Effect of Variation of Alumina on Development of Phases during Iron Ore Sintering

The structure formed during sintering process governs the quality of sinter. Iron ore alumina plays an important role in phases formed, particularly, bonding phase. Increase in alumina content of sinter adversely affects sinter properties, namely, tumbler strength, reduction degradation index and high temperature properties. Pimenta et al. studied the effect of alumina in the range 1.2-1.7 mass% on sinter structure. The alumina content of sinter was varied by addition of bauxite to the basic sinter mix. They inferred that there was slight increase in ferrite formation at higher additions of alumina. In another study by Pimenta and Sheshadri, significant diffusion of alumina in hematite crystals was observed during sintering. Indian iron ores contain alumina mostly in the form of iron aluminate (80%) and rest in the form of oxide. Almost all the alumina is segregated in the hematite crystals.