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

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.