Thermodynamic analysis of the reduction of zinc ferrite with CO-CO2

Abstract

The reduction behavior of zinc ferrite, an important constituent of zinc-bearing metallurgical dust, with CO-CO2 gas was calculated and analyzed according to the thermodynamic principles. The reduction of ZnFe2O4 obeys a stepwise mechanism. ZnFe2O4 is easy to be reduced to ZnO and Fe3O4. ZnO is easier to be reduced than FeO, and a lower volume fraction of CO gas is needed to reduce ZnO at a higher temperature. If the reaction temperature increases from 1100 K to 1400 K, the reducing potential expressed by the volume fraction of CO decreases from 0.4 to 0.01. Aiming to the reduction and separation of metallic zinc from zincbearing dust, it is not necessary to reduce iron oxides to metallic iron, but Fe3O4 or FeO, while zinc oxide should be reduced to metallic zinc. In the upper of the blast furnace, zinc reduction and internal circulation occur and bring harms to blast furnace production, and therefore the zinc load of the blast furnace should be reduced and controlled strictly.

Keywords

• metallurgical dust
• zinc ferrite
• reduction
• thermodynamics