Phase transformation behavior of titanium during carbothermic reduction of titanomagnetite ironsand

The reduction of titanomagnetite (TTM) ironsand, which contains 11.41wt% TiO₂ and 55.63wt% total Fe, by graphite was performed using a thermogravimetric analysis system under an argon gas atmosphere at 1423–1623 K. The behavior and effects of titanium in TTM ironsand during the reduction process were investigated by means of thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. During the reduction procedure, the titanium concentrated in the slag phase, where the phase transformation followed this sequence: FeO + FeTiO₃ → Fe₂TiO₄ → FeTiO₃ → FeTi₂O₅ → TiO₂. The calculated results for the reduction kinetics showed that the carbothermic reduction was controlled by the diffusion of ions through the product layer. Furthermore, the apparent activation energy was 170.35 kJ·mol^-1.