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.

To reveal damage evolution and brittle-ductile synergistic behavior of the gypsum-slag-cement (GSC) ternary cementitious system under uniaxial compression, this study conducted uniaxial compression tests at different curing ages by adjusting the ratios of gypsum, cement, and slag. Combined with digital image correlation (DIC) and scanning electron microscopy (SEM) techniques, a systematic analysis was performed from three perspectives: macroscopic mechanical response, crack propagation characteristics, and microstructural evolution. Results indicated that with extension of curing age, compressive strength, elastic modulus, as well as crack initiation and damage stresses of GSC system significantly increased, while post-peak failure gradually transitioned from typical brittleness to quasi-ductility. Increasing the proportion of cement content helped enhance the material's strength, stiffness, and overall bonding capacity, but led to increased brittleness. Gypsum content exhibited a significant nonlinear influence on material properties. A proportion of 10% effectively promoted internal stress redistribution and synergistic multi-crack propagation, thereby improving toughness and cracking resistance, whereas excessive gypsum tended to cause a decline in structural continuity and deterioration of mechanical performance. Comprehensive comparison revealed that the formula G10S70C20 demonstrated the highest compressive strength and superior deformation coordination ability at curing age of 28 d, with cracks exhibiting a typical symmetrical "X" pattern, indicating optimal comprehensive performance. The findings suggested that synergistic regulation of gypsum and cement was the key to achieving both strength enhancement and an optimized brittle-ductile balance in the GSC system.

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.

As core conductor materials for high-end electronic components and power transmission systems, oxygen-free copper strips require increasingly stringent performance specifications to meet diverse application demands. During cold rolling, different reduction rate distribution significantly influences material properties through microstructure transformation including grain orientation, dislocation density, and texture evolution. Under identical total deformation conditions, this study investigated effects of different cold rolling reduction rate distribution schemes on microstructure, texture, and performance of the material. Results showed that reducing the number of rolling can reduce the number of intermediate annealing and increase reduction rate of each rolling, which enhanced energy storage and nucleation sites formation to elevate recrystallization nucleation rates, ultimately leading to smaller final grain sizes. Increasing single reduction rates improved the proportion of various deformation textures, enhancing product microstructural uniformity. When single reduction rate exceeded 80%, orientation density of {112}<111>(copper), {110}<112>(brass), and {123}<634>(S) deformation textures was significantly enhanced, promoting the formation of strong {001}<100>(cube) textures during recrystallization annealing. Higher cube texture proportions contributed to lower microhardness and slightly improved conductivity of oxygen-free copper strips. The results provided a theoretical basis for adjustment of production process and optimization of product properties of oxygen-free copper strip.

To study the friction and wear properties of CuNi6Sn6 alloy under high-temperature and high-load working condition, an MMU-10G friction-abrasion testing machine was used for experiments, and a LEXT OLS5000 3D confocal laser scanning microscope was utilized to examine the worn surface morphology for determination of wear mechanisms. Under a load of 45 N, friction coefficient of the alloy increased and then decreased with rising ambient temperature. Under a higher load of 75 N, friction coefficient remained relatively stable when ambient temperature was below 150 ℃, but fluctuated significantly at 200 ℃. When the load was increased to 105 N, friction coefficient was only stable below 100 ℃. When ambient temperature was below 150 ℃, wear mass increased with the load. While at 200 ℃, wear mass was relatively large. At lower ambient temperatures, wear mechanism was mainly abrasive wear. As the load increased, it manifested as fatigue pitting and fatigue delamination. Under medium-high temperatures and low loads, adhesive wear predominated; under high temperature and high load, severe plastic deformation and surface burn occurred. When ambient temperature exceeded 150 ℃, wear severity increased. Therefore, CuNi6Sn6 alloy was suitable for service conditions with ambient temperatures below 150 ℃ and loads below 75 N.

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.

Injection characteristics of side-blown lance in a bath smelting furnace directly govern reaction intensity and smelting efficiency. In this study, stirring enhancement mechanism of a novel side-blown lance with an adjustable rotation angle was investigated by computational fluid dynamics (CFD), and structural parameters of the lance were optimized. A volume-of-fluid (VOF) multiphase flow model coupled with the realizable k-ε turbulence model was employed to conduct transient simulations of gas-liquid two-phase flow in an oxygen-enriched side-blown smelting furnace. Influence of lance rotation angle (0°, 15°, 30°, 45°, and 60°) on flow field and mixing performance of the molten bath was analyzed. Results indicated that lance rotation angle exerted a nonlinear control effect on bath hydrodynamics. A moderate rotation angle (around 30°) effectively enlarged gas-induced disturbance region, accelerated interfacial renewal, and improved the uniformity of bath stirring. In contrast, either a non-rotating angle (0°) or an excessively large rotation angle (60°) led to pronounced flow drift and deteriorated local mixing. Overall, the proposed side-blown rotatable lance, through appropriate optimization of rotation angle, can enhance bath stirring while simultaneously ensuring furnace lining integrity and prolonging lance service life. The findings provided a theoretical basis and engineering guidance for lance design and optimization in large-scale oxygen-enriched side-blown smelting furnaces.

As the core equipment of the domestically developed hot-state triple-furnace continuous copper smelting system, the multi-lance top-blown furnace still requires further improvement in process monitoring and intelligent decision-making capabilities. Current challenges include delayed parameter adjustments, pronounced fluctuations in furnace conditions, and suboptimal continuity in production. This research developed a decision optimization system for top-blown furnace operations by integrating metallurgical modeling, industrial data acquisition, and software development. Based on the metallurgical reaction mechanism, the input-output mathematical model of the top-blown furnace was established to enable quantitative determination of core operating parameters such as flux dosage and oxygen volume. A calculation model for key process parameters was created to overcome limitations in real-time process state perception during continuous smelting. Through systematic integration, modules for data acquisition and model computation were encapsulated into a comprehensive decision optimization system. The system provided accurate calculation and decision support for core control parameters. It significantly reduced the uncertainty associated with manual operations but also provided effective technical support for dynamic multi-process coordination and control within the hot-state triple-furnace continuous copper smelting process.

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.

Copper and copper alloys are considered the primary structural material for fusion reactor divertor heat sinks due to their excellent thermal conductivity, thermal stability, mechanical properties, and relatively good resistance to neutron irradiation. However, a lack of in-depth understanding regarding the mechanisms of displacement damage in copper induced by synergistic effects of neutron irradiation and transmuted helium still exists. In this study, the synergistic effects were investigated using molecular dynamics simulations, with a focus on dislocation nucleation mechanisms. Influences of transmuted helium concentration (2000~8000 appm), primary knock-on atom (PKA) energy (1.0~7.0 keV), and simulation temperature (100~900 K) were systematically examined. Results showed that increased helium concentration raised the number of point defects, enhanced pinning effect, and promoted dislocation density and the formation of complex entanglement structures. Higher PKA energy led to a notable rise in length and density of dislocation line. At lower temperatures, rising temperature promoted development of dislocation entanglement structures in the cascade center, while at higher temperatures, it facilitated dislocation annihilation and break-up, resulting in the collapse of these entanglement structures. These findings provided important insights for the design of irradiation-resistant copper alloys for fusion reactors.