The sparation and recovery of tin, zinc and cadmium from tin smelting dust by sulfuric acid leaching—removing arsenic with oxidation hydrolysis—replacing cadmium with zinc powder were studied. And the effects of various factors on the sparation and recovery were investigated. The results show that the leaching rates of Zn and Cd are 93.25% and 89.35%, respectively, and the leaching rates of Sn are less than 0. 1% under the conditions of initial sulfuric acid concentration of 15%, liquid volume to solid mass ratio of 3∶1, leaching time of 120 min and leaching temperature of 90 ℃. When the amount of hydrogen peroxide is 2% and the control end point pH is 5, the mass concentration of As in the leaching solution can decrease to 0.1 mg/L after arsenic removal. Under the conditions of reaction temperature of 60 ℃, dosage of zinc powder 1.0 times of the theoretical amount, stirring speed of 250 r/min and reaction time of 30 min, sponge cadmium with cadmium content above 95% is obtained. The process can realize efficient recovery and utilization of valuable metals in tin smelting dust.

The recovery of As from copper anode slime by chlorination leaching—NaH₂PO₂ selective reduction process was studied. The effects of liquid volume to solid mass ratio, initial acidity, leaching temperature, initial Cl^- mass concentration and leaching time on the leaching rate of As. The effects of reduction temperature, molar ratio of NaH₂PO₂ to As and reduction time on the precipitation rate of As were investigated. The results show that the optimum chlorination leaching conditions are initial acidity of 220 g/L, liquid volume to solid mass ratio of 6/1, leaching temperature of 70 ℃, initial Cl^- mass concentration of 150 g/L and leaching time of 2.5 h. The optimum reduction conditions are reduction temperature of 80 ℃, molar ratio of NaH₂PO₂ to As of 2/1, reduction time of 2 h. Under the optimal conditions the average mass fraction of As is 90.44%, and the product quality can meet the refining requirements of elemental arsenic.

Aiming at the problems such as low settling speed and poor solid-liquid separation effect of a uranium ore high-calcium slurry, static flocculation method was used to settle high-calcium pulp of a uranium ore, and the effects of flocculant type, dosage, mixed flocculant ratio and adding method on the settling effect were investigated. The results show that the settling rate of high calcium pulp can be significantly increased by the mixed flocculant prepared by WZ944 flocculant and 5330 flocculant. The optimal mass ratio of the two flocculants is 1∶1, and the minimum dosage of the mixed flocculant is 35 g/t. The research results can provide reference for the optimization design of the uranium ore solid-liquid separation process.

The preparation of spherical-like battery-grade ferric phosphate by co-precipitation—spray-drying method was investigated using ferrous sulfate heptahydrate (FeSO₄·7H₂O) and ammonium dihydrogen phosphate (NH₄H₂PO₄) as raw materials. The effects of the addition of the surfactant cetyltrimethyl ammonium bromide (CTAB), reaction time, and solution pH on the physical phase and particle size of ferric phosphate were examined. The products were characterized by a laser particle sizer, X-ray powder diffractometer, thermogravimetric analyzer, and field emission scanning electron microscope. The results indicate that under the conditions of a Fe/P molar ratio of 1/1.01, CTAB addition of 0.04 g, reaction time of 1 h, and solution pH of 3.0, the ferric phosphate exhibits the smallest particle size distribution, ranging from 300 to 500 nm, and displays more uniform spherical morphology. Moreover, lithium iron phosphate is prepared by ball milling, mixing and sintering, using the spherical-like ferric phosphate as the precursor iron source. The specific discharge capacity of lithium iron phosphate is150.14 mAh/g at 0.1 C, and the retention rate is 98.9% after 200 cycles at 1 C, the performance is good.

The multi-stage leaching of chromite in HCl-Na₂CrO₄ system has been studied, and the leaching kinetics of main metal elements in chromite has been discussed. The results show that under the optimal conditions of particle size of 45~75 μm, oxidizing agent Na₂CrO₄ dosage of 0.6 times of theoretical dosage, reaction time of 5 h, reaction temperature of 453.15 K, ball to material mass ratio of 1/1, stirring speed of 30 r/min, liquid volume to solid mass ratio of 4 mL/1 g, the three-stage cyclic leaching is carried out, the leaching rates of Cr, Fe, Al and Mg can reach 91.98%, 94.54%, 76.62% and 78.03%, respectively. The acid leaching reaction of chromite is controlled by interfacial chemical reaction. The apparent activation energies of Cr, Fe, Al and Mg are 45.80, 40.43, 42.08 and 43.54 kJ/mol, respectively. In the range of 373.15~473.15 K, and the leaching effect is good.

The electron layer structure and physical chemical properties of rare earth elements are very similar, rare earths are difficult to separaterare. Therefore, the extraction of rare earth is always research hot issue in rare earth metallurgy. A new emulsion extractant was prepared with 6%D2EHPA as the flow carrier, 5%T154 as the surfactant, 3.0 mol/L HCl solution as the inner water phase, sulfonated kerosene as the membrane solvent and control R_oi of 1.5. By using the emulsion extractor to extract La³⁺, Ce³⁺, Sm³⁺, Eu³⁺, Ho³⁺ and Er³⁺ in sulfuric acid system, the optimal kinetic conditions for the extraction of RE(Ⅲ) by emulsion film method (ELM) were determined. The results show that under optimal kinetic conditions of emulsification time of 5 min, extraction time of 6 min, emulsion to water ratio (R_ew) of 0.5, extraction temperature of 25 ℃, the outer water phase is rare earth element aqueous solution. the highest extraction rate of La³⁺ is 99.92%, the maximum enrichment ratio is 3.33, and the mass transfer rate k=9.35×10^-10 m/s. The ELM shows excellent extraction performance and enrichment effect for low concentration La³⁺ solution.

In view of the complex structure, difficult flotation and difficult leaching of low-grade mixed tungsten and molybdenum ore of a domestic company, the synergistic leaching of molybdenum and tungsten from molybdenum tungsten ore by hydrochloric acid pretreatment—pyrolusite+sulfuric acid was studied. The effects of various factors on the leaching rate of tungsten and molybdenum were investigated. The results show that under the conditions of hydrochloric acid concentration of 1.5 mol/L, liquid volume to solid mass ratio of 6.5/1 and atmospheric pressure, the tungsten and molybdenum ores are pretreated with hydrochloric acid. Under the optimal conditions of filter slag of 20 g, particle size of 200 mesh, pyrolusite dosage of 4 g, sulfuric acid of 8 mol/L, liquid volume to solid mass ratio of 5/1, temperature of 90 ℃ and leaching time of 3 h, the leaching rates of molybdenum and tungsten are 83% and 73%, respectively.

Leaching of uranium, thorium and rare earth from the monazite selective solution residue were studied by conventional leaching—two-stage countercurrent leaching was studied. The effects of various factors on the leaching was investigated. The results show that the leaching rates of uranium, thorium and rare earth are 98.66%, 95.37% and 64.23%, respectively under suitable conditions using conventional leaching method. Using the two-stage countercurrent leaching method, the leaching rates of uranium, thorium and rare earth can be increased by 0.5%~1.0%, the residual acid of the leaching solution can be reduced by more than 50%, and the solid-liquid separation performance of the slurry can be improved to a certain extent.

Magnetic mesoporous carbon(MMC) and hydroxyapatite(HAP) composite materials with different mass ratios were prepared by co-precipitation method(MMC@HAP-x x=1, 4, and 6), and used for the removal of radioactive U(Ⅵ) in aqueous solution. The structure, functional groups and surface potential of the MMC, HAP and MMC@HAP-x were characterized by XRD, FT-IR, Zeta. The kinetics, thermodynamics, and the mechanism of MMC@HAP-x adsorption of U(Ⅳ) by the aforementioned materials were systematically studied. The results show that the optimal pH of MMC@HAP-x for U(Ⅵ) is 4.0, and the time required to reach adsorption equilibrium is less than 10 min. The theoretical saturated adsorption capacity of MMC@HAP-6 is 1 164.62 mg/g, and the adsorption process is a spontaneous chemisorption process. The fixation of U(Ⅵ) in MMC@HAP-x is due to the interaction between HAP and $\mathrm{UO}_{2}^{2+}$ to form Ca(UO₂)₂(PO₄)₂·3H₂O. MMC@HAP-6 is a fast uranium adsorbent with the potential to be used for the removal of uranium from radioactive wastewater.

Polyaniline (PANI) coated iron tetroxide was used to prepare of Fe₃O₄@PANI magnetic adsorption material for the adsorption of iodine in water. The morphology and properties of the composite before and after adsorption were characterized by SEM, TEM, FT-IR, XRD, VSM, XPS and Raman, and the adsorption mechanism of the composite was explored. The effects of adsorption time, iodine solution concentration, adsorption temperature and regeneration on the adsorption properties were also investigated. The results show that iodine is bound to benzene ring, quinone ring and nitrogen atom of quinone ring structure unit of polyaniline when coated with ferric tetroxide adsorbed I₂. The adsorption process of I₂ by Fe₃O₄@PANI is endothermic and spontaneous, which accords with the quasi-second-order kinetic model and the Langmuir isothermal adsorption model. At 303.15 K, the theoretical maximum adsorption capacity is 1 777.13 mg/g. After the adsorbent is desorbed with ethanol and recycled for 3 times, the adsorption rate reached 44.22% of the first adsorption rate.