Behaviour of wüstite prepared from Baharia iron ore sinter during reduction with CO–CO2–N2 gas mixture

Abstract

Two wüstite samples were prepared from reagent grade hematite and Baharia iron ore sinter by a gaseous reduction with 50%CO–CO2 gas mixture at 1273 K. Both wüstite samples were isothermally reduced at 1173–1373 K by different ratios of CO/CO2/N2 which closely represent the coke gases in the blast furnace. The influences of temperature and gas composition on the reduction behaviour and the morphology were investigated. The reduction rate of both wüstite samples increased gradually with increasing reaction temperature and also by increasing the CO concentration in the reducing gas mixture. The apparent activation energy values were calculated and correlated with the gas–solid reaction formulations to elucidate the corresponding mechanism at both early and final reduction stages. The reduction rate of pure wüstite samples is most likely controlled by the combined effect of chemical reaction and gaseous diffusion mechanisms while the reduction rate of wüstite from iron ore sinter is most likely controlled by interfacial chemical reaction mechanism.