A new type of discontinuous mining system for deep-sea polymetallic nodules was proposed, consisting of collecting seafloor ore, conveying to buffer by flexible hose, and high-speed lifting of buffer. Then, the design and key equipment selection were carried out for the collecting system, flexible hose conveyance system and buffer lifting system for comprehensively lifting 100 t/h of ores at water depth of 5 200 m in the Minmetals' Contract Area. Furthermore, flexible hose configuration and load characteristics, as well as cable load dynamics during buffer lifting were all analyzed by hydrodynamic simulation. It is shown that with the flexible hose equipped with 18 buoyancy blocks, minimum bending radius of 1.6 m and a maximum tension of 4.98 kN, the whole mining system can satisfy requirements for the minimum bending radius and safe load capacity. During high-speed lifting of buffer, the cable can have the safety factor of comprehensive stress up to 5.22-6.03, exceeding the safety factor stated in national standard. These findings validate the reliability of this new type of deep-sea discontinuous mining system.

In order to address the poor presplit blasting effect on the final slope of the Yulong Copper Mine in Xizang Autonomous Region, the engineering applicable ranges of parameters such as decoupling coefficient, borehole diameter, linear charge density and hole spacing were calculated in consideration of the combined effects of explosion-generated gases and air shock waves, and the presplit blasting parameters were also optimized by performing orthogonal experiment. The results indicate that with a borehole diameter of 120 mm, a linear charge density of 800-1 000 g/m and a hole spacing of 0.9 m, the half-borehole rate after blasting exceeds 95%, the unevenness between adjacent holes is much less than ±5 cm, and the slope gradient deviation is less than ±2°, forming a continuous and regular presplit surface. This confirms the engineering applicability of the theoretically calculated parameter ranges.

A thermodynamic analysis based on HSC Chemistry software reveals the phase evolution of main metals in the production of nickel matte by sulfidation smelting of copper-nickel electroplating sludge, and the optimal process conditions for obtaining medium-grade nickel matte by sulfidation smelting were also analyzed. Theoretical calculation shows that the electroplating sludge with grades of Cu and Ni at 3.0% and 3.5% respectively is smelted at a temperature of 1 300 ℃, with calcium sulfate as a sulfurizing reagent under a smelting atmosphere with in a volume ratio of 60%-75%, and the actual usage of sulfur 1.6-2.0 times the theoretical value. It is expected that medium-grade nickel matte with Fe content less than 20% can be obtained, and the contents of Cu and Ni in the slag with S ratio in the preferred range can be less than 0.20% and 0.43% respectively. It is shown that recovery rates of Cu and Ni exceed 95% and 90% respectively, and the fixation rate of Cr in the slag is over 99.9%. According to the statistical results of production samples, the distribution behavior of Cu, Ni and Cr is basically consistent with the thermodynamic analysis results. This proves that the established mathematical model has good reliability and is of certain guiding significance for production.

Constitutive models of HJC and RHT for different in-situ stress conditions were established by adopting ANSYS/LS-DYNA software, and the effects of blasting on effective stress and rock damage in different constitutive models were analyzed comparatively. The results show that the effective stress variation in the HJC model is more consistent with practical scenarios, while the rock damage in the RHT model can better reflect practical conditions. In-situ stress has a minor impact on effective stress in regions close to blast holes but a significant influence on effective stress in areas farther away. Additionally, in-situ stress has a smaller effect on rock damage in the HJC model, but substantially affects the damage variables in the RHT model.

Although the annual production of low-concentration microfine-grained ilmenite in Pan-Xi region attains over 1 million tons, it is not conducive to adopt flotation process for the subsequent titanium selection due to the microfine particle size, large volume and low concentration of this ore. For this resource, comparative experiments were conducted based on two major flowsheets, including “SLon high-intensity magnetic separation + flotation” and “desliming using new type of cyclone+flotation”. The results show that the latter process flowsheet has a lower consumption of reagents, and the obtained titanium concentrate has better indicators, with a titanium concentrate grading 47.06% TiO₂ at 59.03% recovery with the yield of 20.22%.

Multiferroic BiFeO₃ ceramics were synthesized by chemical co-precipitation. The effects of calcination temperature and time on crystal structure, morphology and grain size of products were investigated. Ions of Ba and Ti were doped to modify the properties of BiFeO₃ ceramics for improving ferroelectric and ferromagnetic properties. It is found that compared to the products before doping, the products with Ba doping at an amount of 30% in mass fraction can have the saturation magnetization enhanced from 4.69 emu/g to 4.93 emu/g; while the products with Ti doping at 10% in mass fraction can have the remnant magnetization enhanced from 0.047 emu/g to 0.164 emu/g. The co-doped ceramic samples combine the effects of A-site and B-site doping and exhibit enhanced multiferroic properties.

Bagasse was calcined under an inert atmosphere to produce biochar, which was then mixed with metakaolin and taken to prepare sugarcane bagasse biochar/geopolymer composite microspheres (BGM) by using sodium silicate as an activator. The microstructure of BGM was characterized by XRD, FTIR, BET and XPS, and its adsorption performance for crystal violet (CV) and methylene blue (MB) was also investigated. Results show that the introduction of biochar can enhance the adsorption capacity of metakaolin-based geopolymer microspheres. The adsorption processes of BGM for both dyes follow the pseudo-second order kinetic model. BGM-20 can have theoretically maximum adsorption capacities of 138.031 mg/g for CV and 79.128 mg/g for MB, which can be well-described by the Langmuir isotherm model. Dynamic adsorption experiments revealed that the time required for adsorption of CV and MB by BGM to reach exhaustion exceeded 8 500 min, indicating that BGM can be taken as a fixed-bed adsorption medium material for dye wastewater treatment.

The immersion end quenching method, combined with hardness testing, metallographic microscopy, scanning electron microscopy and transmission electron microscopy, was used to investigate the effect of quenching rate on the age hardening of 6061 aluminum alloy for building formwork. Results show that when the quenching rate decreases from 305 ℃/s to 26 ℃/s, the post-aging hardness of the alloy remains nearly unchanged. However, when the quenching rate drops below 26 ℃/s, the hardness decreases rapidly with further reduction in quenching rate. At quenching rates below 26 ℃/s, solute atoms precipitate from the supersaturated solid solution during cooling, forming β (Mg₂Si) phases without strengthening effect at grain boundaries, Al₁₃ (Fe, Cr)₃Si₂ dispersoids, and dislocations. This reduces the number of β″precipitates in the grains after aging, thereby lowering the alloy hardness. Lower quenching rates result in more β phases and lower post-aging hardness. It is concluded that the quenching rate shall exceed 26 ℃/s for attaining high hardness alloy.

To achieve the separation of arsenic and antimony from high-arsenic antimony-containing dust, a selective oxidation roasting process was employed with barium oxide as an antimony-fixing agent. The effects of oxygen partial pressure, roasting temperature, roasting time, and the dosage of antimony-fixing agent on the volatilization rates of arsenic and antimony from the dust were explored. The results indicate that with pure oxygen flow rate at 40 mL/min, addition of barium oxide at an amount of 2%, and roasting at 450 ℃ for 60 min, the volatilization rates of arsenic and antimony in the dust can reach 90.46% and 6.79%, respectively. It is shown that the volatile products contain 99.53% As₂O₃ and 0.26% Sb, thus effective separation of arsenic and antimony from high-arsenic antimony-contained dust antimony can be actualized.

The thermal dissipation performance of a battery pack was optimized by thermal simulation, aiming to enhance safety and service life of batteries. A thermal simulation model of the battery pack was established with ANSYS software, and temperature distribution was analyzed for the battery discharged at 1C rate. It is found that the simulation results deviate from actual measurements by less than 0.5 ℃, confirming the high accuracy of the model. Two optimized thermal dissemination schemes were proposed, including I-shaped heatsink and thermally conductive adhesive filling. Study shows that both schemes can effectively improve the thermal dissipation performance, leading to the maximum temperature of cells reduced by 6.0 ℃ and 5.9 ℃, respectively. The scheme of I-shaped heatsink can not only reduce cell temperatures but also significantly reduce temperature differences, resulting in better thermal uniformity.