Abstract
The reduction rate of chromium ore pellet containing coke powder was measured at various temperatures in flowing N2-CO, N2-CO-H2 and N2-CO-CO2 atmospheres.
The pellet diameter and the grain size of coke only slightly influenced the reduction rate, while the effect of the grain size of chromium ore was greater.
The reduction rate increased with the decrease in the partial pressure of CO and with the increase in that of H2. From the result of kinetic analysis based on a shrinking core model, such an effect was elucidated to be caused by the decrease in gaseous diffusion resistance through the pore in reduced layer formed on the surface of chromite grain.
Although CO2 was contained at low concentration (for example, Pco2/Pco=0.02) in furnace atmosphere, it remarkably retarded the progress of reduction and consumed the coke contained in the pellet.
