Reduction kinetics of SnO2 and ZnO in the tin, zinc-bearing iron ore pellet under a 20%CO–80%CO2 atmosphere

• Reduction kinetics of SnO2 and ZnO in the tin, zinc-bearing pellet is studied.
• Reduction of SnO2 is controlled by interfacial chemical reaction at 950 °C–1000 °C.
• Reduction of SnO2 belongs to hybrid control model at 1050 °C–1100 °C.
• Reduction of ZnO is controlled by interfacial chemical reaction at 950 °C–1100 °C.

A novel selective reduction roasting process has been successfully developed for utilizing the complex tin, zinc-bearing iron concentrates by the authors' group. In this study, the isothermal reduction kinetics of SnO2 and ZnO in the preheated iron ore pellet containing tin and zinc was investigated in a 20%CO–80%CO2 gas mixture at temperatures of 950 °C, 1000 °C, 1050 °C and 1100 °C. It was found that the reduction reaction of SnO2 → SnO (g) was controlled by interfacial chemical reaction at 950 °C and 1000 °C, whereas it was controlled by combination of chemical reaction and gas internal diffusion at 1050 °C and 1100 °C. As for the reduction reaction of ZnO → Zn (g), it was always controlled by the interfacial chemical reaction at temperatures of 950 °C–1100 °C.