Search Results (625)

The selective separation of chalcopyrite from pyritic ores represents a major industrial challenge due to inadvertent copper activation. This study systematically investigates the batch flotation kinetics of a complex sulfide ore (Draa Sfar North, Morocco) using a first-order kinetic model ($R^2>0.916$). The impacts of pulp pH, chemical depressants, and specialized collectors were evaluated to optimize the copper/iron selectivity index ($S{I}_{Cu/Fe}$). The results reveal a high-alkalinity paradox: At pH 11.0, chalcopyrite kinetics experience a severe passivation bottleneck ($K_{i,Cu}=0.1330 {\min }^{-1}$). At pH 11.5, selectivity collapses ($SI=2.64$) due to persistent iron sulfide floatability ($K_{i,Fe}=0.2066 {\min }^{-1}$). Conversely, natural pH ($\approx 6.0$) provides a superior baseline ($SI=3.32$), where 40 g/t sodium cyanide (NaCN) yielded a peak index of $S{I}_{Cu/Fe}=10.25$. As an eco-friendly substitute, sodium lignosulfonate (LSNa) achieved outstanding performance ($S{I}_{Cu/Fe}=5.30$), reducing iron kinetics to their lowest level ($K_{i,Fe}=0.0356 {\min }^{-1}$) via ferric–anionic complexation. Furthermore, Danafloat 271 secured the highest collector-driven selectivity ($S{I}_{Cu/Fe}=5.03$) by suppressing the iron matrix ($K_{i,Fe}=0.0306 {\min }^{-1}$) following Hard–Soft Acid–Base principles. This study clarifies specific aspects of selective copper–iron flotation, demonstrating that natural pH circuits with green depressants or selective collectors offer a sustainable alternative. Full article

The performance of the bacterium Acidithiobacillus ferrooxidans and sodium metabisulfite (MBS) as pyrite depressants in seawater flotation was compared. Microflotation experiments were conducted using pure pyrite, while batch flotation tests were performed using a sulfide ore sample containing pyrite. The results showed that A. ferrooxidans was more effective than MBS in depressing pure pyrite flotation. In the presence of the bacterium, pyrite recovery decreased from 95% to 64% at pH 8 and from 96% to 21% at pH 10. In contrast, MBS exhibited superior performance during flotation of the sulfide ore sample, reducing pyrite recovery from 81% to 57% at pH 8 and from 86% to 57% at pH 10. The results suggest that dissolved copper ions present during flotation of the sulfide ore promote the interaction between MBS and pyrite, thereby enhancing its depressant effect. Conversely, the performance of A. ferrooxidans appears to be reduced in complex ore systems because the bacteria may adhere to other mineral surfaces, decreasing their interaction with pyrite. This phenomenon was not observed during flotation of pure pyrite. SEM–EDS analyses confirmed the presence of copper-containing species on the pyrite surface after exposure to copper ions. These findings indicate that MBS is more suitable than A. ferrooxidans for pyrite depression in complex sulfide ores under seawater flotation conditions, particularly when copper-bearing minerals are present. Full article

Although the mineralogical form of occurrence of critical metals is widely recognised as a key factor controlling their recovery during beneficiation, this relationship has rarely been verified directly on freshly mined ore and its primary beneficiation products from Central Asian polymetallic deposits. This raises the research question of how the mineralogical mode of occurrence of Bi, In, Cd, Co, Se, Te and Re governs their distribution between gravity and flotation products. Accordingly, the aim of this study was to establish how the mineralogical form of occurrence of these critical metals determines their distribution among gravity-concentration and flotation products, using ores from the Zhuantobe and Strezhanskoe deposits (Kazakhstan) as a case study. To this end, the mineralogical features and distribution patterns of critical metals during gravity and flotation beneficiation of polymetallic ores from these deposits were investigated by optical microscopy, X-ray diffraction, and SEM-EDS, while metal distribution among beneficiation products was determined by chemical analysis. Sphalerite, galena, pyrrhotite, and silver tellurides were identified as the main carriers of the critical metals, with bismuth occurring as an isomorphic admixture in sphalerite (3.69 wt.%) and galena (1.85 wt.%). During flotation, distribution was governed by mineralogical affinity: cadmium and indium were preferentially concentrated in the zinc concentrate (56.31% and 15.44% recovery, respectively), bismuth in the copper–lead concentrate (23.03%), and selenium and rhenium in the copper-bearing products (23.60% and 37.05%). Correlation analysis of the gravity-concentration products confirmed a close association of cadmium with sphalerite (R² = 0.9998), bismuth with galena and sphalerite (R² = 0.9674), and cobalt with iron-bearing sulfides (R² = 0.9144). These results demonstrate that the distribution of critical metals is governed primarily by their mineralogical form of occurrence rather than by bulk ore content, providing a basis for technologies for the complex processing of polymetallic ores. Full article

Disulfiram (DSF), long used as an aversive agent in alcohol dependence therapy, has recently regained attention as a promising candidate for oncological drug repurposing. After administration, DSF is rapidly reduced to diethyldithiocarbamate (DDC), which, in the presence of Cu²⁺, forms the complex Cu(DDC)₂. This compound acts as a strong inducer of oxidative stress, an inhibitor of the ubiquitin–proteasome system, and a suppressor of endogenous hydrogen sulfide (H₂S) synthesis. DSF also modifies protein and non-protein thiol groups, disrupting cancer cell metabolism and promoting apoptosis. Despite robust preclinical evidence, clinical translation remains limited. Key obstacles include DSF’s rapid metabolism, insufficient availability of free copper ions in humans, and the lack of predictive biomarkers capable of identifying responsive patients. Another challenge is DSF’s low oral bioavailability, which prevents the drug from reaching tumor tissue at therapeutically effective concentrations. Consequently, current research focuses on advanced nanocarrier systems designed to protect DSF from premature degradation and ensure its controlled release within the tumor microenvironment. This review summarizes the multifaceted anticancer mechanisms of DSF and discusses biological and pharmacological factors underlying the discrepancies between experimental findings and clinical outcomes. Full article

Process mineralogy provides valuable information for understanding the mineralogical and textural characteristics of volcanogenic massive sulfide (VMS) deposits and their influence on mineral liberation. This study investigates the relationship between ore texture and chalcopyrite liberation in massive and stockwork/disseminated copper ore samples from a Kuroko-type VMS deposit in the Eastern Black Sea Region of Türkiye. Whole-rock mineralogy, textures, and mineral intergrowth relationships were characterized using X-ray diffraction (XRD), reflected-light ore microscopy, and field-emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FE-SEM/EDS) mapping. Both ore types contain chalcopyrite, pyrite, sphalerite, and galena as the main valuable minerals, with quartz as the predominant gangue mineral. However, they show distinct textural characteristics. In the massive ore, chalcopyrite occurs as fine-grained aggregates filling fractures in cataclastic pyrite and commonly forms complex intergrowths with adjacent sulfides. In contrast, the stockwork/disseminated ore exhibits a more dispersed sulfide distribution within a quartz-rich matrix. Liberation analyses conducted across six particle size fractions, ranging from −600 + 500 to −38 µm, demonstrate that chalcopyrite liberation increases as particle size decreases. The stockwork/disseminated ore consistently exhibits higher liberation than the massive ore across all size fractions. The highest liberation values were achieved in the −38 µm fraction, reaching 98% for the stockwork/disseminated ore and 90% for the massive ore. FE-SEM/EDS mapping confirms that micron-scale sulfide intergrowths in the massive ore limit complete liberation and contribute to its lower liberation efficiency. These findings highlight the influence of ore texture on chalcopyrite liberation and provide useful geometallurgical information for optimizing the grinding and beneficiation of Kuroko-type VMS ores. Full article

Silver (Ag)-based conductive coatings are widely used in electrical contacts due to their excellent electrical conductivity, low contact resistance, good thermal stability and oxidation resistance, although their susceptibility to sulfidation and environmental corrosion is a concern under certain service conditions. In recent years, significant progress has been achieved in both the manufacture and performance optimization of Ag-based coatings to satisfy the demanding requirements of modern electrical and electronic systems. This review summarizes recent advances in fabrication techniques and processing parameters for Ag-based coatings, including electroplating, electroless deposition, magnetron sputtering, electrospark deposition, thermal spraying, and electrical explosion spraying on metallic substrates, particularly on copper and steel substrates. More attention is given to microstructural design strategies, such as the incorporation and homogeneous dispersion of reinforcement or solid lubricant phases within the Ag matrix, to enhance contact reliability and operational endurance. The performance of Ag-based coatings is analyzed in terms of their physical, chemical and mechanical properties, electrical contact resistance, friction and wear behavior, arc erosion resistance, and environmental durability under different service conditions. Key challenges, including coating degradation under high electrical loads, mechanical wear, and corrosive environments, are highlighted. Future research directions are outlined, focusing on multifunctional coating structures that enhance surface performance and ensure the long-term durability of electrical contacts. Full article

The global energy transition and rapid electrification are driving increased demand for copper. However, conventional pyrometallurgical and hydrometallurgical extraction routes are increasingly challenged by declining ore grades and stricter environmental regulations. Bioleaching involves the microbial catalysis of sulfide mineral dissolution and provides a sustainable method for copper recovery from low-grade ores, tailings and secondary resources. This review provides a critical and integrated analysis of copper sulfide bioleaching, covering microbial diversity, molecular mechanisms, mineralogical controls, operational parameters, and industrial applications. This review also examines the functional roles of prominent acidophiles, including the functional roles of prominent acidophiles, including Acidithiobacillus spp., Leptospirillum spp. and thermophilic archaea, in the oxidation of iron and sulfur, mitigation of passivation, and metal solubilization. The molecular underpinnings of these processes are explored by investigating iron and sulfur oxidation gene networks (the rus operon and sox cluster), copper resistance systems (CopA, CusCBA) and biofilm formation pathways. The mineralogical controls on the behavior of chalcopyrite (refractory/passivating), chalcocite (highly reactive) and bornite (intermediate) are critically assessed. The synergistic effects of key operational parameters (temperature, pH, redox potential, aeration and particle size) on leaching kinetics and microbial community dynamics are investigated. The scalability, efficiency and environmental footprint of industrial applications such as heap, dump, stirred-tank and in situ bioleaching are discussed. Despite more than four decades of commercial development, several challenges remain, such as slow chalcopyrite dissolution, passivation, metal toxicity, and scale-up limitations. Emerging solutions such as synthetic microbial consortia, multi-omics technologies, artificial intelligence-assisted optimization, and digital twins are identified as transformative approaches for next-generation biomining. In this review, microbiology, mineralogy, electrochemistry, and process engineering are integrated to demonstrate that biotechnological leaching is among the most promising technologies for the sustainable production of copper and to identify future directions for its industrial application. Full article

Integrated and tunable light sources are critical for advancing quantum nanophotonic chips in quantum computing, communications, and sensing. However, efficient and tunable emission amplification post-fabrication poses major challenges. Hybrid metasurfaces combining niobium pentoxide (Nb₂O₅), copper indium sulfide (CIS) quantum dots or hexagonal boron nitride (hBN), and antimony trisulfide (Sb₂S₃) as a low-loss phase-change material offer a compelling solution for dynamic control and amplification of photoluminescence and quantum light emission. In this work, an active hybrid metasurface supporting tunable bound states in the continuum (BIC) resonances in the visible regime is demonstrated, achieving experimental Q-factors up to 206 at an amorphous state and strong amplification of CIS QDs photoluminescence, as well as quantum light emission of hBN single-photon emitters. The metasurface enables BIC resonance shifts of 33.5 nm in the visible spectrum via phase transition of Sb₂S₃, and 17 nm through dimensional parametric tuning. The experiment demonstrates a highly directional photoluminescence amplification up to 33-fold, alongside broad tunable amplified PL emission upon Sb₂S₃ phase modulation. Furthermore, amplified, tunable, and on-demand strong coupling of hBN single-photon emitters is proposed with the tunable BIC metasurface for next-generation broadband quantum nanophotonic chips. This work sets a new benchmark in reconfigurable nanophotonic platforms for efficient quantum light sources in integrated photonic systems. Full article

Flotation of mixed copper oxide–sulfide ores remains challenging due to low natural floatability of oxide minerals and complex interplay between sulfidization and collector adsorption. This study investigated the combined effect of NaHS-assisted sulfidization and 2,5-dimercapto-1,3,4-thiadiazole (DMTD), an azole-based collector, in terms of enhancing copper recovery from a mixed oxide–sulfide ore. The effects of pulp pH, DMTD, NaHS, and sodium metasilicate dosages, together with pulp solid concentration, were evaluated using response surface methodology. The quadratic model showed high predictive capability (R² = 0.9361), identifying NaHS dosage as the most influential factor. Optimum operating conditions (pH 9.50, DMTD 200 g/t, NaHS 750 g/t, sodium metasilicate 500 g/t, and 25% solids) yielded 64.03% copper recovery. Compared with the plant collector (PAX, Potassium Amyl Xanthate), DMTD increased recovery by 12.6% for highly oxidized ore while producing a higher concentrate grade. Density Functional Theory (DFT) calculations provided molecular insights into the experimental observations, confirming DMTD’s high affinity for sulfidized surfaces. Hybrid solvation models revealed greater thermodynamic stability (ΔE_ads = −6.74 eV) than PAX due to hydrogen bonding with explicit water molecules, while the smaller HOMO–LUMO gap (ΔE_gap = 0.86 eV) supported its superior electron transfer capability and reactivity. These findings demonstrate that NaHS-assisted sulfidization with DMTD is an effective strategy for improving flotation of copper oxide–sulfide ores. Full article

Chrysocolla, a hydrated copper silicate mineral, is notoriously difficult to recover by conventional froth flotation due to its microporous structure, low hydrophobicity, impurity substitutions, and poor response to traditional collectors. This study evaluates the performance and adsorption mechanism of benzohydroxamic acid (BHA) as a collector for chrysocolla flotation under varying pH conditions and collector dosages. Microflotation results showed that chrysocolla recovery increased with BHA concentration, with enhanced flotation occurring at alkaline pH (8–10), consistent with BHA dissociation behavior. Zeta potential measurements indicated selective adsorption of BHA on the chrysocolla surface, while quartz showed minimal interaction, confirming collector selectivity. X-ray photoelectron spectroscopy (XPS) revealed that BHA was chemisorbed through Cu–hydroxamate complex formation. Bench-scale flotation tests on a chrysocolla ore containing 3.7% Cu produced a concentrate grading 26.7% Cu with 35.3% recovery after initial sulfide flotation. Kinetic tests indicated rapid recovery of more floatable copper phases, while scanning electron microscopy (SEM) showed preferential flotation of finer particles. Overall, the results demonstrate that BHA can effectively promote chrysocolla flotation through selective chemisorption, although high collector dosages are required due to the mineral’s high specific surface area and structural complexity. Full article

Mining flotation effluents may contain residual collectors that pose risks to aquatic environments when discharged without adequate treatment. Among these compounds, sodium diethyl dithiophosphate (SDE DTP) is of particular concern due to its persistence and potential ecotoxicological effects. This study evaluated the removal of SDE DTP from aqueous media using commercial activated carbon and thermochemically modified activated carbon prepared through nitric acid oxidation and urea treatment. Batch adsorption experiments were conducted using synthetic SDE DTP solutions and a laboratory-generated flotation effluent obtained from a copper sulfide ore containing approximately 0.5 wt.% Cu. A UV–visible spectrophotometric method was applied for the quantification of SDE DTP in both systems. The effects of adsorbent dosage, solution pH, and surface modification were investigated. Adsorption performance increased with activated carbon dosage and was strongly influenced by pH. Thermochemical modification significantly enhanced adsorption performance, increasing SDE DTP removal from 40% for unmodified carbon to 93% for the modified material. The modified adsorbent also maintained high efficiency in real flotation effluent, achieving 88% removal despite competing dissolved species. These results demonstrate that thermochemically modified activated carbon is a promising functional material for treating flotation effluents contaminated with dithiophosphate collectors. Full article

Copper-based nanopesticides are increasingly explored as nano-enabled alternatives to conventional copper pesticides because they may improve deposition, antimicrobial efficacy, and material-use efficiency. Their environmental risk, however, cannot be inferred from total copper concentration or from the toxicity of pristine particles alone. After agricultural application, copper-based nanoforms may be transported to soils, drainage waters, wetlands, and sediments, where aggregation, dissolution, aging, sulfidation, organic complexation, and biological processing reshape their speciation and bioavailability. This review critically examines copper-based nanopesticides at the benthic interface, with emphasis on environmental transformation, synchrotron-resolved speciation, lower-trophic invertebrate exposure, trophic transfer, and food-web risk. We highlight that sediment-associated organisms are not only toxicity endpoints but also biological processors and vectors of transformed copper species. Evidence from stable-isotope tracing, dietary exposure studies, mesocosms, and micro-food-web experiments shows that copper-based nanoforms can enter aquatic, benthic, and terrestrial food chains. However, most studies demonstrate transfer or accumulation rather than consistent biomagnification across trophic levels. We further argue that future risk assessment should move beyond single-material and single-endpoint testing toward transformation-aware, route-specific, and food-web-relevant frameworks. Integrating total copper analysis with particle-specific measurements, synchrotron-based speciation where analytically feasible, realistic lower-trophic exposure models, and ecosystem-level endpoints will be essential for evaluating the long-term risks of copper-based nanopesticides. Full article

The conventional sulfidization–xanthate flotation of oxide copper minerals is often limited by reagent consumption and the mismatch between surface generation and sulfidization when sulfidization is carried out only during flotation conditioning. To address these limitations, this study proposes an in situ sulfidization strategy during the grinding stage and investigates the combined regulation of grinding media (conventional steel vs. 18% Cr cast iron) and atmosphere (ambient air vs. N₂ purging) on the flotation of a synthetic malachite–dolomite ore. Real-time pulp chemistry monitoring and ethylenediaminetetraacetic acid (EDTA) extraction indicate that the conventional grinding environment has two main disadvantages: Fe dissolution from steel media increases Fe-related surface contamination, while the air-ground pulp promotes the oxidation and consumption of active sulfidizing species. The combined use of high-Cr media and an N₂ atmosphere improved the chemical environment for grinding-stage sulfidization. Specifically, the high-Cr media reduced Fe release and associated surface contamination, while N₂ purging shifted the pulp to a lower-potential environment that was more favorable for preserving active sulfide species. Under standardized reagent conditions, the optimized in situ sulfidization protocol increased copper recovery from 29.79% to 57.47% and improved the concentrate grade from 9.71% to 11.11%. These results suggest that regulating the grinding environment can enhance in situ sulfidization flotation of malachite by reducing Fe interference and controlling pulp redox conditions, providing useful guidance for the efficient beneficiation of oxide copper minerals. Full article

One of the most promising absorber materials for solar applications is copper zinc tin sulfide/selenide (CZTS), which has good optical properties and basic elements that are readily available, affordable, and environmentally acceptable. This study examines how pulse timing and current density affect the electrodeposition of Cu₂ZnSnS₄/Cu₂ZnSn(S,Se)₄ (CZTS/CZTSSe) thin films from a diluted electrolyte, including deposition quality, film configuration, elemental composition, crystallinity, and photovoltaic performance. It evaluates the impact of these factors on device performance, film properties, layer’s compactness, surface homogeneity, microcrack-free morphology, compositional homogeneity, crystallinity, and suitability for solar device manufacturing. Using a pulsed-current technique, CZTS precursor layers were electrodeposited in a low-concentration solution with periodic changes in current density of roughly 5.3–5.9 mA/cm² and pulse-on/off durations of 50/50, 100/100, and 250/250 ms. The deposited precursors were then added to fully built CZTS-based solar cell topologies after sulphurization or selenization. Structural characteristics were analyzed using X-ray diffraction (XRD), and composition and elemental distribution were assessed using energy-dispersive X-ray spectroscopy (EDS). Measurements of transmittance and reflectance were used to evaluate optical properties relevant to photovoltaic performance. In contrast to films deposited at higher current densities and longer off-times, moderate current densities combined with short off-times yield dense, microcrack-free films with improved crystallinity and near-stoichiometric Cu/(Zn + Sn), Zn/Sn, and chalcogen/metal ratios. Additionally, absorber layers with appropriate optical band gaps and improved device performance are produced by these optimized pulse parameters. Overall, the study shows that controlling pulse parameters in diluted electrolytes is a useful tactic for improving the quality of CZTS films and developing low-cost, solution-based fabrication techniques for high-performance CZTS solar cells. Full article

The leaching of chalcopyrite in sulfate or chloride media has been proposed to occur through a combined non-oxidative/oxidative mechanism, where H₂S forms an intermediary species, concurrently with direct oxidative leaching. Some studies have noted that elevated concentrations of Cu(II) improve chalcopyrite leaching in sulfate media. In this study, the role of Cu(II) was investigated in the non-oxidative/oxidative process through electrochemical tests on a chalcopyrite electrode, supported by bulk leach tests. The results of the electrochemical tests are consistent with the formation of H₂S through non-oxidative leaching of chalcopyrite. The H₂S subsequently reacts with Cu(II) to form intermediate cuprous sulfide species, which can be readily oxidized by dissolved oxygen. The bulk leach tests point to a synergy between Cu(II) and O₂, further pointing to the catalytic role of Cu(II). The findings support the feasibility of running heap leaching of chalcopyrite-rich ores at elevated copper concentrations in either chloride or sulfate systems. Full article