Optimization of Copper Recovery and Fluorine Fixation from Spent Carbon Cathode Reduction Copper Slag by Response Surface Methodology

Spent cathode carbon (SCC) contains a considerable amount of soluble fluoride, which is classified as a hazardous emission. In this study, SCC is employed to reduce copper slag, facilitating the recovery of valuable metals, such as copper and iron, while simultaneously fixing soluble fluoride. The results reveal the substantial influences of these factors (temperature, reducing time, and CaO addition) on fluoride fixation, while the reduction temperature and time significantly affect copper recovery. The optimal results of model fitting are that the fluorine fixation is 75.6%, and the copper recovery is 97.2%. The actual fluorine fixation obtained is 75.1%, and the copper recovery is 96.2%, closely aligning with the predicted outcomes of the model. The toxic leaching test and SEM-EDS analysis show that F- is effectively immobilized in the form of stabilized CaF2, avoiding the potential hazard of fluorine.