In view of the comprehensive development and utilization of rare earth as a strategic resource and its co-existing fluorine resources, in light of the urgent demand of Bayan Obo characteristic industries for high-abundance light rare earth and functional fluoride, the acid-base medium circulation-induced crystallization technology was developed with low-concentration fluorine-containing waste acid commonly found in rare earth smelting, rare earth metal electrolysis and other industries as the research object. Based on the principle of reaction kinetics and template effect, a microscopic model of induced crystalline rare earth fluoride was designed. The influence of temperature, concentration, instantaneous relative material quantity, acidity and other technological conditions on the synthesis of crystalline rare earth fluoride was investigated, and the crystallization, combination and substitution mechanisms of fluorine, inducer and rare earth were revealed. The key scientific problem of colloidal precipitation of rare earth fluoride synthesized in liquid phase is solved. The entire set of technologies can realize the high-value utilization of co-associated fluorine resources, ensure that co-associated fluorine resources as an important supplement of strategic mineral resources fluorite, and have significant economic and social benefits and broad application prospects.

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 extraction of iron from fly ash by HCl leaching and electrochemical deposition was studied. The micro-morphology and elemental composition of fly ash were systematically analyzed by SEM-EDS,XRF, ICP and XRD, and the key factors in the leaching process and their effects were investigated. The dynamic changes of pH, current density and Fe ion concentration during electrochemical deposition were also discussed. The results show that the iron leaching rate increased with the increase of HCl concentration, liquid volume to solid mass ratio, leaching temperature and leaching time. In the electrochemical deposition stage, pH increases gradually, while current density and Fe ion concentration decrease. The optimal leaching parameters are HCl concentration of 6 mol/L, liquid volume to solid mass ratio (HCl solution to fly ash) of 8∶1, reaction temperature of 90 ℃, reaction time of 90 min. For the electrochemical deposition process, the voltage is 3 V, the optimal pH range is between 0.5 and 1.9, and the final sediment is pure iron.

A series of impregnated mesoporous silica SBA-15-P507 was prepared by using 2-ethylhexyl phosphate (P507) as extractor and mesoporous nano-silica material (SBA-15) as carrier. The adsorption properties of SBA-15-P507 on Co²⁺ and Ni²⁺ in wastewater were investigated. The results show that under the conditions of adsorbent dosage of 5 g/L, initial mass concentrations of Co²⁺ of 400 mg/L, initial mass concentrations of Ni²⁺ of 400 mg/L, adsorption temperature of 25 ℃, the equilibrium adsorption capacities of Co²⁺ and Ni²⁺ can reach 58.90 and 23.45 mg/g, respectively, and the adsorption equilibrium time is 40 min. The adsorption processes of Co²⁺ and Ni²⁺ conform to the quasi-second-order kinetic equation, and the adsorption isotherms of Co²⁺ and Ni²⁺ conform to the Langmuir isotherm adsorption model. The adsorption reaction of Co²⁺ is endothermic, while that of Ni²⁺ is exothermic. In the mixed simulation system containing Co²⁺ and Ni²⁺, SBA-15-P507(2.0) can selectively adsorb Co²⁺.0.1 mol/L sulfuric acid solution has significant elution effect on Co²⁺ adsorbed by SBA-15-P507(2.0). The research results can provide a new way for the purification of cobalt-nickel wastewater, which has certain theoretical guidance and practical application value.

Removal of iron from high silicon-aluminum ratio and high iron coal gangue using thermally activated enhanced—hydrochloric acid leaching process was studied. The effects of calcination temperature, calcination time, hydrochloric acid concentration, leaching temperature, liquid-to-solid mass ratio, and leaching time on the iron leaching rate were examined, and the process conditions were optimized through orthogonal experiments. The results show that under the optimized conditions of calcination temperature of 500 ℃, calcination time of 1 h, hydrochloric acid concentration of 20%, leaching time of 3 h, leaching temperature of 90 ℃, and liquid-to-solid mass ratio of 4/1, leaching rate of Fe can reach 94.25%. The method can efficiently remove iron from coal gangue while effectively enriching Si and Al elements, providing technical reference for the resource utilization of coal gangue.

The removal method of superstandard components of uranium acid seepage water from sulphur-containing uranium waste rock in a mining area was studied. Firstly, 1 g/L mineral powder was added to the wastewater exceeding the standard to remove Cd, Cu and part U, and then the pH of seepage water from the waste rock landfill on the south and north sides was adjusted from 2.78 and 2.66 to 4.70 and 4.30, respectively, and the optimal contact reaction time was 30 min. The effects of Mg(OH)₂, Ca(OH)₂, Na₂CO₃ and NaOH on the further treatment of U, Mn and Zn in the effluent treated by ore powder were compared. The results show that Ca(OH)₂ has the best removal effects on U, Mn and Zn.Under the conditions of 0.32 and 0.96 g/L of Ca(OH)₂ and pH of 7 ~ 8, the removal rate of U, Cu, Cd, Zn and Mn can reach over 99.8%, over 90%, over 90%, over 95% and over 75.5%, respectively. And the settling speed is fast, and the suspended liquid volume can be reduced by about 70% after standing for 60 min. The precise calculation of the change of ion concentration during the addition of Ca(OH)₂. The results of sediment characterization show that hydrotaltale-like substances are formed during the purification process,Mn²⁺ and Zn²⁺ ions entered the hydrotalc structure and are removed,and uranyl ions may be removed by electrostatic adsorption with hydrotalc, surface complexation or interlayer anion exchange.

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.

The process of synergistic leaching of lithium from waste lithium iron phosphate (LFP) and lithium cobalt oxide (LCO) battery cathode materials was studied, and the feasibility was analyzed by thermodynamics. The influence of various factors on synergistic leaching was investigated,and the leaching slag was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that LFP and LCO can synergistically leach lithium in an acidic system without adding any oxidant or reducing agent. The leaching rates of Li, Co, Fe and P in the cathode materials of waste batteries are 99.99%, 99.99%, 48.00% and 43.77%, respectively, under the optimal leaching conditions of sulfuric acid concentration of 0.7 mol/L, leaching temperature of 40 ℃, leaching time of 60 min, n(LCO)∶ n(LFP)=0.5 and liquid volume to solid mass ratio of 10 mL/1 g. The method can realize the purpose of recovering valuable metals from complex battery cathode materials under low acid conditions, and has certain popularization and application value.

Aiming at the problems such as relatively simple control and intelligent detection model of hydrometallurgical equipment and weak generalization ability,an algorithm model for intelligent control and fault detection of hydrometallurgical equipment based on deep learning was proposed. Firstly, SAC deep reinforcement learning algorithm was used to perform intelligent control of hydrometallurgical equipment. The improved ARIMA algorithm is used to detect the fault of the equipment. In order to further improve the real-time performance of the algorithm, LoRA fine-tuning network is introduced to fine-tune and accelerate the model with low parameters, and LoRA fine-tuning network to fine-tune and accelerate the model with low parameters. The accuracy of the model is 93.24% and the accuracy of fault detection is 91.34%. The practical application effect is good.

An indium-nitrogen-carbon electrode material (PAO/In-N-C) modified with amidoxime was prepared using graphite felt as matrix material by chemical modification and coating, and uranium was extracted from seawater by electrochemical workstation. The effects of the PAO/In-N-C electrode material dosage, applied voltage, pH of spiked seawater and adsorption time on the extraction of uranium from low-concentration spiked seawater were investigated. The ion selectivity and recycling performance of the electrode material were tested, and the interaction mechanism between the electrode and uranyl ions was discussed. The results show that the extraction rate of uranium is 71.16% under the conditions of applied voltage of -3~0 V, PAO/In-N-C electrode material dosage of 7 mg, adsorption time of 400 min, and seawater pH=8.10.PAO/IN-N-C electrode material reduction of uranium in seawater is divided into two steps: electroadsorption and electrodeposition. Firstly, the electromagnetic field is used to accelerate the migration of $\mathrm{UO}_{2}^{2+}$ to the electrode surface, and then the electroneutral compound UO₂ is formed and deposited on the electrode surface. The material has remarkable adsorption kinetics, good ion selectivity and reusability,and is expected to be used for uranium extraction from seawater.