Fundamentals of reduction of CaO·Fe₂O₃ in CO/CO₂ gas at 1000°C

ABSTRACT

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·Fe₂O₃, CaO·Fe₂O₃ samples were prepared by solid-state sintering and reduced by CO/CO₂ mixture gas at 1000°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·Fe₂O₃ was reduced to CaO·FeO·Fe₂O₃ and 2CaO·Fe₂O₃. (2) As CO/(CO + CO₂) = 40%, CaO·FeO·Fe₂O₃ was reduced to CaO·3FeO·Fe₂O₃ and 2CaO·Fe₂O₃, the equilibrium phases were CaO·3FeO·Fe₂O₃ and 2CaO·Fe₂O₃. (3) As CO/(CO + CO₂) = 60%, CaO·3FeO·Fe₂O₃ was reduced to FeO and 2CaO·Fe₂O₃, and 2CaO·Fe₂O₃ was still the stable phase. (4) As CO/(CO + CO₂) = 80%, FeO was reduced to metallic Fe, and 2CaO·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.

KEYWORDS:

• CaO·Fe₂O₃
• sinter
• equilibrium phase
• morphology
• XRD
• SEM-EDS
• SFCA
• reduction pathway

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Research data are not shared.

Additional information

Funding

The financial supports by the National Basic Research Program of China [grant number 2021YFC2902400], and the National Natural Science Foundation of China [grant numbers NSFC 52074074, NSFC 51874080, NSFC 51974073], the Xingliao Talent Project [grant number XLYC2007152], and the Fundamental Research Funds for the Central Universities [grant number N2125036] are much appreciated.