Search Results (597)

Serpentine group minerals, including lizardite, antigorite, and chrysotile, are common gangue minerals in nickel sulfide ores, and exhibit complex and often unexpected wettability that adversely affects flotation efficiency. However, how these serpentine polymorphs differ in surface hydrophobicity is still not well known, making it difficult to explain their distinct flotation behaviors. In this work, molecular dynamics (MD) simulations and experimental contact angle measurements are used to investigate the wettability of the three main serpentine polymorphs. MD simulation results reveal that the contact angles of the lizardite Si–(00$\overline{1}$) surface and Mg–(001) are 78.6° and 71.1°, respectively. Chrysotile exposes the Mg–(001) surface, with a contact angle of 74.9°. The water droplet on the antigorite surface is spread along the SiOH region. Even the Mg–OH-terminated octahedral surfaces of the three serpentine polymorphs can exhibit hydrophobicity, depending on hydroxyl orientation and oxygen bonding configuration. Contact angle measurements show that antigorite (001) is moderately hydrophobic at about 40°, while (020) is highly hydrophilic at about 10°. The combination of Derjaguin–Landau–Verwey–Overbeek (DLVO) theory and hydrophobic interactions between antigorite and air bubbles produces a net attractive force, enabling particle–bubble adhesion. This work provides new insights for controlling serpentine behavior during flotation of copper–nickel ores hosted in ultramafic rocks. Full article

Non-stoichiometric copper sulfide (Cu_2-xS) nanomaterials are promising antibacterial agents, but the role of morphology in regulating their bactericidal performance remains poorly understood. Herein, we rationally design two types of Cu_2-xS nanostructures, namely nanoplates (NPs) and superparticles (SPs). Both materials were prepared via a ligand-directed synthesis method with the comparable sizes, surface ligands, and crystal phase. The antibacterial behaviors of Cu_2-xS NPs and Cu_2-xS SPs against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were investigated under dark and 808 nm near-infrared (NIR) light irradiation. The results showed that under NIR light irradiation, Cu_2-xS SPs exhibit a markedly higher bactericidal efficiency against both E. coli and S. aureus than Cu_2-xS NPs, leading to almost complete eradication of bacterial colonies. Notably, S. aureus shows more sensitive than E. coli, and significant growth inhibition is observed even in the absence of laser irradiation. Mechanistic investigations reveal that hierarchical assembly of primary nanoparticles in SPs can promote multiple internal light scatterings, thereby significantly enhancing light harvesting efficiency and further improving the photothermal conversion efficiency. In addition, the SPs exhibited higher peroxidase-like activity, resulting in enhanced reactive oxygen species (ROS) generation and aggravated oxidative damage, and the accelerated Cu²⁺ release kinetics strengthens ionic toxicity. Full article

4-Sulfanyl-1,2,3-triazole (L1) accelerated the solvent-free CuAAC efficiently with low catalyst loading (0.1 mol% for common azides and 1 mol% for sulfonyl azides). L1 exhibited higher catalytic activity compared to 1,4-substituted 1,2,3-triazole without sulfanyl group (5a) and sulfide, demonstrating that coordination of both sulfanyl and 1,2,3-triazole moieties with copper was critical to enhance the activity of L1. The Cu(OAc)₂/L1 catalytic system displayed high selectivity in synthesis of alkynyl- or azido-involved 1,2,3-triazoles. The di-copper system Cu(OAc)₂/CuBr/L1 promoted the reaction of electron-deficient and less reactive sulfonyl azides well, generating N-sulfonyl-1,2,3-triazoles in good yields, and L1 showed better performance than 1,3-di-o-tolylthiourea (L′). Other features of this protocol included recyclable ligand, 1:1 substance ratio, high yields, wide substance scope, and easily scaled up and facile purification of most products. Full article

Sulfate roasting is a critical pyrometallurgical pre-treatment for extracting Cu and Co from low-grade Cu–Co–Fe sulfide ores, yet conventional phase diagrams provide limited quantitative guidance for process control. To address this gap, a multicomponent/multiphase thermodynamic equilibrium model based on Gibbs free energy minimization was developed to systematically investigate the oxidative roasting behavior of single sulfides (Cu₂S, CoS₂, FeS₂) and their ternary mixture, with respect to air supply, temperature, and total pressure. The model reveals that each sulfide follows distinct, temperature-dependent phase transformation pathways: Cu₂S forms the acid-leachable product CuO·CuSO₄ at temperatures ≤ 588 °C with a stoichiometric air supply of 11.9 mol, transitioning to oxides at ≥800 °C; CoS₂ converts completely to CoSO₄ below 727 °C and to CoO at higher temperatures; FeS₂ yields sulfate phases at low temperatures and iron oxides above 654 °C. In the ternary Cu₂S–CoS₂–FeS₂ system, competitive oxidation reactions produce refractory mixed oxides (CuO·Fe₂O₃, CoO·Fe₂O₃) whose formation is governed by temperature, air supply, and sulfide molar ratios. The results demonstrate that low-temperature roasting (≤641 °C) with precisely controlled air supply maximizes the formation of water-soluble sulfates, providing a quantitative thermodynamic basis for process optimization and enhanced recovery of Cu and Co from complex sulfide ores. 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

Baixintan is a magmatic Ni–Cu sulfide deposit discovered in the central Tuwu–Yandong porphyry Cu belt of the Eastern Tianshan Orogen (ETO) of NW China in 2016. It is in close proximity (~5 km) to the Tuwu Cu deposit, the largest Carboniferous porphyry Cu deposit (~336 Ma) in Xinjiang. The Baixintan Ni–Cu ore is characterized by a high Cu/Ni ratio, but the reason for it remains unclear. To resolve this question, we present petrographic, geochronological, whole-rock geochemical, and S, Pb, Cu, and Lu–Hf isotopic data. Ore-related hornblende olivine websterite (HOW) and hornblende olivine gabbro (HOG) were emplaced at 296.6 ± 1.1 Ma and 289.7 ± 1.2 Ma, respectively, which were formed in an Early Permian post-collisional extensional setting. Whole-rock Pb and zircon Lu–Hf isotopes suggest that the parental magmas were predominantly mantle-derived. The Baixintan HOW and HOG contain abundant hornblende and are enriched in LILEs and LREEs but depleted in HFSEs, suggesting subduction-related metasomatism in their magma source. The sulfide (chalcopyrite, pyrrhotite, and pentlandite) δ³⁴S values cluster around 0‰ (–0.13 to 0.11, n = 11), and the chalcopyrite has uniformly negative but variable δ⁶⁵Cu values (–0.96 to –0.13, n = 6), which suggest that the ore-forming materials were mainly derived from the subduction-metasomatized mantle. Olivine Ni contents are significantly lower than those crystallized under sulfide-unsaturated conditions, implying that olivine fractional crystallization was an important trigger for sulfide melt segregation at Baixintan. Baixintan is the only known magmatic Ni–Cu sulfide deposit in the ETO that shares a Cu-preconcentrated, metasomatized mantle source with a giant porphyry Cu system. Copper pre-enrichment in the magma source may be the main factor for the relatively high Cu/Ni ratio observed in the Baixintan deposit. Full article

The Duolong porphyry copper–gold district, located in the northwestern segment of the Bangongco–Nujiang metallogenic belt on the southern margin of the South Qiangtang terrane (Tibet), hosts typical porphyry-style Cu-Au mineralization with well-defined alteration zoning from potassic through chlorite–sericite to propylitic assemblages. Based on integrated in situ major/trace element and sulfur isotope analyses of pyrite and chalcopyrite from different alteration zones, we identify two discrete episodes of magmatic-hydrothermal activity that exerted distinct controls on metal endowment. Sulfur isotope signatures define a systematic evolution from the earliest, high-temperature potassic stage (δ³⁴S: Py-I −3.70 to −1.16‰, mean −2.14‰; Cp-I −4.92 to −0.90‰, mean −2.54‰) through propylitic alteration (Py-II: 1.20‰–5.16‰, mean 3.06‰) to the later chlorite–sericite stage (Py-III: −2.00 to 1.86‰, mean 0.06‰; Cp-II: −2.50 to 0.58‰, mean −0.77‰), tracking progressive fluid cooling and changing fluid sources. Trace element systematics further discriminate these episodes: sulfides from potassic and chlorite–sericite zones are enriched in trace elements, whereas propylitic pyrite is depleted, with potassic pyrite recording the highest Cu concentrations (559–7256 ppm, mean 2302 ppm) and chlorite–sericite pyrite containing the lowest Au contents (0.01–0.59 ppm, mean 0.10 ppm). Gold mineralization occurs as native gold exsolved from chalcopyrite, and the markedly low Au concentrations in chlorite–sericite pyrite (0.01–0.59 ppm, mean 0.10 ppm) demonstrate that gold exsolution was largely completed during the first, high-temperature magmatic-hydrothermal stage. Collectively, these results establish a detailed geochemical framework linking sulfide composition to specific hydrothermal stages, providing new constraints on the processes of porphyry copper–gold mineralization in a collisional setting. Full article

A nano-CuO/ZnO desulfurizer was successfully prepared via a homogeneous precipitation method, and the effects of Cu doping on its microstructure, oxygen species, desulfurization performance, and reaction mechanism were systematically investigated. The results show that an appropriate Cu doping amount (TZ2, Cu:Zn = 1:18.40) significantly reduces the particle size (to ~10.9 nm) compared with pure ZnO (14.3 nm), leading to an increased number of surface-active sites. XPS and TG analyses reveal that Cu incorporation increases the proportion of lattice oxygen and decreases the concentration of oxygen vacancies, indicating that the modification effect of Cu dominates over the particle size effect in regulating surface oxygen species. Despite the reduced oxygen vacancy concentration, the desulfurization performance is markedly enhanced, with TZ2 exhibiting the longest breakthrough time under oxygen-free conditions at room temperature. This improvement is attributed to the strong interaction between highly dispersed Cu species and the ZnO matrix, which promotes H₂S adsorption and activation. Mechanistic studies demonstrate that, unlike pure nano-ZnO, where oxygen vacancy-mediated reactions dominate, the CuO/ZnO system follows a chemisorption-driven pathway involving the formation of copper sulfides and highly reactive polysulfide intermediates. Furthermore, the presence of oxygen significantly influences the reaction behavior, with an optimal oxygen concentration (~10%) maximizing desulfurization performance by balancing the generation of reactive oxygen species and sulfur intermediates. This work provides new insights into the design of high-performance ZnO-based desulfurizers and highlights the critical role of Cu-induced mechanism transformation. Full article

This study presents a combined process of sulfide precipitation followed by hydrogen peroxide leaching for rhenium recovery from copper smelting waste acid under ambient temperature and pressure. The process first removed copper through selective sulfide precipitation, then achieved co-precipitation of rhenium and arsenic to obtain a rhenium-rich precipitate. Subsequently, exploration of rhenium-containing precipitate leaching using H₂O₂ solution was conducted under isothermal conditions at 20 °C. The effects of H₂O₂ concentration, liquid-to-solid ratio, acidity, and leaching time rhenium extraction efficiency were examined systematically. The optimal leaching conditions were determined as: H₂O₂ concentration of 150 g/L, liquid-to-solid ratio of 5:1 mL/g, stirring speed of 350 r/min, and leaching time of 30 min. Under these conditions, the leaching conversions of rhenium and arsenic reached 96.0% and 93.8%, respectively. Through characterization of precipitate and leaching residue using ICP, SEM-EDS, XRD, and XPS analyses, the process and related reactions were elucidated. Results demonstrated that low-valence rhenium oxides and sulfides serve as the main reactive species during H₂O₂ leaching, whereas organic sulfur, high-valence oxides, and copper sulfide remained stable and resistant to leaching. Selective precipitation of copper effectively eliminated insoluble metal sulfides from rhenium-containing precipitates, thereby enabling efficient separation of rhenium under mild conditions. Full article

Saxony was ruled by two cousins in 1544: John Frederick I (Elector of Saxony) and his cousin Maurice (Duke of Saxony). Both rulers’ names appear on each side of the quarter thalers produced in this year. They were enemies involved in religious wars, although they were both Protestants. Two types of quarter thalers from 1544 occur: a pierced random find from Transylvania (Romania) with four shields on the reverse, heavily worn, and another one with three shields on the obverse side, found in the Głogów Hoard (Poland), which is well preserved. Why did they issue two types in the same year? Was it a matter of silver title or other historical factors? Nondestructive investigation methods were used: XRD revealed the phases within the alloy and patina layer; SEM-EDS revealed the morphological aspects and their elemental compositions, which were correlated with XRF results. The results show that both coins have closer silver amounts, from 91 to 96 wt.%. The EDS results were in good agreement with the XRF results. Lead traces indicated a difference between them: the four-shielded coin is lead-free, while the three-shielded coin has a moderate amount of lead, about 0.5 wt.%. The archeological data evidence that the four-shielded coin issued in 1544 is rarer than the three-shielded one because it was issued during specific historical conditions. Black patina is formed by a mixture rich in copper oxides mixed with silver oxides and Ag₂S. The presence of silver sulfide in the patina layer confirms that the pierced coin was in prolonged contact with the skin surface. Also, the finest traces of minerals embedded in the patina layer (e.g., quartz, kaolinite, and calcite) suggest that they were embedded in the patina via prolonged exposure to particulate matter. The mineral inclusions in the patina would have been more numerous if they were formed underground. Thus, the pierced four-shielded coin was probably worn as jewelry by nomads, while the three-shielded coin was most likely treasured in a well-preserved hoard. Full article

Flotation circuits typically incorporate grinding stages, yet mathematical models for these processes often operate on different principles, leading to misalignment in circuit design. Building on a previously established grinding model for flotation performance, this research introduces significant advances to develop a more comprehensive and industrially relevant framework. The primary innovation is the integration of mechanical entrainment and gangue recovery into the kinetic model, distinguishing between species captured by true flotation and those carried to the surface despite being non-hydrophobic. We developed a robust set of grinding-mill equations based on first-order kinetics to describe the mass-fraction transformation of both true-flotation and entrainment species. To ensure practical applicability, a systematic experimental and modeling methodology for parameter adjustment is introduced, providing a clear sequence for identifying breakage rate constants and flotation kinetic parameters. The proposed strategy was validated using two distinct case studies: an expanded analysis of a copper sulfide ore (ore A) and a new case involving significant gangue entrainment (ore B). The results demonstrate that the model accurately predicts species kinetics, providing a high-fidelity, cost-effective tool to optimize mineral recovery and prevent economic losses from overgrinding in industrial processing plants. Full article

The deep integration of machine learning technology with geological prospecting has brought to the forefront a key challenge: how to construct geological-mineralization models by fusing multi-source data, select model features with guidance from metallogenic factors, build multi-source metallogenic prediction models with geological constraints, and ultimately achieve a thorough integration of domain knowledge and machine intelligence. The Eastern-Central Tianshan region is one of China’s most important copper–nickel mineral resource bases, predominantly hosting magmatic copper–nickel sulfide deposits with significant resource potential. In this context, this paper proposes a metallogenic prediction model based on multi-modal feature fusion technology. The model employs a Residual Neural Network (ResNet) incorporating a Squeeze-and-Excitation (SE) attention mechanism and a Multi-Layer Perceptron (MLP) to extract features from different modalities. It integrates multi-source data, including geochemical information, geological metallogenic factors, and aeromagnetic data. A cross-modal feature interaction module, constructed using attention weighting and a gating mechanism, enables deep fusion of the features. After training, the model achieved a prediction accuracy of 97% on the test set. Compared to a unimodal model constructed using Random Forest, the confidence and discriminative capability of the training results were significantly enhanced, validating the effectiveness of multi-modal feature fusion. Applying the trained model to the study area, a total of 11 prospective metallogenic zones were delineated. These include 4 zones in the peripheries of known deposits and 7 zones in previously unexplored (blank) areas. Notably, some known mineral occurrences fall within the predicted blank-area targets, validating the feasibility and significant value of multi-modal feature fusion in mineral prediction. This work provides a novel methodology for the subsequent integrated processing of multi-source data. Full article

The recycling of spent lithium iron phosphate (LiFePO₄, LFP) batteries is receiving increasing attention as electric-vehicle deployment accelerates worldwide. Pyrometallurgical reduction offers a viable route for large-scale recovery of iron-rich products from spent LFP batteries; however, the resulting Fe-based alloys often retain residual copper (Cu), which deteriorates alloy quality and constrains downstream utilization and refining. In this study, a sulfidation–slag refining process was developed to selectively remove Cu from an Fe–P–Cu alloy produced by dry reduction of spent LFP batteries. FeS was employed as a sulfidizing agent to promote preferential conversion of Cu into sulfide phases, while fayalite (Fe₂SiO₄) slag was introduced to enhance phase separation between metallic and sulfide/slag phases. Thermodynamic calculations coupled with high-temperature experiments were conducted at 1400–1600 °C under various Cu:FeS ratios to identify operating conditions that maximize Cu removal while minimizing Fe loss. The results indicate that Cu is selectively transferred from the metallic phase to Cu–Fe–S sulfide phases, whereas Fe remains predominantly in the metal phase. Under the optimal condition (1400 °C, Cu:FeS = 2:1), the refined metal reached an Fe content of 90.80 wt.%, achieving an Fe recovery of 87.42% and a Cu removal efficiency of 81.13%. The proposed approach provides a practical stepwise refining strategy for upgrading Fe-rich secondary resources recovered from spent LFP batteries and facilitates subsequent impurity-control processes. Full article

Magnetite is extensively developed within various alteration zones of the mining district. Some magnetite is closely associated with copper mineralization, possessing significant research value. The Duobuza Cu (Au) deposit is a typical porphyry-type deposit within the Bangong Co-Nujiang metallogenic belt and was the first porphyry Cu-Au deposit discovered in the Duolong copper–gold ore district. Currently, this deposit contains copper resources exceeding 3 million tons @0.46%, with associated gold resources exceeding 80 tons @0.19 g/t. This study focuses on magnetite from the Duobuza deposit. Through field geological logging and microscopic identification combined with electron microprobe analysis (EMPA) and in situ LA-ICP-MS testing, mineralogical and mineral chemical research on magnetite is conducted. This research aims to elucidate the genesis of magnetite in the Duobuza deposit and its implications for mineral exploration. Five magnetite types with different occurrences can be distinguished in the Duobuza deposit: Mt₁ is magmatic magnetite; Mt₂, Mt₃, Mt₄, and Mt₅ are hydrothermal magnetite, with Mt₅ being closely associated with copper mineralization. Mt₁ is relatively enriched in Ti, V, Al, and Cr but depleted in Mn and Si; Mt₂ is relatively enriched in Ti and Al but depleted in Si and Cr; Mt₃ is relatively enriched in Al but depleted in Mg; Mt₄ is relatively enriched in Ti, Al, V, Zn, and Mn; and Mt₅ is relatively enriched in Mg, Si, Ti, Al, Mn, and Zn but depleted in Cr. Based on the Al + Mn vs. Ti + V discrimination diagram, magnetite formed in a medium- to high-temperature environment, with hydrothermal magnetite Mt₄ forming at the lowest temperature. Vanadium (V) content can be used to estimate the oxygen fugacity (fO₂) during mineralization. Mt₁ exhibits the highest V content, indicating relatively low oxygen fugacity, whereas Mt₄ shows the lowest V content, suggesting relatively high oxygen fugacity. Mt₅ has a higher V content compared to other early-stage hydrothermal magnetites, suggesting that a lower fO₂ formation environment favors the precipitation of metal sulfides in the mining district. Trace element analysis of magnetite from the Duobuza, Bolong, and Naruo mining districts reveals that magnetite from all three deposits is enriched in Si and Al and depleted in Ca and Ni. Magmatic magnetite from the Naruo and Duobuza deposits exhibits similar elemental distribution patterns. Hydrothermal magnetite from the Duobuza deposit shows significantly higher Ti and V contents compared to magnetite from the Bolong and Naruo deposits. Full article

In this paper, a study on the development of indium-doped Cu_xS heterojunction-based conductometry sensors is presented. To fabricate the sensors, thick films of In-Cu_xS heterojunctions were sprayed directly on the alumina sensing platform provided with interdigitated Pt electrodes. The effect of the doping level with different nominal amounts of InCl₃ additive (0%, 3%, and 5%) on the structural, morphological and optical properties of Cu_xS films was first studied by XRD, AFM, UV-Vis and Raman spectroscopy. Moreover, the electrical and sensing characteristics towards low concentrations of hydrogen sulfide (H₂S) in air were investigated. The tests carried out clearly demonstrated the positive effect of In doping on the H₂S sensing performance of Cu_xS. The 5%-doped Cu_xS sensor showed the highest sensitivity to the target gas compared to the other sensor, as well as good stability and selectivity properties. Full article