Kinetics and Reaction Mechanism of Soda Ash Roasting of Ilmenite Ore for the Extraction of Titanium Dioxide

Ilmenite by virtue of being rich in iron often has small concentrations of impurities such as Mn3O4, Al2O3, CaO, Cr2O3, and MgO. Removal of iron and other impurities is essential for the production of pigment grade TiO2. An investigation of the removal of iron was undertaken by roasting the mineral ilmenite with soda ash in air above 873 K. A ternary phase was identified, which played an important role in the overall kinetics. The dependence of temperature, time, mixture composition, and the microstructure of the reaction layer were studied in order to establish the reaction mechanism. We report the results of overall kinetics of roasting reaction by analyzing the activation energy in the temperature range of 873–1173 K and also explain the reaction mechanism. The derived value of activation barrier compares well with the diffusion rates of Fe2+ and Fe3+ ions in the ilmenite lattice.