| In recent years, the demanding of cobalt and selenium is increasing dramatically with its wide applications. However, the resources of cobalt and selenium are relatively scarce in China, so how to increase the recovery of cobalt and selenium from complex secondary materials becomes imperative. Hydrometallurgical processes which are the main technologies of recovery of cobalt and selenium have many advantages including excellent selectivity, low energy consumption and so on; Meanwhile, the accurate and reliable object controlling model in hydrometallurgical process is established for practical production simulation and optimization control while its comparison of input and output, parameters calculation of model and the final composition are all difficult to predict. Based on the analysis of cobalt and selenium metallurgical residue properties and characteristics, combination of thermodynamics analysis, kinetic analysis and optimization design of experiment research in the hydrometallurgical processes, the quality of value element allocation model of hydrometallurgical technological process of cobalt and selenium metallurgical residue was proposed, meanwhile the flow analysis of the value element in the technological process was analyzed which provide the theoretical and technological basis for the industrial processing of cobalt and selenium metallurgical residue, the main conclusions are as follows:The fundamental thermodynamics analysis of cobalt metallurgical residue in the hydrometallurgical process was studied. The metal acidic leaching trend of cobalt metallurgy sluge were as follows: MnO>CoO>NiO>ZnO>Cd2O3>CuO>Fe2O3; Copper was preferentially removed by controling pH value and tempature of acidic leaching solution; In the process of oxidizing and hydrolysis precipitation(pH<4), by adding sodium persulfate in the purification solution after copper precipitation, iron was first oxidized, then manganese which could realize selective precipitation; The higher it increase temperature and pH value of solution after iron and manganese precipitation, the more beneficial to precipitation rate of cobalt it was.The thermodynamics analysis of selenium metallurgical residue show that the kerosene desulfurization temperature should achieve above sulfur melting point; The higher it increase temperature and pH value of oxidization acid leaching solution solution after kerosene desulfurization, the more beneficial to leaching rate of selenium it was. In the selenium reduction process, the greater the initial acidity of solution it had, the more beneficial to precipitation rate of selenium it was.The optimization conditions on treatment of cobalt and selenium metallurgical residue were studied. In the process of acid leaching, the leaching rates of cobalt, zinc, cadmium, nickel, copper, manganese, iron and lead are97.99%,91.79%,96.20%,87.31%,91.20%,89.19%,67.09%and0.14%, respectively.99.93%of copper was preferentially removed with Na2S. During the oxidizing and hydrolysis precipitation, iron and manganese residual amount of solution are about0.0005g/L and0.0018g/L respectively. In the process of cobalt oxidizing precipitation with Na2S2O8,99.81%of cobalt was precipitated. The phase of cobalt product is CoO(OH),which content of cobalt is45.56%. In the whole process, the direct yield recovery rate of copper, manganese, iron and cobalt were88.58%,89.09%,70.01%and93.58%, respectively.The experimental design for optimization of kerosene desulfurization process was done, and the results show that the rate of desulphurization was lager than97%. During the process of oxidization leaching, the leaching efficiencies of selenium and iron are97.76%and12.20%, respectively.99.7%of selenium was precipited with Na2SO3in the leaching solution. The phase of selenium product is Se, which content of selenium is99.63%. In the whole processes, the direct recoveries of surfur, iron and selenium are97.8%,92.84%and98.46%, respectively.The kinetics and its mechanism of leaching cobalt metallurgical residue in sulfur acid system were investigated, the results show that the leaching behavior of cobalt, zinc and copper which have high correlation between them fit well with the kinetic models of unreacted shrinking core reactions. The apparent activation energies for cobalt, zinc and copper extraction are11.69KJ/mol,6.69KJ/mol and5.98KJ/mol, respectively, which indicates that the leaching rate of cobalt, zinc and copper were controlled by diffusion through a porous product layer with chemical reaction rate order of0.74,0.41and0.74respectively and particle size rate order of-1.44,-1.04and-0.84respectively; The leaching kinetic equations of cobalt, zinc and copper are as follows:The kinetics of leaching desulfurization residue in sodium chlorate and sulfur acid system show that the leaching behavior of selenium fit well with the kinetic models of surface chemical reactions control, while iron was not affected. So selenium and iron have low correlation between them. The apparent activation energies for selenium extraction were39.50KJ/mol, which indicated that the leaching rate of selenium was controlled by surface chemical reactions with chemical reaction rate orders:n1of0.15, n2of0.95respectively and particle size rate order of-0.16; The leaching kinetic equation of selenium is as follows:The quality of value element allocation model of technological process of cobalt and selenium metallurgical residue was established based on the analysis of treatment process of cobalt and selenium metallurgical residue and material balance to determine the algorithms of model coefficient. The distribution of overall quality and overall allocation proportion of the prediction model can be quantitatively estimated technological process result. It shows that quality of value element allocation model of technological process can be used for industrial production. The flow analysis of the value element in the technological process of cobalt metallurgical residue are as follows:the single step process and direct yield recovery rate of copper, lead, manganese, iron and cobalt are99.93%and89.36%,99.95%and89.89%,99.69%and70.16%,99.98%and95.38%, which of lead are all both99.88%.The allocation proportion of lead, copper, manganese, iron and cobalt are99.88%,89.36%,89.85%,70.16%and95.38%, respectively. About95.66%of unrecovered zinc,93.35%of unrecovered cadmium,85.80%of unrecovered nickel are existed in the cobalt precipitated solution.The flow analysis of the value element in the technological process of selenium metallurgical residue are as follows:the single step process and direct yield recovery rate of iron and selenium are93.03%and92.78%,99.93%and98.05%, which of surfur are all both99.90%.The allocation proportion of iron, selenium and surfur are92.77%,98.06%and98.06%, respectively. The overall of figures, tables and inferences are153,61,303, respectively. |
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