In the production and processing of NdFeB,more than 30% of rare earth metals will be transferred to the waste, resulting in NdFeB waste can not be effectively used. With the rapid development of new energy automobile industry,the green recycling of NdfeB waste has become a research hotspot in this field. The current research status of hydrometallurgy for recycling NdFeB waste at home and abroad, including acid leaching,precipitation, solvent extraction, alkali decomposition, ionic liquid recovery, hydrolysis and microbial decomposition, are reviewed. At the same time, the technical difficulties facing the current research are pointed out. Finally, the main research direction of NdFeB waste recycling in the future is put forward, which provides valuable reference for the secondary utilization of rare earth resources.

Aiming at the issues of low computational efficiency and insufficient intelligence in predicting hydrometallurgical process parameters, a process optimization control model that utilizes 1D-CNN for predicting copper ion concentration and Seq2Seq for predicting mass transfer rate, with the objective of maximizing economic benefits was proposed. The optimization problem is solved using the DDPG algorithm. The results of numerical simulation and empirical study show that the model can predict the parameters of copper extraction process with high accuracy, realize the effective optimization and adjustment of parameters, and promote the improvement of economic benefits.

The direct leaching of Cu and Co from a copper-cobalt mixed ore in Congo(Kinshasa) by oxidation leaching method and reduction leaching method was studied. The leaching behavior of Cu and Co by the two methods was compared and analyzed. The effect of flotation—oxidation leaching on the leaching rate of copper and cobalt was further discussed. The results show that the leaching rates of Cu for oxidation and reduction leaching are about 80% and 70% respectively, and the leaching rates of Co are about 63% and 57% respectively, and the oxidation leaching effect is better than that of reduction leaching. By using the combined flotation—oxidation leaching process, the Cu and Co grades in closed-circuit flotation concentrates are 16.84% and 6.53%, respectively and the combined recovery rates of Cu and Co are 91.71% and 61.87%, respectively. The recovery effect of Cu and Co can be significantly improved.

The synergistic decomposition of scheelite by HCl-H₂SO₄ was studied. The influence of various process parameters on the decomposition effect was investigated, and the kinetics of decomposition process was discussed. The results show that under the optimal conditions of hydrochloric acid concentration of 22%, liquid volume of concentrated sulfuric acid of 0.5%, liquid volume to solid mass ratio of 2.5∶1, decomposition temperature of 85 ℃, decomposition time of 2 h, stirring rate of 360 r/min, the decomposition rate of calcium tungstate in scheelite is 99.6%, and the decomposition rate is high. The process of HCl-H₂SO₄ synergistic decomposition of scheelite is controlled by chemical reaction and solid film mixing, and the apparent activation energy is 45.52 kJ/mol. The CaWO₄ in scheelite can be efficiently converted into tungstic acid, thus effectively improving the tungsten extraction rate in scheelite.

The efficient utilization of secondary silver-containing resources is of great significance for making up for the shortage of silver ore resources in China, alleviating the contradiction between supply and demand, and ensuring the supply security of national strategic metals. For waste Ag-Cu filler metal, the leaching and separation of copper and silver in the HCl-H₂O₂ system was studied, and high-purity AgCl was prepared. The influence of various factors on the separation effect of copper and silver was investigated. The results show that under the optimized conditions of H₂O₂ excessive coefficient of 1.3, HCl excessive coefficient of 1.4, liquid-solid mass ratio of 11∶1, leaching temperature of 40 ℃, and leaching time of 3 h, the leaching rate of copper can reach 99.38%. The leaching residue is irregular spherical particle with particle size of 2~4 μm. The main phase is AgCl, and the main components are Ag and Cl, with total mass fraction of more than 99%.

Aiming at the dilute acid of copper smelting as raw material, the selective precipitation of copper and removal of arsenic with oxalic acid was studied. The effects of oxalic acid addition dosage, solution pH, stirring speed, reaction temperature and time on the separation of copper and arsenic were investigated. The results show that under the conditions of H₂C₂O₄/Cu molar ratio of 1.1, solution pH=0.4, stirring speed of 500 r/min, reaction temperature of 25 ℃ and reaction time of 30 min, the precipitation rate of copper is more than 98.5%, and the precipitation rate of arsenic is less than 0.20%, copper and arsenic can be separated efficiently.

Lead leaching residue of acid mud contains a large number of complex and scattered precious metals, which has high recovery value. The leaching of selenium, bismuth, copper and mercury from lead leaching residue using a mixture of hydrochloric acid and sulfuric acid as the leaching agent and sodium chlorate as the oxidizing agent was studied. The effects of temperature, dosage of sodium chlorate, leaching time, liquid volume to solid mass ratio and hydrochloric acid concentration on the leaching rates of selenium, bismuth, copper and mercury were investigated. The results show that under the conditions of temperature of 40 ℃, dosage of sodium chlorate as 40% of raw material mass, leaching time of 1 h, liquid volume to solid mass ratio of 4 mL/1 g, hydrochloric acid concentration of 1 mol/L and sulfuric acid concentration of 1.5 mol/L, the leaching rates of selenium, bismuth, copper and mercury are 98.78%, 98.13%, 99.38% and 99.42%, respectively. The method can achieve high efficiency leaching of selenium, bismuth, copper and mercury, and enrich the tin, lead and silver in the residue.

To address the problems such as insufficient real-time data analysis, lack of intelligent decision-making support, and limited dynamic optimization capabilities of in-situ leaching dynamic mining system in practical application, the advantages of integrating Digital Twin technology with the in-situ leaching process for uranium extraction were analyzed. By incorporating advanced technologies such as muon imaging, fiber-optic water level monitoring, advanced sensing technologies, artificial intelligence, and big data analysis, an efficient digital-intelligent uranium mining platform was constructed. The platform includes geological structure model, groundwater seepage model, reactive transport model, and intelligent agent model. The core algorithms cover deep learning, data assimilation, multi-objective optimization, and uncertainty analysis. The establishment of the dynamic in-situ leaching mining system can improve the efficiency of uranium resource development and can provide valuable reference for the extraction of other mineral resources, thus having certain theoretical significance and practical value.

Extracting vanadium from stone coal vanadium ore with sericite as the main material and vanadium in the form of isomorphic vanadium by barium salt roasting—acid leaching was studied. The effects of grinding fineness, dosage of barite, roasting temperature, roasting time, liquid volume to solid mass ratio, sulfuric acid dosage, leaching temperature and leaching time on vanadium leaching rate were investigated. The results show that the vanadium leaching rate can reach 89% under the conditions of grinding fineness of -200 meshes of 70%, barite content of 5%, roasting temperature of 850 ℃, roasting time of 16 h, liquid volume to solid mass ratio of 2.0, sulfuric acid dosage of 8%, leaching temperature of 25 ℃ and leaching time of 2 h. The leaching effect is good.

In order to solve the issue of low automation in the hydrometallurgical process in in-situ leaching of uranium, especially in the preparation of yellowcake from precipitation slurry using plate and frame filter presses, a horizontal belt vacuum filter was selected for the first time in an in-situ leaching of uranium mine to conduct a filtration dewatering experiment on sodium diuranate precipitation slurry. The influence of different operating conditions on moisture content of yellow cake products was investigated. The results show that under the conditions of a filtration vacuum of -0.06~-0.08 MPa, a filter cloth precision of 38 μm, a slurry residence time of 640 s, a feed flow rate of 353~589 kg/h, and a backwash and sealing circulation water flowrate of 10 m³/h, the entire process from cloth feeding to filtration, dewatering, cake discharge, and cloth backwashing can be automatically cycled and run continuously and stably. The product moisture content meets the first-grade standard, satisfying the dewatering capacity requirements for a mine producing about 500 t of metallic uranium per year. The technical feasibility of using belt vacuum filter to dehydrate the precipitated slurry has been preliminatively confirmed. The technical feasibility of using belt vacuum filter for dewatering the precipitation slurry has been preliminatively confirmed. The filtration dewatering process can reduce the labor intensity of operators, reduce the radiation hazard, and improve the automation of the entire hydrometallurgy process, it has value for promotion and application.