Search Results (246)

Rare metal exploration increasingly relies on the integration of heterogeneous geological datasets and advanced analytical methods to improve the efficiency and reliability of mineral prospecting. This study presents the development of a web-based Geographic Information System, Geospatial Information System for Optimized Rare Metal Exploration in Eastern Kazakhstan (GISORMEK), using the central part of the Kalba–Narym rare-metal belt (Eastern Kazakhstan) as a case study. A comprehensive geospatial database was developed through the digitization of archival geological maps and the integration of geological, geochemical, tectonic, geophysical, geomorphological, and mineral occurrence datasets. To complement historical mapping data, Landsat-8 multispectral imagery was incorporated to improve lithological discrimination and identify hydrothermal alteration zones. Two remote sensing techniques were applied: Principal Component Analysis (PCA) for lithological mapping and enhancement of geological features, and band ratio (BR) analysis for the calculation of geological spectral indices, including the iron oxide index and the hydroxyl-bearing (Al–OH) mineral index. The resulting spectral indices were subsequently integrated to generate a predictive hydrothermal alteration map. GISORMEK integrates historical and contemporary datasets within a unified web-GIS framework, ensuring spatial consistency, reproducibility, and accessibility. The proposed framework enhances the interpretation of the mineralization potential of the Kalba–Narym region and provides geospatial platform for supporting rare metal exploration and future mineral prospectivity assessments. Full article

Operational risk assessment in complex industrial systems like mineral processing plants is hindered by inherent uncertainty and incomplete information. This study presents an integrated grey system theory-based framework to address this challenge. Combining Grey Multi-Criteria Decision-Making (GST-MCDM) and Grey Relational Analysis (GRA), the methodology enables a systemic analysis that prioritizes risks, quantifies interdependencies, and measures cumulative burden across four key objectives: time, cost, quality, and safety. Applied to a case study at the Gohar Zamin iron ore processing plant (Iran), the model analyzed 26 operational risks, classifying them into Critical (8 risks), Significant (9), and Controllable (9) tiers. Electrical power shortage (RPS: 0.19) and raw material supply delay (RPS: 0.21) were identified as the most critical risks. The analysis quantified that the safety objective bears the highest cumulative risk burden at 32%, primarily due to human factor vulnerabilities, while cyber-physical threats ranked among the top 8 critical risks. Strong interdependencies were revealed, notably a quality cascade (relational grade: 0.84) between poor consumable materials and final product failure. Sensitivity analysis confirmed high model robustness (Spearman’s p = 0.91). The framework provides managers with an actionable tool for strategic, cluster-based mitigation and evidence-based resource allocation, emphasizing investment in human capital as a core risk reduction strategy. This research contributes a replicable, quantitative methodology for enhancing operational resilience under uncertainty in capital-intensive industries. Full article

Eutrophication in tropical endorheic lakes often persists despite reductions in external nutrient inputs, indicating an important role of internal nutrient loading. However, integrated evidence linking thermal stratification, sediment characteristics, and sediment-derived nutrient release in tropical endorheic lakes remains limited. This study investigated the mechanisms contributing to eutrophication in Lake Batur, a tropical endorheic volcanic lake in Indonesia, through seasonal water-column observations, sediment porewater profiling, diffusive nutrient flux analysis, and sediment characterization. Seasonal observations showed thermal stratification accompanied by hypoxic to anoxic bottom waters, while sediment-derived nutrient flux was dominated by ammonium and phosphate under reducing conditions. Sediment characterization at the representative sampling site revealed mineral assemblages dominated by biogenic silica, aluminosilicate clays, carbonates, and iron-bearing phases that may influence nutrient mobility under low-oxygen conditions. The results indicate strong coupling between thermal stratification, hypolimnetic oxygen depletion, and sediment–water interactions, suggesting that internal loading contributes to maintaining eutrophic conditions in Lake Batur. The endorheic nature of the lake likely enhances nutrient retention because of limited hydrological flushing and prolonged nutrient residence times. These findings improve understanding of eutrophication processes in tropical endorheic volcanic lakes and highlight the importance of considering sediment-derived internal loading together with external nutrient reduction in lake restoration strategies. Full article

Anatase-bearing lateritic ores from Qinglong, Guizhou Province, China, are characterized by extremely low TiO₂ grade, high clay content, fine-grained dissemination, and complex intergrowths with iron oxides, which severely hinder efficient beneficiation. In particular, anatase commonly occurs as ultra-fine particles encapsulated by clay minerals or closely associated with iron oxides, and its surface is often covered by nanoscale goethite films, resulting in surface passivation and pseudo-magnetic behavior. These characteristics lead to a pronounced contradiction between mineral liberation and excessive slime generation during conventional grinding processes. To address these challenges, a high-efficiency pre-concentration flowsheet was developed based on selective desliming, stage grinding, intensive scrubbing, flotation, and weak magnetic separation. Selective desliming via hydrocyclones was adopted, which is inferred to preferentially discard true slimes finer than 10 μm while potentially retaining most fine anatase particles within the underflow. Stage grinding was then applied, which may promote the improved liberation of anatase and early rejection of coarse gangue, and may help reduce overgrinding. Intensive scrubbing was introduced, which is expected to weaken or partially remove iron oxide coatings from the anatase surface, thereby potentially restoring surface activity and reducing pseudo-magnetic interference. Subsequent flotation and low-intensity magnetic separation were optimized to increase the concentrate TiO₂ grade and cut iron impurities, which may be associated with improved surface selectivity and weakened pseudo-magnetic responses. Closed-circuit beneficiation tests demonstrated that a TiO₂ concentrate with a grade of 29.62% and a recovery of 65.4% could be obtained from an ore with an initial TiO₂ grade of only 4.39%. Moreover, approximately 40% of the feed mass was rejected at the pre-concentration stage, significantly reducing the load on downstream separation processes. The proposed process demonstrates promising potential as a technical route for the beneficiation of similar refractory anatase-bearing lateritic ores. Full article

Granite is a major lithology of stone-built cultural heritage across East Asia, the Iberian Peninsula, the Indian subcontinent, Egypt and Italy. Long regarded as durable, it nonetheless undergoes mineralogical, microstructural and macroscopic alteration through pathways that are mechanistically universal yet regionally distinctive in expression. This review synthesizes granite weathering within a multianalytical framework spanning mineralogy, microstructure, geochemistry, environmental drivers and conservation science. Mineral-specific reactions—feldspar hydrolysis, biotite oxidation coupled to clay-mineral genesis, iron-bearing transformations driving surface coloration, quartz-mediated thermal microcracking and accessory-mineral pathologies—are examined as coupled processes governing macroscopic decay. A suite of complementary analytical methods, including non-destructive, minimally invasive and laboratory-based techniques, delivers mechanistic and prognostic resolution unattainable by any single method. Two case settings—the tenth-century rock-carved Buddhas of Gyeongju Namsan and the urban granite of Jongmyo Shrine, Seoul—illustrate how integrated diagnostics resolve coupled decay on natural outcrops and how cumulative atmospheric exposure is recorded in monument-scale fabrics. Chemical weathering indices, environmental controls and conservation implications are unified into a single framework, and key gaps—standardization, time-resolved diagnostics, climate projection, multi-omics coupling, consolidant durability and machine learning—are articulated as a research agenda for granite heritage science. Full article

Comprehensive mineralogical and technological investigations of tin-bearing weathering crusts from the Syrymbet deposit (Northern Kazakhstan), characterized by low tin grades and a high degree of mineral dispersion, are presented. The particle-size distribution, mineralogical composition, chemical composition, and the distribution of tin among size fractions and processing products were studied. The results show that the majority of tin is associated with the fine-grained clay fraction, which contains up to 70%–74% of the total metal inventory. Conventional hydrocycloning and gravity concentration methods were found to be ineffective due to the fine dissemination and encapsulation of tin mineralization, with more than 99% of the tin reporting to gravity separation tailings. In the untreated material, tin mineralization is predominantly represented by cassiterite, as confirmed by electron microscopy and energy-dispersive X-ray microanalysis. Thermal activation at 450 °C under oxygen-free conditions was shown to induce profound transformation of the original cassiterite mineralization. Cassiterite was not detected in the thermally activated products; instead, newly formed multiphase aggregates containing tin, bismuth, iron, silicon, aluminum, carbon, and oxygen were identified. These aggregates exhibit characteristic film-globular morphologies ranging in size from 1–3 to 100–200 μm. As a result of thermal treatment, tin concentrations in the thermal products increased to 1500–1864 g/t, corresponding to ore-grade levels. The obtained results demonstrate the potential of thermal activation as an effective approach for the utilization of previously low-grade tin-bearing weathering crusts and for expanding the tin mineral resource base of Kazakhstan. Full article

The huge demand for natural sand in the global construction industry has caused resource shortages and severe environmental issues. Meanwhile, China produces massive annual iron tailings, and their stockpiling poses prominent potential safety hazards. At present, numerous investigations have been carried out on the fundamental properties of concrete prepared by replacing natural sand with iron tailings sand (ITS). However, most studies are limited to single replacement ratios and conventional strength mix proportions. Systematic research focusing on high-replacement-ratio systems, long-term durability performance, and supporting practical construction technologies for engineering applications remains insufficient. Obvious gaps still exist regarding the key mechanisms and practical operation standards for high-value and large-scale utilization. Against this background, this paper prepares concrete with three strength grades (C30, C40, C50) and six ITS replacement ratios (0%, 20%, 40%, 60%, 80%, 100%). Cube compressive tests and prism axial compressive tests are conducted, combined with SEM microscopic microstructure analysis. Axial compression tests and bearing capacity research are further carried out on reinforced concrete short columns (RCSC) with the optimal replacement ratio. The results show that concrete compressive strength increases first and then decreases with the rise in iron tailings sand concrete (ITSC), with 60% identified as the optimal replacement ratio. At this ratio, the compressive strength of C30, C40 and C50 concrete increases by 24.3%, 11.5% and 12.9%, respectively, while the bearing capacity of short columns rises correspondingly by 18%, 14.1% and 8.1%. Microscopic test results reveal that ITS exerts both physical filling and chemical active effects. Its fine particles fill internal pores inside the matrix and refine the pore structure. Meanwhile, the reactive mineral components contained in ITS can participate in the hydration reaction of the cementitious system, accelerate the hydration rate and generate more dense hydration products. Therefore, ITS facilitates the hydration process and improves the mechanical properties of concrete. A calculation method for the axial bearing capacity of RCSC incorporating ITS is proposed via theoretical analysis. This study provides a theoretical basis for preparing concrete by replacing natural sand with ITS. Using ITS as aggregate is expected to alleviate tailings stockpiling risks, reduce natural sand consumption, and realize solid waste resource recycling. It also offers valuable references for the green development of the construction industry and safety protection in mining areas. Full article

Cobalt occupies an irreplaceable strategic position in renewable energy and high-end advanced industries. As high-grade mineral resources gradually deplete, associated sulfide minerals have attracted increasing attention as alternative sources of cobalt. This study investigated a selective extraction of cobalt from low-grade cobalt-bearing pyrite using oxygen-pressure acid leaching. The Gibbs free energy (ΔG) of key chemical reactions in the leaching system was calculated to verify the thermodynamic feasibility of the process. The effects of critical parameters, including oxygen pressure, initial acidity, stirring speed, leaching time, and temperature, on cobalt leaching efficiency and phase transformation characteristics were systematically investigated. Under optimal conditions of oxygen pressure 1.5 MPa, H₂SO₄ initial acidity 7.36 g·L⁻¹ (0.82 mol/L), stirring speed 300 rpm, leaching duration 120 min, and temperature 230 °C, the cobalt leaching rate reached 98.2%, whereas the leaching rates of iron and aluminum were only 19.79% and 28.11%, respectively. Combined with SEM-EDS, XRD, and XPS characterization results, oxygen pressure acid leaching effectively destroyed the lattice structure of cobalt-bearing pyrite and liberates lattice-hosted cobalt, thereby facilitating efficient cobalt leaching. At high-temperature and oxygen pressure conditions, Fe³⁺ underwent hydrolysis and precipitated as hematite (Fe₂O₃) or hydronium jarosite (H₃O)Fe₃(SO₄)₂(OH)₆, enabling the selective extraction of cobalt. Aluminum in cobalt-bearing pyrite primarily occurred as the stable boehmite (AlOOH) phase, exhibiting excellent acid resistance and low dissolution during leaching. This study broadens the utilization pathway of low-grade cobalt resources and provides valuable insights and a scientific theoretical basis for the efficient treatment of cobalt-containing sulfide concentrates and tailings. Full article

This study investigated the production of spodumene concentrate and lithium carbonate from a low-grade pegmatite ore containing approximately 0.26 wt.% Li₂O. The ore consisted predominantly of a quartz–feldspar aluminosilicate matrix with dispersed spodumene mineralization, which complicates conventional processing approaches. Preliminary lithium concentration was performed by dense media separation (DMS) using an industrially applicable ferrosilicon-based suspension. The highest separation efficiency was achieved for the −4.0/+2.8 mm fraction, producing a DMS concentrate containing 5.77 wt.% Li₂O with 98% lithium recovery. The obtained spodumene concentrate was subjected to decrepitation at 1000–1100 °C to convert α-spodumene into the more reactive β-modification, followed by sulfation roasting with concentrated sulfuric acid at 250–270 °C. The productive leach solution obtained after water leaching contained up to 12.1 g/L Li₂O. After purification from iron-bearing impurities and precipitation with sodium carbonate, a lithium carbonate product containing at least 98.8 wt.% Li₂CO₃ was obtained. Approximately 53% of the lithium contained in the original ore was recovered into the DMS feed fraction, whereas the overall lithium recovery into lithium carbonate reached about 45% relative to the ore and approximately 70% relative to the concentrate. Full article

Iron (Fe) and nickel (Ni) were both foundational to early metabolism, yet their biological trajectories diverged as Earth’s surface redox state changed. Here, we integrate mineral chemistry network analysis, protein metal-site coordination-sphere analysis, and curated redox comparisons to test how geochemistry and metalloprotein architecture co-evolved. Mineral network analyses show broader electronegativity variation and network diversity for Fe-bearing minerals through time relative to Ni-bearing minerals. In structural analyses of protein metal centers in a combined Fe/Ni protein structure set, it is shown that Fe- and Ni-associated environments differ in amino-acid composition, hydropathy structure, and cysteine representation. The greater chemical diversity and electronegativity variation in Fe minerals mirror the higher redox and structural versatility of Fe-binding proteins. The presence of Fe in a broader range of mineral and protein environments demonstrates the chemical adaptability of the metal, from the anoxic Archean to oxidative Earth surface conditions following the Great Oxidation Event. Iron, with its broad redox potential range in Fe-oxidoreductases, has a central role in both anaerobic and aerobic metabolisms. Nickel, by contrast, is less widespread in biology. Today, Ni is predominantly employed in deeply branching anaerobic pathways and by proteins with narrower redox potential ranges. Our results show that evolutionary processes, constrained by metal chemistry, habitually utilize Fe as a redox generalist while retaining Ni in specialized roles. The divergent paths of Ni and Fe, from rocks to proteins, demonstrate the intimate relationship between planetary geochemistry and metabolic origins on Earth and suggest that Fe/Ni geochemistry may inform habitability assessments in extraterrestrial environments when interpreted within specific planetary environmental contexts. Full article

Arsenic contamination in polymetallic mining areas is closely linked to surrounding iron-rich manganese minerals. However, conclusive evidence remains limited regarding the retention and migration process of As(V) in naturally manganese-rich manganese ores (especially those with different manganese/iron mass ratios) under dynamic flow conditions. This study investigated As(V) adsorption and transport by four natural manganese minerals (FM1–FM4) through batch/column experiments, characterization, and numerical modeling. Their Mn/Fe mass ratios were 22.7 for FM1, 4.2 for FM2, 3.7 for FM3, and 16.4 for FM4. Batch experiments showed that As(V) adsorption on FM1–FM3 was better described by the Freundlich model, indicating heterogeneous adsorption behavior. Under the tested experimental conditions, the apparent Langmuir q_m values of these minerals decreased from 0.066 to 0.015 mmol·g⁻¹ with decreasing Mn/Fe ratio. However, As(V) adsorption on FM4, which had the lowest Mn and Fe contents, followed the Langmuir model (q_m = 0.012 mmol·g⁻¹), suggesting monolayer adsorption. Column experiments demonstrated rapid As(V) retention for all minerals. In the time domain, increasing the flow rate from 0.5 to 2.0 mL·min⁻¹ generally advanced breakthrough and shortened the desorption tail, although the breakthrough behavior expressed in pore-volume coordinates was not strictly monotonic for all minerals. The Two-Site Kinetic Attachment Model (TSKAM) successfully simulated these dynamics (R² > 0.90, RMSE < 0.05), revealing adsorption controlled by fast and slow kinetic sites, with slow-site contributions diminishing at higher flow rates. Characterization results indicated that adsorbed arsenic on FM1 remained mainly as As(V) and was immobilized primarily through surface complexation involving surface hydroxyl and Fe/Mn–O groups. XRD and SEM-EDS suggested the participation of Fe/Mn-bearing phases, while XPS on FM1 showed pronounced changes in Mn surface species during adsorption. Therefore, As(V) removal by these natural manganese minerals is a coupled physicochemical process influenced by both mineral properties, including Mn/Fe ratio, specific surface area, pore structure, pH_PZC, and Mn surface-state changes, and hydrodynamic conditions in the polymetallic mining areas. Full article

Arsenic (As) contamination in groundwater represents a critical global environmental health issue. The reductive dissolution of arsenic-bearing iron oxides by dissimilatory metal-reducing bacteria (DMRB) is a key biogeochemical process driving arsenic mobilization and release in groundwater. However, the mechanism of exogenous electron shuttles in this process remains poorly understood. This study investigated the impact of the quinone-based electron shuttle anthraquinone-2,6-disulfonate (AQDS) on the reductive dissolution of arsenic-loaded goethite by the model DMRB Shewanella putrefaciens CN32 (S.P CN32). The mobilization and transformation behaviors of arsenic and iron were compared under different pH conditions and using different arsenic-loading methods (coprecipitation vs. adsorption). Results demonstrated that AQDS acted as an electron transfer mediator. It significantly enhanced the reductive dissolution of Fe(III). It also significantly enhanced the reduction of As(V). These actions collectively accelerated arsenic release and mobilization. The study also revealed a competitive preferential order in microbial reduction, where the thermodynamically more favorable Fe(III) reduction preceded As(V) reduction. Environmental pH co-regulated this process. Its influence worked through microbial activity and mineral surface properties. A neutral pH was most conducive to the AQDS-mediated bioreduction of arsenic and iron. This study elucidates the critical role of electron shuttles in the biogeochemical cycling of arsenic in contaminated sites, providing a scientific basis for a deeper understanding of the formation mechanisms and risk assessment of high-arsenic groundwater. Full article

Natural hydrogen is regarded as a potential resource for the global energy transition, and its accumulation is closely linked to water–rock reactions involving Fe²⁺ bearing minerals and effective sealing conditions. The Liaohe Basin, located on the northeastern margin of the North China Craton within a key metallogenic belt, is surrounded by sedimentary-metamorphic iron deposits and is a potential area for natural hydrogen accumulation. In this study, aeromagnetic and satellite gravity data were integrated to estimate basement depth through gravity interface inversion, followed by three-dimensional magnetic susceptibility and density inversion and structural–mineralization correlation analysis. The results reveal strong basement heterogeneity. Iron-rich anomalous bodies show clustered and belt-like to dome-like distributions, mainly along the transitional zone between deep depressions and basement uplifts. Combined density–magnetic zonation suggests that high-density, high-magnetic units may correspond to iron-rich bodies, whereas high-magnetic, low-density units likely indicate fractured and altered fluid pathways. Based on the measured results of surface hydrogen concentration, it is inferred that the high magnetic anomaly in the uplift transition zone at the edge of the depression might be the coupling area of iron-rich rock bodies and channel zones, which is the priority response area of natural hydrogen in the Liaohe Basin, China. Full article

High-iron red mud presents a major obstacle to comprehensive resource utilization, as iron and aluminum minerals form tightly interwoven and encapsulated structures that resist conventional separation, hindering efficient co-recovery of these valuable elements. This study aimed to address this bottleneck by developing an effective strategy for iron–aluminum separation and synergistic recovery. A reduction smelting process was conducted in a sealed electric furnace using internally carbon-containing red mud pellets, enabling phase reconstruction to regulate aluminum-bearing phases while achieving iron–aluminum separation. XRD and SEM analysis verified that iron oxides were reduced to metallic iron with recovery exceeding 98%, and aluminum-bearing phases were selectively converted into active α-Al₂O₃ and mainly dodecacalcium hepta-aluminate (Ca₁₂Al₁₄O₃₃) in the slag. Under optimized Bayer leaching conditions (150 g/L NaOH, 240 °C, 90 min, liquid-to-solid ratio 6:1), aluminum extraction exceeded 60%, comparable to conventional red mud processing. This work overcomes the technical barrier of iron–aluminum co-recovery from high-iron red mud, offering a practical and efficient route for its sustainable valorization. Full article

The Jiaodong gold-mineralized area is one of the most significant gold districts in China. The newly discovered Moshan gold deposit is hosted in the Late Jurassic Queshan granite, previously considered a prospecting blind zone. In this study, pyrite from the Moshan gold deposit is examined as the primary research subject. To elucidate the ore-forming processes and genetic mechanisms of this deposit, we conducted a comprehensive mineralogical and geochemical study on pyrite, the principal gold-bearing mineral. EPMA and LA-MC-ICP-MS analyses reveal that the pyrite is slightly sulfur-deficient (average S/Fe ratio of 1.976) and exhibits trace element variations (As, Co, and Ni) strongly correlated with distinct metallogenic stages. Gold occurs in various forms, including visible inclusion gold, fracture gold, and invisible nano-particulate gold (Au⁰). The in situ sulfur isotope δ³⁴S values range from 7.11‰ to 9.40‰ (average 8.00‰), displaying high homogeneity and a positive deviation from the troilite in the Canyon Diablo iron meteorite. By integrating pyrite S-Fe relationships, Co-Ni-As systematics, and sulfur isotope characteristics, the study indicates that the Moshan gold deposit originates from a magmatic-hydrothermal source. The ore-forming materials predominantly derive from Mesozoic granite-derived magmatic-hydrothermal fluids, with a minor contribution from crustal basement materials. The depth of mineralization is interpreted as mid-shallow. These findings not only highlight the metallogenic potential of the Queshan granite and clarify the genetic relationship between the Moshan gold deposit and other regional gold deposits but also provide a novel theoretical foundation and technical support for deep gold exploration in the Jiaodong region. Full article