A gold grade prediction model was proposed by combining improved cloud models with improved RBF neural networks. Qualitative information was quantified using DS evidence theory and cloud models, and then quantum particle swarm optimization algorithm and RBF neural network were used to predict the gold grade in ores. The results indicate that the mean square error of this model is 0.009 2, the maximum error is 0.016 1, and the correlation coefficient is 0.940 2, the model can better preserve the qualitative information characteristics, the prediction effect of gold grade is good.

Aiming at the complexity of existing hydrometallurgical process mechanism and the poor accuracy of existing leaching process fault diagnosis methods, an improved dynamic causal diagram was studied to diagnose hydrometallurgical leaching process faults. The dynamic causal diagram was optimized and improved mainly by binary interval number, and the upper and lower limit of conditional probability were weighted to realize the fault diagnosis of hydrometallurgical leaching process. The results show that the fault diagnosis method is more accurate than the conventional method, and can diagnose the faults of leaching process more accurately.

In order to meet the accuracy and timeliness requirements of natural uranium trade reinspection, the working conditions for determining uranium in imported uranium trioxide by wavelength scattering X-ray fluorescence spectroscopy were optimized. Suitable digestion methods, digestion vessels, digestion time and temperature, mylar film, sample quality for determination, and other sample pre-treatment conditions were selected for optimization. The measuring conditions of X-ray tube voltage and current, spectroscopic crystal, wave crest and background angle(2θ), measure the time were determined. The precision, accuracy and reliability of the method were evaluated. The results show that the linear correlation coefficient of the working curve of the method is 0.999 6, and the relative standard deviation (RSD) is 0.029%~0.056%. The relative error between the measurement results and the recommended value of the reference material is ≤0.027%. Compared with the titration method, the absolute deviation of the method is 0.003%~0.093%, the results are accurate and reliable, and The efficiency is 5 times that of titration. The method can meet the requirements for rapid batch analysis of imported uranium trioxide samples.

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.

The influence of fluorine on the production wet-process phosphoric acid is described. The principle, application status, advantages and disadvantages of the main defluorination process of wet phosphoric acid are reviewed. The problems existing in the current defluorination process of wet phosphoric acid are pointed out, and the future development direction is put forward in order to provide reference for the comprehensive utilization of fluorine resources in wet phosphoric acid in our country.

The comprehensive recovery of copper and arsenic from black copper slime by oxidation leaching method was studied. The effects of acidity, hydrogen peroxide content, temperature, leaching time and liquid volume to solid mass ratio on the leaching rate of copper and arsenic were investigated. The results show that under the conditions of acidity of 200 g/L, hydrogen peroxide content of 30%, temperature of 80 ℃, leaching time of 2.0 h, liquid volume to solid mass ratio of 9∶1, the leaching rates of copper and arsenic can reach 99.53% and 98.24%, respectively. After oxidative acid leaching, sodium hydrosulfide is added into the solution at the rate of n(NaHS)/n(Cu)=1.1 to precipitate copper. The mass concentration of copper in the solution after copper and arsenic separation is lower than 0.01 g/L, and the mass concentration of arsenic is greater than 40 g/L. The copper and arsenic are effectively separated. Arsenic-rich liquid can be reduced with sulfur dioxide, and arsenic trioxide and reduced liquid can be returned to the oxidation leaching process.

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.

In order to realize the high value utilization of solid and liquid wastes, extraction of vanadium from vanadium tailings with titanium dioxide waste acid was studied. The effects of leaching temperature, leaching time, solid mass to liquid volume ratio, waste acid concentration and other technological parameters on vanadium leaching rate were investigated by orthogonal experiments, and the optimal leaching conditions were determined. In order to further improve the vanadium leaching rate, the appropriate amount of leaching aid (fluorite) and oxidant (hydrogen peroxide) was discussed. The results show that the order of influence of the process parameters on vanadium leaching rate is leaching temperature> leaching time> solid mass to liquid volume ratio> titanium dioxide waste acid concentration. Under the optimum conditions of temperature of 80 ℃, leaching time of 2 h, solid mass to liquid volume ratio of 1∶5 and waste acid concentration of 5%, the vanadium leaching rate is about 53%. After adding 7% fluorite and 5% hydrogen peroxide, the vanadium leaching rate can be increased to 71.09%.

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.

The leaching of manganese from electrolytic manganese residue with sulfuric acid was studied, and the process parameters were optimized by single factor test and orthogonal test. The phase, structure, morphology and leaching kinetics of electrolytic manganese residue before and after leaching were analyzed. The leaching model was established and the leaching mechanism was explored. The results show that under the optimal conditions of particle size of 200 mesh, stirring speed of 400 r/min, leaching temperature of 95 ℃, sulfuric acid concentration of 1.5 mol/L, leaching time of 120 min and liquid volume/solid mass ratio of 11/1, the leaching rate of Mn can reach 97.90%. Manganese leaching kinetics accords with the liquid-solid shrinkage model and is controlled by chemical reaction. In the process of manganese leaching, the leaching rate of Mn can be improved by controlling the liquid volume/solid mass ratio and temperature.