Oxidation Kinetics, Structural Changes and Element Migration during Oxidation Process of Vanadium-titanium Magnetite Ore

The oxidation kinetics, structural changes, and elements migration during the oxidation process of the vanadium-titanium magnetite (VTM) ore were analyzed. Kinetics analysis indicated that the oxidation process was controlled by diffusion control and could be divided into interface diffusion and lattice diffusion with apparent activation energy of 99.69 kJ/mol and 144.08 kJ/mol in the range of 800 - 1000 °C, respectively. The surface structure changed with the oxidization temperature as follows: dense surface→nano-sized sheets→submicron particles→molten particles. The compact structure changed into porous one because of the elements migration and enrichment. Both Fe and Ti elements migrated in the opposite direction during the oxidation process. The V element in the raw ore stably existed in the form of V5+ state, some vanadium migrated and occupied the tetrahedral sites of the hematite during the oxidation process.