Chlorination Behaviors of Zinc Phases by Calcium Chloride in High Temperature Oxidizing-chloridizing Roasting

Abstract

The high temperature oxidizing-chloridizing roasting is one of useful methods to separate nonferrous metals from pyrite cinder and metallurgy slag. However, as one kind of main nonferrous metals in pyrite cinder and metallurgy slag, the occurrence of zinc is complicated and its chlorination behavior is not demonstrated. In the present study, chlorination behaviors of ZnO, ZnS and ZnFe₂O₄ at the temperature range of 1025–1175°C in air by simulating the chloridizing roasting process of pyrite cinder and metallurgy slag have been investigated. It is shown that ZnS and ZnO is much easier to remove, ZnFe₂O₄ is refractory to remove because of the presence of gangues. If enough chloride additives were added, the differences of Zn removal rate among ZnS, ZnO and ZnFe₂O₄ would disappear. In addition, the presence of Al₂O₃, SiO₂, CaO and MgO decreases the Zn removal rate from ZnFe₂O₄, and the presence of Al₂O₃ and MgO decreases the Zn removal rate from ZnO while the presence of SiO₂ and CaO improves the Zn removal rate from ZnO. Fe₃O₄ influences the Zn removal rate from ZnO and ZnFe₂O₄ positively.