Reduction of Ilmenite with Hydrogen

The kinetics and the mechanism of reduction of synthetic ilmenite by hydrogen in the temperature range of 807-1014 °C were investigated. At temperatures below 876 °C, the temporal profiles of conversion have a sigmoidal shape and indicate the presence of three different stages (induction, acceleration, and deceleration) during the reduction reaction. The apparent activation energy for the reaction is 22.3 kcal/mol, whereas the intrinsic activation energy is 16.9 kcal/mol. Scanning electron microscopy and energy-dispersive X-ray analyses show that the diffusion of Fe product away from the reaction front and through the TiO₂ phase, followed by the nucleation and growth of a separate Fe phase, is an important step affecting the process kinetics. X-ray diffraction and wavelength-dispersive X-ray results indicate that the TiO₂ can be reduced to lower oxides of titanium at temperatures higher than 876 °C.