and hardly any impact on the setting behavior. CC enhanced the precipitation of monocarboaluminate phases and thereby refined the pore size distribution of the binder matrix. SC-M can be produced with up to 40 vol.% CC as cement replacement without having effect on its 28 days mechanical properties.
Full article
(This article belongs to the Special Issue Blended Cements Incorporating Calcined Clay and Limestone)
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Occurrences of Pd–Pt Bismuthotellurides and a Phosphohedyphane-Like Phase in Sulfide Veins of the Monchepluton Layered Complex, Kola Peninsula, Russia
Minerals 2022, 12(5), 624; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050624 - 14 May 2022
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We describe occurrences of platinum-group minerals (PGM) and an uncommon mineral enriched in Cl, and provide a brief review of Cl-bearing minerals associated with basic–ultrabasic complexes. An unusual phosphohedyphane-like phase (~30 µm), close to CaPb4(PO4)3Cl, occurs in
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We describe occurrences of platinum-group minerals (PGM) and an uncommon mineral enriched in Cl, and provide a brief review of Cl-bearing minerals associated with basic–ultrabasic complexes. An unusual phosphohedyphane-like phase (~30 µm), close to CaPb4(PO4)3Cl, occurs in one of the PGM-bearing veins of massive sulfides in the Monchepluton layered complex, Kola Peninsula, Russia. These veins consist of varying amounts of pyrrhotite, pentlandite, chalcopyrite, pyrite and accessory grains of galena; they are fairly abundant in the heavy-mineral concentrate, as are small (<0.1 mm) grains of PGM: michenerite, sperrylite, Bi-enriched members of the merenskyite–moncheite series and kotulskite, also rich in Bi. The PGE mineralization is attributed to a low-temperature deposition at the hydrothermal stage. The pyromorphite–phosphohedyphane solid solution likely formed as a secondary phase under conditions of a progressive build-up of oxygen fugacity via oxidation reactions of a precursor grain of galena and involving Ca, as an incompatible component of the sulfides, in a medium of residual fluid enriched in Cl.
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Open AccessArticle
Research on Factors Affecting Mine Wall Stability in Isolated Pillar Mining in Deep Mines
Minerals 2022, 12(5), 623; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050623 - 13 May 2022
Abstract
This study takes the Dongguashan Copper Mine as its engineering background. Based on the mechanical model of the mine wall under the trapezoidal load of the backfill, a comprehensive evaluation index is proposed, and its calculation equation is derived. On this basis, an
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This study takes the Dongguashan Copper Mine as its engineering background. Based on the mechanical model of the mine wall under the trapezoidal load of the backfill, a comprehensive evaluation index is proposed, and its calculation equation is derived. On this basis, an orthogonal test is designed to explore the influence of mining design parameters on mine wall stability. The results show that the width of the mine wall is the main factor affecting its stability, and increasing the width of the mine wall can significantly improve its stability. When the width of the mine wall is kept above 4 m, its stability is better. When the mechanical parameters of the backfill are poor, the mine wall is prone to overturning failure. The width of the mine room has an influence on the multi-directional loading of the mine wall, but the influence on the stability of the mine wall is low. According to the regression equation calculation, the mine wall safety factor is about 1.46 under the design of G5 mining of Dongguashan Line 52, the stability of the mine wall is good after actual mining and the engineering application effect is ideal, which can provide a theoretical basis for the design of isolation pillar mining in deep mines.
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(This article belongs to the Topic Mining Safety and Sustainability)
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Open AccessArticle
New Petro-Geochemical Data on Carboniferous Mafic Rocks in the Achemmach Area (NW, Fourhal Basin-Moroccan Central Massif)
by
, , , , , , and
Minerals 2022, 12(5), 622; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050622 - 13 May 2022
Abstract
The Achemmach region is located 40 km to the SW from Meknes city and 6 km to the NE frm the Hammam mine. It is part of the Paleozoic massif of Central Morocco. The studied area is formed by two Paleozoic rock-types: (i)
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The Achemmach region is located 40 km to the SW from Meknes city and 6 km to the NE frm the Hammam mine. It is part of the Paleozoic massif of Central Morocco. The studied area is formed by two Paleozoic rock-types: (i) a meta-sedimentary sequence composed of Middle Visean limestone and shale-sandstone withflyschoid of Upper Visean-Namurian age, and (ii) a magmatic rock series represented by volcanic rocks (pillow-lavas), hypovolcanic rocks (dolerites) and olivine-bearing gabbros.Based on the emplacement model, structural framework, relative chronology and petrogeochemistry of the magmatic rocks, for the first time in this area we distinguish: (i) dm to m-sized greenish pillow-lavas, with sharp borders and radius fractures underlined by fine greenish pelitic sedimentary intercalations, indicating recurrent volcanic activity in short episodes. Plagioclases and pyroxenes (augite) microlites, and more rarely phenocrystals, are recognizable in a glassy matrix devoid of recognizable olivine. (ii) Deformed, metamorphosed and altered dolerites dikes intrude the Middle to Upper Visean shale-sandstone formations. They have an overall NE-SW direction with a NW dip. They are composed of sericitized plagioclases, associated with partially to totally amphibolitized pyroxenes, tourmaline with differentdegrees of chlorite substitution, rutile and opaque minerals, in a microliticmesostasis and (iii) olivine-bearing gabbros, outcropping in variable dimensions (a few meters to 20 m). The olivine-bearing gabbros have a granular texture and are mainly made of plagioclases, pyroxenes, olivine, titanite, rutile, apatite and opaque minerals. All igneous minerals have undergone different degrees of replacement by secondary minerals; plagioclases are sericitized and albitized, pyroxenes are amphibolitized and epidotized and olivine is serpentinized and chloritized. Thepetro-geochemical study of these magmatic bodies demonstrates that pillow-lavas basalts and olivine-bearing gabbros have an alkaline affinity, while dolerites are thought to have a transitional alkaline affinity (alkaline-tholeiitic). Therefore, these formations would have been set up in anorogenic intra-continental geodynamic context, corresponding to a basin magmatism in the little evolved opening.
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(This article belongs to the Special Issue Petrology and Geochemistry of Igneous Complexes and Formations)
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Cancer Risk Assessment and Geochemical Features of Granitoids at Nikeiba, Southeastern Desert, Egypt
by
, , , , , and
Minerals 2022, 12(5), 621; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050621 - 13 May 2022
Abstract
Different rock types (syenogranite, alkali feldspar granite and quartz syenite intruded by microgranite dikes and quartz veins) were investigated in the Nikeiba region in Egypt. The main components of the studied intrusive rocks, comprised of granites and quartz syenite, are plagioclase, amphibole, biotite,
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Different rock types (syenogranite, alkali feldspar granite and quartz syenite intruded by microgranite dikes and quartz veins) were investigated in the Nikeiba region in Egypt. The main components of the studied intrusive rocks, comprised of granites and quartz syenite, are plagioclase, amphibole, biotite, quartz and K-feldspar in different proportions. Ground gamma ray measurements show that syenogranite, quartz syenite and microgranite dikes have the highest radioactivity (K, eU, eTh and their ratios) in comparison with alkali feldspar granite. Geochemically, syenogranite, alkali feldspar granite and quartz syenite are enriched with large-ion lithophile elements (LILE; Ba, Rb, Sr) and high field-strength elements (HFSE; Y, Zr and Nb), but have decreased Ce, reflecting their alkaline affinity. These rocks reveal calc–alkaline affinity, metaluminous characteristics, A-type granites and post-collision geochemical signatures, which indicates emplacement in within-plate environments under an extensional regime. U and Th are increased in syenogranite and quartz syenite, whereas alkali feldspar granite shows a marked decrease in U and Th. The highest average values of AU (131 ± 49 Bq·kg−1), ATh (164 ± 35) and AK (1402 ± 239) in the syenogranite samples are higher than the recommended worldwide average. The radioactivity levels found in the samples are the result of the alteration of radioactive carrying minerals found inside granite faults. The public’s radioactive risk from the radionuclides found in the investigated granitoid samples is estimated by calculating radiological risks. The excess lifetime cancer (ELCR) values exceed the permissible limit. Therefore, the granitoids are unsuitable for use as infrastructure materials.
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(This article belongs to the Special Issue Radionuclides and Radiation Exposure in Mine Sites)
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Open AccessArticle
Study on the Shale Hydration Inhibition Performance of Triethylammonium Acetate
by
, , , , , , , , and
Minerals 2022, 12(5), 620; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050620 - 13 May 2022
Abstract
Shale inhibitor is an additive for drilling fluids that can be used to inhibit shale hydration expansion and dispersion, and prevent wellbore collapse. Small molecular quaternary ammonium salt can enter the interlayer of clay crystal, and enables an excellent shale inhibition performance. In
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Shale inhibitor is an additive for drilling fluids that can be used to inhibit shale hydration expansion and dispersion, and prevent wellbore collapse. Small molecular quaternary ammonium salt can enter the interlayer of clay crystal, and enables an excellent shale inhibition performance. In this paper, a novel ionic shale inhibitor, triethylammonium acetate (TEYA), was obtained by solvent-free synthesis by using acetic acid and triethylamine as raw materials. The final product was identified as the target product by Fourier transform infrared spectroscopy (FT-IR). The inhibition performance of TEYA was studied by the mud ball immersion test, linear expansion test, rolling recovery test and particle size distribution test. The results demonstrated that the shale inhibitor shows a good shale hydration inhibition performance. The inhibition mechanism was studied by FT-IR and X-ray diffraction (XRD), respectively; the results showed that triethylammonium acetate TEYA could enter the crystal layer of clay and inhibit it through physical adsorption.
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(This article belongs to the Topic Drilling, Completion and Well Engineering for the Natural Energy Resources Extraction, Storage and Sustainable Management)
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