Effect of TiO2 during Oxidation Roasting Process of Pellet: Kinetic Mechanism and Microstructure

Abstract

This study investigates the effect of TiO2 on the oxidation kinetic mechanism of iron ore concentrate under nonisothermal conditions. Based on the fact that iron‐containing materials are mainly smelted in the form of pellets, the microstructure evolution of pellets with different TiO2 additions during oxidation is studied to verify the accuracy of the kinetic analysis results. The results show that the reaction model is the mechanism describing oxidation of iron ore concentrate under different TiO2 additions at stages I and II. The increase of TiO2 increases E and worsens the oxidation kinetic conditions at stages I and II. This phenomenon is caused by the Fe–Ti solid solution embedded in the hematite particles hindering the recrystallization and large‐scale crystal bridge connection of hematite. The fluctuation amplitude of apparent activation energy (E) at stages I and II is 23.6112 and 19.508 kJ mol−1, respectively. Furthermore, the mechanism of stage III corresponds to the diffusion model, and the increase of TiO2 decreases E and improves the oxidation kinetic conditions. It is due to the loose structure of pellets with the increase of TiO2, facilitating the internal diffusion of reaction gases. The fluctuation amplitude of E is 5.07 kJ mol−1 at stage III.