Effect of Coarse-grain and Low-grade Iron Ores on Sinter Properties

Abstract

In sintering of iron ore, small particles act as a binder that joins larger particles through diffusion and melting. In order to understand the effect of gangue and structure of coarse ore on sinter properties, melt formation in three coarse-grain, low-grade iron ores was investigated. The melt fractions at the sintering temperature were estimated using the phase diagrams and melt fluidity was quantified by testing ore compacts in an infrared furnace. The result indicates that SiO₂ can significantly increase the quantity and fluidity of melt during sintering, whereas the effects of Al₂O₃ and MgO are small. Excessive quantity and fluidity of liquid phase result in merging of micro pores, leaving large pores behind. The impact of blending three ores with a base ore on sinter structure were tested in a mini-sinter pot. The result shows that bonding and pore structure of sinter are dominantly affected by the melt behavior and pore structure of the coarse ore. Relationships between the fluidity index of sinter feed and product properties were explored, showing meaningful and predictable trends. It was demonstrated that fluidity index can be used as parameter to link sinter mix composition and sintering conditions to the properties of the produced sinter.