In order to efficiently enrich indium (In) in zinc oxide dust and realize the directional separation and recovery of associated elements, Zn, Fe, Pb and In were leached from the dust by choline chloride-oxalate dihydrate low eutectic solvent, and the “hydrolytic removal of zinc and lead-ultraviolet light reduction iron removal” process was used to remove impurities step by step. The results show that the leaching rates of Zn, In, Pb and Fe can reach 95.52%, 88.91%, 80.82% and 89.13%, respectively, under the optimal leaching conditions of liquid volume to solid mass ratio of 12 mL/1 g, temperature of 70 ℃ and time of 6 h. Zn/Pb is removed by hydrolytic precipitation, and then Fe is removed by ultraviolet reduction precipitation. After the step-by-step precipitation and impurity removal treatment, the mass fraction of indium in the solution has increased from 0.03% to 1.5%, successfully achieving efficient enrichment of indium and directional separation and recovery of associated elements such as Zn, Pb, and Fe.

The leaching of valuable metals from low-grade lead matte using hydrochloric acid and hydrogen peroxide mixed solution was studied. The effects of initial mass concentration of hydrochloric acid, hydrogen peroxide dosage, ratio of liquid volume to solid mass, leaching temperature and time on the leaching rates of copper, iron and lead were investigated. The results show that under the optimum conditions of hydrochloric acid mass concentration of 150 g/L, hydrogen peroxide to lead matte mass ratio of 3∶1, liquid volume to solid mass ratio of 9∶1, leaching temperature of 50 ℃ and leaching time of 2 h, the leaching rates of Cu, Fe and Pb can reach 90.21%, 33.49%, 31.19%, respectively, and Au and Ag are enriched in the resiclue. Efficient separation from copper is achieved.

For the raw material of quartzite-type quartz ore in Gansu Province, the pretreatment process of “magnetic separation-flotation-roasting and water quenching” was adopted, and then the purification process was carried out by atmospheric pressure acid leaching. The effects of leaching agent type, leaching temperature, liquid volume to solid mass ratio and leaching time on the impurity removal rate of quartz sand were investigated. The research results show that in the mixed acid system of 2 mol/L HF+2 mol/L HCl+2 mol/L HNO₃, under the conditions of leaching temperature of 80 ℃, liquid volume to solid mass ratio of 3 mL/1 g, and leaching time of 7 h, the purity of SiO₂ in the product can be increased from 99.80% of the raw ore to 99.98% and the total impurity removal rate can reach 90%. The results of leaching kinetics analysis indicate that the leaching processes of Al and Fe are controlled by internal diffusion, with apparent activation energies of 7.2 and 21.1 kJ/mol, respectively. The method can provide a certain technology reference for the preparation of high-purity quartz from quartzite-type quartz ore.

The selective separation of manganese and cobalt from the leaching solution of spent ternary lithium batteries by nickel saponification extraction was studied. The effects of extraction agent concentration, pH, phase ratio, saponification rate, and acid concentration on the extraction and stripping performance were systematically investigated. The results show that after adjusting the pH to 4.8 with Ni(OH)₂ and significantly reducing the contents of Fe, Al, and Cu, nickel saponification P204 can achieve efficient extraction of manganese under two-stage cross-flow conditions, with an extraction rate exceeding 99%. Meanwhile, the co-extraction rates of cobalt and lithium are controlled at 18.67% and 9.89%, respectively. After low-acidity washing and sulfuric acid stripping, the stripping rate of manganese reaches 99.96%. Further, nickel saponification P507 is used for two-stage cross-flow extraction of cobalt, achieving a cobalt extraction rate of 99.92% and a co-extraction rate of lithium of 13.68%. After washing and stripping, the stripping rate of cobalt can reach 99.87%. The process significantly reduces the introduction of Na⁺ impurities while achieving efficient separation of manganese and cobalt, leaving nickel and lithium in the system. It provides experimental technical references for the high-purity recovery of multi-metal resources and has potential for further industrial application.

To address the difficulty of separating copper and cobalt coexisting in the leaching solution of low-grade sulfide concentrates after roasting, a combined process of synergistic extraction-stripping-chemical precipitation was investigated to recover copper and cobalt. The results show that using P204+P507 as the extractant achieves copper extraction rate of 99.31% under the conditions of original station pH = 3, V_o∶V_a = 1∶1, and reaction time of 10 min. When N235 + C272 was used as the extractant at copper extract residue pH=4, V_o∶V_a = 2∶1 and reaction time of 10 min, the cobalt extraction rate reaches 99.63%. Using 0.2 mol/L H₂SO₄ as the stripping agent results in stripping efficiencies of 99.65% for copper and 98.65% for cobalt. With NaOH and Na₂CO₃ as precipitants, Cu(OH)₂ with a purity of 99.90% and CoCO₃ with a purity of 99.99% are obtained. The combined separation process can achieve efficient separation of copper and cobalt and produce high-purity products, providing a feasible technical approach for the comprehensive utilization of low-grade sulfur concentrate resources and having certain significance in alleviating the shortage of copper and cobalt resources in China.

Aluminum ammonium reaction cooling crystallization technology was studied to extract aluminum from purification slag of typical ion-type rare earth ore and prepare ammonium alum. The effects of ammonium sulfate dosage, reaction temperature, reaction time, and cooling crystallization temperature on the aluminum crystallization rate were investigated. The results show that under the conditions of molar ratio of ammonium to aluminum of 1.3/1, mass concentration of ammonium sulfate solution of 760 g/L, reaction temperature of 60 ℃, reaction time of 120 min, and cooling temperature of 5 ℃, the aluminum crystallization rate is 94.8%, and the obtained ammonium alum product meets the national standard. The process can effectively achieve the efficient extraction and recovery of aluminum elements from the impurity slag, and has good economic benefits.

Preparation of sulfonic acid-based functionalized biochar (PPBC) by modifying discarded pomelo peels through low-temperature sulfonation method and its application in adsorbing iron ions from high-concentration sulfuric acid solutions was investigated. The effects of adsorption time, temperature, stirring speed, initial mass concentration of iron ions and acidity on the adsorption performance of PPBC were examined, and the adsorption and separation mechanism as well as the recycling and regeneration performance were discussed. The results show that under the optimized conditions of sulfuric acid concentration of 0.1 mol/L, temperature of 55 ℃, stirring speed of 200 r/min, initial mass concentration of iron of 1 000 mg/L, and adsorption time of 120 min, the adsorption rate of PPBC for iron ions reaches 98.2%, and the adsorption capacity is 98.2 mg/g. When the initial mass concentration of iron ions is 5 000 mg/L, the adsorption capacity of PPBC for iron ions reaches a maximum of 324.6 mg/g. The adsorption behavior conforms to the Langmuir isothermal adsorption model and the pseudo-second-order kinetic model, and belongs to monolayer chemical adsorption. After five adsorption-desorption cycles, the regeneration rate of PPBC remains at 87.8%. PPBC has excellent structural stability and reusability, which can provide technical references for the treatment of high-acid and high-iron wastewater and the high-value utilization of agricultural waste.

To enhance the reaction rate of V₂O₃ preparation by hydrogen reduction from V-rich solution, Raney Ni was synthesized by selectively leaching aluminum from a Ni-Al alloy using an alkaline leaching method. This Raney Ni was employed as a catalyst to reduce the activation energy for the hydrogen reduction vanadium precipitation reaction. Characterization results from XRD, SEM, and BET indicate that the leaching of aluminum creates numerous pores and fissures, significantly increasing the specific surface area of the Raney Ni and providing abundant active sites for the hydrogen reduction vanadium precipitation reaction. Under the optimal conditions of Raney Ni dosage of 10 g/L, hydrogen partial pressure of 3 MPa, reaction temperature of 250 ℃, solution pH of 5, and reaction time of 100 min, the vanadium precipitation rate reaches 99.84%. The Raney Ni demonstrates excellent cycling stability, after magnetic separation and five reuse cycles, the purity of the obtained V₂O₃ product remains stable at 99.27%. The apparent activation energy for the Raney Ni-catalyzed hydrogen reduction reaction is determined to be 96.254 4 kJ/mol, indicating that the hydrogen reduction process is primarily controlled by chemical reaction. Raney Ni catalyst exhibits effective vanadium precipitation performance, ease of magnetic separation, and high stability. The V₂O₃ product prepared by catalyzed hydrogen reduction with it have high purity, and certain potential for promotion and application.

The leaching of arsenic with air oxidation method in an alkaline system was studied. Based on the results of thermodynamic analysis, the influence of different factors on the leaching process was investigated. The leaching residue was characterized by XRD and SEM, and the leaching kinetics was discussed. The results show that under the optimized conditions of initial NaOH concentration of 2 mol/L, leaching temperature of 60 ℃, liquid volume to solid mass ratio of 10 mL/1 g, and leaching time of 168 h, the arsenic leaching rate reaches 91.9%. The leaching rate of As is jointly controlled by diffusion and chemical reactions, with apparent activation energy of 83.41 kJ/mol. The method can achieve the purpose of arsenic removal under normal pressure in an alkaline system and has certain value for promotion and application.

Dealkalization of vanadium extraction tailings using calcium oxide was investigated. The effects of calcium oxide dosage, reaction temperature, reaction time, liquid volume to solid mass ratio, and stirring speed on the dealkalization rate were investigated, and the removal behavior of major metals during the dealkalization process was explored. The results indicate that under the optimal conditions of calcium oxide dosage of 19%, reaction temperature of 200 ℃, reaction time of 60 min, liquid volume to solid mass ratio of 2∶1, and stirring speed of 800 r/min, the dealkalization rate of the tailings reaches about 85%, with the Na₂O content in the residue reduces to less than 0.6%. Meanwhile, the process ensures relatively low removal rates for vanadium and chromium. The findings of the study can serve as a technical reference for the comprehensive resource utilization of vanadium extraction tailings.