In view of the problems that alkali to solanite concentrate turned red and acid soluble slurry thickened into foam during comprehensive recovery, which led to product discoloration and decreased production capacity, scanning electron microscopy (SEM) and infrared spectrum analysis were used to analyze the composition of ore pollutants, and the removal effect of calcination method on monazite concentrate contaminants were studied through condition test and pilot plant tests. The results show that the alkali transformation color is mainly caused by the organic matter containing carboxyl group, benzene ring or cycloalkane covering the monazite surface. Under the conditions of calcination temperature of 400 ℃ and calcination time of 40 min, the COD removal rate of alkali to pulp is greater than 94%, and the organic matter removal effect is good, which can solve the problem of 30% reduction in production and processing capacity, reduce power consumption and energy consumption, remove occupational health and other safety and environmental risks caused by fluting in production, and ensure the recovery rate of uranium and rare earth. This method improves the processing process of monazite and has a certain popularization value.

P204 was used to extract copper and cobalt from low concentration cobalt sulphide concentrate leaching solution. The effects of pH of extraction solution, extractor concentration, extraction ratio and time on the extraction efficiency were investigated. The results show that under the conditions of pH=4, P204 volume fraction of 25%, extraction ratio V_O/V_A=1/1, extraction time of 3 min, reverse extractant sulfuric acid concentration of 0.10 mol/L, and reverse extraction ratio V_O/V_A=2/1, the test of two-stage countercurrent extraction, four-stage countercurrent stripping is carried out on the purified liquid of cobalt sulfide concentrate, the mass concentration of cobalt and copper in the raffinate is 338.80 mg/L and 2.96 mg/L, the extraction rate of copper is 98.32%, and 90.03% of cobalt remains in the water phase. Copper and cobalt can be effectively further separated by stripping, which is conducive to preparation of high purity cobalt sulfate.

Aging of biochar can affect its stability and persistence of heavy metals immobilizing in soil, resulting in changes in its inertness. Using peanut shell (PS) as raw material, peanut shell biochar (PSB) was prepared by pyrolysis under the condition of 600 ℃ and hypoxia. Oxidized biochar (OPSB), leached biochar (LPSB) and acidified biochar (APSB) were prepared Y by simulated field oxidation, leaching and acidification of PSB. The effects of these three aging methods on the adsorption efficiency and mechanisms of Cd²⁺by the biochar were investigated using isothermal adsorption models, kinetic models, FT-IR and XRD. The results show that oxidative aging process an significantly enhance the accumulation of oxygen-containing functional groups (—COOH, —OH, etc.) on the surface of the biochar, thereby increasing the adsorption capacity of OPSB for Cd²⁺by 10.13%. Leaching aging process can not cause significant changes in functional group content but result in substantial loss of soluble minerals, leading to a significant decrease adsorption capacity of LPSB for Cd²⁺ by 13.35%. Acidification aging process can affect the adsorptive activity of Cd²⁺ on the surface of the biochar, resulting in a reduction in adsorption capacity of APSB for Cd²⁺ by 26.52%. All four types of biochar exhibite effective adsorption for Cd²⁺, the OPSB showing optimal affinity followed by PSB, LPSB, and APSB. The Langmuir isothermal adsorption model provides better fitting for describing the Cd²⁺adsorption process by all four types of biochars under low pH conditions. Furthermore, the adsorptions processes by all four types of biochars are predominantly governed by physical electrostatic interactions, which is suitable to be described by quasi-first-order kinetic model.

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.

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.

The determination of arsenic content in phosphorus pentoxide by atomic fluorescence spectroscopy method was studied, and the acid medium, acidity, reducing agent concentration, pre reducing agent, and masking agent were determined. The results indicate that the method has good linearity in the range of 1.0~50.0 μg/L, the correlation coefficient is r>0.999, the detection limit is 0.06 μg/L, quantification limit is 0.21 μg/L. The relative standard deviation (RSD) of the 8 sample analysis results is 1.94%, and the spiked recovery rate are 92.87%~101.30%. The test results show no significant difference from the DDTC silver salt method, and this method is a reliable method for detecting arsenic content in phosphorus pentoxide, because it is more convenient and less reagent used.

The adsorption—resolution process of H₂TiO₃ lithium sieves for lithium extraction from salt lake brine was investigated. The crystal shape and morphology of the screen before and after adsorption were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the surface of H₂TiO₃ lithium ion screen has good particle dispersion, loose pores and stable crystal structure after granulation, and the structure does not change significantly after recycling. In the continuous ion exchange system, the 30 columns are divided into 6∶1∶2∶1 according to the four steps of adsorption—washing material—desorption—acid washing, under the optimal conditions of the adsorption feed flow rate of 12 BV/h, the adsorption time of 3 h, the washing flow rate of 1 BV/h, the rinsing time of 30 min, the hydrochloric acid in the analytical process of 0.1 mol/L, analytical temperature of 30~40 ℃, the cyclic analytical time of 1 h, the acid washing flow rate of 8 BV/h, the washing rate of 30 min, the continuous operation of 30 cycles, the adsorption performance is stable, the adsorption capacity is about 6.67 mg/g, the adsorption rate is about 80%, and the Li-rich analytical liquid Li⁺ mass concentration is about 1.2 g/L, ρ(Li⁺)/ρ(Na⁺) is about 1. The method has a certain value of industrial popularization and application.

In order to solve the problem of high impurity in the preparation of beryllium hydroxide by BeSO₄ solution in the process of uranium extraction from high fluoride uranium-beryllium ore, the precipitation of crude beryllium hydroxide with high Fe and Al impurities was studied by resolubility hydrolysis method. The effects of precipitation method of crude Be(OH)₂, the amount of NaOH and resolubility temperature on the resolubility of crude Be(OH)₂ were investigated. The results show that Be and $\mathrm{SO}_{4}^{2-}$ can be separated efficiently by resolubility hydrolysis method, and the content of Fe and Al in the product can be greatly reduced. The high purity BeO products can be prepared by roasting the obtained high purity Be(OH)₂ which meets the industrial standard.