Removal of Cadmium in Process of Nickel Production Out of Cold Purification Waste of Zinc Factories

One of the most crucial production wastes of zinc factories is the cold purification cake, which can be used as feed for nickel production factories. The cake contains metals such as Zn, Cd, and Ni with a high percentage. In separating nickel from the cold purification cake, the high concentration of cadmium in the cake causes a reduction in the efficiency of nickel extraction. Therefore, removing or reducing the cadmium concentration from the leach solution is necessary before extracting the nickel from the solution resulting from the leaching cake. One of the conventional methods in the cadmium removal process is the cementation method. Among the disadvantages of the cementation method, we can mention the removal of other cations in the solution, such as Ni²⁺. Therefore, the main goal of this research is to optimize the cadmium cementation process so that the lowest amount of Ni²⁺ is cemented. This research investigated the parameters influencing nickel and cadmium cementation, including temperature, reaction time, pHi, stirring rate, the amount of zinc powder consumed, and the granulation of zinc powder. The results indicated that the optimal temperature value, reaction time, pHi, and stirring rate are 45 °C, 2 and 5 min, and rpm 250, respectively. Another significant result in this research was the effect of granulation and the amount of zinc powder on the removal percentage. The results indicated that the highest removal percentage for cadmium and the lowest one for nickel occurred in particle size 250 µ. In addition, if the amount of zinc powder used is 1.5 times the stoichiometric value, then the optimal removal of cadmium and nickel will be achieved.

Making an investigation into the effect of parameters influential on the cadmium cementation process and provision of optimal conditions. Determining the appropriate conditions to remove the maximum amount of cadmium against the lowest amount of nickel from the leach solution. Trying for the cementation process of zinc powder to be schematic and performing detailed analyses of cemented materials on the powder to describe the cementation process.