Minerals

24 pages, 6690 KB

Open AccessFeature PaperEditor’s ChoiceReview

Advanced Trends in Shale Mechanical Inhibitors for Enhanced Wellbore Stability in Water-Based Drilling Fluids

by Erxin Ai, Qi Li, Zhikun Liu, Bo Zhang, Liupeng Wang and Chengyun Ma

Minerals 2024, 14(12), 1197; https://doi.org/10.3390/min14121197 - 25 Nov 2024

Cited by 4 | Viewed by 3826

Wellbore instability, particularly in shale formations, presents a great challenge to modern drilling operations. Although conventional chemical inhibitors are frequently employed in water-based drilling fluids, they may not always function in highly reactive or naturally fractured shale formations. In recent years, mechanical inhibitors [...] Read more.

Wellbore instability, particularly in shale formations, presents a great challenge to modern drilling operations. Although conventional chemical inhibitors are frequently employed in water-based drilling fluids, they may not always function in highly reactive or naturally fractured shale formations. In recent years, mechanical inhibitors have attracted attention as a complementary solution to chemical methods. These inhibitors, which include carbon-based, silicon-based, metal-based, and mineral-based particle materials, provide structural support to the wellbore by physically plugging fractures and sealing microfractures. This paper presents a comprehensive review of the mineral types associated with shale wellbore instability as well as a critical analysis of the mechanisms, categories, and effectiveness of mechanical inhibitors in enhancing wellbore stability. The development challenges and prospects of mechanical inhibitors in water-based drilling fluids are also discussed. This review emphasizes the potential of mechanical inhibitors in reducing fluid invasion, preventing wellbore collapse, and improving overall drilling efficiency, which will help facilitate the development and large-scale application of mechanical inhibitors in drilling fluids. Full article

(This article belongs to the Special Issue Clay Minerals: Roles in Oil and Gas Generation, Drilling, and Enhanced Recovery)

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23 pages, 5951 KB

Open AccessFeature PaperEditor’s ChoiceArticle

The Core Story: Intertwined Maternal and Progeny Signatures Enclosed in the Otolith

by Clara Anne Lord, Sophie Berland, Vincent Haÿ and Philippe Keith

Minerals 2024, 14(11), 1176; https://doi.org/10.3390/min14111176 - 20 Nov 2024

Cited by 1 | Viewed by 1406

Abstract

Analytical imaging via synchrotron analysis was used to study sagittal otoliths of four freshwater pipefish species exhibiting amphidromous or freshwater resident lifestyles. We undertook a hyperfine elemental scanning of a 25 μm diameter length area centred on the core, namely the pre-hatch zone, [...] Read more.

Analytical imaging via synchrotron analysis was used to study sagittal otoliths of four freshwater pipefish species exhibiting amphidromous or freshwater resident lifestyles. We undertook a hyperfine elemental scanning of a 25 μm diameter length area centred on the core, namely the pre-hatch zone, corresponding to the sagitta formed during embryogenesis. We analysed calcium (Ca), strontium (Sr), manganese (Mn), chromium (Cr), cobalt (Co), nickel (Ni) and sulphur (S), with the latter serving to count growth increments. Whatever the species, a Ca pit consistently marked the core; the amphidromous species exhibited Mn enrichment at the core and the sagitta formed a week before hatching. These results illustrate common otolith formation mechanistic processes. Sr and heavy metals’ signals in the pre-hatch zone were compared to their signal in the edge of the otolith, an area encompassing the adult freshwater (adFW) environmental signature. We found that Co and Ni otolith signals had no relation to environmental conditions, but it is worth looking into Cr as a marker of early-life environment. While we caution against the use of a Sr:Ca ratio for life history interpretations at the core because of the Ca pit, the Sr signal analysis uncovered possible variations in the parental behaviour that potentially trigger newly-hatched juvenile migration to sea or residency. Finally, our results demonstrate that the microchemistry of otolith formation during early development is a melting of maternal signal during egg yolk elaboration, of the environmental signal during egg incubation, and of individual physiology during early growth. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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12 pages, 2138 KB

Open AccessFeature PaperEditor’s ChoiceCommunication

First Optically Stimulated Luminescence and Radiocarbon Dating of the Late Quaternary Eruptions in the Xilinhot Volcanic Field, China

by Zhiwei Shi, Furong Cui, Zhidan Zhao, Zhida Bai, Zeguang Chang and Junxiang Zhao

Minerals 2024, 14(11), 1181; https://doi.org/10.3390/min14111181 - 20 Nov 2024

Cited by 1 | Viewed by 1300

Abstract

Precise dating of prehistoric volcanic eruptions is essential for reconstructing eruption sequences and assessing volcanic hazards. The timing of the onset and termination of volcanic activity in the Xilinhot volcanic field (XVF) has been a topic of debate for years. Volcanic eruptions in [...] Read more.

Precise dating of prehistoric volcanic eruptions is essential for reconstructing eruption sequences and assessing volcanic hazards. The timing of the onset and termination of volcanic activity in the Xilinhot volcanic field (XVF) has been a topic of debate for years. Volcanic eruptions in this area began during the Pliocene, with the K-Ar (Ar-Ar) method providing reliable ages for early formed volcanic rocks; however, this method is less effective for dating younger volcanic events that occurred since the Late Pleistocene. For younger volcanoes, sediments baked by volcanic materials, organic sediments, and silty mudstones entrapped in lava serve as excellent geological carriers for dating. In this study, suitable samples collected from the XVF were dated using ¹⁴C and optically stimulated luminescence (OSL) methods. The ¹⁴C ages obtained for the Gezishan volcano are ~6.8 cal. ka BP, while its OSL age is ~7.8 ka. The ages dated by these two methods, combined with volcano–sedimentary stratigraphic relationships and volcanic topography, confirm the Holocene eruptions of the Gezishan volcano, categorizing it as a broadly active volcano. The upper boundary age of the sandy loam layer beneath the Gezishan lava flow is ~15.5 ka, indicating that the south lava of the Gezishan effusion occurred later than the late stage of the Late Pleistocene. Additionally, the OSL ages of baked sediments at the bottom of the base surge deposits from a Maar-type volcano and aeolian sand interlayers within a Strombolian-type scoria cone in the study area are ~50 ka and ~60 ka, respectively, representing eruptions in the middle Late Pleistocene. These findings demonstrate that volcanic activity in the XVF remained vigorous during the Late Pleistocene to Holocene. This study provides significant insights for reconstructing the evolutionary history of Xilinhot volcanic activity and assessing regional volcanic hazards. Full article

(This article belongs to the Special Issue Magmatic Evolution through Time of Volcanic Zones: Evidence from Isotopic, Geochemical and Geochronological Data of Eruption Products)

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12 pages, 4933 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Mineral Liberation and Concentration Characteristics of Apatite Comminuted by High-Pressure GRU

by Yongbo Fan, Genghao Zhang, Shihai Li, Li Zhang, Jianqiang Guo and Chun Feng

Minerals 2024, 14(11), 1148; https://doi.org/10.3390/min14111148 - 13 Nov 2024

Cited by 2 | Viewed by 1560

Abstract

Mineral liberation and concentration have always been the core issues in ore processing. The goal of multi-stage crushing and ball milling is liberation because mineral liberation is the foundation of beneficiation. High energy consumption and environmental pollution have always been unavoidable topics. We [...] Read more.

Mineral liberation and concentration have always been the core issues in ore processing. The goal of multi-stage crushing and ball milling is liberation because mineral liberation is the foundation of beneficiation. High energy consumption and environmental pollution have always been unavoidable topics. We put forward the method of high-pressure gas rapid unloading (GRU). Particle size followed MR-R distribution. The scanning electron microscopy data showed that the liberation of apatite particles smaller than 4 mm was sufficient by high-pressure GRU methods, and high-grade apatite concentrated in the particle size range of 0.5 to 4 mm. The average grade of the preferred particle size interval was 3%–5% higher than the original ore. Liberation degrees of apatite less than 4 mm are above 88%, which was beneficial for mineral processing. Compared to the traditional crushing method, the GRU method had a higher liberation and concentration in the particle size range of 0.5 to 4 mm. The total energy consumption was about 1.76 kW·h/t, less than that of the traditional crushing method. Full article

(This article belongs to the Special Issue Selected Papers from the 7th International Conference of Young Scholars in Mineral Processing)

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11 pages, 217 KB

Open AccessFeature PaperEditor’s ChoiceReview

Further Results on the Effects of the Grinding Environment on the Flotation of Copper Sulphides

by Warren J. Bruckard and Graham J. Sparrow

Minerals 2024, 14(11), 1140; https://doi.org/10.3390/min14111140 - 11 Nov 2024

Viewed by 1997

Abstract

Grinding conditions affect the flotation of copper sulphide minerals as changes in the properties of the grinding media and their interactions with the sulphide minerals, and between sulphide minerals themselves, affect the chemical environment in the flotation pulp. Galvanic interactions between steel grinding [...] Read more.

Grinding conditions affect the flotation of copper sulphide minerals as changes in the properties of the grinding media and their interactions with the sulphide minerals, and between sulphide minerals themselves, affect the chemical environment in the flotation pulp. Galvanic interactions between steel grinding media and sulphide minerals, and between sulphide minerals, can lower the pulp potential, decrease the dissolved oxygen concentration in the mineral slurry, and lead to the dissolution of iron and copper from the media and the minerals. As a result, the formation of hydrophilic iron hydroxides and their adsorption on the copper sulphide minerals can be deleterious to copper flotation while pyrite (when present) can be activated to flotation by dissolved copper lowering the grade of the copper concentrate. Electrochemically less active grinding media (e.g., chrome alloy balls rather than mild steel media) can have beneficial effects on flotation performance due to the lower oxidation of the grinding media and consequently the lower production of oxidised iron species in the pulp. Copper activation of pyrite can be decreased by chemical additions to the pulp. In this paper, relevant experimental data published in the last 15 years are discussed. Full article

(This article belongs to the Special Issue Grinding Chemistry and Its Impact on Downstream Processing)

17 pages, 7671 KB

Open AccessFeature PaperEditor’s ChoiceArticle

High-Resolution Reconstruction of Oxidation–Reduction Conditions: Raman Spectroscopy and μ-XRF Analysis of Manganese Nodule and Crust on Tabletop of Western Pacific Magellan Seamounts

by Jinsub Park, Huijeong Hwang, Hyeonho An and Kiho Yang

Minerals 2024, 14(11), 1135; https://doi.org/10.3390/min14111135 - 10 Nov 2024

Cited by 1 | Viewed by 1657

Abstract

Ferromanganese (Fe-Mn) deposits are widely used in paleoenvironmental reconstructions owing to their mineralogical and geochemical properties. We analyzed Fe-Mn deposits using micro-X-ray fluorescence and Raman spectroscopy to study the paleo-ocean environment. Samples were collected from the OSM-XX seamount in the western Pacific. The [...] Read more.

Ferromanganese (Fe-Mn) deposits are widely used in paleoenvironmental reconstructions owing to their mineralogical and geochemical properties. We analyzed Fe-Mn deposits using micro-X-ray fluorescence and Raman spectroscopy to study the paleo-ocean environment. Samples were collected from the OSM-XX seamount in the western Pacific. The Fe-Mn crust was divided into three parts: phosphatized, massive non-phosphatized, and porous non-phosphatized. Vernadite was identified in all layers. Furthermore, in the nodule, high values of Mn, Ni, and Cu were observed near the nucleus, with vernadite and todorokite, and these values decreased outward. A high Mn/Fe ratio near the nucleus indicates early diagenetic processes. Formation of Fe-Mn nodules began around 19–16 Ma, and this period corresponded to a minor phosphatization event and persistent reducing conditions. From 11–10 Ma, the Mn/Fe and Co/Mn ratios decreased due to the formation of a western Pacific warm pool during this period. Subsequently, with the opening of the Indonesian seaway and global cooling, the Mn/Fe and Co/Mn ratios in the Fe-Mn deposits increased again. The comparative analysis of variations in Mn/Fe ratio and vernadite crystallinity in the Fe-Mn deposits confirmed that it is possible to reconstruct paleo-productivity and redox condition changes in the western Pacific Magellan Seamount. Full article

(This article belongs to the Section Mineral Deposits)

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21 pages, 4160 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Investigating the Timing of Carbonate Precipitations and Their Potential Impact on Fossil Preservation in the Hell Creek Formation

by Daigo Yamamura

Minerals 2024, 14(11), 1133; https://doi.org/10.3390/min14111133 - 9 Nov 2024

Cited by 1 | Viewed by 1835

Abstract

Because fossilized skeletal remains and enclosing sedimentary rocks experience similar diagenetic conditions (i.e., temperature, pressure, and pore fluid interaction,) enclosing sedimentary rocks may provide insight into bone diagenesis. A fossil assemblage, including in situ dinosaur fossils, was discovered in Makoshika State Park near [...] Read more.

Because fossilized skeletal remains and enclosing sedimentary rocks experience similar diagenetic conditions (i.e., temperature, pressure, and pore fluid interaction,) enclosing sedimentary rocks may provide insight into bone diagenesis. A fossil assemblage, including in situ dinosaur fossils, was discovered in Makoshika State Park near Glendive, MT. Fossil-bearing sandstone is a crevasse splay deposit, and fossils show no sorting or preferred orientation. Bone-bearing sandstone exhibits evidence for intense diagenesis, suggesting a maximum temperature of ~90 °C. Concretion associated with fossils includes two distinctive matrices: dark- and light-colored matrices. Another concretion was found in channel sandstone near the base of the outcrop. These carbonate phases have distinctive isotopic compositions; δ¹³C values for dark-colored matrices, light-colored matrices, and spheroidal concretion are −7.5, 2.1, and −22.4‰ (VPDB), respectively, and their δ¹⁸O values are 16.4, 25.9, and 17.8‰ (VSMOW), respectively. In contrast, fossilized bone δ¹³C and δ¹⁸O values were −4.4‰ (VPDB) and 20.6‰ (VSMOW), respectively, suggesting fractionation with pore fluid was limited. Early carbonate precipitation evidenced by grain coating may have reduced interaction between pore fluids and fossils. Although concretion formation and permineralization do not appear to directly aid in fossil preservation, concretions preserve valuable evidence for diagenetic history. Full article

(This article belongs to the Special Issue Recent Advances in Bone Diagenesis)

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18 pages, 19629 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Local Crystallographic Texture of Alpha Quartz in Silicified Wood (Late Triassic, Madagascar)

by Alexey Pakhnevich, Tatiana Lychagina, Sancia Morris and Dmitry Nikolayev

Minerals 2024, 14(11), 1128; https://doi.org/10.3390/min14111128 - 8 Nov 2024

Viewed by 2180

Abstract

Compositional and anatomical studies of silicified wood have been carried out extensively all around the world. The classification of silicified wood as such deals with all the forms and phases of silica that come under its umbrella. One such class of silicified wood [...] Read more.

Compositional and anatomical studies of silicified wood have been carried out extensively all around the world. The classification of silicified wood as such deals with all the forms and phases of silica that come under its umbrella. One such class of silicified wood is fossil wood with a high content of quartz, and there are very limited mentions of this category of fossilized wood. The examined wood belongs to gymnosperm and comes from the Upper Triassic deposits of Madagascar. A fresh approach to such samples is adopted by studying the crystallographic texture of the fossil wood to understand the orientation of the crystals replacing the organic matter within the sample. This work focuses on crystallographic texture analysis based on pole figures measured by X-ray diffraction. The intensity of the pole density maxima on the pole figures measured on the heartwood surface part of the analyzed samples is higher than that on the sapwood. This affirms that the crystallographic texture is sharper at the heartwood part compared to the sapwood. The X-ray tomography study, conducted to understand the difference in mineral distribution within the sample, reveals a greater X-ray absorbing phase on the sapwood of both samples. This is due to the concentration of iron compounds, which both replace the remaining conductive structures of the wood and fill the cavities inside them. We believe that this research on silicified wood is the first research work that encompasses crystallographic texture analysis with pole figures, an approach not previously undertaken in similar studies. We hope that our research can be useful in understanding the processes of replacement of organic matter by minerals. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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16 pages, 3757 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Preconcentrating Ultrafine Ilmenite Tailings Using a Laboratory-Scale Reflux Classifier

by Zhenqiang Liu, Zhenhua Su, Bing Liu, Yuhua Wang, Yuxin Zhang, Xuqun Zhong, Kangkang Chen, Xiaoxing Hu and Dongfang Lu

Minerals 2024, 14(11), 1125; https://doi.org/10.3390/min14111125 - 7 Nov 2024

Cited by 6 | Viewed by 1373

Abstract

China is rich in reserves of titanium, but a large amount of titanium resources is lost in the ultrafine tailings, and it is challenging to treat the ilmenite contained in ultrafine ore. The reflux classifier (RC), a novel gravity concentration technology, has been [...] Read more.

China is rich in reserves of titanium, but a large amount of titanium resources is lost in the ultrafine tailings, and it is challenging to treat the ilmenite contained in ultrafine ore. The reflux classifier (RC), a novel gravity concentration technology, has been applied in the preconcentration of ultrafine ilmenite in this study. During this process, the feasibility of using RC for preconcentration of ultrafine ilmenite was explored through theory and conditional experiments. After one-stage preconcentration using RC, the ultrafine ilmenite ore with a TiO₂ grade of 8.77% can be concentrated into a product with a TiO₂ grade of 20.3% and a recovery rate of 82.8%. The tailings grade is as low as 2.44%, and the yield reaches 62.6%. The separation efficiency achieves 50.0%. Experimental results demonstrate that utilizing RC for the preconcentration of ultrafine ilmenite can avoid the influence of weakly magnetic gangue and achieve better results compared to a magnetic separator. Therefore, RC offers a more effective and affordable method for preconcentrating ultrafine ilmenite ore. Full article

(This article belongs to the Special Issue Advances in the Theory and Technology of Physical Separation)

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15 pages, 3187 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Raman Quantitative Measurement on the Cl⁻ Molarity of H₂O-NaCl-CO₂ System: Application to Fluid Inclusions

by Xian He, Wei-Qi Wang, Yu-Zhen Liu and Qiang Sun

Minerals 2024, 14(11), 1121; https://doi.org/10.3390/min14111121 - 6 Nov 2024

Cited by 1 | Viewed by 1579

Abstract

In this study, Raman spectroscopy is applied to determine the salinity of fluid inclusions in the H₂O-NaCl-CO₂ system. In the work, various systems are prepared, such as H₂O-NaCl, H₂O-CO₂, and H₂O-NaCl-CO₂ [...] Read more.

In this study, Raman spectroscopy is applied to determine the salinity of fluid inclusions in the H₂O-NaCl-CO₂ system. In the work, various systems are prepared, such as H₂O-NaCl, H₂O-CO₂, and H₂O-NaCl-CO₂. For the H₂O-NaCl system, the addition of NaCl salts decreases the intensity of the sub-band below 3330 cm⁻¹ but increases the intensity of the sub-band above 3330 cm⁻¹. According to the structural analysis of the H₂O-NaCl system, the spectral changes are mainly related to the interactions between Cl⁻ and water. After the Raman OH stretching bands are fitted into two sub-bands, the intensity ratio between them is used to calculate the Cl⁻ concentrations (molarity scale) of NaCl solutions. Additionally, based on the measured Raman spectra, the effects of CO₂ on water structure may be weak. It is reasonable to ignore the impact of dissolved CO₂ on Raman OH stretching bands. The procedure above can be extended to quantitatively determine the Cl⁻ molarity of the H₂O-NaCl-CO₂ system. To demonstrate its reliability, this method is applied to determine the salinity of synthetic and natural fluid inclusions containing CO₂. Full article

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

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13 pages, 3557 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Preparation and Performance Evaluation of Small-Molecule Ammonium as a Shale Hydration Inhibitor

by Quande Wang, Huifeng He, Yarui Zhao, Jing Rui, Ruichen Jiang, Michal Slaný, Gang Chen and Xuefan Gu

Minerals 2024, 14(11), 1117; https://doi.org/10.3390/min14111117 - 3 Nov 2024

Cited by 2 | Viewed by 1528

Abstract

In this paper, small-molecule quaternary ammonium salts were synthesized by N-alkylation to inhibit hydration swelling and hydration dispersion. The prepared small-molecule quaternary ammonium salt was characterized by Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric analysis (TGA), particle size analysis and Scanning electron microscopy (SEM), [...] Read more.

In this paper, small-molecule quaternary ammonium salts were synthesized by N-alkylation to inhibit hydration swelling and hydration dispersion. The prepared small-molecule quaternary ammonium salt was characterized by Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric analysis (TGA), particle size analysis and Scanning electron microscopy (SEM), and its performance as an inhibitor in clay was evaluated by an anti-swelling test and a linear swelling test. The results show that small-molecule quaternary ammonium salt (TEE-2) synthesized by triethanolamine and epichlorohydrin in ethanol with a molar ratio of 1:1.5 can successfully inhibit the hydration swelling and dispersion of clay. The anti-swelling rate of TEE-2 was 84.94%, the linear swelling rate was 36.42%, and the linear swelling rate of 0.5% TEE-2 was only 29.34%. The hydration swelling of clay in 0.5% TEE-2 solution was significantly inhibited. The hydration inhibition mechanism of the small-molecule quaternary ammonium salt inhibitor 0.5% TEE-2 was analyzed by FTIR, SEM and TGA. It was considered that 0.5% TEE-2 has strong hydration inhibition, which was realized by infiltration and adsorption on the clay surface. Small-molecule quaternary ammonium salts were beneficial for maintaining wellbore stability and reducing the risk of wellbore instability. Full article

(This article belongs to the Special Issue Clay Minerals: Roles in Oil and Gas Generation, Drilling, and Enhanced Recovery)

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18 pages, 5748 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Investigating Physicochemical Methods to Recover Rare-Earth Elements from Appalachian Coals

by Rachel Yesenchak, Scott Montross and Shikha Sharma

Minerals 2024, 14(11), 1106; https://doi.org/10.3390/min14111106 - 30 Oct 2024

Viewed by 1781

Abstract

The demand for rare-earth elements is expected to grow due to their use in critical technologies, including those used for clean energy generation. There is growing interest in developing unconventional rare-earth element resources, such as coal and coal byproducts, to help secure domestic [...] Read more.

The demand for rare-earth elements is expected to grow due to their use in critical technologies, including those used for clean energy generation. There is growing interest in developing unconventional rare-earth element resources, such as coal and coal byproducts, to help secure domestic supplies of these elements. Within the U.S., Appalachian Basin coals are particularly enriched in rare-earth elements, but recovery of the elements is often impeded by a resistant aluminosilicate matrix. This study explores the use of calcination and sodium carbonate roasting pre-treatments combined with dilute acid leaching to recover rare-earth elements from Appalachian Basin coals and underclay. The results suggest that rare-earth element recovery after calcination is dependent on the original mineralogy of samples and that light rare-earth minerals may be more easily decomposed than heavy rare-earth minerals. Sodium carbonate roasting can enhance the recovery of both light and heavy rare-earth elements. Maximum recovery in this study, ranging from 70% to 84% of total rare-earth elements, was achieved using a combination of calcination and sodium carbonate roasting, followed by 0.25 M citric acid leaching. Full article

(This article belongs to the Special Issue Critical Metal Minerals, 2nd Edition)

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16 pages, 819 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Approximation of the Role of Mineralized Collagen Fibril Orientation in the Mechanical Properties of Bone: A Computational Study on Dehydrated Osteonal Lamellar Bone

by Onur Cem Namli and Feride Sermin Utku

Minerals 2024, 14(11), 1107; https://doi.org/10.3390/min14111107 - 30 Oct 2024

Cited by 1 | Viewed by 1420

Abstract

Bone is a natural composite of the hierarchical arrangement of mineralized collagen fibrils in various orientations. This study aims to understand how the orientation of the bone mineral, guiding the removal of water contained in the humidity-responsive layers during dehydration, affects its mechanical [...] Read more.

Bone is a natural composite of the hierarchical arrangement of mineralized collagen fibrils in various orientations. This study aims to understand how the orientation of the bone mineral, guiding the removal of water contained in the humidity-responsive layers during dehydration, affects its mechanical properties. A sublamellar pattern with mineralized collagen fibrils oriented between 0° to 150° at 5° angles was the model studied. Using basic transformational computational methods, dimensional change was calculated in the transverse and oblique planes of osteonal lamellar bone while considering bone components sensitive to dehydration in radial, tangential, and axial orientations. The anisotropy ratios of the change in the dimension of the variable mineralized collagen fibril orientations calculated using the computed model displayed values ranging between 0.847 to 2.092 for the transverse plane and 0.9856 to 1.0207 for the oblique plane. A comparison of the anisotropy results of the suggested model indicated that they approach the experimental results of both transversely and obliquely cut samples. As collagen fibril and mineral orientation take place both temporally and spatially in relationship with the static and dynamic loads placed on the different volumes of bone, the results may imply that the mechanical demands involved in bone resorption and deposition contribute to the formation of this multi-faceted and hierarchically structured natural composite. Full article

(This article belongs to the Special Issue Skeletal Tissues Mineralization)

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19 pages, 3360 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhancing Mineral Exploration Programs Through Quantitative XRD: A Case Study from the Gumsberg Polymetallic Sulphide Deposits, Sweden

by Sheida Makvandi, Evelien Rost, Thomas Witzke, Matteo Pernechele and Hein Raat

Minerals 2024, 14(11), 1100; https://doi.org/10.3390/min14111100 - 29 Oct 2024

Cited by 1 | Viewed by 1976

Abstract

As challenges in precious and base metal exploration intensify due to the diminishing availability of high-grade ore deposits, rising demand, energy costs, and stricter regulations towards net-zero carbon activities, advanced techniques to enhance exploration efficiency are becoming increasingly critical. This study demonstrates the [...] Read more.

As challenges in precious and base metal exploration intensify due to the diminishing availability of high-grade ore deposits, rising demand, energy costs, and stricter regulations towards net-zero carbon activities, advanced techniques to enhance exploration efficiency are becoming increasingly critical. This study demonstrates the effectiveness of quantitative X-ray diffraction (QXRD) with Rietveld refinement, coupled with multivariate statistical analysis (including agglomerative hierarchical clustering, principal component analysis, and fuzzy analysis), in characterizing the complex mineralogy of strata-bound volcanic-associated limestone-skarn Zn-Pb-Ag-(Cu-Au)-type sulphide deposits (SVALS). Focusing on 113 coarse rejects from the Gumsberg project located in the Bergslagen mining district in central Sweden, the research identified five distinct mineralogical clusters corresponding to polymetallic base metal sulphide mineralization, its proximal alteration zones, and variably metamorphosed host rocks. The results reveal significant sulphide mineralization, ranging from disseminated to massive occurrences of sphalerite, pyrrhotite, pyrite, and galena, with trace amounts of secondary minerals like anglesite in certain samples indicating weathering processes. The study also identifies rare minerals such as armenite, often overlooked in traditional geological logging. These findings underscore the potential of QXRD to enhance resource estimation, optimize exploration strategies, and contribute to more efficient and sustainable mineral exploration programs. The accuracy of QXRD was cross-validated with geological logs and geochemical data, confirming its reliability as a mineralogical discrimination tool. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Geological Materials)

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19 pages, 5921 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Geochemical Dynamics and Evolutionary Implications of Sediments at the Xingu–Amazon Rivers’ Confluence: Proxies for Mixing, Mobility and Weathering

by Lucio Cardoso Medeiros Filho, Nils Edvin Asp, Jean Michel Lafon, Thiago Pereira Souza, José Francisco Berredo and Gabriel Negreiros Salomão

Minerals 2024, 14(11), 1101; https://doi.org/10.3390/min14111101 - 29 Oct 2024

Cited by 1 | Viewed by 1692

Abstract

This study investigates the geochemical characteristics and evolutionary implications of sediments at the confluence of the Xingu and Amazon Rivers. The main objective is to understand sediment mixing, mobility, and weathering processes through geochemical proxies. Samples were collected from various sections of the [...] Read more.

This study investigates the geochemical characteristics and evolutionary implications of sediments at the confluence of the Xingu and Amazon Rivers. The main objective is to understand sediment mixing, mobility, and weathering processes through geochemical proxies. Samples were collected from various sections of the lower Xingu River, focusing on its interaction with the Amazon River. Analytical techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS) were employed to analyze major and trace elements. The results reveal significant spatial variations in mineralogical and textural patterns, with sediments forming distinct groupings based on their location. The data suggest that the lower Xingu River is strongly influenced by sediment inputs from the Amazon River, particularly affecting sediment composition and chemical weathering processes. This research highlights the critical interactions between river systems and their implications for the evolution of the Amazon basin, especially regarding sediment contributions from various geological sources. Even though the Xingu River drains cratonic regions at higher elevations, the geochemistry of the bottom sediments confirms that the bedload is derived from heterogeneous sources with primarily intermediate igneous compositions and has undergone substantial recycling during river transport. Full article

(This article belongs to the Special Issue Potentially Toxic Elements: Source, Distribution, Risk Assessment and Remediation)

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26 pages, 11780 KB

Open AccessFeature PaperEditor’s ChoiceReview

Peridotite Weathering and Ni Redistribution in New Caledonian Laterite Profiles: Influence of Climate, Hydrology, and Structure

by Michel Cathelineau, Yoram Teitler, Jean-Louis Grimaud, Sylvain Favier, Fabrice Golfier, Erick Ramanaidou, Sylvain Grangeon, Yohann Kerreveur, Julie Jeanpert, Samuel Étienne, Manuel Muñoz and Marc Ulrich

Minerals 2024, 14(11), 1082; https://doi.org/10.3390/min14111082 - 27 Oct 2024

Cited by 2 | Viewed by 1940

Abstract

The peridotite massifs of New Caledonia are characterised by complex hydrodynamics influenced by intense inherited fracturing, uplift, and erosion. Following the formation of the erosion surfaces and alteration processes, these processes drive chemical redistribution during weathering; particularly lateritisation and saprolitisation. Magnesium, silica, and [...] Read more.

The peridotite massifs of New Caledonia are characterised by complex hydrodynamics influenced by intense inherited fracturing, uplift, and erosion. Following the formation of the erosion surfaces and alteration processes, these processes drive chemical redistribution during weathering; particularly lateritisation and saprolitisation. Magnesium, silica, and trace elements such as nickel and cobalt—released as the dissolution front advances—are redistributed through the system. New observations and interpretations reveal how lateritic paleo-land surfaces evolved, and their temporal relationship with alteration processes since the Oligocene. Considering the geometry of discontinuity networks ranging from micro-fractures to faults, the transfers occur in dual-permeability environments. Olivine dissolution rates are heterogeneously due to differential solution renewal caused by erosion and valley deepening. Differential mass transfer occurs between mobile regions of highly transmissive faults, while immobile areas correspond to the rock matrix and the secondary fracture network. The progression of alteration fronts controls the formation of boulders and the distribution of nickel across multiple scales. In the saprolite, nickel reprecipitates mostly in talc-like phases, as well as minor nontronite and goethite with partial diffusion in inherited serpentine. The current nickel distribution results from a complex interplay of climatic, hydrological and structural factors integrated into a model across different scales and times. Full article

(This article belongs to the Special Issue Chemical Weathering Studies)

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8 pages, 1837 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Gypsum Crystals Formed by the Anhydrite–Gypsum Transformation at Low Temperatures: Implications for the Formation of the Geode of Pulpí

by Andrea Cotellucci, Juan-Manuel Garcia-Ruiz, Fermín Otálora, Àngels Canals, Marco Bruno, Quentin Wehrung, Luca Pellegrino, Dino Aquilano and Linda Pastero

Minerals 2024, 14(11), 1074; https://doi.org/10.3390/min14111074 - 25 Oct 2024

Viewed by 1945

Abstract

Determining the mechanisms of the formation of giant crystals is a challenging subject. Gypsum, calcium sulfate dihydrate (CaSO₄·2H₂O), is known to form crystals larger than one meter in several locations worldwide. These selenite crystals grow at different temperatures, either [...] Read more.

Determining the mechanisms of the formation of giant crystals is a challenging subject. Gypsum, calcium sulfate dihydrate (CaSO₄·2H₂O), is known to form crystals larger than one meter in several locations worldwide. These selenite crystals grow at different temperatures, either in sedimentary or hydrothermal systems. The famous selenite crystals of the geode of Pulpí (Almería, Spain) are known to have grown at a temperature T = 20 ± 5 °C and have been proposed to form in a subaqueous environment by a self-feeding mechanism triggered by anhydrite dissolution and the ripening of microcrystalline gypsum, enhanced by oscillations in temperature. This paper reports the monitored crystallization of gypsum crystals, from anhydrite powder dissolution, inside airtight evaporation-free reactors under oscillating low temperatures (15 °C < T < 25 °C). These crystals are clearly smaller than the ones in the Pulpí mine but exhibit similar habits (i.e., single blocky crystals and twins following the 100 twinning law). The growth rate of gypsum single crystals has been measured to be between 3.8 and 35.3 µm/day. Noteworthy, we document the occurrence of the 100 contact twinning law of gypsum, which is the most widespread twinning law in natural environments but never univocally reported in laboratory experiments. The selection of the 100 contact twinning law has been correlated to the low supersaturation values obtained in the experiment, where the concentration in these long-duration experiments can be safely assumed to be the equilibrium concentration, i.e., 0.3 (at 25 °C) ≤ SI ≤ 0.4 (at 15 °C). We discuss the relevance of our experiment for forming the gypsum crystals of Pulpí in the framework of the geological history of Pulpí mineralization. These laboratory model experiments contribute to a deeper understanding of mineral nucleation and growth processes in natural environments. Full article

(This article belongs to the Special Issue Gypsum Crystals: The Importance and the Role of Calcium Sulphate in Past and Modern Environments)

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16 pages, 5730 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Modeling and Hybrid Inversion of Mineral Deposits Using the Dipping Dike Model with Finite Depth Extent

by Saulo Pomponet Oliveira, Juarez dos Santos Azevedo, Joelson da Conceição Batista and Diego Menezes Novais

Minerals 2024, 14(10), 1054; https://doi.org/10.3390/min14101054 - 21 Oct 2024

Cited by 2 | Viewed by 1467

Abstract

The dipping dike model has shown to be a useful approximation for mineral deposits. To make this model more realistic, we include the thickness, which yields the depth to the bottom, as an additional parameter. The magnetic anomaly is obtained by combining the [...] Read more.

The dipping dike model has shown to be a useful approximation for mineral deposits. To make this model more realistic, we include the thickness, which yields the depth to the bottom, as an additional parameter. The magnetic anomaly is obtained by combining the anomalies of two infinite dikes, so that the resulting expression is simpler than the classical prismatic models with polygonal cross section. We employ a Metropolis-Hasting (MH) algorithm coupled with the Levenberg-Marquardt (LM) method to invert magnetic profiles assuming a model of multiple dike-like sources. We use a few iterations of the LM method to improve the candidate solutions at the end of each random walk generated by MH. The following parameters are obtained: depth to the top, thickness, half-width, horizontal location of the top center, geological dip, in addition to two effective parameters that depend on the intensity of magnetization and the directions of the induced and remanent fields. For synthetic anomalies, both noise-free and noisy magnetic data are considered, with examples presented for each scenario. These examples highlight the discrepancy between models with finite and infinite sources. They also illustrate the higher accuracy of the hybrid MH-LM method over the pure MH approach. Moreover, two field examples related to mineral exploration have been considered: the Pima copper mine, United States, where the relative differences between the parameters obtained by our algorithm and those known from drilling are not higher than 10%, and a magnetic profile over iron ore deposits located in Laje, northeast Brazil, where the inverted parameters were useful for detailing previous studies. Full article

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

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14 pages, 4268 KB

Open AccessFeature PaperEditor’s ChoiceArticle

‘Rhythmite’, Ca₂₉(SiO₄)₈Cl₂₆, an Anthropogenic Phase from the Chelyabinsk Coal Basin (Ural, Russia) with a Complex Modular Structure Related to α-Ca₃SiO₄Cl₂ (‘Albovite’): Crystal Structure, Raman Spectra, and Thermal Expansion

by Margarita S. Avdontceva, Andrey A. Zolotarev, Anastasia S. Brazhnikova, Vladimir N. Bocharov, Natalia S. Vlasenko, Mikhail A. Rassomakhin and Sergey V. Krivovichev

Minerals 2024, 14(10), 1048; https://doi.org/10.3390/min14101048 - 18 Oct 2024

Cited by 1 | Viewed by 1308

Abstract

‘Rhythmite’, Ca₂₉(SiO₄)₈Cl₂₆, an anthropogenic calcium chloride silicate from the Chelyabinsk coal basin (South Ural, Russia), was investigated using chemical microprobe analysis, in situ single-crystal X-ray diffraction analysis (27–727 °C), and Raman spectroscopy. ‘Rhythmite’ is orthorhombic, [...] Read more.

‘Rhythmite’, Ca₂₉(SiO₄)₈Cl₂₆, an anthropogenic calcium chloride silicate from the Chelyabinsk coal basin (South Ural, Russia), was investigated using chemical microprobe analysis, in situ single-crystal X-ray diffraction analysis (27–727 °C), and Raman spectroscopy. ‘Rhythmite’ is orthorhombic, Pnma: a = 17.0749(6), b = 15.1029(5), c = 13.2907(4) Å, and V = 3427.42(18) Å³ (R₁ = 0.045). The crystal structure of ‘rhythmite’ consists of a porous framework formed by Ca-O bonds and SiO₄ tetrahedra with additional Ca²⁺ cations and Cl⁻ anions in the structure interstices. The framework is built up from multinuclear [Ca₁₅(SiO₄)₄]¹⁴⁺ fundamental building blocks (FBBs) cut from the crystal structure of α-Ca₃SiO₄Cl₂ (‘albovite’). The FBBs are linked by sharing common Ca atoms to form a network with an overall pcu topology. The empirical chemical formula was calculated as Ca_29.02(Si_7.89Al_0.05P_0.05)_Ʃ7.99O₃₂Cl₂₆ (on the basis of Cl + O = 58). ‘Rhythmite’ is stable up to 627 °C and expands slightly anisotropically (α_max/α_min = 1.40) in the ab and bc planes and almost isotropically in the ac plane (α₃₃/α₁₁ = 1.02) with the following thermal expansion coefficients (×10⁶ °C⁻¹): α₁₁ = 14.6(1), α₂₂ = 20.5(4), α₃₃ = 15.0(3), and α_V = 50.1(6) (room temperature). During expansion, the silicate tetrahedra remain relatively rigid with average bond length changes of less than 0.5%. A structural complexity analysis indicates that ‘rhythmite’ is complex, with I_G,total = 920.313 (bits/u.c.), which significantly exceeds the average value of structural complexity for silicates and is caused by the modular framework construction and the presence of a large number of independent positions in the crystal structure. Full article

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

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19 pages, 15038 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Enhancing Iron Ore Grindability through Hybrid Thermal-Mechanical Pretreatment

by Sefiu O. Adewuyi, Hussin A. M. Ahmed, Angelina Anani, Abdu Saeed, Haitham M. Ahmed, Reem Alwafi and Kray Luxbacher

Minerals 2024, 14(10), 1027; https://doi.org/10.3390/min14101027 - 14 Oct 2024

Viewed by 1701

Abstract

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron [...] Read more.

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron ore grinding behavior. Thermal pretreatment was performed using conventional and microwave approaches, while mechanical pretreatment was conducted with a pressure device using a piston die. Results indicate that conventional (heating rate: 10 °C; maximum temperature: 400 °C), microwave (2.45 GHz, 1.7 kW, 60 s), and mechanical (14.86 MPa, zero delay time) pretreatments improved the studied iron ore grindability by 4.6, 19.8, and 15.4%, respectively. Meanwhile, conventional-mechanical and microwave-mechanical pretreatments enhanced the studied iron ore grindability by 19.2% and 22.6%, respectively. These results suggest that stand-alone mechanical pretreatment or microwave pretreatment may be more beneficial in improving the grinding behavior of the studied fine-grain iron ore sample. The results of the mechanical pretreatment obtained in this study may be used in a simulation of the HPGR system for grinding operations of similar iron ore Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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18 pages, 11767 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Aeschynite Group Minerals Are a Potential Recovery Target for Niobium Resources at the Giant Bayan Obo Nb–REE–Fe Deposit in China

by Bo Yang, Li Yang, Yong-Gang Zhao, Guo-Ying Yan, Jian-Yong Liu, Wen-Xiang Meng, Jun-Fang Yu, Lei Chen, Xiao-Chun Li and Xian-Hua Li

Minerals 2024, 14(10), 1029; https://doi.org/10.3390/min14101029 - 14 Oct 2024

Cited by 8 | Viewed by 2154

Abstract

With the development of the steel industry, China’s demand for niobium is increasing. However, domestic niobium resources are not yet stably supplied and are heavily dependent on imports from abroad (nearly 100%). It is urgent to develop domestic niobium resources. The Bayan Obo [...] Read more.

With the development of the steel industry, China’s demand for niobium is increasing. However, domestic niobium resources are not yet stably supplied and are heavily dependent on imports from abroad (nearly 100%). It is urgent to develop domestic niobium resources. The Bayan Obo deposit is the largest rare earth element deposit in the world and contains a huge amount of niobium resources. However, the niobium resource has not been exploited due to the fine-grained size and heterogeneous and scattered occurrences of Nb minerals. To promote the utilization of niobium resources in the Bayan Obo deposit, we focused on the mineralogical and geochemical characterization of six types of ores and mineral processing samples from the Bayan Obo deposit, using optical microscopes, EPMA, TIMA, and LA–ICP–MS. Our results show that: (1) the niobium mineral compositions are complex, with the main Nb minerals including aeschynite group minerals, columbite–(Fe), fluorcalciopyrochlore, Nb–bearing rutile, baotite, fergusonite–(Y), fersmite, and a small amount of samarskite–(Y). Aeschynite group minerals, columbite–(Fe), and fluorcalciopyrochlore are the main niobium-carrying minerals and should be the primary focus of industrial recycling and utilization. Based on mineralogical and geochemical investigation, the size of the aeschynite group minerals is large enough for mineral processing. Aeschynite group minerals are thus a significant potential recovery target for niobium, as well as for medium–heavy REE resources. The Nb–rich aegirine-type ores with aeschynite group mineral megacrysts are suggested to be the most significant niobium resource for mineral processing and prospecting. Combined with geological features, mining, and mineral processing, niobium beneficiation efforts of aeschynite group minerals are crucial for making breakthroughs in the utilization of niobium resources at the Bayan Obo. Full article

(This article belongs to the Special Issue Mineral Resources in North China Craton)

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15 pages, 9591 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of Steel and Poly Vinyl Alcohol Fibers on the Development of High-Strength Geopolymer Concrete

by Shaik Hussain, John Matthews, Sudhir Amritphale, Richard Edwards, Elizabeth Matthews, Niloy Paul and John Kraft

Minerals 2024, 14(10), 1007; https://doi.org/10.3390/min14101007 - 5 Oct 2024

Cited by 7 | Viewed by 1567

Abstract

The present study focuses on the mechanical performance of steel and polyvinyl alcohol fibers embedded in the geopolymer matrix. A high-strength geopolymer concrete with fly ash, slag and silica fume as precursors and sodium hydroxide and sodium silicate solutions as activators has been [...] Read more.

The present study focuses on the mechanical performance of steel and polyvinyl alcohol fibers embedded in the geopolymer matrix. A high-strength geopolymer concrete with fly ash, slag and silica fume as precursors and sodium hydroxide and sodium silicate solutions as activators has been tested for its strength in compression and flexure. The influence of fibers on flowability, long-term shrinkage and sulphuric acid attack on the geopolymer concrete has also been studied. The dosage of fibers was maintained at 1%, 2% and 3% by volume, and fibers of length 13 mm have been used in the study. Results indicate that slag with 3% steel fibers by volume had a predominant influence on the strength development of steel fiber-reinforced geopolymer concrete, yielding a compressive strength of 107 MPa after 28 days. Blast furnace slag resulted in increasing the shrinkage of concrete due to rapid gel formation owing to the presence of calcium ions, although the fibers helped reduce the shrinkage to some extent. The strength of steel fiber geopolymer concrete was superior to PVA fiber geopolymer concrete; however, after an acid attack, the strength of steel fiber geopolymer concrete was reduced more than PVA fiber geopolymer concrete due to the enhanced corrosion resistance of PVA fibers. Full article

(This article belongs to the Special Issue Geopolymers: Synthesis, Characterization and Application)

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31 pages, 15724 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Mineralogy and Geochemistry of Listvenite-Hosted Ni–Fe Sulfide Paragenesis—A Case Study from Janjevo and Melenica Listvenite Occurrences (Kosovo)

by Konrad Kluza, Jaroslav Pršek and Sławomir Mederski

Minerals 2024, 14(10), 1008; https://doi.org/10.3390/min14101008 - 5 Oct 2024

Cited by 1 | Viewed by 2762

Abstract

The main goal of this paper is to determine the order of the paragenetic sequence and phase transitions of the Ni–Fe sulfide association hosted in listvenites. Listvenites are hydrothermally altered mafic and ultramafic rocks that are often associated with active tectonic settings, such [...] Read more.

The main goal of this paper is to determine the order of the paragenetic sequence and phase transitions of the Ni–Fe sulfide association hosted in listvenites. Listvenites are hydrothermally altered mafic and ultramafic rocks that are often associated with active tectonic settings, such as transform faults, suture zones, and regional extensional faults, usually in contact with volcanic or carbonate rocks. Listvenitization is displayed by a carbonation process when the original olivine, pyroxene, and serpentine group minerals are altered to Mg–Fe–Ca carbonates (magnesite, calcite, dolomite, and siderite), talc, quartz, and accessory Cr spinel, fuchsite, and Ni–Fe sulfides. The formed rocks are highly reactive; therefore, very often, younger hydrothermal processes are observed, overprinting the mineralogy and geochemistry of the original listvenitization products, including accessory Ni–Fe sulfide paragenesis. The studied samples of listvenites were collected from two locations in Kosovo (Vardar Zone): Janjevo and Melenica. The Ni–Fe sulfide textures and relationships with the surrounding listvenite-hosted minerals were obtained using reflected and transmitted light microscopy, while their chemical composition was determined using an electron microprobe. They form accessory mono-or polymetallic aggregates that usually do not exceed 100 μm in size disseminated in the studied listvenites. Generally, the paragenetic sequence of Ni–Fe sulfides is divided into three stages. The first pre-listvenite magmatic phase is represented by pentlandite and millerite. The second listvenite stage consists of Ni–Co bearing pyrite I (Ni content up to 11.57 wt.% [0.24 apfu], and Co content up to 6.54 wt.% [0.14 apfu]) and differentiated thiospinels (violarite + siegenite ± polydymite). The last, late listvenite stage is represented by younger gersdorffite−ullmannite and base metal mineralization: pyrite + marcasite + sphalerite + galena ± chalcopyrite ± sulfosalts. The findings obtained should help in the interpretation of many disseminated accessory Ni–Fe–Co mineralizations associated with mafic and ultramafic rocks worldwide. Full article

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

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24 pages, 6021 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Analytical Techniques for Detecting Rare Earth Elements in Geological Ores: Laser-Induced Breakdown Spectroscopy (LIBS), MFA-LIBS, Thermal LIBS, Laser Ablation Time-of-Flight Mass Spectrometry, Energy-Dispersive X-ray Spectroscopy, Energy-Dispersive X-ray Fluorescence Spectrometer, and Inductively Coupled Plasma Optical Emission Spectroscopy

by Amir Fayyaz, Muhammad Aslam Baig, Muhammad Waqas and Usman Liaqat

Minerals 2024, 14(10), 1004; https://doi.org/10.3390/min14101004 - 2 Oct 2024

Cited by 8 | Viewed by 4829

Abstract

Rare earth elements (REEs) hold significant industrial, scientific, and modern technological worth. This study focused on detecting and quantifying REEs in various geological ore samples. These samples were collected from different REE-bearing locations recommended by geological experts. The analysis was conducted using laser-induced [...] Read more.

Rare earth elements (REEs) hold significant industrial, scientific, and modern technological worth. This study focused on detecting and quantifying REEs in various geological ore samples. These samples were collected from different REE-bearing locations recommended by geological experts. The analysis was conducted using laser-induced breakdown spectroscopy (LIBS) and laser ablation time-of-flight mass spectrometry (LA-TOF-MS). In this work, LIBS methodology was employed using three different configurations: standard LIBS, LIBS with an applied magnetic field, and LIBS with both an applied magnetic field and target sample heating within an optimal temperature range. Elements from the REE group, specifically lanthanum (La), cerium (Ce), and neodymium (Nd), were identified and quantified. To detect, quantify, and validate the results from LIBS and LA-TOF-MS, we utilized an array of analytical techniques—Energy-Dispersive X-ray Spectroscopy (EDX), Energy-Dispersive X-ray Fluorescence Spectrometer (ED-XRF), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Interestingly, the quantitative results for REEs (La, Ce, and Nd) in the ore samples obtained using the LIBS technique with various configurations were found to be in agreement with those from LA-TOF-MS, EDX, XRF, and ICP-OES. In addition, LIBS enables detailed microchemical imaging, allowing the map of the spatial distribution of elements within the mineral–ore matrix. The high-resolution microscale elemental mapping of REEs was accomplished using the emission lines Ce (II) at 446.0 nm, La (II) at 492.1 nm, and Nd (II) at 388.8 nm. By integrating multiple analytical techniques, our study enabled the construction of a complete elemental distribution map, providing new insights into the geochemical processes and mineral composition of rare earth ores, while advancing geochemistry and contributing valuable data for rare earth resource exploration. Full article

(This article belongs to the Special Issue Laser-Induced Breakdown Spectroscopy (LIBS) Applied to Determination of Rare Earth Elements and Critical Minerals)

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21 pages, 1691 KB

Open AccessFeature PaperEditor’s ChoiceReview

Ultrasonic Enhancement for Mineral Flotation: Technology, Device, and Engineering Applications

by Xiaoou Zhang, Huaigang Cheng, Kai Xu, Danjing Ding, Xin Wang, Bo Wang and Zhuohui Ma

Minerals 2024, 14(10), 986; https://doi.org/10.3390/min14100986 - 30 Sep 2024

Cited by 6 | Viewed by 3103

Abstract

In the past five years, the number of articles related to ultrasonic mineral flotation has increased by about 50 per year, and the overall trend is on the rise. The most recent developments in ultrasonics for flotation process intensification are reviewed herein, including [...] Read more.

In the past five years, the number of articles related to ultrasonic mineral flotation has increased by about 50 per year, and the overall trend is on the rise. The most recent developments in ultrasonics for flotation process intensification are reviewed herein, including effects of ultrasound treatment on an aqueous slurry, improvement in flotation methods and technological processes, device development tracking, and application effects in mineral process engineering. At this point in time, there are pilot-scale flotation tests to evaluate the feasibility of ultrasonic pretreatment technology for industrial use to enhance residue flotation separation, and the results showed that the recovery rate of concentrate is increased by about 10%. Four aspects of ultrasonic flotation process improvement are summarized, namely, changing the ultrasonic parameters, the synergistic effect of ultrasound and reagents, the ultrasonic effect of particles with different-sized fractions, and application to new systems. In addition, the effect of ultrasonic flotation mechanisms is explored through a quadratic model and numerical simulation. The combination of ultrasonic flotation with other fields, such as magnetic fields, to enhance the separation efficiency and recovery of minerals is also a future trend. It is also proposed that ultrasonic flotation technology will be used with big data, industrial Internet of Things, and automatic control technology to achieve deep bundling, optimizing the flotation process by implementing remote monitoring and control of the flotation process. Full article

(This article belongs to the Special Issue Industrial Minerals Flotation—Fundamentals and Applications)

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42 pages, 852 KB

Open AccessFeature PaperEditor’s ChoiceReview

Chiral Minerals

by David Avnir

Minerals 2024, 14(10), 995; https://doi.org/10.3390/min14100995 - 30 Sep 2024

Cited by 8 | Viewed by 3571

Abstract

Hundreds of minerals are chiral, that is, they appear in nature in two forms—left-handed and right-handed. Yet except for quartz, this key structural property has remained, by and large, in shadow in the world of minerals in research, in museum displays and for [...] Read more.

Hundreds of minerals are chiral, that is, they appear in nature in two forms—left-handed and right-handed. Yet except for quartz, this key structural property has remained, by and large, in shadow in the world of minerals in research, in museum displays and for collectors. This review is devoted to providing a full picture of chiral minerals in nature. It starts with a general outline of the crystallographic background needed for the characterization of chiral minerals, continues with a detailed description of the many chemical and physical processes leading to their formation and follows with their chemical reactivities and transformations, with their physical properties and with the ways to analyze and identify them. Many tables with listings of various types of chiral minerals are provided. The “missing-glove” situation, in which the recognition that a chiral mineral appears in nature in two distinctly forms is, by and large, missing, is described, and it is hoped that this review will spark interest in this aspect of nature’s crystals. Full article

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

22 pages, 9844 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Numerical Investigation of Heterogeneous Calcite Distributions in MICP Processes

by Lingxiang Wang, Yajie Chu, Xuerui Wang, Pengzhi Pan and Dianlei Feng

Minerals 2024, 14(10), 999; https://doi.org/10.3390/min14100999 - 30 Sep 2024

Cited by 2 | Viewed by 1366

Abstract

Microbially induced calcite precipitation (MICP) is a sustainable and environmentally friendly technology with applications in soil stabilization, concrete crack repair, and wastewater treatment. This study presents an improved Darcy-scale numerical model to simulate the MICP processes in heterogeneous porous media. It focuses on [...] Read more.

Microbially induced calcite precipitation (MICP) is a sustainable and environmentally friendly technology with applications in soil stabilization, concrete crack repair, and wastewater treatment. This study presents an improved Darcy-scale numerical model to simulate the MICP processes in heterogeneous porous media. It focuses on the effects of porosity heterogeneity, characterized by average porosity and correlation length, as well as injection strategies. Both average porosity and correlation length are critical factors influencing mass transport and calcite distribution during MICP treatment. An increase in average porosity leads to significant reductions in transport distance and total calcite mass. Notably, in the case of low averaged porosity, a larger correlation length results in more heterogeneous calcite distributions. However, there exists an upper threshold value of the initial averaged porosity (

ϕ_{0} = 0.45

) above which the heterogeneity of the calcite does not present clear dependence on the correlation length. Additionally, injection strategies significantly impact the consolidation effects. Compared to continuous injection, using the phased injection strategy can greatly improve the precipitated calcite area and mass due to its high utility and the efficiency of reactants. Full article

(This article belongs to the Special Issue Mineral Dissolution and Precipitation in Geologic Porous Media)

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20 pages, 6163 KB

Open AccessFeature PaperEditor’s ChoiceReview

Review on the Challenges of Magnesium Removal in Nickel Sulfide Ore Flotation and Advances in Serpentinite Depressor

by Fengxiang Yin, Chengxu Zhang, Yao Yu, Chenyang Lv, Zhengbo Gao, Bingang Lu, Xiaohui Su, Chunhua Luo, Xiangan Peng, Belinda McFadzean and Jian Cao

Minerals 2024, 14(10), 965; https://doi.org/10.3390/min14100965 - 25 Sep 2024

Cited by 9 | Viewed by 2034

Abstract

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in [...] Read more.

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in sulfide nickel ores, particularly serpentine, pose significant challenges to the flotation of nickel sulfide ores. The presence of magnesium silicate gangue leads to a series of issues, including increased energy consumption in subsequent smelting processes, accelerated equipment wastage, and increased SO₂ emissions, which severely impact the comprehensive utilization of nickel resources in sulfide nickel ores. In this regard, flotation depressants are the most direct and effective method to reduce adverse influences caused by magnesium silicate gangue in the flotation of nickel sulfide ore concentrate. Based on the characteristics of the typical magnesium-containing nickel sulfide ore, this review illustrates the difficulties of the depression of magnesium silicate gangue during the flotation of nickel sulfide ore and gives an overview of the common depressants from six aspects (chelation depressants, dispersion depressants, flocculation depressants, depressants for grinding, depressants for slurry adjustment and combination depressants). Each section summarizes the relevant depression mechanisms and analyzes the advantages and disadvantages of various reagents, providing a reference for designing depressants specifically targeting serpentine. Full article

(This article belongs to the Special Issue Selected Papers from the 7th International Conference of Young Scholars in Mineral Processing)

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18 pages, 3488 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Adsorption of Ciprofloxacin and Lidocaine by Non-Fibrous Raw Mg-Clays: The Role of Composition and Texture

by Maria Eugenia Roca-Jalil, Telma Musso, Vanina Rodriguez-Ameijide, Micaela Sanchez, Andrea Maggio, Miria Teresita Baschini, Gisela Pettinari, Luis Villa, Manuel Pozo and Alejandro Pérez-Abad

Minerals 2024, 14(10), 966; https://doi.org/10.3390/min14100966 - 25 Sep 2024

Cited by 1 | Viewed by 1340

Abstract

This study evaluated non-fibrous Mg-clays as potential adsorbents of emerging contaminants (ECs) from water. The materials were characterized, and their textural and structural properties were related to their ability to remove two model EC molecules: ciprofloxacin (CPX) and lidocaine (LID). The results showed [...] Read more.

This study evaluated non-fibrous Mg-clays as potential adsorbents of emerging contaminants (ECs) from water. The materials were characterized, and their textural and structural properties were related to their ability to remove two model EC molecules: ciprofloxacin (CPX) and lidocaine (LID). The results showed that Ad-6 and Ad-7 are mixed-layer kerolite/stevensite, while Ad-5 and Ad-8 are mainly composed of smectite minerals like stevensite and saponite, respectively. Ad-8 exhibited the highest CPX-adsorption capacity (0.91 mmol·g⁻¹ clay), likely due to its saponite content. Mixed-layer materials also performed well, with Ad-6 and Ad-7 achieving an adsorption capacity of 0.8 and 0.55 mmol·g⁻¹ clay, respectively. Adsorption studies suggested that CPX is adsorbed through ion exchange in materials with high smectite content (Ad-8 and Ad-5), while interstratified materials showed enhanced retention due to kerolite presence, which improves their porous structures. Similar findings were observed for LID, indicating a cationic-exchange mechanism for LID adsorption in all the materials and suggesting that the molecular size of the EC could regulate the removal capacity of these materials. This work showed that the studied Mg-clays could be effectively used for the removal of pharmaceutical pollutants, expanding their commercial possibilities. Full article

(This article belongs to the Special Issue Mineralogical and Geochemical Characterization of Geological Materials)

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15 pages, 4732 KB

Open AccessFeature PaperEditor’s ChoiceArticle

About the Origin of Carbonado

by Valentin Afanasiev, Vladimir Kovalevsky, Alexander Yelisseyev, Rudolf Mashkovtsev, Sergey Gromilov, Sargylana Ugapeva, Ekaterina Barabash, Oksana Ivanova and Anton Pavlushin

Minerals 2024, 14(9), 927; https://doi.org/10.3390/min14090927 - 11 Sep 2024

Viewed by 4125

Abstract

Carbonado is a specific variety of diamonds, typical representatives of which are distributed in the diamond placers of Central Africa, Brazil, and Venezuela. Carbonado consists of the microcrystalline aggregates of diamonds, with inclusions of mineral matter. These aggregates appear as fragments that are [...] Read more.

Carbonado is a specific variety of diamonds, typical representatives of which are distributed in the diamond placers of Central Africa, Brazil, and Venezuela. Carbonado consists of the microcrystalline aggregates of diamonds, with inclusions of mineral matter. These aggregates appear as fragments that are rounded to varying degrees. Carbonado has been known for a long time, but its primary sources have not been found and its genesis remains unclear. We have substantiated the hypothesis that the most probable precursor of carbonado is shungite. Shungite is a specific form of non-crystalline, non-graphitic, fullerene-like carbon. Shungite rocks, currently known in Karelia (Russia), are natural microdispersed composite materials containing shungite—carbonaceous matter and mineral components of different compositions. The content of carbonaceous matter in shungite rocks is from less than 10% to 98%. The carbon isotopic composition of shungite is light ẟ¹³C from −25‰ to −40‰. The age of shungite rock is more than 2 billion years old, but earlier shungite was probably much more widespread. Known shungite rocks are more than 2 billion years old, but earlier shungite was probably much more widespread. Shungite rocks could recrystallize into diamond rock upon subduction to high pressure and temperature. The diamond rocks could then be exhumed to the Earth’s surface, where they could undergo disruption and reworking with formation of those very fragments that are known as “carbonado”. Full article

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

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20 pages, 12039 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Innovative Seismic Imaging of the Platinum Deposits, Maseve Mine: Surface and In-Mine

by Moyagabo Rapetsoa, Musa Manzi, Ian James, Mpofana Sihoyiya, Raymond Durrheim and Michelle Pienaar

Minerals 2024, 14(9), 913; https://doi.org/10.3390/min14090913 - 6 Sep 2024

Cited by 4 | Viewed by 4586

Abstract

Maseve Mine is located in the western limb of the Bushveld Complex, recognized as the largest layered igneous intrusion in the world. The study shows results from surface (SP1, SP2, and SP3) and tunnel (T3a, T3b, and TP4b) reflection seismic profiles, totaling 4150 [...] Read more.

Maseve Mine is located in the western limb of the Bushveld Complex, recognized as the largest layered igneous intrusion in the world. The study shows results from surface (SP1, SP2, and SP3) and tunnel (T3a, T3b, and TP4b) reflection seismic profiles, totaling 4150 m. Tunnel seismic data were acquired using a seismic landstreamer and spiked geophones with 5 m receiver and shot spacing, as well as a sledgehammer for shots due to space constraints and safety. The profiles, 10–50 m above mineral deposits, crossed major geological structures. Surface seismic profiles used cabled systems and wireless sensors with 5 m and 10 m receiver spacing, respectively, and a 500 kg drop hammer as a source with 10 m shot spacing. Despite high noise levels from mine infrastructure and power cables, a careful processing workflow enhanced target reflections. Interpretation was constrained using borehole data, geological models, and 2D/3D seismic modeling. The processed data exhibit gently dipping reflections associated with faults and dykes, imaging the target mineralization (Merensky Reef and Upper Group 2) and a possible extension. Tunnel seismic experiments demonstrated the application of seismic methods using in-mine infrastructure, while surface experiments proved efficient, illustrating small-scale seismic surveys’ capability to image the subsurface, adding value in active mining environments for exploration with cost-effective seismic equipment. Full article

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

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22 pages, 7448 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Dissolution Mechanisms and Surface Charge of Clay Mineral Nanoparticles: Insights from Kinetic Monte Carlo Simulations

by Inna Kurganskaya

Minerals 2024, 14(9), 900; https://doi.org/10.3390/min14090900 - 2 Sep 2024

Cited by 2 | Viewed by 1816

Abstract

The widespread use of clay minerals and clays in environmental engineering, industry, medicine, and cosmetics largely stems from their adsorption properties and surface charge, as well as their ability to react with water. The dissolution and growth of minerals as a function of [...] Read more.

The widespread use of clay minerals and clays in environmental engineering, industry, medicine, and cosmetics largely stems from their adsorption properties and surface charge, as well as their ability to react with water. The dissolution and growth of minerals as a function of pH are closely related to acid–base reactions at their surface sites and their surface charge. The vivid tapestry of different types of surface sites across different types of clay minerals generates difficulties in experimental studies of structure–property relationships. The aim of this paper is to demonstrate how a mesoscale stochastic kinetic Monte Carlo (kMC) approach altogether with atomistic acid-base models and empirical data can be used for understanding the mechanisms of dissolution and surface charge behavior of clay minerals. The surface charge is modeled based on equilibrium equations for de/protonated site populations, which are defined by the pH and site-specific acidity constants (pK_as). Lowered activation energy barriers for these sites in de/protonated states introduce pH-dependent effects into the dissolution kinetics. The V-shaped curve observed in laboratory experiments is reproduced with the new kMC model. A generic rate law for clay mineral dissolution as a function of pH is derived from this study. Thus, the kMC approach can be used as a hypothesis-testing tool for the verification of acid–base models for clay and other minerals and their influence on the kinetics of mineral dissolution and growth. Full article

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

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21 pages, 5593 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Moment Estimation from Time Domain Electromagnetic Data

by Marc A. Vallée and Mouhamed Moussaoui

Minerals 2024, 14(9), 888; https://doi.org/10.3390/min14090888 - 30 Aug 2024

Cited by 1 | Viewed by 1501

Abstract

Moment representations have been proposed to facilitate the interpretation of geophysical time domain electromagnetic responses. We present a new methodology for estimating these moments from field data for different system waveforms when on-time and off-time measurements are available. Quadrature impulse response moments are [...] Read more.

Moment representations have been proposed to facilitate the interpretation of geophysical time domain electromagnetic responses. We present a new methodology for estimating these moments from field data for different system waveforms when on-time and off-time measurements are available. Quadrature impulse response moments are estimated by a recursive relation involving moments of the input waveform and moments of the observed response. After adapting this method to time domain electromagnetic applications—in particular, MEGATEM and AeroTEM (AirTEM) airborne electromagnetic systems—we present the results from applying this method on synthetic and real data collected over the Reid–Mahaffy test site in northern Ontario, Canada. Full article

(This article belongs to the Special Issue Advances in Magnetic and Electromagnetic Techniques for Mineral Exploration: Enhancing Resource Discovery)

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32 pages, 7574 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Source Rock Assessment of the Permian to Jurassic Strata in the Northern Highlands, Northwestern Jordan: Insights from Organic Geochemistry and 1D Basin Modeling

by Dina Hamdy, Sherif Farouk, Abdelrahman Qteishat, Fayez Ahmad, Khaled Al-Kahtany, Thomas Gentzis, Luigi Jovane and Amr S. Zaky

Minerals 2024, 14(9), 863; https://doi.org/10.3390/min14090863 - 25 Aug 2024

Cited by 6 | Viewed by 2704

Abstract

The present study focused on the Permian to Jurassic sequence in the Northern Highlands area, NW Jordan. The Permian to Jurassic sequence in this area is thick and deeply buried, consisting mainly of carbonate intercalated with clastic shale. This study integrated various datasets, [...] Read more.

The present study focused on the Permian to Jurassic sequence in the Northern Highlands area, NW Jordan. The Permian to Jurassic sequence in this area is thick and deeply buried, consisting mainly of carbonate intercalated with clastic shale. This study integrated various datasets, including total organic carbon (TOC, wt%), Rock-Eval pyrolysis, visual kerogen examination, gross composition, lipid biomarkers, vitrinite reflectance (VRo%), and bottom-hole temperature measurements. The main aim was to investigate the source rock characteristics of these strata regarding organic richness, kerogen type, depositional setting, thermal maturity, and hydrocarbon generation timing. The Permian strata are poor to fair source rocks, primarily containing kerogen type (KT) III. They are immature in the AJ-1 well and over-mature in the NH-2 well. The Upper Triassic strata are poor source rocks in the NH-1 well and fair to marginally good source rocks in the NH-2 well, containing highly mature terrestrial KT III. These strata are immature to early mature in the AJ-1 well and at the peak oil window stage in the NH-2 well. The Jurassic strata are poor source rocks, dominated by KT III and KT II-III. They are immature to early mature in the AJ-1 well and have reached the oil window in the NH-2 well. Biomarker-related ratios indicate that the Upper Triassic oils and Jurassic samples are source rocks that received mainly terrestrial organic input accumulated in shallow marine environments under highly reducing conditions. These strata are composed mostly of clay-rich lithologies with evidence of deposition in hypersaline and/or stratified water columns. 1D basin models revealed that the Upper Triassic strata reached the peak oil window from the Early Cretaceous (~80 Ma) to the present day in the NH-1 well and from ~130 Ma (Early Cretaceous) to ~90 Ma (Late Cretaceous) in the NH-2 well, with the late stage of hydrocarbon generation continuing from ~90 Ma to the present time. The present-day transformation ratio equals 77% in the Upper Triassic source rocks, suggesting that these rocks have expelled substantial volumes of hydrocarbons in the NH-2 well. To achieve future successful hydrocarbon discoveries in NW Jordan, accurate seismic studies and further geochemical analyses are recommended to precisely define the migration pathways. Full article

(This article belongs to the Special Issue Environmental Geochemistry and Mineralogy: Application for Hydrocarbon Exploration and Ore Deposits)

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45 pages, 22848 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Syn-Sedimentary Exhalative or Diagenetic Replacement? Multi-Proxy Evidence for Origin of Metamorphosed Stratiform Barite–Sulfide Deposits near Aberfeldy, Scottish Highlands

by Norman R. Moles, Adrian J. Boyce, Matthew R. Warke and Mark W. Claire

Minerals 2024, 14(9), 865; https://doi.org/10.3390/min14090865 - 25 Aug 2024

Cited by 3 | Viewed by 2359

Abstract

Bedded barite, Fe-Zn-Pb sulfides, carbonates, and cherts within Ediacaran (Dalradian Supergroup) graphitic metasediments near Aberfeldy in Scotland have previously been interpreted as chemical sediments precipitated from hydrothermal fluids episodically exhaled into marine basins filled with organic-rich mud, silt, and sand. Lithological variation and [...] Read more.

Bedded barite, Fe-Zn-Pb sulfides, carbonates, and cherts within Ediacaran (Dalradian Supergroup) graphitic metasediments near Aberfeldy in Scotland have previously been interpreted as chemical sediments precipitated from hydrothermal fluids episodically exhaled into marine basins filled with organic-rich mud, silt, and sand. Lithological variation and compositional diversity in pyrite and sphalerite reflect varied redox environments and proximity to hydrothermal discharges. Thick beds (>2 m) of barite have relatively uniform δ³⁴S of +36 ± 1.5‰, considered to represent contemporaneous seawater sulfate, as negative Δ¹⁷O indicates incorporation of atmospheric oxygen during precipitation in the water column. However, certain features suggest that diagenetic processes involving microbial sulfate reduction modified the mineralogy and isotopic composition of the mineralization. Barite bed margins show decimeter-scale variation in δ³⁴S (+32 to +41‰) and δ¹⁸O (+8 to +21‰), attributed to fluid-mediated transfer of dissolved barium and sulfate between originally porous barite and adjacent sediments, in which millimetric sulfate crystals grew across sedimentary lamination. Encapsulated micron-sized barium carbonates indicate early diagenetic barite dissolution with incorporation of sulfur into pyrite, elevating pyrite δ³⁴S. Subsequently, sulfidation reactions produced volumetrically minor secondary barite with δ³⁴S of +16 to +22‰. Overall, these processes affected small volumes of the mineralization, which originally formed on the seafloor as a classic SEDEX deposit. Full article

(This article belongs to the Special Issue Stratabound Barite Deposits: Mineralogy, Isotope Geochemistry and Geochronology)

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31 pages, 7774 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Monchegorsk Mafic–Ultramafic Layered PGE-Bearing Complex (2.5 Ga, Kola Region, Russia): On the Problem of Relationships between Magmatic Phases Based on the Study of Cr-Spinels

by Pavel Pripachkin, Tatiana Rundkvist, Artem Mokrushin and Aiya Bazai

Minerals 2024, 14(9), 856; https://doi.org/10.3390/min14090856 - 24 Aug 2024

Viewed by 1170

Abstract

The composition of Cr-spinels from rocks of the Monchegorsk layered complex (2.5 Ga) basically corresponds to the evolutionary trend that is typical for layered mafic–ultramafic intrusions (late magmatic phases contain Cr-spinels enriched in Fe and depleted in Mg, Cr, and Al). Cr-spinels within [...] Read more.

The composition of Cr-spinels from rocks of the Monchegorsk layered complex (2.5 Ga) basically corresponds to the evolutionary trend that is typical for layered mafic–ultramafic intrusions (late magmatic phases contain Cr-spinels enriched in Fe and depleted in Mg, Cr, and Al). Cr-spinels within the Dunite Body of the Sopcha massif are almost identical to those within the Dunite Block rocks and are close to those from harzburgite of the NKT massif. Cr-spinels within the satellite bodies of the Ore Layer 330 are shown to have zonal structure, which confirms their origin from a new portion of melt, which may have been injected with several pulses. The composition of accessory Cr-spinels may indicate that the layered complex of rocks of the South Sopcha massif was formed from the most evolved portion of magmatic melt (linked with the Monchetundra intrusion), and its vein complex may be considered the one formed at the final stages of the magmatic system evolution. The composition of Cr-spinels from the Pentlandite Gorge mafic–ultramafic rocks may indicate that they are fragments of the NKT massif and not of the Monchetundra massif, as it was believed earlier. Full article

(This article belongs to the Section Mineral Deposits)

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39 pages, 3652 KB

Open AccessFeature PaperEditor’s ChoiceReview

Coal and Coal By-Products as Unconventional Lithium Sources: A Review of Occurrence Modes and Hydrometallurgical Strategies for Metal Recovery

by Ewa Rudnik

Minerals 2024, 14(8), 849; https://doi.org/10.3390/min14080849 - 22 Aug 2024

Cited by 9 | Viewed by 3912

Abstract

Lithium, a critical material for the global development of green energy sources, is anomalously enriched in some coal deposits and coal by-products to levels that may be considered economically viable. Recovering lithium from coal, particularly from coal gangue or coal ashes, offers a [...] Read more.

Lithium, a critical material for the global development of green energy sources, is anomalously enriched in some coal deposits and coal by-products to levels that may be considered economically viable. Recovering lithium from coal, particularly from coal gangue or coal ashes, offers a promising alternative for extracting this element. This process could potentially lead to economic gains and positive environmental impacts by more efficiently utilizing coal-based waste materials. This review focuses on lithium concentrations in coal and coal by-products, modes of lithium occurrence, methods used to identify lithium-enriched phases, and currently available hydrometallurgical recovery methods, correlated with pretreatment procedures that enable lithium release from inert aluminosilicate minerals. Leaching of raw coal appears inefficient, whereas coal gangue and fly ash are more feasible due to their simpler composition and higher lithium contents. Lithium extraction can achieve recovery rates of over 90%, but low lithium concentrations and high impurity levels in the leachates require advanced selective separation techniques. Bottom ash has not yet been evaluated for lithium recovery, despite its higher lithium content compared to feed coal. Full article

(This article belongs to the Special Issue Beneficiation and Extraction of Critical Metals from Ores and Secondary Resources)

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23 pages, 3689 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Gypsum on Mars: A Detailed View at Gale Crater

by David Vaniman, Steve Chipera, Elizabeth Rampe, Thomas Bristow, David Blake, Johannes Meusburger, Tanya Peretyazhko, William Rapin, Jeff Berger, Douglas Ming, Patricia Craig, Nicholas Castle, Robert T. Downs, Shaunna Morrison, Robert Hazen, Richard Morris, Aditi Pandey, Allan H. Treiman, Albert Yen, Cherie Achilles, Benjamin Tutolo, Elisabeth Hausrath, Sarah Simpson, Michael Thorpe, Valerie Tu, David J. Des Marais, John Grotzinger and Abigail Fraeman Show full author list Hide full author list

Minerals 2024, 14(8), 815; https://doi.org/10.3390/min14080815 - 12 Aug 2024

Cited by 10 | Viewed by 4042

Abstract

Gypsum is a common mineral at Gale crater on Mars, currently being explored by the Mars Science Laboratory (MSL) rover, Curiosity. In this paper, we summarize the associations of gypsum with other sulfate minerals (bassanite, anhydrite, jarosite, starkeyite, and kieserite) from the [...] Read more.

Gypsum is a common mineral at Gale crater on Mars, currently being explored by the Mars Science Laboratory (MSL) rover, Curiosity. In this paper, we summarize the associations of gypsum with other sulfate minerals (bassanite, anhydrite, jarosite, starkeyite, and kieserite) from the lowest levels of the crater’s northern moat zone (Aeolis Palus) up through ~0.8 km of the stratigraphic section in the lower slopes of the sedimentary mound developed around the central peak, Aeolis Mons (informally, Mount Sharp). The analysis is based on results from the CheMin X-ray diffraction instrument on Curiosity, supplemented with information from the rover’s versatile instrument suite. Gypsum does not occur with the same frequency as less hydrous Ca-sulfates, likely, in most cases, because of its dehydration to bassanite and possibly to anhydrite. All three of these Ca-sulfate phases often occur together and, along with other sulfates, in mixed assemblages that are evidence of limited equilibration on a cold, dry planet. In almost all samples, at least one of the Ca-sulfate minerals is present, except for a very limited interval where jarosite is the major sulfate mineral, with the implication of more acidic groundwater at a much later time in Gale crater’s history. Although observations from orbit reveal a sulfate-rich surface, currently active dark basaltic dunes at Gale crater have only small amounts of a single sulfate mineral, anhydrite. Gale crater has provided the most complete mineralogical analysis of a site on Mars so far, but the data in hand show that Gale crater mineralogy is not a blueprint with planet-wide application. The concurrent study of Jezero crater by the Mars 2020 mission and comparisons to what is believed to be the most extensive deposit of gypsum on Mars, in the dune fields at the north polar ice cap, show significant diversity. Unraveling the stories of gypsum and other sulfates on Mars is just beginning. Full article

(This article belongs to the Special Issue Gypsum Crystals: The Importance and the Role of Calcium Sulphate in Past and Modern Environments)

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22 pages, 5061 KB

Open AccessFeature PaperEditor’s ChoiceArticle

A Protocol for Electron Probe Microanalysis (EPMA) of Monazite for Chemical Th-U-Pb Age Dating

by Bernhard Schulz, Joachim Krause and Wolfgang Dörr

Minerals 2024, 14(8), 817; https://doi.org/10.3390/min14080817 - 12 Aug 2024

Cited by 4 | Viewed by 2659

Abstract

A protocol for the monazite (LREE,Y,Th,U,Si,Ca)PO₄ in situ Th-U-Pb dating by electron probe microanalyser (EPMA) involves a suitable reference monazite. Ages of several potential reference monazites were determined by TIMS-U-Pb isotope analysis. The EPMA protocol is based on calibration with REE-orthophosphates and [...] Read more.

A protocol for the monazite (LREE,Y,Th,U,Si,Ca)PO₄ in situ Th-U-Pb dating by electron probe microanalyser (EPMA) involves a suitable reference monazite. Ages of several potential reference monazites were determined by TIMS-U-Pb isotope analysis. The EPMA protocol is based on calibration with REE-orthophosphates and a homogeneous Th-rich reference monazite at beam conditions of 20 kV, 50 nA, and 5 µm for best possible matrix matches and avoidance of dead time bias. EPMA measurement of samples and repeated analysis of the reference monazite are performed at beam conditions of 20 kV, 100 nA, and 5 µm. Analysis of Pb and U on a PETL crystal requires YLg-on-PbMa and ThMz-on-UMb interference corrections. Offline re-calibration of the Th calibration on the Th-rich reference monazite, to match its nominal age, is an essential part of the protocol. EPMA-Th-U-Pb data are checked in ThO₂*-PbO coordinates for matching isochrones along regressions forced through zero. Error calculations of monazite age populations are performed by weighted average routines. Depending on the number of analyses and spread in ThO₂*-PbO coordinates, minimum errors <10 Ma are possible and realistic for Paleozoic monazite ages. A test of the protocol was performed on two garnet metapelite samples from the Paleozoic metamorphic Zone of Erbendorf-Vohenstrauß (NE-Bavaria, western Bohemian Massif). Full article

(This article belongs to the Special Issue In-Situ Microanalytical Techniques in Geological and Geochronological Research)

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14 pages, 3452 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Influence of Pore Water Chemistry on Particle Association and Physical Properties of Lime-Treated Bentonite

by Enza Vitale, Dimitri Deneele and Giacomo Russo

Minerals 2024, 14(8), 795; https://doi.org/10.3390/min14080795 - 2 Aug 2024

Cited by 2 | Viewed by 1155

Abstract

In the present work, an investigation on the influence of the chemical environment on the sedimentation behaviour of bentonite suspensions is performed with particular reference to the effect of lime addition on the clay particle arrangement. The role of lime content, cation valence [...] Read more.

In the present work, an investigation on the influence of the chemical environment on the sedimentation behaviour of bentonite suspensions is performed with particular reference to the effect of lime addition on the clay particle arrangement. The role of lime content, cation valence and source of calcium ions is considered in the experimental work. At the microscale, particle interaction is analysed by means of zeta potential measurements. Soil fabric formation during sedimentation and its physical properties are inferred from dynamic light scattering measurements, sedimentation tests and Atterberg limits. The addition of cations to pore water promotes the flocculation of montmorillonite particles favouring the formation of particle aggregates, whose dimension depends on ion valence and concentration. The final height of sediments reflects the combined effect of the mutual interactions among particles and the development of secondary phases due to pozzolanic reactions. The influence of clay mineralogy and its effects on the physical properties of lime-treated bentonite is highlighted by comparison with experimental evidence on lime-treated kaolin. Full article

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

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25 pages, 3020 KB

Open AccessFeature PaperEditor’s ChoiceReview

Exploring Low-Grade Iron Ore Beneficiation Techniques: A Comprehensive Review

by Mompati Mpho Bulayani, Prasad Raghupatruni, Tirivaviri Mamvura and Gwiranai Danha

Minerals 2024, 14(8), 796; https://doi.org/10.3390/min14080796 - 2 Aug 2024

Cited by 19 | Viewed by 9138

Abstract

The beneficiation of low-grade iron ores is a key research and development topic in the mineral processing industry. The gradual exhaustion of high-grade iron ore reserves, and rising consumer iron and steel demand globally necessitate efficient low-quality iron ore beneficiation to meet steelmaking [...] Read more.

The beneficiation of low-grade iron ores is a key research and development topic in the mineral processing industry. The gradual exhaustion of high-grade iron ore reserves, and rising consumer iron and steel demand globally necessitate efficient low-quality iron ore beneficiation to meet steelmaking quality requirements. This comprehensive review explores various beneficiation techniques for low-quality iron ore, focusing on conventional methods including comminution, froth flotation and gravity separation. This article discusses the principles, processes, and equipment used in these techniques and highlights recent advancements and research efforts in the field. This review also emphasizes the importance of effective beneficiation processes in enhancing economic viability, sustainable resource management, and environmental conservation. Furthermore, it presents a case study of iron ore deposits in Botswana, highlighting the potential economic growth and sustainable development that can be achieved by maximizing resource utilization through reductive roasting, followed by magnetic separation of iron ore using semi-bituminous coal as a reductant. Overall, this review provides valuable insights into low-grade iron ore beneficiation techniques and their significance in meeting the growing demand for high-quality iron and steel products. Full article

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

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19 pages, 8127 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Key Technologies for Surface-Borehole Transient Electromagnetic Systems and Applications

by Qingming Guo, Yurong Mao, Liangjun Yan, Wenhui Chen, Jupeng Yang, Xingbing Xie, Lei Zhou and Haojin Li

Minerals 2024, 14(8), 793; https://doi.org/10.3390/min14080793 - 31 Jul 2024

Cited by 3 | Viewed by 1919

Abstract

The nonferrous metal mines in China are rapidly depleting due to years of mining, and it has become difficult to identify new mineral resources in the periphery of the old mining area. In order to deal with this situation, advanced technologies and equipment [...] Read more.

The nonferrous metal mines in China are rapidly depleting due to years of mining, and it has become difficult to identify new mineral resources in the periphery of the old mining area. In order to deal with this situation, advanced technologies and equipment must be deployed. The borehole transient electromagnetic method (TEM) has become a key technology due to its deep investigative capabilities within conductive geological structures. In the present study, in order to meet the exploration needs at depths of less than 3000 m, surface-borehole TEM exploration was used to analyze the characteristics of electromagnetic signals generated by a long wire source and a large loop source, providing essential data for the development of key technologies, such as sensor parameter design and signal gain optimization of the TEM system in the borehole. This study discussed in detail two key technical problems as follows: firstly, the efficient synchronization mechanism between the ground transmitter system and the borehole electromagnetic signal acquisition system ensured the accuracy and timeliness of data acquisition; and secondly, the realization of mass storage technology, which effectively solved the problem of mass storage and real-time transmission of data in a deep borehole environment. The effectiveness of the surface-borehole TEM systems with a long wire source and a large loop source was verified by tests in real mines. The surface-borehole electromagnetic signal acquisition system developed in this study effectively collected electromagnetic signals in the borehole, and the results accurately reflected the stratigraphic information of mineral resources in the study area. This study can pave a new technical path for the exploration of deep and peripheral areas of non-ferrous metal mines and provide valuable experience and insights for mineral resource exploration in similarly complex geological environments. Full article

(This article belongs to the Special Issue Geophysical Signatures of Mineral Deposits in Tropical and Subtropical Settings)

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39 pages, 3950 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Expanded Insights into Martian Mineralogy: Updated Analysis of Gale Crater’s Mineral Composition via CheMin Crystal Chemical Investigations

by Shaunna M. Morrison, David F. Blake, Thomas F. Bristow, Nicholas Castle, Steve J. Chipera, Patricia I. Craig, Robert T. Downs, Ahmed Eleish, Robert M. Hazen, Johannes M. Meusburger, Douglas W. Ming, Richard V. Morris, Aditi Pandey, Anirudh Prabhu, Elizabeth B. Rampe, Philippe C. Sarrazin, Sarah L. Simpson, Michael T. Thorpe, Allan H. Treiman, Valerie Tu, Benjamin M. Tutolo, David T. Vaniman, Ashwin R. Vasavada and Albert S. Yen Show full author list Hide full author list

Minerals 2024, 14(8), 773; https://doi.org/10.3390/min14080773 - 29 Jul 2024

Cited by 12 | Viewed by 3812

Abstract

This study presents mineral composition estimates of rock and sediment samples analyzed with the CheMin X-ray diffraction instrument on board the NASA Mars Science Laboratory rover, Curiosity, in Gale crater, Mars. Mineral composition is estimated using crystal-chemically derived algorithms applied to X-ray [...] Read more.

This study presents mineral composition estimates of rock and sediment samples analyzed with the CheMin X-ray diffraction instrument on board the NASA Mars Science Laboratory rover, Curiosity, in Gale crater, Mars. Mineral composition is estimated using crystal-chemically derived algorithms applied to X-ray diffraction data, specifically unit-cell parameters. The mineral groups characterized include those found in major abundance by the CheMin instrument (i.e., feldspar, olivine, pyroxene, and spinel oxide). In addition to estimating the composition of the major mineral phases observed in Gale crater, we place their compositions in a stratigraphic context and provide a comparison to that of martian meteorites. This work provides expanded insights into the mineralogy and chemistry of the martian surface. Full article

(This article belongs to the Special Issue Mineralogy and Geochemistry of Mars: Everything You Need to Know about the Red Planet)

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15 pages, 2881 KB

Open AccessFeature PaperEditor’s ChoiceArticle

In Search of Phytoremediation Candidates: Eu(III) Bioassociation and Root Exudation in Hydroponically Grown Plants

by Max Klotzsche, Viktor Dück, Björn Drobot, Manja Vogel, Johannes Raff, Thorsten Stumpf and Robin Steudtner

Minerals 2024, 14(8), 754; https://doi.org/10.3390/min14080754 - 26 Jul 2024

Cited by 1 | Viewed by 1205

Abstract

Lanthanides and actinides are emerging contaminants, but little is known about their uptake and distribution by plants and their interactions in the rhizosphere. To better understand the fate of these metals in plants, the bioassociation of 2, 20 and 200 µM Eu(III) by [...] Read more.

Lanthanides and actinides are emerging contaminants, but little is known about their uptake and distribution by plants and their interactions in the rhizosphere. To better understand the fate of these metals in plants, the bioassociation of 2, 20 and 200 µM Eu(III) by five hydroponically grown crops endemic to Europe was assessed. The metal’s concentration and its speciation were monitored by inductively coupled plasma mass spectrometry and laser spectroscopy, whereas root exudation was investigated by chromatographic methods. It has been shown, that Eu(III) bioassociation is a two-stage process, involving rapid biosorption followed by accumulation in root tissue and distribution to the stem and leaves. Within 96 h of exposure time, the plant induces a change of Eu(III) speciation in the liquid medium, from a predominant Eu(III)aquo species, as calculated by thermodynamic modelling, to a species with longer luminescence lifetime. Root exudates such as citric, malic, and fumaric acid were identified in the cultivation medium and affect Eu(III) speciation in solution, as was shown by a change in the thermodynamic model. These results contribute to a comprehensive understanding of the fate of lanthanides in the biosphere and provide a basis for further investigations with the chemical analogues Cm(III) and Am(III). Full article

(This article belongs to the Special Issue Radionuclide Interactions with Natural and Synthetic Solids)

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14 pages, 4332 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Impacts of Impurity Removal Chemical Pretreatment Procedures on the Composition and Adsorption Properties of Bentonites

by Tatiana Koroleva, Victoria Krupskaya, Ekaterina Tyupina, Ivan Morozov, Pavel Kozlov, Boris Pokidko, Sergey Zakusin and Tatiana Zaitseva

Minerals 2024, 14(8), 736; https://doi.org/10.3390/min14080736 - 23 Jul 2024

Cited by 2 | Viewed by 1936

Abstract

This work is based on a detailed study of samples from three industrial bentonite deposits in Russia (10th Khutor, Zyryanskoe) and Kazakhstan (Taganskoe). The samples of the listed bentonites were undergoing stage-by-stage purification from carbonates, organic matter, and non-clay iron-bearing phase procedures. The [...] Read more.

This work is based on a detailed study of samples from three industrial bentonite deposits in Russia (10th Khutor, Zyryanskoe) and Kazakhstan (Taganskoe). The samples of the listed bentonites were undergoing stage-by-stage purification from carbonates, organic matter, and non-clay iron-bearing phase procedures. The conducted research revealed changes in the composition of bentonites already at the first stage of purification, which, however, were not noted for all bentonites, as well as a change in the forms of Fe in smectite structure. The latter is probably associated with changes in cis- and trans-vacant positions. Sorption characteristics with respect to ¹³⁷Cs are determined using the localization and charges in the smectite layer and the slight changes during purification, along with the specific surface area indicators. Full article

(This article belongs to the Special Issue Adsorption Properties and Environmental Applications of Clay Minerals)

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13 pages, 4021 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Accuracy and Precision of the Geopyörä Breakage Test

by Marcos Bueno, Thiago Almeida, Leonardo Lara, Malcolm Powell and Homero Delboni

Minerals 2024, 14(8), 738; https://doi.org/10.3390/min14080738 - 23 Jul 2024

Cited by 1 | Viewed by 1335

Abstract

The Geopyörä breakage test uses two counter-rotating wheels to nip and crush rock specimens with a tightly controlled gap between rollers. This paper presents the detailed measures conducted to evaluate the accuracy and precision of energy measurements across various ore types using the [...] Read more.

The Geopyörä breakage test uses two counter-rotating wheels to nip and crush rock specimens with a tightly controlled gap between rollers. This paper presents the detailed measures conducted to evaluate the accuracy and precision of energy measurements across various ore types using the Geopyörä. Force measurement was assessed just for its precision. The outputs were compared directly to the drop weight test (DWT) measures of fragmentation at the same energy and fitted A and b parameters. Test reproducibility was evaluated using a Round-Robin methodology, testing several samples in multiple laboratories. The results confirmed that the new test has sufficient accuracy to match DWT results and excellent precision to assure reproducibility. Full article

(This article belongs to the Special Issue Comminution and Comminution Circuits Optimisation: 3rd Edition)

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27 pages, 380 KB

Open AccessFeature PaperEditor’s ChoiceReview

Recent Uses of Ionic Liquids in the Recovery and Utilization of Rare Earth Elements

by Francisco Jose Alguacil, Jose Ignacio Robla and Olga Rodriguez Largo

Minerals 2024, 14(7), 734; https://doi.org/10.3390/min14070734 - 22 Jul 2024

Cited by 5 | Viewed by 4844

Abstract

The importance of rare earth elements as a basis for the development of new technologies or the improvement of existing ones makes their recovery from raw and waste materials necessary. In this recovery, hydrometallurgy and its derivative solvometallurgy play key roles due to [...] Read more.

The importance of rare earth elements as a basis for the development of new technologies or the improvement of existing ones makes their recovery from raw and waste materials necessary. In this recovery, hydrometallurgy and its derivative solvometallurgy play key roles due to their operational characteristics, which are emphasized with the use of ionic liquids. This manuscript reviews the most recent advances (2023 and 2024) in the use of ionic liquids in unit operations (leaching and separation technologies) aimed at the recovery of these valuable and strategic metals. Moreover, a comprehensive review is presented of the use of these chemicals in the development of advanced materials containing some of these rare earth elements. Full article

(This article belongs to the Special Issue Solvent Extraction of Rare-Earth Elements with Ionic Liquids and Deep Eutectic Solvents)

12 pages, 5585 KB

Open AccessFeature PaperEditor’s ChoiceArticle

FIB-SEM Study of Archaeological Human Petrous Bones: 3D Structures and Diagenesis

by Jamal Ibrahim, Eugenia Mintz, Lior Regev, Dalit Regev, Ilan Gronau, Steve Weiner and Elisabetta Boaretto

Minerals 2024, 14(7), 729; https://doi.org/10.3390/min14070729 - 21 Jul 2024

Viewed by 2016

Abstract

The petrous bone generally preserves ancient DNA better than other fossil bones. One reason for this is that the inner layer of the petrous bone of pigs and humans contains about three times as many osteocytes as other bones, and hence more DNA. [...] Read more.

The petrous bone generally preserves ancient DNA better than other fossil bones. One reason for this is that the inner layer of the petrous bone of pigs and humans contains about three times as many osteocytes as other bones, and hence more DNA. A FIB-SEM study of modern pig petrous bones showed that the 3D structure of the thin inner layer is typical of woven bone that forms in the fetus, whereas the thicker outer layer has a lamellar structure. The lamellar structure is common in mammalian bones. Here we study human petrous bones that are about 2500 years old, obtained from three Phoenician sites in Sicily, Italy. A detailed FIB-SEM study of two of these bones, one well preserved and the other poorly preserved, shows that the 3D bone type structure of the human petrous inner layer is woven bone, and the outer layer is lamellar bone. These are the same bone type structures found in pig petrous bones. Furthermore, by comparing nine differently preserved petrous bones from the same archaeological region and age, we show that their collagen contents vary widely, implying that organic material can be significantly altered during diagenesis. The mineral crystals are better preserved and hence less crystalline in the inner layers compared to the outer layers. We therefore infer that the best-preserved DNA in fossil petrous bones should be found in the thin inner layers immediately adjacent to the otic cavity where much more DNA is initially present and the mineral phase tends to be better preserved. Full article

(This article belongs to the Section Biomineralization and Biominerals)

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20 pages, 4968 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Characterization of Incremental Markings in the Sagittal Otolith of the Pacific Sardine (Sardinops sagax) Using Different Imaging Modalities

by Kelsey C. James, Uwe Kierdorf, Victoria Cooley, Viktor Nikitin, Stuart R. Stock and Horst Kierdorf

Minerals 2024, 14(7), 705; https://doi.org/10.3390/min14070705 - 12 Jul 2024

Cited by 1 | Viewed by 4886

Abstract

Teleost fish possess calcium carbonate otoliths located in separate chambers (utriculus, sacculus, and lagena) of their membranous labyrinth. This study analyzed the surface topography of the sagittal otolith of the Pacific sardine (Sardinops sagax) and the daily and annual increments in [...] Read more.

Teleost fish possess calcium carbonate otoliths located in separate chambers (utriculus, sacculus, and lagena) of their membranous labyrinth. This study analyzed the surface topography of the sagittal otolith of the Pacific sardine (Sardinops sagax) and the daily and annual increments in these otoliths. The otolith surface, characterized by laser scanning confocal microscopy for the first time, consisted of a system of prominent ridges and valleys (grooves), but it is unclear whether these structures are functional or represent time-resolving markings reflecting growth periodicity. Within the first-year volume, daily increments, each consisting of an incremental (more mineralized) and a discontinuous (less mineralized) zone, were resolved by optical microscopy and backscattered electron (BSE) imaging in the scanning electron microscope (SEM). Daily growth increments could, however, not be resolved in volumes formed after the first year, presumably because otolith growth markedly slows down and spacing of incremental markings narrows in older fish. Throughout otolith growth, the crystalline network continues across the discontinuous zones. Fluorochrome labeling provides additional information on growth after the first year. Compared with optical and BSE imaging, synchrotron microComputed Tomography of intact otoliths (with 0.69 µm volume elements) was less able to resolve daily increments; X-ray phase contrast reconstructions provided more detail than reconstructions with absorption contrast. Future research directions are proposed. Full article

(This article belongs to the Special Issue Skeletal Tissues Mineralization)

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21 pages, 3649 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Comparing the Performance of Hydrocyclones and High-Frequency Screens in an Industrial Grinding Circuit: Part I—Size Separation Assessments

by Bruna Silveira Costa, Maurício Guimarães Bergerman and Homero Delboni Júnior

Minerals 2024, 14(7), 707; https://doi.org/10.3390/min14070707 - 12 Jul 2024

Cited by 1 | Viewed by 2520

Abstract

Industrial ball milling circuits usually include hydrocyclones in a closed configuration to achieve a specified grinding size. Although hydrocyclones are relatively simple to operate, their classification performance is generally low, leading to significant fines recirculation within the circuit, consequently overgrinding the product. Conversely, [...] Read more.

Industrial ball milling circuits usually include hydrocyclones in a closed configuration to achieve a specified grinding size. Although hydrocyclones are relatively simple to operate, their classification performance is generally low, leading to significant fines recirculation within the circuit, consequently overgrinding the product. Conversely, high-frequency screening potentially shows a relatively higher separation efficiency, as the entrainment of fines to the coarse product is significantly reduced. The present work compares the performance of hydrocyclones—HC and high-frequency screens—HFS based on four surveys conducted in Nexa’s Vazante Zinc ore industrial grinding circuit in Vazante, Brazil, which processes zinc silicate ore. The comparisons included the partition of solids, water split, and particle size distributions. Whiten’s partition curve model was adopted to obtain the selected performance parameters through mass balancing the experimental data. The industrial surveys comprised three different size separation configurations, i.e., HC-Only, HFS-Only, and a combined HC-HFS setup. In all cases, the assessments consistently indicated higher separation performances with HFS compared to the HC operation. The final product associated with the HC+HFS configuration showed a narrower size distribution around the grinding size. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Extractive Metallurgy of Base and Precious Metals)

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