Fundamentals of Reduction of CaO·Fe2O3 in CO/CO2 Gas at 1000°C

Calcium ferrite is the most basic bonding phase in sinter and the matrix of Silico-ferrites of calcium and aluminium (SFCA). In order to better understand the fundamentals of the reduction of CaO center dot Fe2O3, CaO center dot Fe2O3 samples were prepared by solid-state sintering and reduced by CO/CO2 mixture gas at 1000 degrees C. Then, the equilibrium phase and morphology were tested by XRD and SEM-EDS. The experimental results indicated that (1) As CO/(CO + CO2) = 20%, CaO center dot Fe2O3 was reduced to CaO center dot FeO center dot Fe2O3 and 2CaO center dot Fe2O3. (2) As CO/(CO + CO2) = 40%, CaO center dot FeO center dot Fe2O3 was reduced to CaO center dot 3FeO center dot Fe2O3 and 2CaO center dot Fe2O3, the equilibrium phases were CaO center dot 3FeO center dot Fe2O3 and 2CaO center dot Fe2O3. (3) As CO/(CO + CO2) = 60%, CaO center dot 3FeO center dot Fe2O3 was reduced to FeO and 2CaO center dot Fe2O3, and 2CaO center dot Fe2O3 was still the stable phase. (4) As CO/(CO + CO2) = 80%, FeO was reduced to metallic Fe, and 2CaO center dot Fe2O3 was reduced to metallic Fe and CaO. The finding from this work may be used as a theoretical foundation for the research of the reduction of SFCA.