The preparation of nickel, cobalt and manganese ternary precursors by coprecipitation method was studied. The effects of ammonia concentration, system pH, reaction time and reaction temperature on the properties of the precursors prepared by coprecipitation method were investigated. The results show that under the optimal conditions of ammonia concentration of 1 mol/L, pH=12, reaction temperature of 55 ℃ and reaction temperature of 28 h, the prepared precursor products have good particle size distribution, uniform spheroid shape and dense crystallization. The first discharge capacity of the cathode material after calcination is 169.14 mAh/g and the first efficiency is 88.32% under the charge and discharge system of 2.8~4.4 V and 0.2 C.

Platinum and its composite powder are widely used in electronic information, energy, automotive and other high-end manufacturing fields, due to its unique performance. With the high-quality and rapid development of Chinese advanced equipment manufacturing industry, higher requirements are put forward for the performance of platinum and its composite powder, and the demand for dosage is increasing. In this paper, the most widely used liquid phase method for preparing platinum and its composite powder at home and abroad is reviewed. The research progress of sol-gel method, hydrothermal method, microemulsion method and liquid phase chemical reduction method for preparing platinum and its composite powder is summarized, and the advantages and problems of various method in the process of preparing precious metal powder are also summarized. The development direction of efficient preparation of platinum and other precious metals ultrafine powders is prospected.

The desorption of tungsten and molybdenum from ZGA351 porous strong basic anion exchange resin using NaOH+NaNO₃ as desorption agent and H₂O₂ as strong oxidant was studied. The effects of combined adsorbent composition,concentration of NaOH, concentration of NaNO₃, concentration and dosage of H₂O₂, flow rate ratio of NaOH+NaNO₃/H₂O₂ and desorption times on the desorption of tungsten and molybdenum were investigated. The results show that under the conditions of NaOH concentration of 1.5 mol/L, NaNO₃ concentration of 5%, H₂O₂ addition of 1.2 times the theoretical doasge, H₂O₂ concentration of 30%, the NaOH+NaNO₃/H₂O₂ flow rate of 40 for 6 times, the tungsten and molybdenum desorption rate are 99.48% and 99.38%, respectively. The molybdenum penetration adsorption capacity of the resin is 107.10 g/L, which is similar to that of the new resin 107.77 g/L, indicating that the adsorption properties of ZGA351 resin remained basically unchanged after one desorption and cyclic adsorption. The mass concentration of tungsten in the primary desorption solution is 3.82 g/L, the mass concentration of molybdenum is 10.71 g/L, and the ratio of molybdenum to tungsten is 2.80. After adjusting the acid, it can be directly put into the subsequent industrial production section to make ammonium molybdate products. The results of 30 desorption and adsorption cycles show that the service life of the resin can meet the requirements of industrial production cost. The method synchronizes the process of liquid absorption oxygenation and resin regeneration.The process is simplified, the production cost is reduced, and a feasible process route is explored for the desorption process of large pore strong basic anion exchange resin.

The adsorption and desorption properties of MTA1701 and RCX5143 macroporous weak basic anionic resins for rhenium recovery in arsenic reduction solution were studied. The effects of pretreatment method, time,temperature,acidity and equilibrium concentration on adsorption of rhenium using resin were investigated by static adsorption. Static desorption of ammonia water was used to investigate the effects of ammonia concentration, desorption volume ratio, desorption time and desorption times on the desorption rate of supported resin. The results show that the properties of the two resins are similar, and the adsorption reaction of the resin is in accordance with the quasi-second-order reaction kinetics model after the pretreatment of sulfuric acid soaking. The thermodynamic results show that decreasing temperature is beneficial to the adsorption of rhenium. The static equilibrium adsorption capacity decreased with the increase of acidity and increased with the increase of equilibrium concentration. Under the conditions of ammonia concentration of 10%, V(ammonia)∶V(resin) of 2∶1, desorption time of 20 min for 2 times desorption, the desorption rates of the two resins are all greater than 99.5%.

The comprehensive recovery of copper and arsenic from black copper slime by oxidation leaching method was studied. The effects of acidity, hydrogen peroxide content, temperature, leaching time and liquid volume to solid mass ratio on the leaching rate of copper and arsenic were investigated. The results show that under the conditions of acidity of 200 g/L, hydrogen peroxide content of 30%, temperature of 80 ℃, leaching time of 2.0 h, liquid volume to solid mass ratio of 9∶1, the leaching rates of copper and arsenic can reach 99.53% and 98.24%, respectively. After oxidative acid leaching, sodium hydrosulfide is added into the solution at the rate of n(NaHS)/n(Cu)=1.1 to precipitate copper. The mass concentration of copper in the solution after copper and arsenic separation is lower than 0.01 g/L, and the mass concentration of arsenic is greater than 40 g/L. The copper and arsenic are effectively separated. Arsenic-rich liquid can be reduced with sulfur dioxide, and arsenic trioxide and reduced liquid can be returned to the oxidation leaching process.

The influence of fluorine on the production wet-process phosphoric acid is described. The principle, application status, advantages and disadvantages of the main defluorination process of wet phosphoric acid are reviewed. The problems existing in the current defluorination process of wet phosphoric acid are pointed out, and the future development direction is put forward in order to provide reference for the comprehensive utilization of fluorine resources in wet phosphoric acid in our country.

The effects of solution coordination environment on the extraction of vanadium by P204 were investigated. The effects of chloride, fluoride and sulfate ions on the extraction of vanadium and their coordination with vanadium were examined at different pH. The results show that for the extractant using an organic phase composition of 20%P204+5%TBP+75%sulfonated kerosene, at phase ratio of V_O/V_A=1/2 and extraction time of 8 min, chloride ions can effectively enhance vanadium extraction. At pH=1.0 and [Cl^-]=5 mol/L, the vanadium extraction can reach 87.93%. When the pH is 1.4~2.2, fluoride ions in a certain concentration range can promote the extraction, and the best promotion effect is achieved when [F^-]=0.05 mol/L. The concentration of fluoride ion is greater than 0.2 mol/L, and the extraction is inhibited. When pH=1.8 and 2.2, the concentration of sulfate has little effect on vanadium extraction. But when pH=1.0 and [$\mathrm{SO}_{4}^{2-}$]=1.5 mol/L, the vanadium extraction rate is only 52.22%, and the high concentration of sulfate can significantly inhibit vanadium extraction. The thermodynamic results show that coordination groups VOCl⁺ and VOF⁺ can enhance vanadium extraction process. When the concentration of fluoride ion is higher than 0.2 mol/L, the coordination anion VOF₃ formed by VO²⁺ and multiple F^- prevents the cation exchange reaction of P204.

The leaching of molybdenum from molybdenite by oxygen pressure water leaching method was studied.The effects of ore size, oxygen partial pressure, temperature and stirring speed on oxidation of molybdenite were investigated, and the distribution of oxidation products in solid and liquid phases was discussed. The results show that the oxidation of molybdenite can be promoted by the decrease of ore particle size and the increase of oxygen partial pressure, temperature and stirring speed. The oxidation products first enter the liquid phase. When the liquid phase is saturated with $\mathrm{MoO}_{4}^{2-}$, the oxidation products will enter the slag phase in the form of MoO₃. The oxidation of molybdenum during oxygen pressure water leaching of molybdenite can be described by the unreacted nuclear shrinkage model.The reaction rate is controlled by the mixed control model, and the apparent activation energy is 40.55 kJ/mol.

Chitosan microspheres (HTCC) were prepared by hydrothermal method, and Amino-modified chitosan adsorbent (AHTCC) was prepared by epoxidization and amination method to adsorb low concentration uranium in wastewater. The structure, composition and thermal stability of AHTCC were characterized by infrared spectrometer, elemental analyzer and thermogravimetric analyzer, and the adsorption and desorption properties of AHTCC for uranium were investigated. The results show that AHTCC has a good adsorption effect on uranium in solution at pH=5~8. Under the condition of equilibrium mass concentration of uranium adsorption of 120 mg/L, the adsorption capacity reaches the 151.6 mg/g. Its adsorption rate is faster in the initial 60 min and reaches equilibrium at 180 min. Using 80 g/L Na₂CO₃+20 g/L NaHCO₃ as the desorption agent, the desorption rate of uranium is 97.5%. For real uranium containing wastewater with high concentration of impurities, the removal rate of uranium can reach 95.6% after single adsorption by AHTCC.

In order to realize the high value utilization of solid and liquid wastes, extraction of vanadium from vanadium tailings with titanium dioxide waste acid was studied. The effects of leaching temperature, leaching time, solid mass to liquid volume ratio, waste acid concentration and other technological parameters on vanadium leaching rate were investigated by orthogonal experiments, and the optimal leaching conditions were determined. In order to further improve the vanadium leaching rate, the appropriate amount of leaching aid (fluorite) and oxidant (hydrogen peroxide) was discussed. The results show that the order of influence of the process parameters on vanadium leaching rate is leaching temperature> leaching time> solid mass to liquid volume ratio> titanium dioxide waste acid concentration. Under the optimum conditions of temperature of 80 ℃, leaching time of 2 h, solid mass to liquid volume ratio of 1∶5 and waste acid concentration of 5%, the vanadium leaching rate is about 53%. After adding 7% fluorite and 5% hydrogen peroxide, the vanadium leaching rate can be increased to 71.09%.