Optimizing the Cementation Process of Leach Solution of Cold Purification Cake: Maximum Removal of Cadmium and Minimum Removal of Nickel

The primary purpose of this article is to prepare the solution obtained from leaching Ni–Cd cake for the extraction of nickel solvent with high purity. Due to the high cadmium concentration in the leach solution, cadmium acts as a disturbing ion in the solvent extraction process and reduces the efficiency of nickel extraction. Therefore, to increase the extraction efficiency, it is necessary to prepare the leach solution. Thus, this article aims to determine the maximum removal of cadmium and minimum nickel to prepare solvent extraction unit feed. First, the parameters affecting the cementation process were determined. The design of the experiment was done with the help of Design-Expert software. By studying the statistical analysis of the software, the importance of influencing the parameters of the objective function becomes clearer. The results showed that all selected parameters positively affect the nickel cementation process. In contrast, time, pH_i, and the amount of zinc powder significantly affect cadmium removal. In conclusion, after examining and comparing the four conditions in the Optimization section of the Design-Expert software, the optimal conditions were determined to be a temperature of 56 °C, a time of 10 min, a pH_i of 3, a stirrer speed of 520 rpm, a zinc powder amount of 1.95 times the molar stoichiometry, and a zinc powder particle size of 60 mesh. Also, the optimal removal rates of cadmium and nickel were predicted as 98.5 and 6.87%, respectively.