Effect of TiO2 on compressive strength and microstructure of high basicity iron ore pellets

High basicity (basicity 2) magnetite pellets containing TiO2(1-7%) were studied in the laboratory. Ca(OH)(2) is used as a flux for the production of raw balls. The raw balls were made from laboratory-scale balls and discs, preheated at 900 & DEG;C and roasted at 1220 & DEG;C for 15 min. The phase composition, thermal decomposition performance, microstructure, and element distribution of preheated and roasted pellets were systematically analysed by XRD, TG, and SEM-EDS. The results show that suitable TiO2 content can promote the oxidation of magnetite, but the content should not exceed 5%. With the increase of TiO2 content, the compressive strength of preheated pellets first increases and then decreases, while the liquid content in roasted pellets decreases, while the porosity increases and the compressive strength decreases. The reason is that the formation of calcium titanate inhibits the formation of calcium ferrite liquid phase, and its continuous aggregation obstructs the crystallization of haematite, resulting in high porosity and lower compressive strength. The increased weight loss of the pellets is due to the breakdown of calcium hydroxide. According to the above experimental results, a schematic diagram of oxidation mechanism is given, which provides a theoretical basis for the study of titanium-containing pellets with high basicity.