Abstract
Calcium ferrite phases have been considered as wonderful bonding phase in iron ore sinters. Plenty of works have reported the formation behaviors of calcium ferrites roasted under various O2 partial pressures. However, the local sintering zone where the coke breeze is combusted is not oxidizing atmosphere but weakly reducing atmosphere, which inevitably affects the formation of calcium ferrites. In the present study the formation of calcium ferrites roasted under CO–CO2–N2 atmosphere was investigated using XRD, SEM–EDS, TG–DSC, etc. It was found that Ca2Fe2O5 (2CaO·Fe2O3) and ternary calcium ferrites (CaO·FeO·Fe2O3 and CaO·3FeO·Fe2O3) were easily formed under 1–10vol.% CO/(CO+CO2+N2) atmosphere, and the formation reactions of calcium ferrites were promoted by increasing the roasting temperature and CO content of the mixed gas. CaO·FeO·Fe2O3 and CaO·3FeO·Fe2O3 had much lower melting point than 2CaO·Fe2O3 which was beneficial to the formation of liquid phases during the iron ore sintering process. The formation of calcium ferrites under CO–CO2–N2 atmosphere can be regarded as CaO substitute for FeO in Fe3O4 (FeO·Fe2O3).
Published Version
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