Arsenic removal from pyrite cinders in Na₂S-NaOH solution with parameters optimized using the response surface methodology

Pyrite cinder is one of the important secondary resources; however, the arsenic typically contained in pyrite cinder is harmful to metallurgical process. The removal of arsenic can improve the value of pyrite cinders. Thus, a pretreatment method for removal of arsenic from pyrite cinders using a Na₂S-NaOH solution was investigated in this paper. A single factor experiment was conducted to determine the appropriate concentration ranges of NaOH and Na₂S, and then the response surface methodology (RSM) was used to optimize the leaching parameters. The results indicate that the optimized RSM model is reliable. The temperature, NaOH concentration, and Na₂S concentration have significant effects on the arsenic removal. The higher temperature is found to be favorable to the leaching of arsenic, and a significant interaction is found between the concentrations of NaOH and Na₂S. The content of arsenic in the leaching slag can be reduced to 0.08% at 80℃ when the concentration of NaOH and Na₂S is 0.34 and 0.12 mol·L^-1, respectively.