As an important secondary resource rich in Nd, Pr, Dy and other rare earth elements, the recycling of NdFeB permanent magnet waste is not only related to the supply security of rare earth strategic resources, but also has great significance for reducing environmental pollution and promoting sustainable development. The source, basic physical and chemical characteristics of NdFeB permanent magnet waste and the recycling technology of rare earth elements are summarized. The basic principles and research progress of fire, wet and other recycling processes are reviewed. The advantages and disadvantages of the technology are analyzed. The future development direction of NdFeB waste recycling rare earth technology is prospeced, in order to promote the technological progress and sustainable development in this field.

The extraction of lithium from fly ash by roasting activation with sodium carbonate and leaching with sulfuric acid was studied. The effects of mass ratio of fly ash to sodium carbonate, roasting temperature, roasting time, liquid-solid mass ratio, sulfuric acid concentration, acid leaching temperature and acid leaching time on the leaching rate of lithium were investigated. The dynamic analysis of the leaching process was carried out by using the core-shrinkage model. The results show that under the condition of 800 ℃, fly ash and sodium carbonate are mixed and roasted for 180 min according to the mass ratio of 1∶1, and then leaching with 2 mol/L sulfuric acid at 90 ℃ for 120 min, remarkable leaching effect can be obtained, and the leaching rate of lithium can reach 99.97%, the leaching process is mainly controlled by diffusion. The study has a certain guiding significance for the leaching and recovery of lithium from solid waste resources.

The magnetic porous magnesium oxide(m-MgO) was prepared with nano-ferric oxide (Fe₃O₄) as the core and MgCl₂ as the magnesium source, and was used for adsorption of U(Ⅵ) in aqueous solution. The physicochemical properties of MgO and m-MgO were characterized by FT-IR, XRD, VSM and Zeta potential. The effects of solution pH, temperature, and oscillation time on the adsorption of U(Ⅵ) by MgO and m-MgO were investigated. The results show that the optimal conditions for uranium adsorption by MgO and m-MgO are pH=3.5, adsorbent dosage of 10 mg, and oscillation time of 720 min. The adsorption process conforms to the pseudo-second-order kinetic model and the Sips isotherm adsorption model, with a theoretical adsorption capacity of 454.16 mg/g, and the increase of temperature is conducive to the spontaneous adsorption. Therefore, m-MgO is expected to be used to separate and recover uranium from radioactive wastewater.

In order to comprehensively recover the valuable components from decommitted high-nickel ternary lithium batteries,lithium was selectively extracted by sulphation roasting and water leaching, and the water leaching residue was then processed by aging leaching,impurity removal and coprecipitation to prepare nickel-cobalt-manganese hydroxide. The results show that the optimum conditions of sulfation roasting are n(H₂SO₄)∶n(Li)=1.4∶1, roasting temperature of 600 ℃, roasting time of 1 h, and the water leaching rate of Li, Mn can reach 94.36%, 11.03%, respectively, Ni and Co hardly leaching. Under the conditions of acid-ore ratio of 1.74, curing temperature of 120 ℃, curing time of 120 min and liquid volume to solid mass ratio of 7.5 mL/1 g, the aqueous leaching slag is cured and acid leaching. The leaching rates of Li, Ni, Co, Mn, Cu, Fe and Al are 97.86%, 89.16%, 95.09%, 100%, 63.6%, 99.71% and 56.76%, respectively. Under the optimum conditions of pH=3.38, precipitation temperature of 60 ℃ and precipitation time of 60 min, the precipitation rates of Fe, Al and Cu in the solution can reach 100%, 98.07% and 82.51%, respectively. Nickel cobalt manganese hydroxide can be formed by co-precipitation after pH adjustment. Under the optimal conditions of pH=9.44, co-precipitation temperature of 55 ℃ and co-precipitation time of 120 min, the precipitation rates of Ni, Co and Mn can reach 99.6%, 100% and 98.72%, respectively.

In order to develop a high efficiency, environmental protection, low energy consumption of heavy metal Cr (Ⅵ) adsorbent magnetic biochar (MBC) was obtained by co-precipitation reaction in a mixture of FeSO₄·7H₂O and FeCl₃·6H₂O with alkali modified biochar as the substrate. polyethyleneimine(PEI) was then used as an amination agent and glutaraldehyde was as a cross-linking agent to produce PEI-functionalized magnetic biochar composites(PEI/MBC) for Cr(Ⅵ) removal, PEI/MBC was characterized by SEM,XRD and FT-IR. The effects of solution pH, adsorbent dosage and competitive ions on the adsorption properties for Cr(Ⅵ) were investigated,the results show that the highest adsorption amount of 105.94 mg/g is achieved under the conditions of initial Cr(Ⅵ) concentration of 50 mg/L, an adsorbent dosage of 0.2 g/L, temperature of 30 ℃ and pH=2. The adsorption was affected by the changes of competitive anions and temperature, the quasi-second-order kinetic equation can well reflect the adsorption behavior of Cr(Ⅵ) on PEI/MBC, and the isothermal adsorption data is consistent with the Freundlich isothermal adsorption model, the adsorption of Cr(Ⅵ) is a spontaneous endothermic process, with ΔG<0, ΔS=144.82 J/(mol·K) and ΔH=39.84 kJ/mol.

Electrolysis of Manganese using Ionic liquid choline chloride as additive instead of selenium dioxide, under simulated industrial electrolytic conditions was studied. The electrolytic products were characterized by SEM and XRD, and the electrochemical mechanism of the cathode was analyzed by cyclic voltammetry(CV) and cathode polarization curve(LSV). The results show that the electrolytic product with ionic liquid choline chloride as additive has smooth, dense surface, and has a metallic luster. The addition of choline chloride can promote manganese deposition and inhibit hydrogen evolution. Under simulated industrial electrolysis conditions, the current efficiency is up to 68.1%.

In view of the problems of low impurity removal rate and low grade of germanium concentrate in the washing process of tannin germanium residue, the As, Zn and Fe impurities in tannin germanium residue were effectively removed by washing with dilute sulfuric acid solution. The effects of sulfuric acid mass concentration, washing temperature and washing time, liquid volume to solid mass ratio on the removal rate of As, Zn and Fe impurities and Ge loss rate were investigated. The results show that under the conditions of sulfuric acid mass concentration of 60 g/L, liquid volume to solid mass ratio of 5 mL/1 g, washing temperature of 60 ℃,first washing time of 120 min, second washing and third washing time of 60 min, the cumulative removal rates of As, Zn and Fe can reach over 88%, 97% and 95%, respectively. Ge cumulative loss rate is less than 1.50%. The Ge and As grades of germanium concentrate prepared by three-stage countercurrent pickling and oxidation roasting process are 34.45% and 0.54%, respectively, which meet the tertiary standard of germanium concentrate.

The synthesis of a polyethylene imine-functionalized biochar aerogels (LSBC-CTS/PEI) using lotus seed powder, chitosan and polyethylene imine as materials, and used for adsorption of U(Ⅵ) in wastewater was studied. The results show that LSBC-CTS/PEI exhibit a looser structure with interconnections, and contains very rich amine-based functional groups, which can provide more adsorption sites for U(Ⅵ) coordination. The selective adsorption of U(Ⅵ) by LSBC-CTS/PEI is greatly affected by pH. The adsorption is mainly composed of single-layer chemisorption, which belongs to a spontaneous endothermic process, and is more suitable for description by quasi-second-order kinetics and Langmuir isothermal adsorption model. The selectivity of LSBC-CTS/PEI to uranium is 84.91%, and the maximum adsorption capacity is 533.89 mg/g. The adsorption material has high adsorption capacity of uranium, good selectivity, and convenient separation of solid and liquid, so it has the certain value of application.

The preparation of electronic grade phosphoric acid by deep removing arsenic from wet-process phosphoric acid is an important technical link to develop phosphorus chemical industry with high quality and promote the technological transformation of phosphorus chemical industry. Electronic grade phosphoric acid requires a mass fraction of arsenic less than 1×10^-7 kg/kg, but because the physicochemical parameters of arsenic and phosphorus are similar, how to achieve the deep separation of arsenic from phosphoric acid has become the key to the preparation of electronic grade phosphoric acid. In this paper, the main international and domestic quality standards for electronic grade phosphoric acid products are systematically reviewed, and the harm of arsenic to electronic grade phosphoric acid etched microelectronic components is summarized. The research progress, advantages and disadvantages of chemical precipitation, crystallization, electrodeposition, electrodialysis and adsorption are summarized, and the development trend of electron grade phosphoric acid prepared by wet phosphoric acid is prospected.

The composition, preparation methods, and mass transfer mechanisms of ELM (emulsion liquid membrane), SLM (supported liquid membrane), and PIM (polymeric inclusion membrane), and the research progress of these three types of membranes in hydrometallurgy in recent 5 years are reviewed. Additionally, the advantages and disadvantages of the three membranes in hydrometallurgy were summarized, and the solution to the problems such as ELM films exhibited instability and difficulties with emulsion breaking, SLM membranes tended to be unstable with the membrane phase is lost to the water phase and PIM demonstrated lower mass transfer efficiency requiring longer time to reach equilibrium are proposed. Finally, the future development direction for the three membranes in the field of hydrometallurgy are prospected, providing a crucial foundation for further promoting the application of membrane extraction technology in hydrometallurgy and expediting the industrial production of membrane extraction technology.