Improving High-Alumina Iron Ores Processing via the Investigation of the Influence of Alumina Concentration and Type on High-Temperature Characteristics

Aiming at the effective utilization of the abundant high-alumina iron ores with low iron grade, the influence of alumina concentration and type on high-temperature characteristics was clarified based on the analyses of eight typical iron ores. The results indicate that high-temperature characteristics of iron ores in various alumina types are different. Higher Al2O3 concentration is deleterious to assimilability and liquid phase fluidity, but the influence extent of each alumina type is substantially different. Kaolinite (Al2O3&middot
2SiO2&middot
2H2O) contributes to correspondingly better assimilability, followed by hercynite (Fe(Fe, Al)2O4), gibbsite (Al(OH)3), diaspore (AlO(OH)), and free state alumina (Al2O3) in turn. Diaspore promotes relatively higher liquid phase fluidity, followed by kaolinite, free state alumina, and hercynite, while gibbsite possesses the maximum adverse impact. Kaolinite and hercynite are more beneficial to form dendritic or acicular silico-ferrite of calcium and alumina (SFCA) with high strength due to the better reactivity, and gibbsite and diaspore lead to more formation of relatively lower strength lamellar or tabular SFCA, while free state alumina is preferable to form disseminated SCFA with rather poorer strength. Kaolinite and hercynite are the most desirable alumina types for sintering rather than free state alumina.