Effect of Na2O on the Reduction of Fe2O3 Compacts with CO/CO2

Compacts of Fe2O3 and Fe2O3 doped with varying amounts of Na2O were isothermally reduced at several temperatures, using CO/CO2 mixed gas in a vertical resistance furnace. To determine the effect of Na2O on the reduction of Fe2O3 compacts, the mass loss due to oxygen removal was continuously recorded, from which the reduction rate and rate constant were obtained. Na2O was found to retard the reduction of Fe2O3 compacts. The apparent activation energy (E (a)) of reaction and the mathematical relationship for pore gas diffusion suggested that the reduction behavior at the initial stages was controlled by a combination of pore gas diffusion and interfacial chemical reaction. At the intermediate and late stages of reduction, pore gas diffusion was the sole contributing factor. Morphological examination of the reduced compacts showed the formation of a liquid phase during the reduction process, which appeared to lower the rate of reaction. DOI: 10.1007/s11663-012-9738-z (C) The Minerals, Metals & Materials Society and ASM International 2012