Pilot-scale dechlorination of CuCl residue from zinc hydrometallurgy by microwave roasting

Abstract

Most Zn hydrometallurgy factories adopt Cu2SO4 as a dechlorination reagent from zinc solution recently, thus much CuCl residue was produced. The present process of treating this residue is washing CuCl residue with water or sodium carbonate solution, which would bring a lot of trouble for water treatment and waste discharge. In this study, a method of roasting the residue with microwave energy is adopted for not only dechlorination of the CuCl residue and also recycle Cl therein as HCl. The pilot-scale equipment system includes a 20 KW microwave roasting equipment, a dust collection and a tail gas adsorption system. The experiments result shown that under following parameters of microwave roasting: 108 Kg CuCl residue with a grain size of -60 mesh, stirring speed at 10 r/min, roasting at 350°C for 4 h, the dechlorination rate is as high as 78.54 %, and a product of CuO with a Cl concentration of less than 3.7% can be obtained. What’s more, the tail gas was analyzed as air and HCl, which can be absorbed as byproduct of hydrochloride. The power consumption for treating such CuCl residue with microwave energy is only about 488.88kW • h/t.