Fundamentals of the Reduction of SFC in CO/CO₂ Gas at 1000°C

Abstract

SFC (Sillico-Ferrite of Calcium) is a kind of simplified SFCA (Sillico-Ferrite of Calcium and Aluminum) with no Al₂O₃. SFC and SFCA are believed to be the most desirable bonding phase in sinter. In order to better understand the fundamentals of the reduction of SFC, a series of experiments on the SFC reduction were carried out in the present work, including phase equilibria tested by XRD, morphology tested by SEM-EDS, and reduction pathway under the different CO/CO₂ mixture gas at 1000°C. The experimental results indicated, (1) in the case of CO = 20% and 40%, most of Fe₂O₃ in SFC was reduced to FeO. The equilibrium phases were FeO, CaO·Fe₂O₃, and CaO·SiO₂. (2) In the case of CO = 60%, CaO·Fe₂O₃ was reduced to generate FeO and 2CaO·Fe₂O₃. The equilibrium phases were FeO, 2CaO·Fe₂O₃, and CaO·SiO₂. (3) In the case of CO = 80% and 90%, FeO was reduced to Fe, and 2CaO·Fe₂O₃ was reduced to generate Fe and CaO. The equilibrium phases were Fe, CaO, and CaO·SiO₂. The findings from this work may provide guidelines for the improvement of sintering production and blast furnace performances.

Schematic diagram of the reduction pathway of SFC.