The characteristics, industrial application status and research progress of hydrometallurgy for low grade laterite nickle ore by reduction roasting—normal pressure ammonia leaching and high-pressure acid leaching (HPAL), as well as the development of three generations of HPAL technology are summarized. The nickle-cobalt precipitation and enrichment technology and the application are introduced. The processes advantages and disadvantages of the H₂S precipitation, MgO precipitation, direct NaOH precipitation are analyzed. The effectiveness of new precipitation process with alkali conversion and crystal seed activation has been explored. The development prospect of laterite nickel hydrometallurgical process is also prospected.

With the rapid expansion of the scale of nuclear energy, the proper treatment of radioactive waste generated by the nuclear industry has become one of the most important issues for the further development of nuclear energy. Cyclodextrin, as a kind of cyclic oligosaccharide composed of several glucopyranose units, has a good prospect of application in the field of radioactive ions adsorption and separation, because of its special molecular structure of internal hydrophobicity and external hydrophilicity. However, due to the presence of a large number of hydroxyl groups in the cyclodextrin molecules, they are easily soluble in water. Generally, the solidification of cyclodextrins to insoluble solids is always needed before being used as adsorption materials. Depending on the different methods of "solidification", cyclodextrin based adsorbent materials can be divided into three types:loaded cyclodextrin materials, cyclodextrin polymer materials, and cyclodextrin inclusion complex materials. The synthesis and application research advances of the three types of cyclodextrin adsorbent materials in radioactive ion adsorption and separation are summarized, the related adsorption mechanisms are discussed. Besides, the perspectives of the cyclodextrin based adsorbents in the field of radioactive ion adsorption are presented.

Arsenic containing non-ferrous metal and precious metal sulfide ore will produce acidic high concentration arsenic solution in the smelting process, which has the characteristics of high arsenic concentration, complex composition, large changes, strong toxicity and difficult to store, such as direct discharge without treatment, will have a great impact on the environment and human health. In this paper, the principles, advantages and disadvantages of chemical precipitation method, evaporation enrichment method and metal powder method are reviewed, as well as the research progress of each method, so as to provide reference for the development of arsenic removal technology.

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.

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.

Manganese dioxide in pyrolusite was directly reduced to manganese sulfate by high-temperature roasting with ammonium sulfite as reducing agent, so as to achieve efficient extraction of pyrolusite. The effects of mass ratio of ammonium sulfite to pyrolusite, roasting temperature and time, leaching temperature and time on the extraction rate of manganese were investigated, and the optimum process conditions were determined. The results show that the optimal conditions are the mass ratio of ammonium sulfite to pyrolusite of 0.75∶1, roasting temperature of 500 ℃, roasting time of 1.5 h, leaching temperature of 25 ℃, leaching time of 30 min. Under the conditions, the leaching rate of manganese and iron is about 93% and about 9.5%, respectively. The extraction effect of manganese is good.

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 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.

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.

Combined extraction of nickel and cobalt from nickel chloride solution using di (2-ethylhexyl) phosphonic acid (P204) and triisooctylamine (N235) as extractants was studied. The effects of organic phase P204 volume fraction, phase ratio, solution pH, saponification rate, organic phase N235 volume fraction, Cl^- mass concentration, and reaction temperature on the purification and impurity removal of nickel chloride solution were investigated. The results show that after removing impurities by P204 extraction, N235 is used to extract cobalt and molybdenum from P204 raffinate, the mass concentrations of Ni²⁺ is 218.10 g/L, and the mass concentrations of Cu²⁺, Fe³⁺, Co²⁺, and Zn²⁺ in the residual solution 1.1, 1.2, 1.0 and 0.1 mg/L, respectively, under the conditions of 20% volume fraction of P204 in the organic phase of the P204 extraction and impurity removal process, V_O/V_A=1. 5/1, raw material solution pH=3.5, saponification rate of 50%, reaction temperature of 40~50 ℃, and N235 volume fraction of 16% in the organic phase of the N235 extraction process, V_O/V_A =1.2/1, Cl^- mass concentration≥280 g/L, reaction temperature of 40~50 ℃, P204 Raffinate pH=3.0, and hydrochloric acid acidification concentration of 3 mol/L, which can meet the requirements of producing high quality electrodeposited nickel cathodes.

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.

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 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.

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.

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 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.