Optimal allocation of limonite in sintering process

Improvements in ore blending could be realized by an optimal match of iron ores, sinters, and fuel conditions. To further increase iron grade and reduce the cost of ore blending, in view of the actual raw material and fuel conditions of the 500 m² large-scale sintering machine of S Steel company, the conventional physical and chemical properties of the iron ore powders used and their basic characteristics under high-temperature sintering were studied using sintering cup experiments in this study. The content of the adhesion powder, the theoretical liquid phase formation, and performance with different limonite ratios were simulated and calculated using the FactSage 7.1 software. The microstructures of sinters were also analyzed using a mineral phase microscope. The results show that Australian limonite exhibits coarse particle size, weak mineralization ability, low assimilation temperature, poor bonding phase strength, but strong liquid phase absorption. When the mass fraction of limonite is increased from 45% to 55%, the OD ore mass fraction of the magnetite concentrate is increased to 15% and the mass fraction of the OC ore is reduced to 10%, improving the sinter drum strength and RDI_{+3.15 mm}. When the OD ore ratio of the magnetite concentrate is increased, not only the proportion of adhesion powder is increased, improving the amount and performance of liquid phase formation, but the liquid phase distribution also becomes uniform and overmelting is eliminated. On the other hand, increasing the ratio of the OC ore can improve the particle size composition of the sinter mixture and reduce the amount of liquid phase absorbed by the limonite, thus increasing the strength of the sinter. Therefore, a higher ratio of magnetite concentrate under a high amount of limonite is conducive to stabilizing the sinter quality and improving the overall sinter performance.