Optimization of the hybrid pyro-hydrometallurgical sulfation roasting method to recover selenium from copper anode slimes

Copper anode slimes are a byproduct of electrolytic copper refineries which usually contains many valuable elements such as Au, Ag, PGMs (platinum-group metals), Cu, Se, Pb, As and Sb. Anode silmes is generally considered as the main source of the world’s selenium and one of the important sources for the extraction of precious metals. Several methods have been used for processing and recovery of selenium from anode slimes. One of the prevalent industrial methods is sulfation roasting. In this research, the sulfation roasting method was optimized to recover selenium from copper anode slimes that is able to minimize the environmental pollutions and energy consumption. D-optimal design based on response surface methodology was used for modeling of the roasting stage. The effect of the two parameters of liquid to solid ratio and temperature on the roasting process was investigated. The selenium recovery was optimized and at the optimum condition of L/S of 1.9 mL/g and temperature of 247.3 °C, Se recovery was found to be 99.99 %. The head sample of the copper anode slimes was characterized by x-ray diffraction (XRD), x-ray fluorescence (XRF) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The selenium purity was determined to be 97.08 % by ICP.