Crystal structure of calcium and aluminium silicoferrite in iron ore sinter

Abstract

The crystal structures of real and synthetic iron ore sinters were compared. In the Fe₂O₃-CaO-Al₂O₃- SiO₂ system, the crystal structure of a synthetic solid solution of CaO.2Fe₂O₃ (CF₂) was studied by X-ray powder diffraction. As the Al₂O₃ content in pure CF₂ increased, the formation of hemicalcium ferrite increased. On the other hand, CF₂ content decreased and hematite increased as the SiO₂ content increased. The crystal structure of CF₂ with Al₂O₃ and SiO₂ (calcium and aluminium silicoferrite, also known as silicoferrite of calcium and aluminium, SFCA) changed from monoclinic to triclinic, and the unit cell volume decreased when the Al₂O₃/SiO₂ ratio increased. The solubilities of Al₂O₃ SiO₂ in CF₂ were 5-7 wt-% and 2-4 wt-%, respectively at 1250°C.