Search Results (299)

The increasing global demand for pavement infrastructure has intensified the consumption of non-renewable construction materials, particularly natural aggregates and soils, raising significant environmental and resource sustainability concerns. In response, there is a growing need to explore alternative materials that can reduce reliance on these finite resources. Mine tailings, generated in large volumes from mining operations, have emerged as a promising substitute due to their potential to enhance asphalt concrete performance while mitigating environmental impacts associated with their disposal. This study presents a comprehensive review of the application of selected mine tailings in asphalt mixtures. It critically examines their physicochemical properties and evaluates their influence on key performance characteristics of asphalt pavements. The review further highlights the various applications, benefits, and limitations associated with their use. Despite increasing research interest, the field remains relatively underdeveloped, with limited experimental validation for practical pavement applications. The findings of this study provide valuable insights into the sustainable utilisation of mine tailings and identify key research gaps, offering direction for future experimental and field-based investigations in pavement engineering. The study observed that the performance of asphalt mixtures incorporating mine tailings from aluminium, copper and iron by-products is largely dependent on the physicochemical and mineralogical characteristics of these materials. The particle size, specific area and presence of reactive oxides are essential ingredients for improved interaction with the bitumen content of the mixture. Full article

This study examines the impact of regrinding on the interfacial properties of sulfide minerals and the flotation performance of weathered copper–porphyry tailings. The feed material is characterized by a low copper grade (0.17%) and a high proportion of oxidized species (53.84%), which contribute to its inherent chemical stability and poor flotation kinetics. The findings indicate that regrinding serves a dual role: facilitating the liberation of mineral intergrowths and inducing mechanical surface renewal. This renewal is characterized by a significant decrease in the oxidation–reduction potential (ORP) and an intensification of the surface reactivity. Experimental results identify an optimal grinding fineness of 77–81% passing −0.045 mm, yielding a copper recovery of 16.26% in the absence of a sulfidizing agent. The integration of sodium sulfide (400 g/t) with regrinding significantly enhances recovery to 36.37%, driven by the establishment of a reducing environment (ORP ≈ −150 mV) and the chemisorption-mediated activation of mineral surfaces. While ultrafine grinding (90–100% passing −0.045 mm) further increases recovery to 51.47%, it is accompanied by deleterious sliming effects and a subsequent loss of process selectivity. The study confirms that mechanical surface rejuvenation and the optimization of electrochemical conditions are critical for improving the processing efficiency of anthropogenic resources, providing a theoretical framework for establishing rational beneficiation regimes. Full article

Copper smelter slag represents a significant secondary resource of critical metals, while flotation tailings serve as an abundant sulfur-bearing waste stream. This study investigated a waste-on-waste sulfation roasting approach for the selective recovery of Cu, Ni, and Co from fayalite copper smelter slag using flotation tailings as an in situ sulfur source and sodium metabisulfite (SMBS, Na₂S₂O₅) as a sulfation promoter. The effects of roasting temperature, roasting time, slag-to-tailings ratio, SMBS dosage, and water-leaching conditions were systematically evaluated. Under the optimum conditions of a slag-to-tailings ratio of 1:1, roasting at 600 °C for 4 h with 30 wt% SMBS addition, followed by water leaching at 25 °C for 2 h, extraction efficiencies of 85.5% Cu, 81.6% Ni, and 87.1% Co were achieved, while Fe dissolution remained below 5%, demonstrating high selectivity. Phase and microstructural analyses by XRD, FTIR, SEM, and TG–DTA revealed that pyrite oxidation generated sulfur oxides required for metal sulfation, whereas SMBS promoted sulfur release and sulfate stabilization, enhancing sulfation efficiency. Thermodynamic analysis further confirmed the feasibility of sulfide oxidation and sulfate formation within the investigated temperature range. The results demonstrate that the synergistic use of tailings and SMBS enables efficient low-temperature sulfation roasting of fayalite slag and provides a promising route for the selective recovery of valuable metals from metallurgical waste materials. Full article

Cobalt has emerged as a strategic critical metal due to its essential role in rechargeable batteries, high-performance alloys, catalysts, and clean energy technologies. However, its supply chain remains heavily dependent on cobalt produced as a by-product of copper and nickel mining and is geographically concentrated, particularly in the Democratic Republic of Congo. This review provides a comprehensive assessment of cobalt geology, mineralogy, global reserves, market trends, primary extraction routes, and emerging secondary recovery strategies. Unlike previous reviews that address these topics separately, this work integrates geological occurrence, mineralogical characteristics, extraction technologies, and resource circularity within a unified framework aimed at evaluating future cobalt supply resilience. The main cobalt-bearing deposit types of sediment-hosted Cu–Co deposits, Ni–Co laterites, and magmatic Ni–Cu–Co sulphide deposits are compared in terms of their mineralogical characteristics and processing requirements. Hydrometallurgy is identified as the dominant industrial route, typically combining high-pressure acid leaching (HPAL) with downstream purification and recovery processes such as solvent extraction and electrowinning (SX–EW). Emphasis is placed on the relationship between ore mineralogy and process selection, as well as on the growing integration of secondary resources, including tailings, slags, and spent batteries, into existing cobalt production chains. Despite promising recovery rates at laboratory scale, challenges remain in impurity control, economic scalability, and integration into established refining infrastructure. This review demonstrates that secondary resources are evolving from supplementary feedstocks to strategically important contributors to cobalt supply. Future supply security will depend on feedstock diversification, more flexible refining systems, improved impurity management, and the implementation of sustainable circular-economy strategies. Full article

Significant amounts of smelting slag are generated during the production of steel, refined copper, and refined magnesium. These slags contain abundant valuable metallic elements, such as Fe, Cu, Zn, Co, and Mg, that have not been fully utilized in the past. This study proposes a method for modifying copper slag by mixing it with steel slag and magnesium slag, followed by roasting with additions of Fe₂O₃ and MgO. The samples were roasted at 1400 °C for 30 min, cooled to 1000 °C at 1.5 °C/min, and then water-quenched to room temperature. Phase transformations during modification were analyzed using FactSage 8.0, DSC–TG, and XRD. The effects of factors such as the content of Fe₂O₃ and MgO on the modification efficiency were investigated. The results indicate that, under the condition of maintaining a steel slag: copper slag: magnesium slag ratio of 37:37:26 and adjusting the basicity (CaO/SiO₂ ratio) with CaO to 2.0, the addition of Fe₂O₃ and MgO promotes the formation of spinel. However, excessively high contents of Fe₂O₃ and MgO lead to refinement of the spinel grains and reduce the iron grade of the concentrate. Within the investigated composition range, the samples with total Fe₂O₃ and MgO contents of 27.66 wt% and 7.56 wt%, respectively, showed the best magnetic separation performance among the tested compositions. Through magnetic separation, the concentrate has good economic and industrial application value in industries such as steelmaking and powder metallurgy, while the tailings can be utilized as raw materials for manufacturing ceramics, glass–ceramics, cement, and concrete. Full article

A study was conducted to characterize the performance of a HydroFloat^® coarse particle flotation (CPF) cell using rougher tailings samples from an industrial copper mining operation. The work involved measuring internal hydrodynamic variables under a wide range of operating conditions. The effect of different operational and hydrodynamic conditions on the metallurgical performance of the HydroFloat^® cell was also evaluated. Gas dispersion measurements, such as bubble size distribution, superficial gas velocity (J_g), superficial area flux (Sb), and residence time distribution (RTD), were recorded, enabling a detailed analysis of the cell’s operation. Results show that copper recovery is strongly influenced by the superficial gas velocity (J_g) and the superficial liquid velocity (J_l). It was observed that the bubble diameter (d₃₂) remained relatively constant at 0.5 mm across all operating conditions, which is well below typical bubble sizes for conventional flotation cells. This suggests that contrary to what may be expected, in this kind of machine, small bubbles are able to float coarse particles. Bubble image inspection suggests that the HydroFloat^® cell creates conditions conducive to bubble–particle aggregates, which would explain how small bubbles can float coarse particles. This study contributes to the understanding of CPF and establishes a framework for optimization in copper concentrators. Full article

Fresh flotation tailings represent an underutilized archive of mineralogical and geochemical information in which multiple strands of evidence for ore-forming processes and post-depositional modification can be preserved. Detailed characterization of tailings is also vital for assessment of their future potential as a secondary source of recoverable by-products. This study investigates residual mineral speciation and mineral distributions in size fractions of tailings from the Prominent Hill iron oxide–copper–gold (IOCG) deposit, South Australia, with emphasis on rare earth element (REE) minerals and associated phases containing uranium (U). Assemblages of REE minerals can be highly complex at the micron scale and include sequences of mineral replacement, notably monazite → florencite, and monazite → synchysite. Bastnäsite-(Ce) commonly appears paragenetically early and is frequently altered or replaced by synchysite and parisite, supporting episodes of REE remobilization and reconcentration over geological time. Uranium is closely associated with REEs, and U-mineral assemblages are similarly characterized by intricate replacement relationships between uraninite and secondary phases. Uraninite is variably replaced by coffinite and the U-carbonate wyartite, reflecting changes in redox state, silica activity, and fluid composition. Additional replacement pathways from uraninite to Cu–Fe sulphides, including bornite and chalcopyrite, are documented and indicate coupled dissolution–reprecipitation of sulphides and U-minerals during superimposed hydrothermal activity. Preservation of mineralogical relationships within tailings drawn from multiple parts of a large deposit highlights their value as an essentially untapped library of information to reconstruct deposit evolution, complementing traditional study of selected drill core samples. Systematic investigation of tailings from large deposits can improve genetic models for large copper deposits, including but not restricted to IOCGs, and provide essential insights into REE behaviour, uranium remobilization, and critical metal potential. These findings emphasize the scientific and economic value of tailings-based studies for improved resource characterization, refining metallogenic interpretations, guiding future exploration strategies, and assessing opportunities for reprocessing and metal recovery in large ore systems worldwide across diverse geological settings. Full article

The mining industry faces increasing challenges related to the growing volume of tailings generated during mineral processing. This study presents a case study of the Complex Mine Waste Reduction (CMWR) concept implemented at the Polkowice Concentrator operated by KGHM Polska Miedź S.A. The approach integrates coarse ore sorting with tailings reprocessing for construction material production. Sorting improves flotation feed quality by rejecting low-grade gangue, while reprocessing converts fine tailings into value-added products. The combined implementation reduces tailing deposition by up to 22% and improves the operational copper recovery in flotation while maintaining overall process recovery at an essentially unchanged level. The results demonstrate the potential of integrated solutions for sustainable and circular mining. Full article

Textural and geochemical analysis of intertidal sediments in the southern Atacama region makes it possible to identify sites primarily affected by mining-related pollution, based on a multivariate statistical analysis of the concentrations of five elements (Fe, Cu, Zn, As, Pb) and their geoaccumulation indices. These concentrations are not correlated with grain size, which is dominated by the sandy fractions. Spearman’s matrix and principal component analysis make it possible to distinguish between two groups of elements (group A: Fe-Cu-As; group B: Zn-Pb), with a strong correlation between them (ρ ≥ 0.51; p < 0.01) and the first two components explain 96.3% of the variance. Three heavily polluted sites (Playa Blanca, Bahía Sarco and Chañaral de Aceituno; I_geo Cu > 8) have been identified linked to waste from the washing of tailings, a copper smelter and frequent boat trips. In addition, four moderately polluted sites (Playa Grande, Balneario Caldera, the mouth of the Copiapó River and Carrizal Bajo; 1.7 < I_geo Cu < 8; 1.2 < I_geo Pb < 2.6), mainly due to activities associated with mining and oil refineries, have been identified. Full article

This study presents an integrated approach for the processing of technogenic tailings from the Balkhash concentrator, combining hydrocyclone classification, microfluidic separation, bioleaching, and geopolymer synthesis. The tailings are characterized by a fine-dispersed silicate matrix and low concentrations of valuable metals, which limit the efficiency of conventional processing methods. Hydrocyclone classification enables effective size separation and stabilization of particle size distribution, providing suitable feed for downstream processes. Microfluidic separation demonstrated selective concentrations of copper, increasing its content in the central fraction up to 0.52–0.58% with recovery up to 70–75% under optimal flow conditions. Bioleaching experiments using acidophilic microorganisms (Acidithiobacillus ferrooxidans and A. thiooxidans) revealed strong dependence on process parameters, achieving maximum recoveries of Cu (63%), Zn (58%), and Fe (43%) at pH 1.8–1.9 and 31–32 °C. The solid residues after bioleaching, composed mainly of aluminosilicates, were successfully utilized for geopolymer synthesis. The obtained geopolymer samples exhibited low water absorption (not exceeding 9.1%) and high compressive strength, meeting the requirements of Kazakhstan standard 26633-2015 (ISO 22965-1). The production of geopolymer materials from these residues contributes to the environmental rehabilitation of tailings storage facilities. The novelty of this work lies in the integration of microfluidic separation with bioleaching for fine tailing processing, enabling both selective metal recovery and subsequent conversion of residues into functional geopolymer materials. The proposed approach provides a sustainable pathway for simultaneous resource recovery and waste valorization, contributing to circular economy strategies in the metallurgical industry. Full article

Mining activities generate large volumes of waste that pose both environmental liabilities and potential secondary resource value. A significant fraction of these materials still contains recoverable copper, making leaching a promising strategy for reprocessing and valorization, given the natural decline in ore grade. This study presents a PRISMA-based systematic review of recent literature on leaching technologies applied to mining waste, with emphasis on technical performance, environmental implications, and economic feasibility. The reviewed residues include tailings, slags, copper smelter dusts, sludges, waste rock, leaching residues, and other secondary mining and metallurgical wastes. The main leaching routes identified were acidic, biological, alkaline, and hybrid systems, including conventional H₂SO₄ leaching, pressure oxidative leaching, chloride-based systems, glycine- and ammonia-based alkaline media, organic acids, deep eutectic solvents, and biologically mediated processes. Reported Cu recoveries ranged from low values in refractory systems to near-complete extraction under optimized conditions. Overall, copper recovery was controlled primarily by the mineralogical occurrence of Cu rather than by leaching category alone. In contrast, the highest recoveries were generally associated with intensified conditions capable of overcoming sulfide- and silicate-related constraints. Environmental and circular economy benefits were frequently claimed but less often demonstrated through direct evidence, while economic assessment remained limited. Future research should better integrate mineralogical interpretation, environmental verification, and economic feasibility. Full article

This study investigates the differential settling behavior of binary particle suspensions through a combination of theoretical modeling and batch settling experiments. A classical zone-formation differential settling model is adopted, and a comprehensive experimental program is designed to generate data for model evaluation. Batch settling tests conducted using fine copper tailings and coarse silica sands show that distinct settling zones can be identified, and the solids’ concentrations of the particle species are consistent with theoretical predictions. However, the behavior within the sediment region differs from model assumptions, as a range of solids’ concentrations is observed, suggesting the presence of a transition zone rather than a sharp transition from the hindered settling region to a sediment with maximum solids’ concentration. Experimental observations of the sediment boundary also reveal a discrepancy between theoretical predictions and measured propagation velocities. This discrepancy is attributed to inter-species interactions arising from differential settling velocities, which are not accounted for in conventional models. The results highlight the limitations of widely used differential settling models and emphasize the importance of incorporating species–species interactions and transition zone behavior to improve the prediction of settling behavior in multi-species suspensions. Full article

Antimicrobial resistance (AMR) is a global health threat that continues to concern scientists because it can be driven not only by antibiotic misuse but also by environmental factors. Mining-related heavy metal pollution can apply strong selective pressure on microbial communities, leading to a significant increase and spread of antibiotic resistance genes (ARGs) in the environmental ecosystems. Here, we critically review the emerging role of mining environments as hotspots of environmental resistomes and the mechanisms by which heavy metal contamination drives co-selection of antibiotic resistance. There is also evidence that mining environments, such as AMD systems, mine tailings, contaminated sediments, and mining-impacted soils, harbor highly diverse microbiomes enriched with different resistance determinants. Heavy metals such as copper, zinc, cadmium, mercury, and arsenic promote ARG co-selection through co-resistance, cross-resistance, and co-regulation mechanisms. Widespread co-occurrence of metal- and antibiotic-resistance genes on mobile genetic elements such as plasmids, integrons, and transposons has been demonstrated in metagenomic studies. Environmental dissemination pathways, such as water systems, agricultural soils, wildlife interactions, and occupational exposure, may promote the spread of resistance genes outside mining sites. Mining ecosystems are underrecognized and potentially important reservoirs of antimicrobial resistance. This review highlights the importance of integrating environmental resistome surveillance into existing global AMR monitoring frameworks to understand underlying ecological drivers of resistance evolution. Tackling metal-driven antibiotic resistance requires innovative, solution-based interdisciplinary research, enhanced environmental screening and soil and water testing practices, and sustainable mining practices within the One Health paradigm. Full article

The Liwu copper deposit, located on the western margin of the Yangtze Block, is a typical metamorphic-hosted polymetallic Cu deposit with significant deep exploration potential. To constrain its mineralization-forming processes and primary halo characteristics, this study focuses on the Heiniudong ore segment. Based on portable X-ray fluorescence (XRF) data obtained from drill cores and underground samples, a comprehensive geochemical analysis of 20 elements was conducted. Elemental background values and anomaly thresholds were determined using the iterative sigma (σ) elimination method. Pearson correlation analysis and hierarchical cluster analysis were applied to identify element associations, while the Grigorian zonation index method was employed to investigate axial zoning patterns of primary halos. The results demonstrate that Cu exhibits strong positive correlations with S, Fe, Ag, Cd, Sn, and Bi, indicating a medium- to high-temperature hydrothermal sulfide mineralization system. The primary halo displays well-defined vertical zonation, with Ba–Sr–Sb–As representing the front halo, Zn–Pb–Cu–Ag–Sn–Fe–Cd the near-ore halo, and Bi–Mo–W–Th the tail halo. A clear axial zonation sequence is established. The vertical variation in the geochemical ratio (As × Sr × Sb)/(Mo × Bi × W) exhibits a characteristic “low–high–low–high” pattern, reflecting the superposition of the front halo of a deeper concealed orebody with the tail halo of the upper known orebody under multistage hydrothermal remobilization and structural overprinting. Integrated with the coexistence of front halo and tail halo anomalies and strong alteration in drill hole WT03, the results indicate that the southwestern extension of WT03 along southwest-dipping ductile–brittle detachment structures represents the most promising deep exploration target. Full article

The causative event in transmissible spongiform encephalopathies is the misfolding of the prion protein (PrP), a process influenced, in a way that is not yet fully understood, by transition metal ions, particularly copper, which modulate folding, aggregation, and redox activity. In this study, we investigated the interaction of copper(II) ions with the prion fragment PrP(95–126), which includes the non-octarepeat high-affinity sites His96 and His111, as well as an amyloidogenic tail involved in PrP misfolding and membrane interaction. UV–vis and circular dichroism analyses revealed the predominant formation of a 1:1 Cu/PrP(95–126) complex, accompanied by modest restructuring, consistent with an increased aggregation propensity upon copper binding. The Cu/PrP(95–126) complexes exhibited limited redox activity toward catechol substrates, which was further reduced in membrane-mimetic systems such as SDS micelles and large unilamellar vesicles (LUVs). His96 appears not to play a critical role in copper coordination or redox activation. This study explores the coordination modes and reactivity of copper(II) with PrP, as well as employing a membrane mimic, aspects that are still highly controversial in the literature, providing insights for further in vitro studies. Full article