8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

In the current work, the reduction route of CaO·Fe2O3 (CF) was investigated and the comparison of CF and Fe2O3 (H) on their reduction kinetics was made. Non-isothermal reduction experiments of powdery CF and H heating up to 1123K with a rate of 10K·min−1 in a continuous stream of 30% CO and 70% N2 were conducted through thermo-gravimetric analysis. It found that the reduction processes of CF and H begin at 873 and 623K, respectively. Reduction rate analysis and subsequent X-Ray diffraction measurements at various stages revealed that the reduction of CF can be divided into two steps (CF→C2F→Fe), whereas that of H mainly comprises three steps (H→M→W→Fe). Activation energy was calculated by Freeman-Carroll method and the average values of CF and H reduction are 49.88 and 43.74 kJ·mol−1, respectively. Model function was calculated by Malek method and the results indicated that the reduction of CF can be described by random instant nucleation and two-dimensional growth of nuclei model, its corresponding model function is Avrami-Erofeev equation with the integral form of [-ln(1-α)]n, whereas the reduction of H was expressed initially by tertiary chemical reaction model (α=0.1~0.5) with the integral form of 1-(1-α)3, and subsequently by two dimensional cylindrical diffusion model (α=0.5~0.9) with the integral form of α+(1-α)ln(1-α).