Abstract
Pure wustite was prepared from the gaseous reduction of reagent grade (99.5%) Fe2O3 at 1000 degrees C, in 50CO-50CO(2) gas mixture. Compacts of 0.5% and 2%SiO2 doped wustite were made and annealed for 3 h at 1000 degrees C in 50CO-50CO(2) gas mixture. These compacts were isothermally reduced in H-2, CO and 50H(2)-50CO mixture at a temperature range 900-1050 degrees C. The oxygen weight loss during reduction process was recorded as a function of time. X-ray diffraction (XRD), SEM and porosity measurements were used to characterise the annealed and reduced samples. The influences of temperature, gas composition and silica contents on the reduction behaviour and the morphology were investigated. It was observed that the addition of silica decreased the porosity owing to the formation of iron silicate phases. The reduction rate increases with temperature and in presence of hydrogen in the gas mixture while it decreases with increasing silica content owing to decreasing porosity of compacts. 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 reduced iron was formed in different morphology including whiskers and platelets structures which are temperature and gas composition dependent.