Removal of Zn and Pb from Fe2O3-ZnFe2O4-ZnO-PbO mixture by selective chlorination and evaporation reactions

Selective chlorination and evaporation reactions could become one of the useful methods for the treatment of steelmaking dust containing zinc and lead. In the present study, chlorination rate of Fe2O3-ZnFe2O4-ZnO-PbO mixture with Ar-Cl-2-O-2 gas (P-Cl2 = 0.5 X 10(4) to 2.0 X 10(4) Pa, P-O2 = 1.0 X 10(4) to 5.1 X 10(4) Pa) has been measured at 1073 K by gravimetry and the effects of partial pressures of chlorine and oxygen on the chlorination and evaporation rates have been investigated. Zinc oxide and lead oxide contained in the oxide mixture were selectively chlorinated and zinc and lead chlorides evaporated to gas phase, while iron oxide remained as oxide in a chlorinated residue. By chlorinating with Ar-Cl-2 gas, over 99% of zinc and lead could be removed from oxide mixture and approximately 3% of iron has been lost by chlorination and evaporation reactions simultaneously. To decrease the loss of iron oxide and improve the efficiency of selective chlorination and evaporation reactions, chlorination by using Ar-Cl-2-O-2 gas has been conducted and the enrichment of oxygen gas effectively depressed the chlorination of iron oxide, while the removal efficiency of zinc and lead was maintained.