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.

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.

The change of iron grade in the leaching residue and the leaching kinetics under normal pressure and pressure were examined. The pressure leaching of nickel and cobalt from a high iron and low grade laterite nickel ore in Indonesia with sulfuric acid was studied. The results show that under the conditions of acid/ore ratio of 260 kg/t, leaching temperature of 250 ℃ (corresponding to water vapor pressure of 4.0 MPa), liquid volume/solid mass ratio of 3/1, stirring speed of 300 r/min, particle size of 100 mesh and reaction time of 1 h, the leaching rates of nickel, cobalt and iron are 98.1%, 98.3% and 4.7%, respectively, and the iron grade can reach 51.3%. The leaching processes of nickel and cobalt under pressure and atmospheric pressure are in line with the shrinkage kernel model of interfacial chemical reaction control, and the activation energies of the reactions are 116 kJ/mol and 91 kJ/mol under pressure, respectively, and the activation energies of the reaction under atmospheric pressure are 41 kJ/mol and 53 kJ/mol, respectively. The leaching is mainly goethite under normal pressure, and chromite, magnetite and other mineral phases under high pressure.

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.

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.

In order to promote the recovery and utilization of valuable resources in steel slag, the leaching behavior of each element in converter steel slag in mixed acid (citric acid+nitric acid) system was studied. The effects of mixed acid concentration, reaction time, reaction temperature, liquid volume to solid mass ratio, and slag particle size on the leaching rate of each valuable element were examined. The results show that acid concentration, reaction time, liquid volume to solid mass ratio, and slag particle size have significant impact on the leaching rate of calcium, magnesium, iron, manganese and phosphorus. The reaction temperature has little effect on the leaching rate of each element. Under the conditions of steel slag particle size of 65 μm, leaching temperature of 298 K, leaching time of 30 min, liquid volume to solid mass ratio of 300∶1 and stirring speed of 800 r/min, the leaching rate of phosphorus is 88.15% with 0.01 mol/L nitric acid and 20.8 mmol/L citric acid. And effective leaching of phosphorus is obtained.

Gallium, indium, cadmium, selenium, tellurium, germanium, thallium and other rare disperse elements are often present in copper deposits, and accurate analysis of these elements is beneficial to comprehensive utilization of minerals. The determination of Ga, Ge, In, Tl, Se, Te and Cd in copper ore by microwave digestion and inductively coupled plasma mass spectrometry was established. The symmetric sample size, acid system, ethanol concentration, microwave digestion work conditions and mass spectrum interference were optimized. The results show that under optimized conditions, the linear correlation coefficient of the calibration curve is greater than 0.999 5, and the detection limit is 0.002~0.19 μg/g. The relative standard deviations (RSD, n=6) are 2.63%~13.84%, and the standard recoveries are 90.4%~110.6%. The method is accurate and reliable, and the results are consistent with the standard method.