Kinetic investigation of synthetic zinc ferrite reduction by hydrogen

Abstract

Zinc ferrite is one of the main components present in the electric arc furnace dust. Furthermore, it is necessary to know the mechanisms involved on the zinc ferrite to determine a process for reusing the electric arc furnace dust. Thus, the aim of this paper is to evaluate the kinetic parameters of the reduction of synthetic zinc ferrite pellets by mixture containing hydrogen. The kinetic investigation was performed via Forced Stepwise Isothermal Analysis method in the temperature range of 500–950 °C. The reducing gas was a mixture of hydrogen (10%) and argon (90%). In addition, Thermo-cal software was used in order to support the reduction reaction behavior. The results indicated that between 550 and 750 °C only iron oxide was reduced. In this step, the nucleation was found to be the controlling mechanism, and an activation energy of 84.9 kJ mol−1 was determined. In temperature >800 °C, it was noted an influence of diffusion on the reduction reaction. Images obtained from scanning electron microscope suggested a change in the pellets microstructure after this temperature presenting a sintered structure. The activation energy of 188 kJ mol−1 was determined at this step.