Search Results (8,399)

Search Parameters:
Journal = Minerals

Order results

Result details

Results per page

Show export options Show export options

Select all

Export citation of selected articles as:

19 pages, 21581 KiB

Open AccessArticle

A Review of the Genetic Mechanism of Megacrystalline Uraninite in the Kangdian Region, China

by Minghui Yin, Zhengqi Xu, Chengjiang Zhang, Youliang Chen, Hao Song and Jian Yao

Minerals 2024, 14(7), 642; https://doi.org/10.3390/min14070642 - 24 Jun 2024

Viewed by 223

Abstract

Naturally occurring granular uranium particles are typically fine and are often found as accessory minerals. However, reports of megacrystalline uraninite are rare. The discovery of megacrystalline uraninite is a significant achievement in uranium prospecting and mineralogy in the Kangdian region and China. Our team’s research and review of previous studies have led to a systematic summary of the formation age, genetic types, relationship with migmatization, and metallogenic dynamic background of megacrystalline uraninite in the Kangdian region. The key findings are as follows: (1) the formation age of megacrystalline uraninite is Neoproterozoic (790–770 Ma); (2) migmatization preceded uranium mineralization; (3) the formation of megacrystalline uraninite is linked to high-temperature, low-pressure metamorphism caused by partial melting; (4) and the formation of megacrystalline uraninite may be associated with the Rodinia rifting event. This review aims to enhance our understanding of uranium mineralization during the Neoproterozoic in China and worldwide. Full article

(This article belongs to the Special Issue Advances in Uranium Metallogenic Theory, Exploration and Exploitation)

27 pages, 7075 KiB

Open AccessArticle

Middle Silurian–Middle Devonian Magmatic Rocks in the Eastern Segment of the Northern Margin of the North China Craton: Implications for Regional Tectonics

by Bin Li, Jingsheng Chen, Fan Yang, Miao Liu, Yanqing Zang and Chao Zhang

Minerals 2024, 14(7), 641; https://doi.org/10.3390/min14070641 - 23 Jun 2024

Viewed by 301

Abstract

This paper presents a detailed study including LA-ICP-MS zircon U-Pb dating, geochemical, zircon Hf isotope, and whole rock Sr-Nd isotope analysis of magmatic rocks from the Yitong County, Jilin Province, NE China. These data are used to better constrain the Middle Silurian–Middle Devonian tectonic evolution in the eastern segment of the northern margin of the North China Craton (NCC). Zircon U-Pb dating results show that the Ximangzhang tonalite formed in the Late Silurian (425 ± 6 Ma); the basalt, andesite, and metamorphic olivine-bearing basalt in the Fangniugou volcanic rocks formed in the Middle Silurian (428 ± 6.6 Ma) and Middle Devonian (388.4 ± 3.9 Ma, and 384.1 ± 4.9 Ma). The Late Silurian tonalites are characterized by high SiO₂ and Na₂O and low K₂O, MgO, FeOT, and TiO₂, with an A/CNK ratio of 0.91–1.00, characteristic of calc-alkaline I-type granite. They are enriched in Rb, Ba, Th, U, and K, and depleted in Nb, Sr, P, and Ti, with positive ε_Nd(t) (+0.35) and ε_Hf(t) (+0.44 to +6.31) values, suggesting that they mainly originated from the partial melting of Meso–Neoproterozoic accretionary lower crustal material (basalt). The Middle Silurian basalts are characterized by low SiO₂, P₂O₅, TiO₂, and Na₂O and high Al₂O₃, FeOT, and K₂O, enriched in Rb, Ba, Th, U, and K and depleted in Nb, Ta, Sr, P, and Ti, indicative of shoshonitic basalt. The Late Silurian tonalites have positive ε_Nd(t) (+4.91 to +6.18) values and primarily originated from depleted mantle magmas metasomatized by subduction fluids, supplemented by a small amount of subducted sediments and crustal materials. The Middle Devonian volcanic rocks exhibit low SiO₂, TiO₂, and Na₂O and high K₂O, and MgO, enriched in Rb, K, and LREEs and depleted in Nb, Ta, Sr, and HREEs, characteristic of shoshonitic volcanic rocks. Their ε_Nd(t) (+2.11 to +3.77) and ε_Hf(t) (+5.90 to +11.73) values are positive. These characteristics indicate that the Middle Devonian volcanic rocks primarily originated from depleted mantle magmas metasomatized by subduction fluids, with the addition of crustal materials or subducted sediments during their formation. Based on regional geological data, it is believed that the study area underwent the following evolutionary stages during the Silurian–Devonian period: (1) active continental margin stage of southward subduction of the Paleo–Asian Ocean (PAO) (443‒419 Ma); (2) arc-continent collision stage (419‒405 Ma); (3) post-collision extension stage (404‒375 Ma); (4) active continental margin stage, with the PAO plate subducting southward once again (375‒360 Ma). Full article

(This article belongs to the Special Issue Tectonic–Magmatic Evolution and Mineralization Effect in the Southern Central Asian Orogenic Belt)

21 pages, 1777 KiB

Open AccessArticle

Characteristics and Mechanism of the Ore-Forming Fluids in the Shimensi Tungsten Polymetallic Deposit in Southeastern China

by Peng Wang, Zhanghuang Ye and Xiaohua Zong

Minerals 2024, 14(7), 640; https://doi.org/10.3390/min14070640 - 23 Jun 2024

Viewed by 285

Abstract

The Shimensi super-large tungsten polymetallic deposit is located in the Late Jurassic–Early Cretaceous Porphyry–Skarn tungsten ore belt in the south Yangtze metallogenic belt. There are three types of mineralization: veinlet-disseminated type, thick quartz vein type and hydrothermal cryptoexplosive breccia type. Based on geological studies, this paper presents new petrographic, microthermometric, laser Raman spectroscopic and hydrogen and oxygen isotope research on the fluid inclusions from the deposit. The results show that there are five different types of fluid inclusions: liquid-rich inclusions, vapor-rich inclusions, pure liquid inclusions, pure vapor inclusions, and fluid inclusions containing a solid crystal. The homogenization temperatures of the fluid inclusion range from 140 °C to 270 °C, the salinities are 3 wt.%–5 wt.% NaCl_eq and the densities of ore-forming fluid range from 0.64 g/cm³ to 0.99 g/cm³. For the analyses of laser Raman spectroscopy, the ore-forming fluids can be approximated by a Ca²⁺-Na⁺-SO₄²⁻-Cl⁻ fluid system with small amounts of CO₂, CH₄ and N₂. Otherwise, the data of the pressure, pH and Eh show a fluid metallogenic environment of low pressure, weak acid and weak reduction. The values of the homogenization temperature in the three types of orebodies suggest that the mineralization is characterized by a decrease in temperature under the conditions of fluid immiscibility. The H-O isotope values are interpreted to indicate that the ore-forming fluids are mainly composed of magmatic water, and meteoric water is added with the process of magma rising. Full article

25 pages, 7560 KiB

Open AccessArticle

New Strategies in Archaeometric Provenance Analyses of Volcanic Rock Grinding Stones: Examples from Iulia Libica (Spain) and Sidi Zahruni (Tunisia)

by Lluís Casas, Roberta Di Febo, Anna Anglisano, África Pitarch Martí, Ignasi Queralt, Cèsar Carreras and Boutheina Fouzai

Minerals 2024, 14(7), 639; https://doi.org/10.3390/min14070639 - 23 Jun 2024

Viewed by 306

Abstract

Archaeometry can help archaeologists in many ways, and one of the most common archaeometric objectives is provenance analysis. Volcanic rocks are often found in archaeological sites as materials used to make grinding tools such as millstones and mortars or as building materials. Petrographic characterization is commonly applied to identify their main mineralogical components. However, the provenance study of volcanic stones is usually undertaken by comparing geochemical data from reference outcrops using common descriptive statistical tools such as biplots of chemical elements, and occasionally, unsupervised multivariate data analysis like principal component analysis (PCA) is also used. Recently, the use of supervised classification methods has shown a superior performance in assigning provenance to archaeological samples. However, these methods require the use of reference databases for all the possible provenance classes in order to train the classification models. The existence of comprehensive collections of published geochemical analyses of igneous rocks enables the use of the supervised approach for the provenance determination of volcanic stones. In this paper, the provenance of volcanic grinding tools from two archaeological sites (Iulia Libica, Spain, and Sidi Zahruni, Tunisia) is attempted using data from the GEOROC database through unsupervised and supervised approaches. The materials from Sidi Zahruni have been identified as basalts from Pantelleria (Italy), and the agreement between the different supervised classification models tested is particularly conclusive. In contrast, the provenance of the materials from Iulia Libica remained undetermined. The results illustrate the advantages and limitations of all the examined methods. Full article

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

20 pages, 813 KiB

Open AccessReview

Technological Advancement in Solar Photovoltaic Recycling: A Review

by Monserrat Martínez, Yahaira Barrueto, Yecid P. Jimenez, Dennis Vega-Garcia and Ingrid Jamett

Minerals 2024, 14(7), 638; https://doi.org/10.3390/min14070638 - 22 Jun 2024

Viewed by 441

Abstract

This review examines the technological surveillance of photovoltaic panel recycling through a bibliometric study of articles and patents. The analysis considered the number of articles and patents published per year, per country, and, in the case of patents, per applicant. This analysis revealed that panel recycling is an increasingly prominent research area. However, the number of patents filed annually has varied in recent years, averaging fewer than 200 per year. The state-of-the-art review identified three main types of treatment for photovoltaic panel recycling: mechanical, chemical, and thermal. Among these, mechanical treatment serves as a preliminary stage before the recovery of valuable elements, which is achieved through chemical or thermal processes. The articles reviewed cover a range of processes, including hydrometallurgical and pyrometallurgical methods, and explore various classification processes, solvents, and oxidizing agents. In contrast, patents predominantly focus on pyrometallurgical processes. This analysis is supplemented by a survey of market-ready technologies, many of which include stages such as size reduction or delamination followed by pyrometallurgical processes. Additionally, the review highlights the collection processes implemented by some companies, noting that the volume of panels considered waste is currently insufficient to maintain a continuous and year-round operational process. This study identifies key challenges such as (i) reducing solar panel size due to the EVA polymer complicating conventional machinery use, (ii) high process costs from the need for high temperatures and costly additives, (iii) the environmental impact of thermal treatments with high energy consumption and air pollution, and (iv) the necessity for environmentally friendly solvents in hydrometallurgical treatments to reduce contamination during recycling. Future directions include developing specific machinery for panel size reduction, either creating or modifying a polymer to replace EVA for easier treatment, adopting hydrometallurgical treatments with green solvents proven effective in recycling minerals and electronic waste, and addressing the lack of detailed information on industrial processes to make more precise recommendations. Full article

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

20 pages, 9384 KiB

Open AccessArticle

Petrogenetic Implications of the Lithium-Rich Tongtianmiao Granite Pluton, South China: Evidence from Geochemistry and Geochronology

by Xinhui Yu, Yongzhang Zhou, Wei Cao, Hanyu Wang, Can Zhang, Lifeng Zhong, Wu Wei, Zhiqiang Wang, Jianying Yao, Zhiqiang Chen and Qinghe Xu

Minerals 2024, 14(7), 637; https://doi.org/10.3390/min14070637 - 21 Jun 2024

Viewed by 365

Abstract

The South China Block, a region renowned for its extensive granite distribution and rich metal deposits, serves as a natural laboratory for the study of granite-related mineralization. This research focuses on the Tongtianmiao granite pluton, which is located at the intersection of the Qin-Hang and Nanling metallogenic belts and has been confirmed as a significant lithium mineral resource. Despite its discovery and ongoing development, the lithium-rich Tongtianmiao pluton has been understudied, particularly concerning its petrogenesis, which has only recently come to the forefront of scientific inquiry. By integrating an array of petrogeochemical data with geochronological studies derived from zircon and monazite dating, this study provides insights into the magmatic processes related to lithium enrichment in the Tongtianmiao granites. The Tongtianmiao granites are classified as A-type granites characterized by high SiO₂ contents (69.18–78.20 wt.%, average = 74.08 wt.%), K₂O + Na₂O contents (4.59–8.34 wt.%, average = 6.86 wt.%), A/CNK > 1.2, and low concentrations of Ca, Mg, and Fe. These granites are enriched in alkali metals such as Li, Rb, and Cs but are significantly depleted in Ba, Sr, and Eu. They show no significant fractionation of light or heavy rare-earth elements but present characteristic tetrad effects. A finding of this study is the identification of multiple ages from in situ zircon U–Pb dating, which implies a prolonged history of magmatic activity. However, given the high uranium content in zircons, which could render U–Pb ages unreliable, emphasis is placed on the monazite U–Pb ages. These ages cluster at approximately 172.1 ± 1.1 Ma and 167.9 ± 1.6 Ma, indicating a Middle Jurassic period of granite formation. This timing correlates with the retreat of the Pacific subduction plate and the associated NE-trending extensional fault activity, which likely provided favorable conditions for lithium enrichment. The study concluded that the Tongtianmiao granites were formed through partial melting of crustal materials and subsequent underplating by mantle-derived materials, and were contaminated by strata materials. This process resulted in the formation of highly differentiated granite through magmatic differentiation and external forces. These findings have significant implications for understanding the petrogenesis of lithium-rich granites and are expected to inform future exploration endeavors in the Tongtianmiao pluton. Full article

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

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

---

Figure 6

---

Figure 7

---

Figure 8

---

Figure 9

---

Figure 10

---

Figure 11

---

Figure 12

---

Figure 13

---

Figure 14

16 pages, 5196 KiB

Open AccessArticle

Optimization of Flotation Conditions for Long-Flame Coal Mud by Response Surface Method

by Linfang Ao, Hongbo Zhang, Jingkun Zhang and Guoping Li

Minerals 2024, 14(7), 636; https://doi.org/10.3390/min14070636 - 21 Jun 2024

Viewed by 223

Abstract

With the application of modern coal mining technology and the fact that there are fewer and fewer high-quality coal seams, the quality enhancement and utilization of low-rank coal are gaining more and more attention. To solve the problems of high consumption of chemicals and low recovery of refined coal in the flotation separation process of low-rank coal, the long-flame coal from the Inner Mongolia Autonomous Region of China was selected as the research object, and the factors affecting the flotation process were analyzed and optimized by adopting the response surface method and establishing a regression model with high precision and reliability. The test results showed that the primary and secondary relationships of the factors on the fine coal yield were as follows: slurry concentration > frother dosage > collector dosage; and the primary and secondary relationships of the factors on the flotation refinement index were as follows: slurry concentration > collector dosage > frother dosage. The optimal conditions for flotation were 2453.09 g/t of collector, 795.84 g/t of frother, and 50.04 g/L of slurry concentration. Under these conditions, the fine coal yield was 51.51%, and the relative error of 53.71% was 4.27%. The flotation refinement index was 21.34%, and the relative error with the predicted value of 21.58% was 1.12%. The relative error of the experimental results was within a reasonable range, which indicated that the regression model obtained by the response surface method was highly reliable. The research results are of great significance to strengthen the comprehensive utilization of long-flame coal in full particle size and improve the economic benefits of coal enterprises. Full article

(This article belongs to the Special Issue An Overview of Applications and Types of Flotation Reagents: Performance, Efficiency and Optimization)

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

---

Figure 6

---

Figure 7

---

Figure 8

18 pages, 15596 KiB

Open AccessArticle

Paleo-Sedimentary Environment and Formation Mechanism of the Organic-Rich Shale of the Permian Lucaogou Formation, Jimsar Sag, Junggar Basin, China

by Zhongying Zhao, Senhu Lin, Xia Luo and Lijun Zhang

Minerals 2024, 14(7), 635; https://doi.org/10.3390/min14070635 - 21 Jun 2024

Viewed by 223

Abstract

The Jimsar Sag is an important shale oil exploration target area in the Junggar Basin, northwestern China. The Permian Lucaogou Formation, with a thickness of 200–300 m, is the primary exploration target. High-frequency variation in lithology is a typical feature of the Lucaogou Formation, reflecting the fluctuation of the depositional environment and organic matter enrichment. The evolution of the depositional environment and accumulation mechanism of organic matter still need to be elucidated for the Lucaogou Formation. High-resolution sampling of the entire Lucaogou Formation was applied to a 248 m long core from Well JX in the Jimsar Sag to examine the depositional environment and organic matter enrichment. The findings unveiled that the Lucaogou Formation was deposited under a hot and arid climate, within the confines of a closed saline paleo-lake, where sediments endured an extended period of anoxic conditions, displayed periodic oscillations in paleo-temperature and paleo-salinity values over time, alongside a continuous rise in paleo-water depth. The predominant source lithology of the Lucaogou Formation is felsic igneous rock. Small-scale transgression and hydrothermal sedimentation occurred during the deposition of the Lucaogou Formation. The prevailing hot climate and enduring reducing environment fostered ideal circumstances for the enrichment of organic matter in the Lucaogou Formation. Due to different sedimentary environments and enrichment mechanisms, organic matter is enriched in two modes in the Lucaogou Formation. Full article

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

---

Figure 6

---

Figure 7

---

Figure 8

---

Figure 9

---

Figure 10

---

Figure 11

---

Figure 12

11 pages, 1534 KiB

Open AccessArticle

The Effect of an Anionic Polyacrylamide on the Flotation of Chalcopyrite, Enargite, and Bornite

by Ginna Jimenez, Pablo Cabrera, Angie Rodriguez, Camilo Cuervo and Leopoldo Gutierrez

Minerals 2024, 14(7), 634; https://doi.org/10.3390/min14070634 - 21 Jun 2024

Viewed by 628

Abstract

Water recycling in mining is essential to decrease water usage, which results in the accumulation of high concentrations of inorganic and organic substances in the process water. Consequently, adverse impacts on the flotation process of copper sulfides may arise. High-molecular-weight polymers based on anionic polyacrylamides (PAMs) are used as tailing flocculants in mineral processing plants. The recirculation of water recovered from the tailing thickeners to the flotation process introduces residual PAMs, which can impact the flotation of important copper sulfides like chalcopyrite, bornite, and enargite. This issue has been rarely studied. In this work, results on the effect of an anionic polyacrylamide (PAM) of medium–low anionicity on the flotation of chalcopyrite, enargite, and bornite are reported and analyzed. The results show that PAM molecules depress the flotation of chalcopyrite, enargite, and bornite under a wide range of pH values. The experimental data indicate that the depressing effect of PAMs on copper sulfides increases with pH. The zeta potential results reveal that this parameter becomes less negative with the addition of PAMs, indicating interactions between PAM molecules and the surfaces of the copper sulfides. PAM adsorption on copper sulfides increases with pH, which correlates with the flotation and zeta potential data. It is proposed that the interactions between PAM molecules and copper sulfides are explained by the presence of surface iron and copper hydroxides that create chemically active adsorption sites. Full article

(This article belongs to the Special Issue Development of Flotation of Chalcopyrite)

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

12 pages, 4228 KiB

Open AccessArticle

Application of a Multi-Technique Approach to the Identification of Mineral Polymorphs in Histological Samples: A Case of Combined Use of SEM/EDS and Micro-Raman Spectroscopy

by Alessandro Croce, Donata Bellis, Caterina Rinaudo, Laura Cagna, Giorgio Gatti, Annalisa Roveta, Marinella Bertolotti and Antonio Maconi

Minerals 2024, 14(7), 633; https://doi.org/10.3390/min14070633 - 21 Jun 2024

Viewed by 504

Abstract

In the last few years, an increasing interest has developed regarding the application of different techniques for the identification of pollutants inside the tissues deriving from patients affected by benign or neoplastic diseases. Particular attention was paid to neoplasia linked to particular exposures, e.g., heavy metals, carbon dusts, silica, asbestos. As regards the last pollutant, a wide body of scientific literature has been collected, considering the severe effects caused by mineral fibers on human health. Optical and electronic microscopies were widely applied to identify the fibers in respiratory and extra-respiratory organs to detect the minerals and to link their presence to an exposure source and to understand their role in cancer development. The main advantage of electron microscopy lies in the possibility of coupling the microscopes with energy dispersive spectrometers and also collecting data on the elemental composition of various inorganic phases. In term of sample preparation and time of analysis, the most utilized microscope technique is Scanning Electron Microscopy with an annexed energy dispersive spectrometer (SEM/EDS), allowing for the morphological and chemical characterization of the observed particles/fibers. Moreover, this technique is envisaged by Italian Law for asbestos identification in air and bulk samples. On the other hand, this technique does not allow a reliable identification of the mineral phase in the case of polymorphs with the same chemical formula but different crystal structures. In this work, the coupling of a spectroscopical technique—micro-Raman spectroscopy—to SEM/EDS is proposed for a sure phase identification of particles, showing EDS spectra with ambiguous phase identification, observed in samples of tissues from patients affected by colorectal cancer and living in an asbestos-polluted area. In these tissues, different particles with EDS spectra that do not allow a sure identification of the phase—in particular calcium-rich particles and titanium oxides—were successively analyzed by micro-Raman spectroscopy. Thanks to this last technique, it was possible to ascribe the mineral phases associated to these particles to “aragonite” (a calcium carbonate polymorph) and to “anatase” (a Ti dioxide polymorph). Full article

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

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

17 pages, 4445 KiB

Open AccessArticle

Paleoredox Conditions, Paleoproductivity, and Terrigenous Sediment Influx of the Lower-Middle Cenomanian Strata in the Abu Gharadig Basin, Northern Egypt

by Ahmed Mansour, Michael Wagreich, Sameh S. Tahoun, Mohamed S. Ahmed and Thomas Gentzis

Minerals 2024, 14(6), 632; https://doi.org/10.3390/min14060632 - 20 Jun 2024

Viewed by 346

Abstract

During the Late Cretaceous (Cenomanian), significant disruptions in the carbon cycle, global warming, and episodes of oceanic anoxia occurred, leading to the deposition of organic carbon-rich sediments. In well BED2-3, located in the BED2 gas field within the Abu Gharadig Basin (north Western Desert, Egypt), the lower-to-middle Cenomanian Bahariya Formation displays thick alternating layers of sandstones, siltstones, and shales. Detailed geochemical analyses were conducted on thirty-three cutting samples from the Bahariya Formation, focusing on total organic carbon (TOC), whole-rock elemental geochemistry, and carbonate content. These geochemical measurements provided valuable information regarding paleoredox conditions, marine biological productivity, terrigenous sediment influx, weathering and paleoclimate conditions, and mechanisms influencing organic matter accumulation. The enrichment factors (EF) of redox-sensitive trace elements were utilized to infer oxygenation conditions and marine biological productivity during the deposition of the Bahariya Formation. The stratigraphic distribution of redox-sensitive elements allowed for the Bahariya Formation to be categorized into lower and middle-upper intervals. The results revealed that the lower interval exhibited strong-to-enriched EF values of redox-sensitive elements and fair-to-rich TOC content, indicating a prevalent anoxic setting during deposition. In contrast, the middle-upper interval displayed weakly-to-slightly enriched EF values with poor-to-fair TOC content, suggesting deposition under oxic-suboxic redox conditions. By examining Al-normalized redox-sensitive ratios and their correlations with TOC content, significant relationships were observed in the lower interval, indicating a coupling between the enrichment of redox-sensitive elements and organic matter. This suggests enhanced biological productivity during deposition of the lower interval compared to the relatively low productivity during deposition of the middle-upper interval of the formation. These conditions controlled the production and preservation of organic matter in the lower interval, while the middle-upper interval suffered from organic matter dilution and destruction due to an increased influx of terrigenous material and lower biological productivity. Geochemical proxies related to detrital materials provided evidence of alternating terrigenous sediment flux, consistent with shifts between coarse- and fine-grained fractions and related facies of sandstones, siltstones, and shales. These findings align with active continental weathering in the source terrane and deposition under enhanced warm-humid climatic conditions, with intermittent arid-to-semi-arid phases. These conclusions are further supported by the palynomorph assemblages and clay mineralogy within the Bahariya Formation. Full article

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

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

---

Figure 6

---

Figure 7

21 pages, 4180 KiB

Open AccessArticle

Mineralogical Method as an Effective Way to Predict Gold Ore Types of Deposits in Platform Areas (East of the Siberian Platform)

by Zinaida Nikiforova

Minerals 2024, 14(6), 631; https://doi.org/10.3390/min14060631 - 20 Jun 2024

Viewed by 278

Abstract

The study of the mineralogical and geochemical features of placer gold and the mechanisms of its distribution in the territory east of the Siberian platform, overlain by a thick cover of Mesozoic–Cenozoic deposits, where traditional methods of searching for gold fields are not effective, allowed researchers, for the first time, to establish the stages of ore formation and to predict the types of gold deposits and their location. The identified indicators of placer gold (morphology, granulometry, chemical composition, micro-inclusions, and internal structures) indicate that ore occurrences in both the Precambrian and Mesozoic stages of ore formation were primary sources of placer gold. The identification of characteristic indicators in placer gold for certain types of gold deposits allowed researchers to prove the formation of gold ore sources east of the Siberian platform for the first time: low-sulfide quartz gold, gold–ferruginous quartzite, gold–copper–porphyry, and gold–platinoid formations are found in the Precambrian stage of ore formation and gold–silver, gold–sulfide–quartz, and gold–rare metal formations are found in the Mesozoic stages of ore formation. Thus, for the first time, based on a huge amount of factual material, it is proved that the mineralogical and geochemical features of placer gold carry enormous information about both the endogenous origin of gold (stages of ore formation—Precambrian and Mesozoic) and the expected type of formation of the predicted deposits. It is established that the predicted type of ore sources corresponds to a certain geological and structural position; this contributes to a more correct selection of methods for searching for ore and placer gold deposits in closed territories and assessing their prospects. In general, the application of the mineralogical method for the first time makes it possible to develop criteria for predicting resources and types of gold deposits, and to assess the prospects of gold mining potential in platform areas at a new level of knowledge. Full article

(This article belongs to the Special Issue Native Gold as a Specific Indicator Mineral for Gold Deposits, 2nd Edition)

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

---

Figure 6

---

Figure 7

---

Figure 8

---

Figure 9

21 pages, 4973 KiB

Open AccessArticle

Discrete Element Modeling of the Breakage of Single Polyhedral Particles in the Rotary Offset Crusher

by Titus Nghipulile, Mulenga Murray Bwalya, Indresan Govender and Henry Simonsen

Minerals 2024, 14(6), 630; https://doi.org/10.3390/min14060630 - 20 Jun 2024

Viewed by 242

Abstract

Innovation in comminution is expected to continue unabated to address the inefficiencies that are inherent in comminution circuits. The rotary offset crusher (ROC) is a new comminution device with a promising performance potential in terms of throughput due to the enhanced speed of transportation induced by the centrifugal force of the discs. However, the processes driving the comminution of particles trapped in the conical space between the two discs of the crusher are not fully understood. To gain a better insight into the comminution process in this device, discrete element modeling (DEM) simulations were conducted to study the breakage of a single particle for the crusher operated under two different dynamic conditions, i.e., (1) a stationary top disc and (2) both discs rotating at the same speed. For both scenarios, the speed of the discs was varied between 550 and 2350 rpm. Experimental testwork was also conducted with the laboratory prototype to generate the data that were used to calibrate the breakage parameters of the Ab × t₁₀ breakage model. Simulations were performed using polyhedral UG2 ore particles that were generated with the in-built particle generator in the DEM simulator. The simulated ROC, which is operated with both discs rotating, outperformed the ROC with a stationary top disc in terms of the specific input energy and throughput. The crusher with a stationary top disc is characterized by high shear forces (suggesting a higher wear rate), specific input energies greater than 1 kWh/t, and low throughputs (<50 kg/h). The ROC operated with a stationary disc is not recommended for hard rock applications due to expected excessive wear of crushing surfaces and higher energy consumption. The freewheeling discs are recommended, but there is scope to optimize the crusher performance in terms of the power draw, size reduction, and throughput by manipulating the difference between the speeds of the discs. There is also scope to optimize the crusher performance when it is simulated with many particles. Once the full performance potential of the ROC is established, it will then be important to benchmark it against the existing crushers in the minerals industry as well as other industries where crushers are used. Full article

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

► Show Figures

Figure 1

---

Figure 3

---

Figure 4

---

Figure 5

---

Figure 6

---

Figure 7

---

Figure 8

---

Figure 9

---

Figure 10

---

Figure 11

---

Figure 11 Cont.

---

Figure 12

---

Figure 13

---

Figure 14

---

Figure 15

Abstract

Surface wettability is determined by the attraction of a liquid phase to a solid surface. It is typically quantified by using contact angle measurements at mineral surfaces in the case of the flotation of mineral particles. Contact angle research to describe wettability has been investigated at different scales by sessile drop measurements, molecular dynamic simulation, and atomic force microscopy. In this study, the density functional theory (DFT) was employed for predicting the surface free energy and contact angles of a well-known hydrophobic phyllosilicate mineral talc and a well-known hydrophilic phyllosilicate mineral muscovite based on the calculated interfacial energy and surface charge. The results revealed that the predicted contact angle at the atomic scale was larger than the experimental value, and identified two interactions: electrostatic interaction and hydrogen bonding, between the hydrophilic muscovite surface and the water layer, while a water-exclusion zone of 3.346 Å was found between the hydrophobic talc surface and the first water layer. This investigation gives a new perspective for wettability determination at the atomic scale. Full article

Search Results (8,399)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

Saved Queries

Search Filter Reset All

Years

Feature Papers

Article Types

Countries / Regions

Search Results (8,399)

Further Information

Guidelines

MDPI Initiatives

Follow MDPI