Recycling Utilization of Zinc-Bearing Metallurgical Dust by Reductive Sintering: Reaction Behavior of Zinc Oxide

A process is being developed to recycle zinc-bearing metallurgical dust by reductive sintering. In the present work, the reaction behavior of zinc and iron oxides was studied in different conditions in CO–CO2 atmosphere, to understand the processes involved and determine the optimal conditions. The results showed that dezincification started to become significant when the coke addition was 9.0 wt.% of the amount of raw material, the corresponding CO content in the gases being 20 vol.%. Iron oxide played an important role in the reduction of ZnO: when the CO content was less than 20 vol.%, ZnO and Fe3O4 reacted to generate ZnFe2O4, CO2 being the oxidizer that promoted the conversion of Fe2+ to Fe3+. Increasing the temperature was also conducive to the generation of ZnFe2O4. The effect of iron oxide on the ZnO reduction gradually weakened when the CO content was increased above 20 vol.%. To realize reduction of ZnO and increase the removal rate of zinc, the atmosphere and temperature should be controlled in the thermodynamic stability region of FeO and Zn, where zinc vaporizes and is removed in elemental form.