Microstructure and Chemical Transformation of Natural Ilmenite during Isothermal Roasting Process in Air Atmosphere

Ilmenite is a vital raw material for the production of metal titanium and titanium-containing materials. In this paper, microstructure and chemical transformation of natural ilmenite in air atmosphere were investigated by the analysis of XRF, X-ray diffractometer, and SEM-EDS. Results showed that the untreated ilmenite had three layers after oxidation at 800 °C for 60 min, which were Fe2O3, TiO2 and the inside mixture layer of Fe2O3 and TiO2 in turn. Subsequently, it was roasted at 900 °C, and Fe2Ti3O9 was firstly developed between Fe2O3 and TiO2 layers. With the increase in the roasting time, the Fe2Ti3O9 layer was decomposed into Fe2TiO5 and TiO2, and Fe2Ti3O9 continued to be formed along the diameter direction toward the center of the particle until Fe2TiO5 and TiO2 were formed as the final products in the center of particles. Pseudorutile in natural ilmenite was directly decomposed into TiO2 and Fe2O3 in the roasting process.