Infiuence of temperature on the selective chlorination and evaporation reactions of zn and pb in EAF dust

Abstract

Large amount of dust is produced during ironmaking and steelmaking process and it should be recycled or treated for the sake of environmental protection. Particularly, the dust produced in electric arc furnace (EAF) process is quite special because of its abundance in Zn and Pb, which makes it inappropriate for recycling to the conventional steelmaking process. Chlorination and evaporation method is a possible choice to treat the dust, in which Zn and Pb are selectively chlorinated and recovered as gaseous chlorides while the chlorination of Fe can be prevented in its oxidizing atmosphere. In the present study, the feasibility of the selective chlorination and evaporation reaction of Zn and Pb in EAF dust was confirmed in the mixing atmosphere of Cl2 and O2 gas (PO2 = 9.0 × 104 Pa and PCl2 = 1.0 × 104 Pa). Change of oxide phase with reaction time was also analyzed by XRD measurement. The influence of temperature on the chlorination and evaporation reaction rate and removal fractions of Zn and Pb was investigated by gravimetric method and composition analyses at the temperature range from 923 K to 1073 K. The chlorination and evaporation rate increased with increasing temperature from 923 to 1073 K and the removal fractions of Zn and Pb after 60 min at 1023 or 1073 K reached approximately 98% and 99%, respectively. Simultaneously, it was confirmed that small portion of Fe was chlorinated and evaporated from the dust in the present experimental conditions.