Minerals

21 pages, 6318 KiB

Open AccessArticle

Iron Extraction from South African Ilmenite Concentrate Leaching by Hydrochloric Acid (HCl) in the Presence of Reductant (Metallic Fe) and Additive (MgSO₄)

by Khetho Daba, Munyadziwa Mercy Ramakokovhu, Tajudeen Mojisola, Mxolisi Brendon Shongwe and Nthabiseng Ntholeng

Minerals 2022, 12(10), 1336; https://doi.org/10.3390/min12101336 - 21 Oct 2022

Cited by 1 | Viewed by 2664

Abstract

The high content of iron in ilmenite ore poses a great challenge, particularly in the synthesis of titanium-containing products due to high susceptibility of iron (Fe) to corrosion. Direct leaching of ilmenite ore in hydrochloric acid (HCl) encouraging Fe dissolution was investigated. The [...] Read more.

The high content of iron in ilmenite ore poses a great challenge, particularly in the synthesis of titanium-containing products due to high susceptibility of iron (Fe) to corrosion. Direct leaching of ilmenite ore in hydrochloric acid (HCl) encouraging Fe dissolution was investigated. The influence of variable parameters, the use of additives, and the addition of metallic iron powder were studied to establish the optimum leaching parameters. The results showed that ilmenite with the particle size distribution of +150 µm yielded better efficiencies when leaching was performed with an acid concentration of 7.5 M and a solid-to-acid ratio of 1:10 at 90 °C. An agitation speed of 450 rpm yielded a superior Fe extraction of about 92.32% and a 2.40% titanium (Ti) loss. The addition of both metallic Fe and the MgSO₄ additive significantly enhanced Fe dissolution and decreased Ti recovery in a leach solution. It was found that leaching under optimum conditions produced a solid residue with 1.37% Fe impurity while 98.63% was extracted. The leached residue was comprised of 91.4% TiO₂ rutile phase and contained a high content of the ilmenite FeTiO₃ (4.37%) and SiO₂ (2.23%) impurities, while Al₂O₃, MgO, MnO₂, CaO, V₂O₅, MnO₂, and Cr₂O₃ were below 0.13%. The high TiO₂ content in the leached residue makes it suitable for use as feed in the production of synthetic rutile. The leaching kinetics of Fe dissolution was found to conform to the shrinking core model, where diffusion through the product layer is rate controlling. The calculated activation energy according to the Arrhenius equation was 19.13 kJ/mol. Full article

(This article belongs to the Special Issue Advances in Reagents for Mineral Processing)

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18 pages, 9075 KiB

Open AccessArticle

Study on Facies Modeling of Tight Sandstone Reservoir Using Multi-Point Geostatistics Method Based on 2D Training Image—Case Study of Longdong Area, Ordos Basin, China

by Naidan Zhang, Shaohua Li, Lunjie Chang, Chao Wang, Jun Li and Bo Liang

Minerals 2022, 12(10), 1335; https://doi.org/10.3390/min12101335 - 21 Oct 2022

Cited by 5 | Viewed by 2106

Abstract

The Longdong area in the Ordos basin is a typical fluvial reservoir with strong heterogeneity. In order to clarify the distribution law of underground reservoirs in the Longdong area, it is necessary to establish and optimize a 3D geological model to characterize the [...] Read more.

The Longdong area in the Ordos basin is a typical fluvial reservoir with strong heterogeneity. In order to clarify the distribution law of underground reservoirs in the Longdong area, it is necessary to establish and optimize a 3D geological model to characterize the heterogeneity of reservoirs. This is of great significance for accelerating the exploitation of tight sandstone gas in the southwest of the Ordos basin. This study takes the P₂h₈ member of the Ct3 research area in the Longdong area as an example, analyzes the core and logging curve shape to divide the sedimentary microfacies, and establishes the facies model. In particular, in view of the difficulty in obtaining 3D training images under the existing conditions in the study area, we use the multi-point geostatistics method combining sequential two-dimensional condition simulation and the direct sampling method to establish the facies model. This method can simulate the 3D geological model by using the 2D training images composed of the digital plane facies diagrams and the well-connection facies diagrams. In addition, we choose the object-based method and sequential indicator method for comparative experiments to verify the feasibility of this method (sequential two-dimensional condition simulation combined with the direct sampling method) from many aspects. The results show that the multi-point geostatistics method based on 2D training images can not only match the well data, but also show the geometric characteristics and contact relationship of the simulation object. The distribution characteristics of sandbody thickness and modeling results are consistent with the actual geological conditions in the study area. This study explores the feasibility of this method in the 3D geological simulation of large-scale fluvial facies tight sandstone reservoirs. Additionally, it also provides a new idea and scheme for the modeling method of geologists in similar geological environments. Full article

(This article belongs to the Special Issue Reservoir Geology and Oil & Gas Reservoir Characterization)

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19 pages, 3706 KiB

Open AccessArticle

An Alternative Technology to Obtain Dewatered Mine Tailings: Safe and Control Environmental Management of Filtered and Thickened Copper Mine Tailings in Chile

by Carlos Cacciuttolo and Edison Atencio

Minerals 2022, 12(10), 1334; https://doi.org/10.3390/min12101334 - 21 Oct 2022

Cited by 9 | Viewed by 3550

Abstract

An alternative process to obtain a high degree of dewatering tailings that produces a high-density product is presented in this article. This technology involves the combination of tailings particle grain size classification by hydrocyclones (HC) and tailings dewatering by horizontal vibratory screens (HVS). [...] Read more.

An alternative process to obtain a high degree of dewatering tailings that produces a high-density product is presented in this article. This technology involves the combination of tailings particle grain size classification by hydrocyclones (HC) and tailings dewatering by horizontal vibratory screens (HVS). It makes it possible to dewater tailings to a high grade of performance. This alternative technology (HC-HVS) involves the recovery of water from the coarse fraction of tailings (sands) through two hydrocycloning stages, followed by a dewatering stage of cycloned tailings sands on horizontal vibratory screens, to reduce moisture content and turn it into a “cake”. The resulting coarse fraction tailings are easily transported to a dry stack tailings storage facility (TSF). The fine fraction of tailings (slimes) can be dewatered on thickener equipment to recover part of the process water. Finally, this article describes the main benefits of this alternative dewatered tailings technology with an emphasis on (i) dewatering technology evolution over the last 17 years; (ii) process stages features; (iii) pilot test results; (iv) tailings properties analysis (such as particle grain size distribution, fines content) and (v) lessons learned about the experience gained in the operation of Mantos Blancos case study with dry stack tailings storage facility. Full article

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

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20 pages, 13243 KiB

Open AccessArticle

The Depositional Mechanism of Hydrothermal Chert Nodules in a Lacustrine Environment: A Case Study in the Middle Permian Lucaogou Formation, Junggar Basin, Northwest China

by Jiaquan Zhou, Hailin Yang, Hanlin Liu and Yue Jiao

Minerals 2022, 12(10), 1333; https://doi.org/10.3390/min12101333 - 20 Oct 2022

Cited by 2 | Viewed by 2106

Abstract

Although chert deposits are limited in geological distribution, their geological and geochemical characteristics can provide important information to reconstruct paleoenvironmental and diagenetic processes. For the Permian period, cherts are utilized to trace global silicon cycles and hydrothermal activities in relation to the Permian [...] Read more.

Although chert deposits are limited in geological distribution, their geological and geochemical characteristics can provide important information to reconstruct paleoenvironmental and diagenetic processes. For the Permian period, cherts are utilized to trace global silicon cycles and hydrothermal activities in relation to the Permian Chert Event. In Northwest China, Permian chert nodules have recently been discovered in both the southeastern and northwestern margins of the Junggar Basin. We conducted an analysis of the mineralogy, petrology and geochemistry of chert nodules of the Lucaogou Formation in the southeastern margin of the Junggar Basin to identify silicon sources and determine the precipitation mechanism of chert nodules. As evidenced by petrology, the chert nodules were mainly composed of crypto-microcrystalline silica (94.33% on average), with development of a soft-sediment deformation structure, indicating the synsedimentary deposition of silicon. Proven by trace elements, high Eu/Eu* ratios (average 2.14), low total rare earth element content (average 6.03 ppm), low La_N/Yb_N ratios (average 0.17) and low Y/Ho ratios (average 25.25) in chert nodules supports the hydrothermal source of silicon. The wide distribution of authigenic metal-bearing minerals and the significant positive Eu anomalies observed suggest that the chert depositions in the Lucaogou Formation intermittently received high-temperature (>250 °C) hydrothermal fluids, likely associated with the initiation of the Bogda Rift in the middle Permian. Following rapid cooling down and differential compaction, siliceous sediments dehydrated and deformed, finally forming chert nodules. Full article

(This article belongs to the Section Mineral Deposits)

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16 pages, 3067 KiB

Open AccessArticle

Investigation of the Distribution of Heavy Metals in the Soil of the Dahuangshan Mining Area of the Southern Junggar Coalfield, Xinjiang, China

by Qiang Zeng, Li Shen, Tong Feng and Ruirui Hao

Minerals 2022, 12(10), 1332; https://doi.org/10.3390/min12101332 - 20 Oct 2022

Cited by 1 | Viewed by 1308

Abstract

Coal mining activities have a series of impacts on the local eco-environment, such as air pollution due to the release of toxic gases, contamination of soil with heavy metals, disturbance and contamination of surface and subsurface water, and damage to land resources with [...] Read more.

Coal mining activities have a series of impacts on the local eco-environment, such as air pollution due to the release of toxic gases, contamination of soil with heavy metals, disturbance and contamination of surface and subsurface water, and damage to land resources with surface subsidence and accumulation of solid waste materials. This study investigated the distribution of heavy metals in mining sites by analyzing the heavy metal content in soil samples from different sites in the Dahuangshan mining area of the southern Junggar coalfield (Xinjiang, China). The results show that area C has the highest Cu content; and area B has the highest Mn content, the highest Zn content, the highest As content, and the highest Cd content, which indicate that area B underwent potential multiple heavy metal contamination. It also shows that the Cd is the major heavy metal for all three areas. The different eco-environmental indices, including the Nemerow comprehensive pollution index, the geo-accumulation index, and the potential ecological risk index, all show the same results, i.e., that Cd is the major potential contaminant in all three types of soil. Full article

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

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20 pages, 6158 KiB

Open AccessArticle

Effects of Freeze–Thaw Cycling on Dynamic Compressive Strength and Energy Dissipation of Sandstone

by Bangbiao Wu, Ling Yang, Yong Mei, Yunhou Sun, Jinming Liu and Jun Shen

Minerals 2022, 12(10), 1331; https://doi.org/10.3390/min12101331 - 20 Oct 2022

Cited by 3 | Viewed by 1146

Abstract

In this study, the dynamic compressive strength and dissipated energy of rocks were investigated under hydrostatic pressure after different freeze–thaw cycles (FTCs). A split Hopkinson pressure bar (SHPB) with a lateral confining pressure chamber was used for the dynamic testing of sandstone specimens. [...] Read more.

In this study, the dynamic compressive strength and dissipated energy of rocks were investigated under hydrostatic pressure after different freeze–thaw cycles (FTCs). A split Hopkinson pressure bar (SHPB) with a lateral confining pressure chamber was used for the dynamic testing of sandstone specimens. The results indicated that under a certain loading rate and hydrostatic pressure, both the dissipative energy and dynamic compression strength of rocks decreased with the increase in the number of FTCs. The hydrostatic pressure significantly increased the dissipated energy and dynamic compression strength of rocks, and the enhancement became more pronounced as the number of FTCs increased. By analyzing the energy and damage characteristics of the specimens, after 40 FTCs, the internal damage of the specimens became critical and desensitized the dissipated energy to the loading rate. Based on the testing results, an empirical function was proposed to describe how the dissipated energy was related to the number of FTCs, hydrostatic pressure, and loading rate. It was demonstrated that the dissipated energy had a negative linear relation with FTC, which was enhanced by confinement. The dissipated energy of the specimen corresponded to the dynamic compression strength according to a quadratic function. Full article

(This article belongs to the Special Issue Failure Characteristics of Deep Rocks)

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19 pages, 12255 KiB

Open AccessArticle

Influences of Inclined Pre-Existing Flaw on Shale Failure Modes in Uniaxial Compression Tests

by Yuxin Ban, Qiang Xie, Jun Duan and Xiang Fu

Minerals 2022, 12(10), 1330; https://doi.org/10.3390/min12101330 - 20 Oct 2022

Cited by 1 | Viewed by 994

Abstract

Numerous studies have focused on the mechanical properties of shale specimens to support hydraulic fracturing in shale gas engineering. However, the failure modes of shale specimens containing a pre-existing flaw are still not clear. A series of uniaxial compression tests were conducted on [...] Read more.

Numerous studies have focused on the mechanical properties of shale specimens to support hydraulic fracturing in shale gas engineering. However, the failure modes of shale specimens containing a pre-existing flaw are still not clear. A series of uniaxial compression tests were conducted on shale specimens containing a pre-existing flaw coupled with acoustic emission (AE) technology and a high-speed camera. A slow enough and variable loading speed scheme (0–50 kN: 0.1 kN/s, 50–100 kN: 0.05 kN/s; 100-failure: 0.02 kN/s) is adopted to allow microcracks to fully develop. The damage mechanism in the mesoscale from moment tensor inversion of the AE signals and the cracking behaviors on the macroscale were associated. Both the pre-existing flaw and the bedding layers had significant influences on the mechanical characteristics, progressive cracking, and failure modes of the shale specimens. The peak stress increases fluctuated as the bedding layer angle

α

increases, and the maximum and minimum values take place at

α = 90 °

and

α = 0 °

, respectively. In addition, the pre-existing flaw, the bedding layers, and the compression stress field jointly control the failure modes of the shale specimens. It was found that the

α = 0 °

specimen failed due to tension splitting, the

α = 30 °

specimen failed due to tension splitting and shear across the matrix, the

α = 60

specimen failed due to shear across the shale matrix and shear along the bedding layers, and the

α = 90 °

specimen failed due to tension along the bedding layers and shear across the shale matrix. The study can provide some references to the construction of complex crack networks in shale gas engineering. Full article

(This article belongs to the Special Issue Reservoir and Geochemistry Characteristics of Black Shale)

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20 pages, 8453 KiB

Open AccessArticle

Surrounding Rock Stability in Unsupported Roof Area and Rapid Heading Technique for Deep Arch Coal Roadways under Goaf

by Yewu Bi, Mingxing Wang, Chao Wu and Yucheng Huang

Minerals 2022, 12(10), 1329; https://doi.org/10.3390/min12101329 - 20 Oct 2022

Cited by 2 | Viewed by 1238

Abstract

In order to achieve rapid heading of deep arch coal roadways under goaf, the maximum unsupported roof distance (URD), surrounding rock stability of unsupported roof area and influencing factors, and rapid heading equipment and processes for these roadways are investigated in the context [...] Read more.

In order to achieve rapid heading of deep arch coal roadways under goaf, the maximum unsupported roof distance (URD), surrounding rock stability of unsupported roof area and influencing factors, and rapid heading equipment and processes for these roadways are investigated in the context of the working face geology and mining conditions of Coal #9 of a certain coal mine, through theoretical analysis, numerical simulation, equipment modification, and construction process optimization. The following work is carried out: (1) Based on the thin shell theory, a mechanical model of a top cover cylindrical shell for roadways with an arch section is built. The formula for calculating the maximum URD of arch roadways is developed. The influences of roadway width, tensile strength, buried depth, and arch height on the maximum URD are analyzed. The theoretical maximum URD is worked out to be 2.4 m. (2) Numerical simulation reveals that when the URD is around 2 m, the arch roadway is free of tensile failure and the surrounding rock is well stable; when the URD is greater than 4 m, tensile failure occurs on the roadway sides, and the surrounding rock becomes less stable. Therefore, the maximum URD for numerical computation is set to 2–3 m. No additional failure occurs on the arch roof with the increase in URD, suggesting that an arch roof has the best stability. Properly increasing URD can help U-steel to gain support strength more quickly. In the shallow part of a roadway surrounding rock under goaf, failures are primarily determined by vertical stresses, whereas in the deep part, failures are determined by horizontal stresses. (3) A combined onboard standing platform + onboard beam lift device and a new onboard temporary support device for long excavation are developed as a solution to the low shed and temporary support efficiency and safety of roadways with a URD of 2.4 m and used on-site in conjunction with the optimized construction process. The result shows an average footage of over 550 m per month with a peak footage of 846.4 m and 16 supports totaling 14.1 m per shift. Additionally, the forming quality of a shed roadway is good enough to accommodate normal mining of the working face, consequently the rapid heading of the roadway. Full article

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

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22 pages, 17420 KiB

Open AccessArticle

Failure Behavior of Cuboid Granite Sample with a Circular Hole beneath a Bonding Fracture under Biaxial Compression

by Diyuan Li, Jingtai Jiang and Feihong Gao

Minerals 2022, 12(10), 1328; https://doi.org/10.3390/min12101328 - 20 Oct 2022

Cited by 1 | Viewed by 1328

Abstract

Ore bodies incubating within fault zones are a common phenomenon in geological strata and pose a huge challenge for underground mining. To effectively exploit mineral resources, the layout of the mining roadway and the interaction between the roadway and geological fault must be [...] Read more.

Ore bodies incubating within fault zones are a common phenomenon in geological strata and pose a huge challenge for underground mining. To effectively exploit mineral resources, the layout of the mining roadway and the interaction between the roadway and geological fault must be considered. In this paper, a bonding fracture was formed on granite samples to simulate a closed fault, under which a circular hole was fabricated to simulate the roadway of the gold mine. We performed a biaxial compression test at a true-triaxial electrohydraulic servo testing system for granite samples with a combined fracture-hole structure. It is worth noting that the fracture inclination β and relative distance between fracture and hole L were taken into account. The digital image correlation (DIC) technique was used to observe the displacement and strain field evolution around the fracture-hole structure. Our results demonstrate that (1) the strength of the granite sample decreases with increasing bonding fracture dip angle β, and the displacement drops between the hanging wall and foot wall raised in both the horizontal and vertical displacement directions. Macroscopic cracks become dense, and the failure degree becomes severe around simulated fault areas. (2) With the increase in the distance L, the strength of the granite sample increases, the influence of the hole on the slip of the fracture plane is weakened, and the discontinuity of displacement becomes less obvious. (3) The maximum principal strain field quantitatively reveals the details of the crack initiation, propagation, and coalescence around the fracture-hole structure, and displacement nucleation is observed in the vertical displacement field. Full article

(This article belongs to the Special Issue Failure Characteristics of Deep Rocks)

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34 pages, 19066 KiB

Open AccessArticle

New Insights into the Evolution and Footprints of the Paraíba Au-Cu-Mo Deposit, Alta Floresta Mineral Province (Brazil), through Integration of Spectral and Conventional Methods

by Luciano Poggi, Diego Fernando Ducart, Maria José Mesquita, Igor Camargo Moreira, Márcia Elisa Boscato Gomes and Carlos Roberto de Souza Filho

Minerals 2022, 12(10), 1327; https://doi.org/10.3390/min12101327 - 20 Oct 2022

Cited by 1 | Viewed by 2613

Abstract

The Paraíba is an Au-Cu-Mo deposit located in the southern part of the Amazon Craton, in the Alta Floresta Mineral Province, Mato Grosso State, Brazil. It is composed of Au-Cu-bearing quartz veins and Cu-Mo-rich hydrothermal breccias and stockworks, both associated with several hydrothermal [...] Read more.

The Paraíba is an Au-Cu-Mo deposit located in the southern part of the Amazon Craton, in the Alta Floresta Mineral Province, Mato Grosso State, Brazil. It is composed of Au-Cu-bearing quartz veins and Cu-Mo-rich hydrothermal breccias and stockworks, both associated with several hydrothermal alteration zones. The integration of spectral (reflectance and imaging spectroscopy) and conventional techniques (core logging, petrography, mineral chemistry, and scanning electron microscopy) was applied to map alteration zones, identify mineral parageneses, and determine the evolution of the deposit to generate a solid proxy for mineralized zones. This study shows an overlapping of two different mineralization systems in the AFMP, referenced hereafter as alteration Groups 1 and 2. Group 1 is an Orogenic Gold system related to Au-Cu-rich quartz veins in phyllonites and mylonites. Group 2 is a Cu-Mo Porphyry system related to a syenogranite intrusion and the subsequent generation of several hydrothermal alteration zones, Cu and Mo hydrothermal breccias, and stockwork mineralization. This study reveals several alteration footprints, guides, and vectors for the mineral exploration of these deposits in the Alta Floresta Mineral Province. Full article

(This article belongs to the Special Issue Footprints of Mineral Systems)

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30 pages, 431 KiB

Open AccessReview

A Review on Detection Techniques, Health Hazards and Human Health Risk Assessment of Arsenic Pollution in Soil and Groundwater

by Vaidotas Valskys, Howlader Rahidul Hassan, Stanislaw Wołkowicz, Jonas Satkūnas, Gintautas Kibirkštis and Gytautas Ignatavičius

Minerals 2022, 12(10), 1326; https://doi.org/10.3390/min12101326 - 20 Oct 2022

Cited by 10 | Viewed by 2159

Abstract

One of the most significant elements in the environment is arsenic (As). It is a hazardous metalloid that causes contamination of soil and water supplies as a result of numerous anthropogenic and natural sources. This pollution has detrimental impacts on human health and [...] Read more.

One of the most significant elements in the environment is arsenic (As). It is a hazardous metalloid that causes contamination of soil and water supplies as a result of numerous anthropogenic and natural sources. This pollution has detrimental impacts on human health and the ecosystem, making it crucial to monitor and control. The release of As from minerals into the soil and groundwater depends on the kind of mineral, pH, and redox conditions. As is typically found in two forms, trivalent arsenic (As³⁺, arsenite) and pentavalent arsenic (As⁵⁺, arsenate), both of which are inorganic and extremely deadly. When it comes to toxicity, arsenite is more dangerous than arsenate. Many people have been affected by As poisoning, due to exposure to As through water and food. Nowadays, accurate, fast measurement of As in the field remains a technical challenge; however, the X-ray fluorescence method is considered the most reliable, cost effective and capable of measuring a wide spectrum of metals. Health risk assessment is a crucial parameter to estimate the health hazards of the As molecule. The risk assessment approach proposed by the USEPA is common and widely used, amongst others. On the numerous health risk assessment models/frameworks used to foresee the carcinogenic and non-carcinogenic health impacts brought on by As-contaminated water, little information is currently accessible. This discussion also emphasizes the need for more study on the risks to human health posed by specific As species (both organic and inorganic) found in As-contaminated water. Full article

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

13 pages, 3399 KiB

Open AccessArticle

Provenance and Stratigraphy of the Upper Carboniferous—Lower Permian Strata of October Revolution Island (Severnaya Zemlya Archipelago): Implications for Geological History of the Russian High Arctic

by Victoria Ershova, Andrei Prokopiev, Daniel Stockli, Daria Zbukova and Anton Shmanyak

Minerals 2022, 12(10), 1325; https://doi.org/10.3390/min12101325 - 20 Oct 2022

Cited by 1 | Viewed by 1441

Abstract

Small depressions across the north-eastern part of October Revolution Island (Severnaya Zemlya archipelago, Kara terrane) are filled with continental terrigenous rocks, dated as Upper Carboniferous–Lower Permian in age based on palynological data. These rocks overlie Ordovician volcaniclastic rocks above a prominent angular unconformity. [...] Read more.

Small depressions across the north-eastern part of October Revolution Island (Severnaya Zemlya archipelago, Kara terrane) are filled with continental terrigenous rocks, dated as Upper Carboniferous–Lower Permian in age based on palynological data. These rocks overlie Ordovician volcaniclastic rocks above a prominent angular unconformity. U-Pb dating of detrital zircons from the Late Carboniferous–Lower Permian rocks reveals that most grains are Ordovician in age, ranging between 475–455 Ma. A subordinate population of Silurian detrital zircons is also present, contributing up to 15% of the dated population, while Precambrian grains mainly yield Neo-Mesoproterozoic ages and do not form prominent peaks. The combined U-Pb and (U-Th)/He ages indicate that most zircon (U-Th)/He ages were reset and average at ca. 317 Ma, suggesting ~6–7 km of Late Carboniferous uplift within the provenance area. This provenance area, mainly comprising Ordovician magmatic and volcanic rocks, was located close to the study area based on the coarse-grained nature of Late Carboniferous–Lower Permian rocks of north-eastern October Revolution Island. Therefore, we propose that Late Paleozoic tectonism significantly affected both the southern margin of the Kara terrane, as previously supposed, and also its north-eastern part. We propose that the Late Paleozoic Uralian suture zone continued to the north-eastern October Revolution Island and was responsible for the significant tectonic uplift of the studied region. This suture zone is now hidden beneath the younger Arctic basins. Full article

(This article belongs to the Special Issue Recent Contributions of Female Scientists to the Advancement of Mineral Science)

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12 pages, 5051 KiB

Open AccessArticle

Lithium Enrichment by the Carbothermal Reduction of Spodumene Ore and the Preparation of Manganese-Silicon Alloy

by Mingliang Yang, Ke Yan, Rui Ji, Xi Cui, Wenzheng Zhang and Tao Qu

Minerals 2022, 12(10), 1324; https://doi.org/10.3390/min12101324 - 20 Oct 2022

Cited by 1 | Viewed by 1442

Abstract

To increase the low utilization rate of spodumene ore during lithium extraction, spodumene ore was subjected to carbothermic reduction to enrich lithium and prepare a manganese-silicon alloy. The experimental results showed that during thermal reduction, lithium was volatilized and collected in the condensation [...] Read more.

To increase the low utilization rate of spodumene ore during lithium extraction, spodumene ore was subjected to carbothermic reduction to enrich lithium and prepare a manganese-silicon alloy. The experimental results showed that during thermal reduction, lithium was volatilized and collected in the condensation zone. The Li₂O content in the lithium condensate was 41.72%, which was 10.85 times higher than that of the raw material. The effects of varying reduction temperatures and times on the lithium volatilization rate and direct yield of Mn₅Si₃ alloy were investigated. The best process conditions were 1873 K for 6 h. Under these conditions, the lithium volatilization rate was 97.65%, and the direct yield of Mn₅Si₃ was 86.47%. Full article

(This article belongs to the Special Issue Clean Utilization of Nonferrous Metal Resources)

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15 pages, 2863 KiB

Open AccessEditor’s ChoiceArticle

Structural and Elastic Behaviour of Sodalite Na₈(Al₆Si₆O₂₄)Cl₂ at High-Pressure by First-Principle Simulations

by Gianfranco Ulian and Giovanni Valdrè

Minerals 2022, 12(10), 1323; https://doi.org/10.3390/min12101323 - 20 Oct 2022

Cited by 2 | Viewed by 2018

Abstract

Sodalite Na₈(Al₆Si₆O₂₄)Cl₂ (space group

P \bar{4} 3 n

) is an important mineral belonging to the zeolite group, with several and manyfold fundamental and technological applications. Despite the interest in this mineral from [...] Read more.

Sodalite Na₈(Al₆Si₆O₂₄)Cl₂ (space group

P \bar{4} 3 n

) is an important mineral belonging to the zeolite group, with several and manyfold fundamental and technological applications. Despite the interest in this mineral from different disciplines, very little is known regarding its high-pressure elastic properties. The present study aims at filling this knowledge gap, reporting the equation of state and the elastic moduli of sodalite calculated in a wide pressure range, from −6 GPa to 22 GPa. The results were obtained from Density Functional Theory simulations carried out with Gaussian-type basis sets and the well-known hybrid functional B3LYP. The DFT-D3 a posteriori correction to include the van der Waals interactions in the physical treatment of the mineral was also applied. The calculated equation of state parameters at 0 GPa and absolute zero (0 K), i.e., K₀ = 70.15(7) GPa, K’ = 4.46(2) and V₀ = 676.85(3) Å3 are in line with the properties derived from the stiffness tensor, and in agreement with the few experimental data reported in the literature. Sodalite was found mechanically unstable when compressed above 15.6 GPa. Full article

(This article belongs to the Section Clays and Engineered Mineral Materials)

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14 pages, 3414 KiB

Open AccessArticle

Solvent Extraction Studies of Copper from a Heap Leach Liquor Using Mextral 5640H

by Mostafa Hosseinzadeh, Jochen Petersen and Asghar Azizi

Minerals 2022, 12(10), 1322; https://doi.org/10.3390/min12101322 - 20 Oct 2022

Cited by 1 | Viewed by 3188

Abstract

In this study the extractive capability of Mextral 5640H was investigated for extraction of copper from a heap leach liquor. In this regard, the influence of parameters such as pH (0.2–2.8), extractant concentration in kerosene diluent (2.5%–10% v/v), temperature (25–70 [...] Read more.

In this study the extractive capability of Mextral 5640H was investigated for extraction of copper from a heap leach liquor. In this regard, the influence of parameters such as pH (0.2–2.8), extractant concentration in kerosene diluent (2.5%–10% v/v), temperature (25–70 °C), contact time (0–300 s), stirring speed (100–1200 rpm), phase ratio (O/A) (0.6–1.8) and Cu initial concentration (0.5–2 g/L) in the leach liquor were examined and optimized. The findings demonstrated that the Mextral 5640H extractant had a very high efficiency and selectivity in copper extraction from the leachate. 98.17% Cu, with less than 0.5% of Fe and Mn, were extracted at pH 1.6, 10% (v/v) Mextral 5640H concentration, ambient temperature (25 °C), 400 rpm stirring speed, 2 min contact time and an O/A phase ratio of 1:1. Under equilibrium conditions it was found that one mol of Cu is extracted by 7 mol of Mextral 5640H. Additionally, analysis using a McCabe–Thiele diagram suggests a two-stage extraction to reach the maximum extraction of copper (99.5%) from the leachate at operational condition using industrial mixer-settlers. Furthermore, a thermodynamic study was conducted, and the measured values of ΔH = 15.13 kJ/mol, ΔG = −6.95 kJ/mol and ΔS = 74.10 J/mol/K indicate an endothermic, spontaneous nature and high affinity of copper extraction. Full article

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

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13 pages, 2416 KiB

Open AccessArticle

An Analytical Model for the Excavation Damage Zone in Tunnel Surrounding Rock

by Xiaoding Xu, Yuejin Zhou, Chun Zhu, Chunlin Zeng and Chong Guo

Minerals 2022, 12(10), 1321; https://doi.org/10.3390/min12101321 - 19 Oct 2022

Cited by 1 | Viewed by 1388

Abstract

An accurate theoretical model to predict the extent and mechanical behavior of the excavation damage zone (EDZ) in the surrounding rock of deep-buried tunnel is of great importance for the practical engineering applications. Using the elastic-plastic theory and combined with the analysis on [...] Read more.

An accurate theoretical model to predict the extent and mechanical behavior of the excavation damage zone (EDZ) in the surrounding rock of deep-buried tunnel is of great importance for the practical engineering applications. Using the elastic-plastic theory and combined with the analysis on the stress characteristics of the tunnel surrounding rock, this paper present a predict model for the EDZ formation and evolution. A three-zone composite mechanical model was established for the tunnel surround rock and the corresponding stress state and displacement field of three zones were derived. The effects of the strain softening and dilatancy during rock deformation was taken into account. The correctness of the proposed model was validated by the existing theoretical models. A sensitivity analysis for different influencing factors in this model was also performed. The results can benefit for the future numerical and experimental studies. Full article

(This article belongs to the Topic Support Theory and Technology of Geotechnical Engineering)

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27 pages, 8553 KiB

Open AccessArticle

Processes Associated with Multiphase Dolomitization and Other Related Diagenetic Events in the Jurassic Samana Suk Formation, Himalayan Foreland Basin, NW Pakistan

by Hamad-ur- Rahim, Shazia Qamar, Mumtaz Muhammad Shah, Mercè Corbella, Juan Diego Martín-Martín, Hammad Tariq Janjuhah, Dídac Navarro-Ciurana, Vasiliki Lianou and George Kontakiotis

Minerals 2022, 12(10), 1320; https://doi.org/10.3390/min12101320 - 19 Oct 2022

Cited by 13 | Viewed by 2200

Abstract

Foreland fold and thrust belts always represent a complex diagenetic history of carbonate succession, particularly multiphase dolomitization, due to the multi-sourcing nature of fluids affecting syn-to post-depositional successions. The present work documents a comprehensive study on the diagenetic changes, particularly dolomitization patterns in [...] Read more.

Foreland fold and thrust belts always represent a complex diagenetic history of carbonate succession, particularly multiphase dolomitization, due to the multi-sourcing nature of fluids affecting syn-to post-depositional successions. The present work documents a comprehensive study on the diagenetic changes, particularly dolomitization patterns in the Jurassic carbonates (Samana Suk Fm) in the Lesser Himalayan fold and thrust belt, NW Pakistan. To better understand the processes involved, integrated field/petrographic, geochemical, isotopic, and micro-thermometric studies were carried out. Field observations indicate that dolostones appear as light grey to brown stratabound and patchy units within the formation. Petrographic analysis reveals that fabric destructive matrix dolomite (RD-I) and fabric preserving replacive dolomite (RD-II) phases are present as distinct units. In addition, saddle dolomite cement (SD) and fracture-filling calcite (CC) are also observed in association with replacive dolomite cement. Geochemical analysis (EPMA) showed that Fe, Mn, and Ba concentrations in matrix dolomite are relatively less than those of replacive/saddle dolomite and fracture-filling calcite, suggesting a hydrothermal source of replacive/saddle dolomite in reducing conditions. Furthermore, stable isotope studies of RD-I showed non-depleted δ¹⁸O values, which represent coeval seawater signatures of Jurassic carbonates. RD shows depleted δ¹⁸O values and non-depleted δ¹³C, respectively, indicating burial or elevated temperature of dolomitization. Fracture-filled calcite represents lighter δ¹⁸O values and δ¹³C, indicative of relatively high temperatures. ⁸⁷Sr/⁸⁶Sr ratios of all diagenetic phases range from 0.707718 to 0.710747, showing more radiogenic values indicates interaction fluids with more radiogenic sources. Fluid inclusion micro-thermometry data of saddle dolomite shows T_H ranging from 102.8 to 186 °C, and salinity ranging from 11.7 to 19.4 eq. wt.% NaCl, suggesting hot saline brines are responsible for the dolomitization. Fracture-filling calcite shows T_H ranging from 68.0 to 98.4 °C and salinity ranging from 6.9 to 13.1 eq. wt.%. NaCl suggests moderately hot and saline solutions are responsible for their formation. In conclusion, the above-mentioned studies indicate two distinct processes of dolomitization are involved in the formation of matrix and replacive/saddle-type dolomites. RD-I has formed in the evaporative setting, whereas RD has formed due to the interaction of hydrothermal fluids during burial. Fracture-filling calcite is produced from hot subsurface solutions during uplift related to the Himalayan orogeny. Full article

(This article belongs to the Special Issue Diagenesis and Geochemistry of Carbonates)

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18 pages, 3739 KiB

Open AccessReview

Development of Hydraulic Lifting System of Deep-Sea Mineral Resources

by Qiong Hu, Zhenfu Li, Xiaoyu Zhai and Hao Zheng

Minerals 2022, 12(10), 1319; https://doi.org/10.3390/min12101319 - 19 Oct 2022

Cited by 4 | Viewed by 3005

Abstract

Lifting coarse mineral particles from thousands of meters of seabed to the supportive vessSel is a crucial part of exploitation of deep-sea mineral resources, and the vertical transportation part is a key component of the deep-sea mining system. Three typical vertical transportation schemes [...] Read more.

Lifting coarse mineral particles from thousands of meters of seabed to the supportive vessSel is a crucial part of exploitation of deep-sea mineral resources, and the vertical transportation part is a key component of the deep-sea mining system. Three typical vertical transportation schemes are discussed and compared from the aspects of working mechanism, structural scheme, transportation capacity, system efficiency and implementation feasibility in the context of commercial exploitation of deep-sea polymetallic nodules. The conclusion is that the hydraulic pipeline lifting system with a centrifugal pump is a comprehensive scheme. Furthermore, the basic composition and function of the hydraulic lifting system are introduced, and the transportation performance indicators and technical requirements under commercial mining conditions are analyzed. As the key equipment of the lifting system, the structural characteristics, design theory, transportation performance analysis methods and research progress of the lifting pump are described. A 1000 m sea trial was carried out. The lifting system, the tests of the centrifugal pump and the sea trial are introduced. Full article

(This article belongs to the Special Issue Exploitation, Transportation and Processing of Deep-Sea Mineral Resources)

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21 pages, 9376 KiB

Open AccessArticle

Rapid Removal of Cr(VI) from Aqueous Solution Using Polycationic/Di-Metallic Adsorbent Synthesized Using Fe³⁺/Al³⁺ Recovered from Real Acid Mine Drainage

by Khathutshelo Lilith Muedi, Vhahangwele Masindi, Johannes Philippus Maree and Hendrik Gideon Brink

Minerals 2022, 12(10), 1318; https://doi.org/10.3390/min12101318 - 19 Oct 2022

Cited by 4 | Viewed by 1547

Abstract

The mining of valuable minerals from wastewater streams is attractive as it promotes a circular economy, wastewater beneficiation, and valorisation. To this end, the current study evaluated the rapid removal of aqueous Cr(VI) by polycationic/di-metallic Fe/Al (PDFe/Al) adsorbent recovered from real acid mine [...] Read more.

The mining of valuable minerals from wastewater streams is attractive as it promotes a circular economy, wastewater beneficiation, and valorisation. To this end, the current study evaluated the rapid removal of aqueous Cr(VI) by polycationic/di-metallic Fe/Al (PDFe/Al) adsorbent recovered from real acid mine drainage (AMD). Optimal conditions for Cr(VI) removal were 50 mg/L initial Cr(VI), 3 g PDFe/Al, initial pH = 3, 180 min equilibration time and temperature = 45 °C. Optimal conditions resulted in ≥95% removal of Cr(VI), and a maximum adsorption capacity of Q = 6.90 mg/g. Adsorption kinetics followed a two-phase pseudo-first-order behaviour, i.e., a fast initial Cr(VI) removal (likely due to fast initial adsorption) followed by a slower secondary Cr(VI) removal (likely from Cr(VI) to Cr(III) reduction on the surface). More than 90% of adsorbed Cr(VI) could be recovered after five adsorption–desorption cycles. A reaction mechanism involving a rapid adsorption onto at least two distinct surfaces followed by slower in situ Cr(VI) reduction, as well as adsorption-induced internal surface strains and consequent internal surface area magnification, was proposed. This study demonstrated a rapid, effective, and economical application of PDFe/Al recovered from bona fide AMD to treat Cr(VI)-contaminated wastewater. Full article

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

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22 pages, 6289 KiB

Open AccessArticle

Mineralogical and Geochemical Characteristics of Carbonates and Their Geological Significance to the Fuli Pb-Zn Deposit, Yunnan Province

by Xingyu Liang, Bo Li, Chengnan Zhang, Huaikun Qin, Gao Li and Xinyue Zhang

Minerals 2022, 12(10), 1317; https://doi.org/10.3390/min12101317 - 19 Oct 2022

Cited by 4 | Viewed by 1912

Abstract

Mississippi Valley-Type (MVT) deposits are among the main types of Pb-Zn deposits that feature carbonate minerals as the main gangue minerals; their formation runs through the entire metallogenic process of MVT deposits. Therefore, carbonate minerals contain rich information on metallogenic fluid evolution and [...] Read more.

Mississippi Valley-Type (MVT) deposits are among the main types of Pb-Zn deposits that feature carbonate minerals as the main gangue minerals; their formation runs through the entire metallogenic process of MVT deposits. Therefore, carbonate minerals contain rich information on metallogenic fluid evolution and are thus important prospecting indicators. The Fuli Pb-Zn deposit in eastern Yunnan is located in the southeast of the Sichuan-Yunnan-Guizhou (SYG) Pb-Zn metallogenic province, which is the biggest producer of zinc and lead in China and contains more than 400 deposits and over 20 million tons of Pb + Zn reserves. The ore occurs in the interlayer fracture zone of Middle Permian Yangxin Formation Dolomite, and the orebody shape is generally stratiform. The main metal-bearing minerals of this deposit are sphalerite, galena, and pyrite; the gangue minerals mainly comprise dolomite and calcite. Three mineralized stages are observed (the early metallogenic period, the main metallogenic period, and the late metallogenic period) according to the characteristics of stratigraphic output, the intercalated contact relationship of gangue minerals, and the alteration characteristics of the wall rock. To determine the source and properties of the ore-forming fluid and the ore-forming process of the Fuli Pb-Zn deposit, different stages of mineralogy and trace element geochemical characteristics of hydrothermal dolomite were systematically studied. The minerals were observed under microscope and subjected to in situ analysis by LA-ICP-MS and C–O isotope test. The δ¹⁸O_SMOW value of the dolomite in the metallogenic period was between 13.29‰ and 20.55‰, and the δ¹³C_PDB value was between −4.13‰ and 3.5‰. Dolomite of the metallogenic period mainly came from the dissolution of carbonate wall rocks, while C in the ore-forming fluid came from the wall rocks. A few dolomites showed a trend of depleting δ¹³C_PDB and δ¹⁸O_SMOW at the same time, implying the influence of sedimentary rock contamination in the mantle multiphase system. The lower δ¹⁸O was due to the exchange of O isotopes between the wall rocks and the depleted δ¹⁸O in ore-forming fluids. From the early to the later stage of mineralization, the ore-forming fluid changed from alkaline to neutral to weakly acidic due to a decrease in the oxygen fugacity and temperature of the fluid; this change resulted in the precipitation of sulfide and dolomite in the deposit. From the early to the late stages of mineralization, Fe and Mn showed a downward trend. Fe and Mn entered the alkaline environment of the carbonate minerals, while Fe and Mn were released into the acidic fluid, indicating that due to the metasomatism from strong to weak, their metallogenic environment evolved from alkaline to acidic. From the early to the late stage of mineralization, Sr showed an upward trend, which might indicate that the continuous reaction between the hydrothermal fluid and the wall rock continuously released Sr into the fluid. The Fe-Sr and Mn-Sr diagrams show that two kinds of fluid mixing occurred in the ore-forming process. The Fuli Pb-Zn deposit may have formed from mineral precipitation caused by the mixing of the metal-rich, oxidized acidic fluid and the sulfur-rich, reduced alkaline fluid. The results show that the Fuli Pb-Zn deposit belongs to MVT deposits. Full article

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

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13 pages, 5459 KiB

Open AccessReview

Phosphatic Biomineralization in Scyphozoa (Cnidaria): A Review

by Olev Vinn

Minerals 2022, 12(10), 1316; https://doi.org/10.3390/min12101316 - 18 Oct 2022

Cited by 9 | Viewed by 1644

Abstract

Phosphatic biomineralization is unknown in modern species of Scyphozoa (Cnidaria). However, some extinct groups of Scyphozoa, such as conulariids and Sphenothallus, were capable of secreting phosphatic exoskeletons. Both conulariids and Sphenothallus used apatite to improve the mechanical properties of their skeletons, which [...] Read more.

Phosphatic biomineralization is unknown in modern species of Scyphozoa (Cnidaria). However, some extinct groups of Scyphozoa, such as conulariids and Sphenothallus, were capable of secreting phosphatic exoskeletons. Both conulariids and Sphenothallus used apatite to improve the mechanical properties of their skeletons, which offered better protection than the non-biomineralized periderms. The skeletons of conulariids and Sphenothallus have a lamellar microstructure. The shell lamellae of conulariids are often pierced by tiny pores. Several apatitic mineral structures have been described in conulariids and Sphenothallus, including plywood-like structures. Different lattice parameters of the apatite indicate that the biomineralization mechanisms of the phosphatic cnidarians Sphenothallus and conulariids differed from each other. Full article

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

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16 pages, 8466 KiB

Open AccessArticle

Asphaltene Behavior during Thermal Recovery: A Molecular Study Based on Realistic Structures

by Saad Alafnan

Minerals 2022, 12(10), 1315; https://doi.org/10.3390/min12101315 - 18 Oct 2022

Cited by 1 | Viewed by 1319

Abstract

Asphaltene precipitation and deposition can occur at both the surface and subsurface levels, leading to the formation of organic-based scales. Asphaltene precipitation can also lead to changes in petrophysical properties such as wettability, which affects the ultimate recovery. Asphaltene precipitation is linked to [...] Read more.

Asphaltene precipitation and deposition can occur at both the surface and subsurface levels, leading to the formation of organic-based scales. Asphaltene precipitation can also lead to changes in petrophysical properties such as wettability, which affects the ultimate recovery. Asphaltene precipitation is linked to changes in fluid composition driven by pressure drawdown and temperature variation across the reservoir. Thus, asphaltene deposition can adversely influence the ultimate recovery. Thermal recovery methods are invoked to mitigate the adverse effects of asphaltene precipitation. The behavior of asphaltene under thermal recovery along with the link between the asphaltene molecular structure and its response to the increase in temperature during thermal recovery are not fully understood. In this paper, realistic asphaltene structures based on actual crude samples were recreated on a computational platform, and several characteristics of the asphaltene structures (density, viscosity, and interfacial tension) were evaluated during the heating process. The density of asphaltene was correlated with the percentage of aromatic carbon in its structure. The viscosity and interfacial tension decreased substantially as the temperature increased. The IFT reduced by approximately 30 mN/m as the temperature was increased from 300 K to 450 K. Moreover, the mechanical stability of asphaltene was found to be highly influenced by heating. The findings provide nanoscale insights into the behavior of asphaltene during thermal recovery, which can be used to improve the design of thermal recovery processes. Full article

(This article belongs to the Special Issue Mineralogical, Petrophysical and Hydromechanical Properties of Reservoirs and Caprocks)

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27 pages, 2580 KiB

Open AccessReview

Review of Filters for Air Sampling and Chemical Analysis in Mining Workplaces

by Judith C. Chow, John G. Watson, Xiaoliang Wang, Behrooz Abbasi, Wm. Randolph Reed and David Parks

Minerals 2022, 12(10), 1314; https://doi.org/10.3390/min12101314 - 18 Oct 2022

Cited by 3 | Viewed by 3311

Abstract

This review considers the use of filters to sample air in mining workplace environments for dust concentration measurement and subsequent analysis of hazardous contaminants, especially respirable crystalline silica (RCS) on filters compatible with wearable personal dust monitors (PDM). The review summarizes filter vendors, [...] Read more.

This review considers the use of filters to sample air in mining workplace environments for dust concentration measurement and subsequent analysis of hazardous contaminants, especially respirable crystalline silica (RCS) on filters compatible with wearable personal dust monitors (PDM). The review summarizes filter vendors, sizes, costs, chemical and physical properties, and information available on filter modeling, laboratory testing, and field performance. Filter media testing and selection should consider the characteristics required for mass by gravimetry in addition to RCS quantification by Fourier-transform infrared (FTIR) or Raman spectroscopic analysis. For mass determination, the filters need to have high filtration efficiency (≥99% for the most penetrable particle sizes) and a reasonable pressure drop (up to 16.7 kPa) to accommodate high dust loading. Additional requirements include: negligible uptake of water vapor and gaseous volatile compounds; adequate particle adhesion as a function of particle loading; sufficient particle loading capacity to form a stable particle deposit layer during sampling in wet and dusty environments; mechanical strength to withstand vibrations and pressure drops across the filter; and appropriate filter mass compatible with the tapered element oscillating microbalance. FTIR and Raman measurements require filters to be free of spectral interference. Furthermore, because the irradiated area does not completely cover the sample deposit, particles should be uniformly deposited on the filter. Full article

(This article belongs to the Special Issue Mineralogic Analysis of Respirable Dust)

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10 pages, 2633 KiB

Open AccessArticle

Mechanical Characteristics of Sandstone under High Temperature and Cyclic Loading in Underground Coal Gasification

by Ji’an Luo and Jun He

Minerals 2022, 12(10), 1313; https://doi.org/10.3390/min12101313 - 18 Oct 2022

Cited by 3 | Viewed by 1253

Abstract

In the process of underground gasification of coal, the top rock of coal seam will experience a certain high temperature action and be in a complex stress environment. Therefore, it is of great theoretical and engineering significance to study the effect of cyclic [...] Read more.

In the process of underground gasification of coal, the top rock of coal seam will experience a certain high temperature action and be in a complex stress environment. Therefore, it is of great theoretical and engineering significance to study the effect of cyclic unloading and loading on mechanical properties of rocks under high temperature action. In this thesis, the stress–strain curves of sandstone under different high-temperature treatments are obtained by conducting graded loading and unloading tests on sandstone treated at room temperature and at 200 °C, 400 °C, 600 °C, and 800 °C, respectively. The research content of this paper is as follows: the peak stress, peak strain, elastic modulus, Poisson’s ratio, internal friction angle, and cohesion of sandstone in the destruction stage of sandstone. The results show that the peak strain and cohesion of sandstone show an increasing trend with the increase of temperature from room temperature to 800 °C; the peak stress shows a decreasing trend with the increase of temperature from room temperature to 800 °C; the modulus of elasticity tends to increase from 200 °C to 400 °C and to decrease with temperature in the rest of the period; the Poisson’s ratio tends to increase from 600 °C to 800 °C and to decrease with temperature in the rest of the period; the internal friction angle increases sharply within room temperature to 200 °C, decreases slowly within 200–600 °C, and decreases sharply when the temperature exceeds 600 °C. The results of the study will provide important reference significance for the design and engineering application of the gasifier of a coal-bed underground gasification project. Full article

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

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16 pages, 4824 KiB

Open AccessArticle

Recovery of Lead (II) Ions from Aqueous Solutions Using G-26 and MTS9570 Resins with Sulfonic/Phosphonic Functional Groups

by Salem Elfeghe, Qiuyue Sheng, Abbas Mamudu, Lesley Anne James and Yahui Zhang

Minerals 2022, 12(10), 1312; https://doi.org/10.3390/min12101312 - 18 Oct 2022

Cited by 2 | Viewed by 1550

Abstract

This study presents Pb(II) recovery/removal from water solutions using two different commercial ion-exchange resins, i.e., Dowex G-26 with sulfonic functional group and Puromet™ MTS9570 with sulfonic and phosphonic functional groups. Overall, 100% Pb(II) recovery/removal by both resins was obtained at solution pH 3.5, [...] Read more.

This study presents Pb(II) recovery/removal from water solutions using two different commercial ion-exchange resins, i.e., Dowex G-26 with sulfonic functional group and Puromet™ MTS9570 with sulfonic and phosphonic functional groups. Overall, 100% Pb(II) recovery/removal by both resins was obtained at solution pH 3.5, resin dosage 25 g/L, adsorption time 30 min, room temperature, and initial Pb(II) concentration 1000 mg/L. Langmuir, Freundlich, and Temkin isotherms were used to model the experimental data. The mechanism of the adsorption process was investigated using kinetic and thermodynamic models. The experimental data fitted very well with the pseudo-second-order kinetic model, and thermodynamic analysis showed that the adsorption of Pb(II) from acidic solution onto both resins was a spontaneous and endothermic process in nature. Regeneration of the resins loaded with lead ions was tested for three cycles to evaluate the resin recyclability. Good stability of G-26 and performance degradation of MTS9570 resin was observed. Full article

(This article belongs to the Special Issue Towards a Sustainable Management of Mine Wastes: Reprocessing, Reuse, Revalorization and Repository, Volume II)

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15 pages, 3837 KiB

Open AccessFeature PaperArticle

Mineralogical Factors Affecting the Dense Medium Separation of Nickel Sulfide Ores

by Keshree Pillay, Aubrey Njema Mainza, Deshenthree Chetty and Megan Becker

Minerals 2022, 12(10), 1311; https://doi.org/10.3390/min12101311 - 18 Oct 2022

Cited by 2 | Viewed by 2484

Abstract

Dense medium separation (DMS) is often used to reject a large portion of gangue material upfront to create cost and energy savings during processing. As lower-grade ores with complex mineralogy are being increasingly exploited, the properties of the gangue minerals begin to play [...] Read more.

Dense medium separation (DMS) is often used to reject a large portion of gangue material upfront to create cost and energy savings during processing. As lower-grade ores with complex mineralogy are being increasingly exploited, the properties of the gangue minerals begin to play a more important role in the upgrading of the ore. It is therefore important to understand these mineralogical factors to be able to select suitable processing routes for specific ore types. Two nickel sulfide deposits in southern Africa were chosen as case studies to understand differences in DMS efficiency when applied to different ores: Ore A and Ore B. Both ores showed nickel upgrades using DMS and the products were then characterized using QEMSCAN, with the aid of X-ray diffraction and electron probe microanalysis. Overall, particle density remains the main control on the separation, followed by sulfide texture, with massive and net-textured sulfides having larger grain sizes and therefore better liberation than disseminated sulfides. In addition to the concentration of sulfides, primary and secondary silicate minerals are separated by their density differences, which can affect the recovery of finely disseminated sulfides associated with them. Particle size is also important in DMS, with material near the cut-point density separating on size rather than density. The understanding of the mineralogical properties affecting DMS can aid in the prediction of the suitability of DMS for different ore types. Full article

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

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14 pages, 5373 KiB

Open AccessArticle

Analysis of the Selective Flotation of Elemental Gold from Pyrite Using Diisobutyl Monothiophosphate

by Weiping Liu, Jan Dean Miller, Wei Sun and Yuehua Hu

Minerals 2022, 12(10), 1310; https://doi.org/10.3390/min12101310 - 17 Oct 2022

Cited by 5 | Viewed by 1541

Abstract

The gold contained in copper ores is an important resource for the gold industry. In some cases, elemental gold is present and can be recovered by selective flotation. It has been reported that the gold grade and recovery can be increased, without sacrificing [...] Read more.

The gold contained in copper ores is an important resource for the gold industry. In some cases, elemental gold is present and can be recovered by selective flotation. It has been reported that the gold grade and recovery can be increased, without sacrificing the copper recovery, by replacing AERO 3477 (diisobutyl dithiophosphate (DTP)) with AERO 7249 (mixture of diisobutyl monothiophosphate (MTP) and diisobutyl dithiophosphate (DTP)) as the main collector. The fundamental understanding of the improvement in selectivity with the addition of MTP in the flotation of elemental gold from pyrite is limited and is the subject of this paper. In this regard, the hydrophobicity and selectivity of DTP and MTP in the flotation of pyrite and gold are compared and discussed. Density functional theory (DFT) was used to examine the electron density, reactivity, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) of the MTP and DTP collectors. The interaction energies for the adsorption of MTP and DTP from fresh pyrite, oxidized pyrite and gold surfaces were calculated and discussed with respect to the experimental results reported in the literature. Molecular dynamics simulation (MDS) was used to examine the adsorption state of MTP and DTP on the pyrite (100) and Au (111) surfaces. Full article

(This article belongs to the Special Issue Recent Advances in Extractive Metallurgy)

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3 pages, 195 KiB

Open AccessEditorial

Editorial for Special Issue “Modeling, Design, and Optimization of Multiphase Systems in Minerals Processing, Volume II”

by Freddy A. Lucay and Luis A. Cisternas

Minerals 2022, 12(10), 1309; https://doi.org/10.3390/min12101309 - 17 Oct 2022

Viewed by 883

Abstract

The manuscripts published in the 2019 Special Issue “Modeling, Design, and Optimization of Multiphase Systems in Minerals Processing” [...] Full article

(This article belongs to the Special Issue Modeling, Design and Optimization of Multiphase Systems in Minerals Processing, Volume II)

19 pages, 6298 KiB

Open AccessArticle

Mineralogical, Geochronological, and Geochemical Characteristics of Early Cretaceous Granite in South China: Implications for Tectonic Evolution and REE Mineralization

by Yue Qin, Yongfeng Cai, Wei Fu, Zhixuan Han, Panfeng Liu, Changling Lao, Yongshan Zhao, Zhengchao Han and Yun Zhou

Minerals 2022, 12(10), 1308; https://doi.org/10.3390/min12101308 - 17 Oct 2022

Cited by 1 | Viewed by 1671

Abstract

One of the most important geological features of South China are the widespread Mesozoic igneous rocks that play a key role in revealing the tectonic evolution of South China. Due to the thick covering of vegetation and Quaternary sediments, the early Cretaceous magmatism [...] Read more.

One of the most important geological features of South China are the widespread Mesozoic igneous rocks that play a key role in revealing the tectonic evolution of South China. Due to the thick covering of vegetation and Quaternary sediments, the early Cretaceous magmatism in southwestern South China is still not well constrained. In this paper, we report newly identified early Cretaceous granites in Guangxi, South China. Zircon U–Pb dating results showed that representative fine-grained and coarse-grained granites in northeastern Guangxi indicate the early Cretaceous ages of 141 ± 3 Ma and 141 ± 4 Ma, respectively. Geochemically, both fine-grained and coarse-grained granites had high 10,000 × Ga/Al ratios and belonged to A-type granite. They had undergone high degrees of magma differentiation, as evidenced by extremely negative Sr, Ba, and Eu anomalies. They had high REE (rare earth elements) contents (>451 ppm). The fine-grained granites were characterized by higher HREE (heavy rare earth elements) contents, lower LREE (light rare earth elements) contents, and lower LREE/HREE ratios than the coarse-grained granites. Integrated with regional geological data, the early Cretaceous granites were likely formed in a back-arc extensional environment in response to the increased subduction angle of the Paleo-Pacific plate. Different REE contents in the fine- and coarse-grained granites may be a result of fractional crystallization. Magma differentiation and hydrothermal alteration might have played an important role in REE mineralization of the early Cretaceous granites in Guangxi. Full article

(This article belongs to the Special Issue Applications of U-Th-Pb Geochronology of Accessory Minerals)

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23 pages, 9955 KiB

Open AccessArticle

Application Study of Empirical Wavelet Transform in Time–Frequency Analysis of Electromagnetic Radiation Induced by Rock Fracture

by Quan Lou, Xiangyun Wan, Bing Jia, Dazhao Song, Liming Qiu and Shan Yin

Minerals 2022, 12(10), 1307; https://doi.org/10.3390/min12101307 - 17 Oct 2022

Cited by 7 | Viewed by 1400

Abstract

The time–frequency characteristics of electromagnetic radiation (EMR) waveform induced by rock fracture are very important to the monitoring and early–warning using the EMR method for the mine rockburst. The empirical wavelet transform (EWT), as a waveform time–frequency analysis method, has the advantages of [...] Read more.

The time–frequency characteristics of electromagnetic radiation (EMR) waveform induced by rock fracture are very important to the monitoring and early–warning using the EMR method for the mine rockburst. The empirical wavelet transform (EWT), as a waveform time–frequency analysis method, has the advantages of a clear theoretical basis, convenient calculation, and no modal aliasing. To apply EWT to the field of EMR time–frequency analysis, the operation of Fourier axis segmentation of EWT is improved. In detail, the adaptive selection method for a window width of closing operation and the adaptive determination method of segment number of Fourier axis are proposed for EWT. The Fourier axis obtained by short–time Fourier transform (STFT) is used in the EWT process, rather than that obtained by discrete Fourier transform (DFT), taking a better Fourier axis segmentation effect. The improved EWT together with Hilbert transform (HT) applied to the time–frequency analysis for the EMR waveform of rock fracture, and the time–frequency spectrum obtained by EWT–HT can well describe the time–frequency evolution characteristics. Compared with STFT and Hilbert–Huang transform (HHT), EWT–HT has significant advantages in time–frequency resolution and overcoming modal aliasing, providing a powerful tool for time–frequency analysis for the EMR waveform induced by rock fracture. Full article

(This article belongs to the Special Issue Rockburst Mechanism and Its Prevention and Control in Underground Mines)

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