New Process Of Recovering Valuable Metal From Low-grade Zn With High-grade Cd Slag And The Study Of Reaction Kinetics Model

The recovery and reutilization of the solid waste is the most interesting issue of the environmental protection nowadays. According to the present condition of the mass slag, which is produced from the factory of smelting zinc hydrometallurgically and has not handled because of the limit of the fund and technology. With the ever-depleting supply of valuable elements, the task of comprehensively recovering them from the slag becomes significant. It is very important not only in the reutilization of resources and environmental protection, but also in the economic effect of the enterprise.Based on the present situation of recovery and reutilization of the low-grade Zn with high-grade Cd slag, laboratorial-scale experiments about new technology have been studied systematically in this paper. The slag used in the experiment contains 15.92%Zn, 25.04%Cd, 12.18%Cu, 0.34%Fe, 0.29%Mn. The purpose of the present study is to make use of these characteristics to probe a new hydrometallurgical approach to recover and utilize multiple elements in copper-bearing cadmium slag.A study on the reaction kinetics of leaching slag comprehensively was carried out. The effects of acidity, solid/liquid ratio, reaction temperature, leaching time on the comprehensive leaching rate were determined. According to experiment, the optimum conditions obtained are as follows: acidity=10%, temperature=80 , S/L ratio=l:5, time=300min. Under the optimum conditions, the comprehensive leaching rate is more than 89%. The leaching reaction is a typicaloxido-reduction, and the results show that the leaching process can be simulated with a shrinking core model. The comprehensive leaching rate is controlled by the diffusion of reacting reagents in a porous solid layer.An empirical equation for the leaching reaction kinetics is established,which expressed by the equation of . It provides thetheoretical basis for the process of leaching low-grade Zn bearing high-grade Cd slag with high performance and low consumption. The activation energy calculated according to the Arrhenius equation is 8.193 kJ/mol.Several current processes of cementating Cd and Cu, and removing Fe and Mn ion in leaching solution are described in this paper. The effects of PH value of leaching solution, reaction temperature and time, zinc powder, the stirring speed, and others on the cementation or remove rate is analyzed and discussed in detail in this one. Under the optimum conditions, the Cd-cementation rate is more than 99.98%, the Cu- cementation rate is above 99.99%, and the Fe-removal rate is more than 90%.According to the gradual finization of current zinc and cadmium product, this paper is focused on the trend of the zinc and cadmium fine chemical engineering product with high additional worth. It puts one's figure on the orientation of the next stage.