With the calcium-magnesium slag generated in recycling process of spent Li-ion batteries as raw material, battery-grade lithium carbonate was prepared by adopting a process consisting of leaching for decomposition, purification, lithium precipitation and carbonization for decomposition. The results show that with the addition of MgSO₄·7H₂O at 1.1 times of the theory amount, initial pH of 1.5, reaction time of 2.0 h, solid-liquid ratio of 1∶6, reaction temperature of 90 ℃, and final pH of 3.5, the leaching rate of Li can reach 98.39% and the mass concentration of Li in the lixivium is 18.03 g/L. Then, the obtained lixivium is subjected to processes of defluorination with resin, impurity removal with NaOH, and Na₂CO₃ precipitation, and crude lithium carbonate can be obtained with purity of 95.11%. By adopting a process consisting of carbonization, removal of calcium and magnesium with resin, and pyrolysis, a battery-grade lithium carbonate with purity of 99.64% can be prepared. It is shown that by using this processing technique, the lithium recovery rate can reach 95.08%, presenting good prospect in industrial application.

An argyrodite-type sulfide solid electrolyte Li₆PS₅Cl (LPSC) was solid-phase synthesized by adopting high energy ball milling in combination with heat treatment. It is found that prolonging ball milling time is conducive to crushing, mixing, grain refinement and amorphization reaction process of raw material powder; increasing sintering temperature is beneficial to the formation of a single pure phase, but too high temperature for sintering can make electrolyte melted and decomposed, leading to destroyed crystal structure. It is found that after 10 hours of ball milling and 8 hours of sintering at 550 ℃, the synthesized sulfide solid electrolyte exhibits higher ionic conductivity, reaching 3.57×10^-3S/cm.

Rare earth elements are important resources for national development and industrial upgrading, and it is critical to establish an improved rare earth policy system. Based on the constructed analysis framework of rare earth policies, 48 rare earth policies issued from 1985 to 2022 in China were evaluated by using text data mining, social network and policy modeling consistency (PMC)-index model from three aspects, including the evolution process of rare earth policies, policy network and quantitative policy analysis. It is found that the evolution of China's rare earth policies can be divided into four stages, among which standardizing the exploitation procedure for rare earth resources and rectifying the order of rare earth market have always been the focus of China's rare earth policies. A policy network has been initially constructed, but there is poor correlation among policies and there are many isolated policies, which indicates that the correlation among policies needs to be strengthened. The overall design of the polices is reasonable, but there are some deficiencies in incentive measures and effectiveness. Finally, some suggestions are put forward to optimize and improve China's rare earth policies based on the features and shortcomings.

After an introduction of the current status of gallium resources and analysis of the occurrence state of gallium in sodium aluminate solution, zinc smelting slag, tailings from vanadium extraction and coal-based solid waste, progress in the research of gallium extraction processes is elaborated and the adaptability, advantages and disadvantages of each technique are also summarized. Finally, based on the discussion of problems faced by the gallium industry and the development direction in the future, it is suggested that iteration and upgrading of gallium extraction processes should be vigorously promoted based on China's scale advantage in alumina industry.

The basic flow of Midrex and HYL/Energiron technologies for direct reduction in a shaft furnace and the direct reduced iron output by each processing technique in recent years are firstly introduced, and then the equipment, raw materials and process characteristics of those two technologies are analyzed based on comparison. Based on the expounding of technical R&D and investment of global steel companies in these two technologies, it is pointed out that the development of hydrogen-based direct reduction process in a shaft furnace is closely related to grade of pellet ore, heat adsorption during hydrogen-based reduction reaction process, technologies for large-scale green hydrogen production and production cost among others. It is important for sustainable development of Chinese iron and steel industry to adopt hydrogen-based direct reduction in a shaft furnace that conforms to the national conditions.

The acid leaching solution of cathode materials from spent lithium iron phosphate batteries was taken as raw material, and iron, phosphorus and lithium elements therein were recovered by adopting an oxidation-precipitation process. The effects of factors, including endpoint pH value of reaction system, reaction temperature, concentration of sodium hydroxide, dripping rate of sodium hydroxide, and the volume ratio of hydrogen peroxide to acid leaching solution, on the precipitation rates of iron and phosphorus and the loss of lithium during the precipitation process were all investigated. Results show that with the endpoint pH value of 2.5, temperature of 75 ℃, sodium hydroxide with concentration of 1.5 mol/L, sodium hydroxide solution at a dripping rate of 7.7 mL/min, and hydrogen peroxide and acid leaching solution in a volume ratio of 1∶60, the average precipitation rates of iron and phosphorus are 99.86% and 98.23%, respectively, and the average loss of lithium is just 1.23%. Under the above-mentioned conditions, iron and phosphorus in the solution can be effectively removed and recycled in the form of iron phosphate, presenting a lower loss rate of lithium. After 5 h-heat treatment at 700 ℃, it is shown that the chemical composition of iron phosphate can meet the industrial standard.

With bamboo as a raw material, different hard carbon materials were prepared by different impurity removal processes, and the effects of those processes on the impurity content, physical structure and sodium storage performance of hard carbon were explored. The results show that after impurity removal treatment, the bamboo-derived hard carbon has reduced impurity content and specific surface area, and increased interlayer spacing. With the preparation cost and the sodium storage performance of hard carbon comprehensively taken into consideration, acid leaching is chosen as the impurity removal process for hard carbon. It is shown that at a current density of 30 mA/g, the anode material with prepared hard carbon can have an initial Coulombic efficiency of 83.87% and a reversible specific capacity of 308.96 mAh/g；it demonstrates a capacity retention rate of 96.57% after 100 cycles at a current density of 300 mA/g, showing excellent sodium storage performance.

A new short-process preparation technique for battery-grade iron phosphate was explored with iron powder and phosphoric acid as main raw materials. The effects of iron powder dissolution mechanism, iron phosphate reaction conditions, and mother liquor recycle on product indicators were investigated. The results show that the dissolution rate of iron powder can reach 97.92% at a temperature of 70 ℃, with phosphoric acid at a concentration of 20%, iron and phosphorus at a ratio of 1/3, and iron powder at a size of 150 μm；after 1 h precipitation at 100 ℃, with an addition of hydrogen peroxide at 110% of the theoretical amount, an iron phosphate with D₅₀ of 2 μm was prepared with the precipitation rate of 98.86%. The obtained iron phosphate has stable crystal form with uniform crystal grains, and the contents of elemental impurities are significantly lower than the requirements specified in the HG/T 4701—2021 standard. The precipitated mother liquor in the process can be recycled, leading to actualization of low-carbon and green production.

A side blowing furnace was adopted to treat the leaching residue of copper anode slime and recover valuable metals therein comprehensively. The effects of soda dosage, granular coal dosage, precipitation time and top flue gas temperature on the recovery rates of main metals Pb, Sb, Bi, Au and Ag were investigated. The results show that with soda at an amount of 2.5%, granular coal at an amount of 3%, the precipitation time of 1.5 h, and the top flue gas temperature of 750 ℃, the precious lead product is obtained after processing, grading 1 544 g/t Au (1.84 times enrichment), 10.37% Ag (1.4 times enrichment), 22.89% Pb (2.1 times enrichment), and 27.45% Bi (2.2 times enrichment).

Based on the analysis of patent application trend, major applicants and technological development in recycling of spent lithium iron phosphate batteries by leaching process, a list of key patents of mainstream technologies is presented. The results show that the number of patent applications for recycling of spent lithium iron phosphate batteries by leaching process has been steadily increasing since 2015, and oxidative acid leaching is the mainstream technology at present, with other technologies keeping in pace. However, some outdated technologies are being phased out.