As one of the most common constituent of gangue in iron ore, it has been known that alumina plays an important role in the formation of silico ferrite of calcium aluminum (SFCA), which are derivatives of calcium ferrites. SFCA is the most desirable bonding phase in iron ore sinter due to its high reducibility and mechanical strength. Alumina has been known to promote the formation of SFCA in the sintering process of iron ore, but it also increases the porosity of sintered ore and viscosity of primary melt, and decreased the physical properties of the sintered ore. In order to achieve better understanding about the effect of alumina on sintered iron ore, three kinds of powdered iron ores were investigated under similar condition of identical alumina source and content. The iron ores used in the experiments were Carajas, Yandi, and Australian Premium Iron (API) ores. The formation temperature of primary melt, phase composition, and porosity of each sintered iron ore were measured to find out how they are related. Results showed that the estimated temperature of initial primary melt formation decreased with the addition of small amount of alumina then increased with the further addition of alumina in Yandi ore while in Carajas and API ores, the initial primary melt formation temperature was always increasing with alumina addition. More amount of calcium ferrites were formed in the Yandi and API ores sinter than in the Carajas ore sinter, which showed that the Yandi and API ores have better reactivity since they are goethite-based ores. It was concluded that the amount of calcium ferrites generated and porosity were competing factors that may govern the physical properties of sintered iron ores.
展开▼
