High-arsenic white dust was processed by adopting a process consisting of alkaline roasting and water leaching to remove the arsenic therein, and the water leaching residue was then subjected to first-stage sulfuric acid leaching for separation between copper and zinc, followed by second-stage hydrochloric acid leaching for separation between lead and bismuth, so as to comprehensively recover various metals. The effects of alkali-to-ore ratio, roasting temperature and time on arsenic removal by water leaching, along with the suitable process parameters for two stages of acid leaching and stepwise treatment of acid leachate were systematically explored. Firstly, 3 h roasting at 300 ℃ with alkali-to-ore ratio of 0.9 followed by water leaching of calcine achieved arsenic removal rate of 98.88%; and then, the obtained leaching residue with liquid-to-solid ratio of 4 mL/g was leached at 90 ℃ for 2 hours with sulfuric acid at an initial concentration of 2.5 mol/L, resulting in the leaching rates of copper and zinc reaching 98.32% and 99.14%, respectively. After that, the sulfuric acid leaching residue at a liquid-to-solid ratio of 4 mL/g was leached at 90 ℃ for 2 hours with hydrochloric acid at concentration of 2.5 mol/L, leading to the bismuth leaching rate up to 98.42%. The previously obtained sulfuric acid leachate was then added by 1.1 times the theoretical amount of sodium sulfide, resulting in copper precipitation rate of 99.87%, and the generated solution was then subjected to evaporation and crystallization, resulting in a zinc recovery of 99.23%. While the previously generated hydrochloric acid leachate was neutralized to pH of 3, leading to a bismuth recovery rate of 99.74%. It is concluded that such combined process can actualize comprehensive recovery and utilization of valuable elements in high-arsenic dust.

Processing technique for recovering germanium from zinc oxide dust are introduced, including the status quo of conventional leaching, high-pressure leaching, ultrasonic-enhanced leaching and leaching with microwave pretreatment, and their advantages and disadvantages are then analyzed based on comparison. Furthermore, techniques for extraction and concentration of germanium from the obtained leachate are also compared with each other, and the research directions in the future is proposed for recovering scattered element germanium from zinc oxide dust, which provides a reference for the progress in this field.

In consideration of disadvantages of long process flow and low total recovery of lithium for the traditional preparation process of battery-grade lithium carbonate, it is proposed that a combined process consisting of impurity removal, transformation of sulfate radicals and thermal decomposition be adopted to directly prepare battery-grade lithium carbonate from polymetallic lithium sulfate solution, and then solvent extraction should be employed to recover lithium from washing water and mother liquor of lithium precipitation. In the impurity removal process, the pH of solution is adjusted to 10.0, and sodium dimethyldithiocarbamate (SDD) is added for deep removal of impurities; the obtained solution is added with barium carbonate paste, with a solid-liquid ratio of 1∶12 and a CO₂ flow rate of 60 L/h, and the transformed lithium bicarbonate solution is generated after 1 h reaction; in the following thermal decomposition stage, lithium carbonate solid is produced after 90 min reaction at 91-92 ℃ by adding an appropriate amount of calcium and magnesium ion chelating agent, stirring at a rate of 400 r/min. After washing with deionized water and drying, a battery-grade lithium carbonate product is produced with a purity of 99.85%. The washing water is combined with the mother liquor of lithium precipitation, and then subjected to solvent extraction, resulting in a stripping solution with a lithium content of 26.22 g/L. It is shown that the total lithium recovery rate from this process can reach 98.08%.

In consideration of high-content of copper and lead therein, copper smelting dust was decided to be leached with a mixed solution of sulfuric acid and sodium chloride. The leachate was then subjected to zinc powder replacement for recovering sponge copper, and the leaching residue was subjected to flotation to achieve effective separation between copper and lead. It is found that with sulfuric acid at an initial concentration of 2.0 mol/L, sodium chloride at concentration of 4.0 mol/L and liquid-solid ratio of 4∶1, 2-h leaching at 90 ℃ results in leaching rates of As and Cu reaching 99.19% and 80.69%, respectively; and the copper replacement rate reaches 92.48% from the copper containing solution with pH of 2 at 50 ℃ by replacing with zinc powder at an amount of 1.8 times of solution. Surface analysis technique reveals that Bi (Ⅲ) remaining on the surface of copper sulfide significantly inhibits the flotation of copper sulfide. Therefore, washing pretreatment shall be added before flotation. After that, a flotation process consisting of one roughing, two cleaning and two scavenging can produce a copper concentrate grading 56.17% Cu at 94.15% recovery, and a lead concentrate with 58.01% Pb grade at 99.14% recovery. It is concluded that this comprehensive treatment by a combined beneficiation and metallurgical route for copper smelter dust can provide a reference in the treatment of other smelting dusts.

A phosphoric acid - ammonium sulfite leaching system was employed to leach valuable metal elements such as nickel, cobalt and manganese from cathode materials of spent ternary lithium-ion batteries. The effects of phosphoric acid concentration, concentration of ammonium sulfite monohydrate, temperature and time of reaction on the total leaching rate of valuable metals were investigated. It is found that with phosphoric acid at the concentration of 0.8 mol/L, ammonium sulfite monohydrate at the concentration of 25 g/L, reaction at 70 ℃ for 90 min can result in the total leaching rate of valuable metals up to 95.2%. After the acid leaching process is kinetically fitted using the shrinking unreacted core model, it is shown that the leaching process is controlled by surface chemical reaction.

A 316L-Al₂O₃ coating with an introduction of Si was prepared on the surface of 40Cr steel bar by ultra-high-speed laser cladding. Effects of Si on the microstructure, microhardness, wear resistance and corrosion resistance of the coating were investigated by means of optical microscope, scanning electron microscope, microhardness tester, friction and wear testers, electrochemical workstation among others. The results show that the 316L-Al₂O₃ coating is mainly composed of austenite and Al₂O₃. And an addition of Si refines the grain size and also leads to the generation of FeSi intermetallic compounds in the coating, which increases the coating hardness by 18.97%. It is found that the Si-containing 316L-Al₂O₃ coating exhibits improved wear resistance and corrosion resistance, and its wear volume and self-corrosion current density are 19.1 × 10^-3 mm³ and 6.93 × 10^-8 A/cm², respectively.

With sludge as the main raw material and corn straw as a carbon raiser, porous sludge-based activated carbon (PSAC) was prepared by adopting the ZnCl₂ activation method. The adsorption performance of PSAC for removal of organic dye Rhodamine B (Rh B) was investigated, and the corresponding adsorption mechanism was also explored. Results indicate that PSAC has a rich pore structure, a high specific surface area (703.14 m²/g), and abundant oxygen-containing functional groups, with a point of zero charge (PZC) of 4.2. The adsorption kinetics of Rh B onto PSAC follows the Lagergren's pseudo-second-order kinetic model, and the adsorption isotherm is better fitted to the Langmuir equation. At 298 K, the saturated adsorption capacity of PSAC for Rh B reaches 196.08 mg/g. The adsorption process is dominated by chemical adsorption, and is spontaneous, endothermic and entropy-driven process. Electrostatic interaction, hydrogen bond interaction, π-π interaction and hydrophobic interaction all play certain roles in the adsorption process, among which electrostatic interaction is the main driving force.

The effects of addition of Mn, Ti and Cr on microstructures and properties of Al-Zn-Mg-Cu-Zr alloys were investigated by performing room-temperature tensile test, intergranular corrosion test and electrochemical corrosion test, combined with microstructural characterization techniques such as optical microscopy, scanning electron microscopy and transmission electron microscopy. The results demonstrate that additions of Mn, Ti and Cr can effectively inhibit alloy recrystallization and promote fine and dispersed precipitation of η′ phase. This leads to grain boundary precipitates in a continuous chain-like distribution changed to be discontinuously distributed in a line. Consequently, the yield strength, tensile strength and elongation of the alloys are improved, and the depth of intergranular corrosion and the corrosion current density are reduced; meanwhile the polarization resistance is increased. It is shown that both mechanical properties and corrosion resistance of alloys are significantly enhanced.

In order to investigate the seismic and fire resistance performance of hot-rolled SQ460FRW steel, the steel was kept at a temperature range from 250 ℃ to 650 ℃ for 1 hour to simulate fire environment, and the microstructure evolution and seismic and fire resistance performance of SQ460FRW steel after different heat treatment were analyzed. The results show that granular bainite (GB) and ferrite (F) can be observed in SQ460FRW steel before and after high-temperature heat treatment, but the degree of decomposition of martensite/austenite (M/A) islands in microstructure is different. After heat treatment at 250-650 ℃, internal friction curve of SQ460FRW steel shows that the SKK peak gradually decreases from 3.926 × 10^-4 to 1.348 × 10^-4, and the carbide precipitation gradually increases from 8.78% to 65.96%. Compared to hot-rolled SQ460FRW steel, SQ460FRW steel has little change in its strength and plasticity after heat treatment at low-temperature (250 ℃) and medium temperature (350 ℃), but has remarkably higher yield strength and increased yield ratio after heat treatment at or above 450 ℃. It is shown that SQ460FRW has its yield ratio less than 0.85 after treatment at or below 550 ℃. After treatment at 250-550 ℃ for 1 h, SQ460FRW steel can have its tensile properties up to the requirements for earthquake and fire resistant steel in GB/T 19879—2023 and GB/T 28415—2023 standards, and it can have higher strength after treatment at 550 ℃. It is concluded that after SQ460FRW steel for construction is heat-treated at 250-650 ℃, its yield ratio exhibits a negative linear correlation with room-temperature internal friction.

To investigate the relationship between interfacial heat transfer coefficient and evolution of interfacial contact during vacuum-assisted high pressure die casting, a combined approach of neural network and numerical simulation was adopted to obtain interfacial heat transfer coefficient and high-precision temperature field. By calculating the actual contact area between casting and mold during solidification, the evolution process of interfacial contact in vacuum-assisted high pressure die casting was studied. It is found that the variation trend of interfacial heat transfer coefficient is consistent with that of the actual contact area. Based on the variation of the actual contact area, the evolution of interfacial contact is divided into five stages. At different stages, pressure retards the decrease in the actual contact area by different actions and enhances the interfacial heat transfer coefficient. At the third stage (C), pressure has a direct impact on the actual contact area, resulting in a reduction of 8.5%-15.0%; at the fourth stage (D), the actual contact area is reduced by 49%.