Recovery of zinc and lead from electric arc furnace dusts through the oxy – chlorination route

Abstract

Recycling of steel in electric arc furnaces generates a flue dust known as electric arc furnace dust (EAFD). EAFD contain appreciable amount of Fe, Zn, and Pb. It is also toxic due to the heavy metal content and fine particle size. Landfilling or waste disposal of EAFD is banned in many industrialized countries. Processing of EAFDs for recovery of valuable metals such as Zn and Pb could be beneficial to both resource and environmental conservation. This paper presents the lab scale results of an innovative approach of EAFD treatment method for selective recovery of Zn and Pb and producing a residue suitable for recycling in the iron and steel industry. Chlorination of different oxide constituents of EAFD such as ZnFe2O4 and Fe2O3, in their pure form, was studied between 600 - 1050 oC. The results suggest that, oxygen partial pressure has a significant effect on retarding the rate of chlorination/volatilization of iron. The results were extrapolated for treatment of EAFD. It was observed that, more than 99 % Zn and 97 % Pb could be recovered as volatile chlorides (in the condensates) at 800 oC, without having any iron impurity. The chlorination residue was found to contain 2.5 times more iron than the original EAFD. The iron present in the residue is mostly hematite, which could facilitate their recycling back in the iron and steel industry.