Effects of Compound Silicate Gangue on Formation of Complex Calcium Ferrite During Sintering Process

In order to improve the quality of sinter produced by Baiyunebo iron ore concentrate, the effects of compound silicate gangue containing kalium and natrium on formation of complex calcium ferrite were studied using minisintering test device, optical microscope (OM) analysis and scanning electron microscope (SEM)/energy dispersive X-ray spectroscopy (EDX) analysis. The results show that with the increasing of K2O and Na2 O content in sintering samples, K2O and Na2O highly enriched in the glassy phases, the contents of complex calcium ferrite and hematite in sinter decreased and the porosity increased; the mineral microstructure exhibited large cavities and thin framework and became inhomogeneous. The compound silicate gangue containing kalium and natrium significantly inhibited the generation of complex calcium ferrite (SFCA). When the content of K2O and Na2O was higher in samples, a part of K2O and Na2O entered into complex calcium ferrite, which caused the fine grains of SFCA with acicular and columnar to agglomerate into coarse grains, and its bonding effect to iron oxides reduced. The content of K2O and Na2O in sinter had effects on quantity, composition and morphology of complex calcium ferrite.