Conventional treatment methods for complex copper slags originating from zinc smelting are often constrained by high energy consumption, intricate workflows, and low metal recovery efficiencies. To address these challenges, a streamlined, high-efficiency technology based on cyclone electrowinning was developed. This novel process enabled the synergistic leaching of copper, zinc, and indium while selectively extracting copper, effectively obviating the need for solvent extraction and its associated organic pollution risks. This study specifically investigated electrolytic migration behavior of metal ions—predominantly Cu²⁺—during direct cyclone electrowinning of polymetallic leachates. Utilizing a four-stage stepwise depletion protocol, the process yielded cathode copper with a purity exceeding 99.97% and a current efficiency greater than 97.83%. By significantly simplifying the traditional "leaching-purification-electrowinning" circuit, this technology provided a green, cost-effective pathway for the circular utilization of copper resources from complex polymetallic slags.

Non-ferrous metallurgical slags generated during pyrometallurgical smelting of non-ferrous metals cause environmental pollution as a stockpile, but slags also have enormous potentials for waste heat recovery and valuable metal recycling. This paper systematically synthesized common and specific physicochemical characteristics of non-ferrous metallurgical slags. It focused on research progress, core principles, process optimization directions, technical advantages, and application bottlenecks of waste heat recovery technologies for three typical slags (copper slag, ferronickel slag, and lead slag), which were classified into physical methods and chemical methods, and summarized research hotspots and development trends of each technology. Physical methods were centered on synergistic technology of granulation and heat exchange, while chemical methods focused on synergistic recovery of waste heat and resources. Cascaded recovery system integrating the two is the main development direction in the future. This paper provided theoretical reference and technical support for industrial upgrading and green development of waste heat recovery technologies for non-ferrous metallurgical slags.

The iron and steel industry is a cornerstone of the national economy, yet its production process generates a massive amount of solid waste, among which iron and steel slag is the primary by-product. For a long time, the stockpiling and landfilling of this slag have not only occupied vast land resources but also posed potential threats to the soil, water, and atmosphere due to heavy metal ions in leachate and dispersion of dust. However, steel slag is a secondary resource awaiting development, which is rich in valuable elements such as calcium, silicon, iron, aluminum, magnesium, and manganese, as well as rare metals like vanadium and titanium. Main phases of steel slag include dicalcium silicate, tricalcium silicate, and calcium ferrite. Resourcezation potential of steel slag comes from two aspects. On one hand, technologies such as magnetic separation, gravity separation, or reduction roasting can recover iron and rare metals. On the other hand, high calcium and silicon content endows it with the potential to substitute for natural mineral resources. Achieving efficient recovery of valuable elements from steel slag and comprehensive application of the overall material is crucial for promoting green, circular, and low-carbon development of the iron and steel industry. This review systematically summarized physicochemical properties of steel slag, focusing on technical principles and research progress in recovering major valuable elements like iron, calcium, and silicon, as well as rare elements such as vanadium and titanium. Simultaneously, it comprehensively outlined current status of steel slag utilization in fields such as building materials, environmental remediation, and agriculture. Finally, it analyzed current technological challenges and provided an outlook on future research directions, offering a theoretical reference and technological pathways for high value resources utilization of steel slag.

To address issues of high cost of traditional cement-based filling materials and poor bonding of ultra-fine tailings as a component, a solid-waste-based cementitious material was developed for the backfill of a molybdenum mine in Shaanxi Province. Steel slag, slag, and desulfurization gypsum were used as main raw materials, formulated with a performance modifier. The formulation of the solid-waste-based cementitious material was studied by varying the content and fineness of slag powder. The optimal formulation was selected to investigate application performance of backfill bodies and micromorphology of hydration products of the cementitious material. Results showed that the optimal formula of the solid-waste-based cementitious filling material was 60% slag powder (407 m²/kg), 20% steel slag powder, 20% desulfurization gypsum, and 0.6% performance regulator. Under this ratio, compressive strength of backfill bodies at all curing ages was superior to that of P·O 42.5 cement, with 28-day compressive strength reaching up to twice that of the cement group. Moreover, when cement-sand ratios were 1∶7, 1∶15, and 1∶16, respectively, strength requirements of different backfill zones were satisfied. Meanwhile, the material exhibited excellent fluidity and volume stability. Leaching toxicity indexes of all backfill bodies were lower than the limits specified in GB 8978—1996, indicating favorable environmental safety. Main hydration products were acicular-rod ettringite and fibrous gel-like C-S-H gel, which were interwoven to form a dense structure. The solid-waste-based cementitious filling material developed in this study had potentials of realizing resource utilization of solid waste and reducing backfill costs, providing technical support for green and efficient backfill of mines.

C19210 is one of the Cu-Fe-P alloys extensively employed in the electronics industry. In order to enhance strength and electrical conductivity of the alloy, thermo-mechanical treatment was applied. In this work, the influences of deformation heat treatment on the mechanical properties, electrical conductivity, and microstructure of C19210 were investigated. Results showed that the optimal properties, including a Vickers hardness of 134HV, tensile strength of 445 MPa, electrical conductivity of 88.4%IACS, and elongation of 16.3%, can be achieved through an optimized combinatorial process: solution treatment at 900 ℃ for 120 min, primary cold rolling (80% reduction) with aging at 450 ℃ for 240 min, followed by secondary cold rolling (50% reduction) and aging at 450 ℃ for 60 min. Microstructural observations revealed that combined effects of precipitation strengthening from dispersed precipitates and grain refinement from fine recrystallized grains contributed to the improvement of strength and electrical conductivity. These findings provided a theoretical and practical foundation for optimizing the performance and engineering application of Cu-Fe-P alloys.

Grain boundary diffusion technology has emerged as a pivotal approach to overcome bottlenecks of high cost and significant remanence loss in traditional single-alloy methods by precisely regulating the distribution of heavy rare earths (HREs), thereby markedly enhancing the coercivity of NdFeB magnets. This study proposed composite diffusion sources formed by blending Tb-Al-Cu HRE alloys with pure Nd powder at varying ratios, systematically investigating their diffusion modification effects on both HRE-free and HRE-containing substrates. Experimental results demonstrated that under optimal diffusion source ratios, the maximum coercivity enhancements for the two substrates reached 1.036 T and 0.959 T, respectively, with remanence attenuation controlled within 0.59 kGs and 0.43 kGs. When TbAlCu-to-pure-Nd ratio was 3∶2 (for HRE-free substrates) or 2∶3 (for HRE-containing substrates), the magnets exhibited optimal comprehensive performance, achieving 48UH and 45EH grade levels, respectively. Microstructural analysis revealed that HRE-free substrates developed increased grain boundary phases, refined grains, and core-shell structures after diffusion, while HRE-containing substrates showed a significant increase in non-magnetic grain boundary phases. By designing composite diffusion sources, this study achieved remarkable magnetic performance improvements with low HRE consumption, offering a novel strategy for the green preparation and resource-efficient utilization of high-performance NdFeB magnets.

Copper smelting slag, the primary solid waste generated from pyrometallurgical copper production, is rich in valuable metals such as Cu (0.5%~4.6%) and Fe (30%~49%), making it a significant secondary resource for recovery. However, over 80% of the global copper slag is still disposed of by stockpiling, which not only occupies land resources but also poses environmental threats due to the migration and release of toxic elements like Pb and As. Efficient recovery of copper and iron from copper slag is therefore of great significance for ensuring resource security and promoting the green transformation of the nonferrous metals industry. This paper systematically reviewed physicochemical properties and mineralogical characteristics of copper smelting slag, and provided an in-depth analysis of technical principles and research status of various processes, including flotation, pyrometallurgy (reducing roasting-magnetic separation, smelting reduction, oxidizing roasting-magnetic separation), hydrometallurgy (chemical leaching, bioleaching), and combined processes. Current technologies still face common challenges such as low copper-iron separation efficiency, low iron recovery rate, and difficulties in the full-component utilization of secondary slag. On this basis, future research is prospected to focus on the synergistic extraction mechanisms of copper and iron, low-carbon intensification technologies, and stepwise utilization of full components, aiming to provide theoretical support for resources utilization, detoxification, and high-value utilization of copper smelting slag.

This paper innovatively proposed thin vapor chambers based on gradient porosity copper foam/copper mesh composite structure to meet heat dissipation requirements of 5G communication equipment with high power density. Through two-way pore gradient design, thickness of copper foam was compressed from 1.6 mm to 0.15 mm by hot pressing technology at the evaporation end, forming a high-density microporous structure to enhance capillary. The condensation end was configured with 150 μm pore copper mesh to optimize the working medium reflux path, significantly reducing flow resistance. Experimental results showed that the design can reduce temperature fluctuation from 10.3 ℃ to 5.2 ℃ (a decrease of 49%) under a heat load of 65 W, with a thermal resistance (ΔR_th) of only 0.08 ℃/W. In particular, the gradient structure shortened start-up time to 8 s, providing a new idea for heat dissipation of miniaturized electronic devices. This study provided a new paradigm for the miniaturization and heat dissipation of high-power electronic devices, balancing efficient heat transfer and structural reliability. Design concept of the three-stage flow channel (large hole for evaporation end → middle hole for transition layer → small hole for copper mesh) can be extended to other high heat density application scenarios.

Multi-phase refractory materials were prepared using copper slag tailings and waste high-alumina bricks. Thermodynamic behavior of copper slag tailings during sintering was studied by XRD and TG-MS. Influence of copper slag tailing and waste high-alumina brick content on mechanical properties and high temperature properties of refractory materials were studied. Microstructure and phase transition process of multi-phase refractory materials were studied by SEM-EDS and XRD. Results showed that decomposition product of iron olivine in copper slag tailings reacted in-situ with alumina in waste high-alumina brick, and finally formed a mullite-corundum composite crystal phase combined with Fe-Al intercrystalline phase. When mass fraction of waste high-alumina brick and copper slag tailing was 40% and 10%, respectively, comprehensive performance of refractory material was the best. Compressive strength was 110.4 MPa, refractoriness under load reached 1 399 ℃, and strength retention rate after thermal shock was more than 80%. Research results provided a new prospective for high-value utilization of copper slag tailings and waste high-alumina bricks which are the main solid waste in copper smelting industry.

To explore new pathways for utilization of copper tailings and mine waste rocks, these two materials were selected as raw materials to prepare sintered permeable brick. X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF) techniques were employed to analyze mineral phase structure and chemical composition of tailings and waste rocks. Sintering mechanism was then analyzed. Compression molding method, with waste rocks as aggregates, was chosen to prepare sintered permeable bricks with a high content of tailings. An in-depth exploration was conducted on the effects of four factors, namely firing temperature, holding time, particle size of waste rocks, and content of tailings, on comprehensive performance of the brick. Ideal combination of the factors required further enhancement of mechanical strength while ensuring permeability performance of the brick, achieving a balance between strength and permeability of the brick. Research results indicated that the optimal process parameters were a firing temperature of 1 180 ℃, a holding time of 80 min, a particle size of waste rocks ranging from 2.00 to 3.35 mm (6~10 mesh), and a tailings content of 60%. Permeable brick prepared under this process exhibited a flexural strength of 4.23 MPa and a permeability coefficient of 10.1×10⁻² cm/s, both of which complied with requirements of the national standard GB/T 25993—2023 "permeable paving bricks and permeable paving flags".