Carbothermic reduction of llmenite (FeTiO₃) and rutile (TiO₂)

The mechanically activated carbothermic reduction mechanism of ilmenite has been examined by a combination of steady-state and dynamic thermal techniques coupled with X-ray diffraction. The reaction was found to proceed via an initial, rapid reduction to elemental iron and rutile, which was followed by a slow reduction of rutile to a series of oxides of the general formula Ti_nO_2n-1 until Ti₃O₅ was formed, which was found to be relatively stable. Iron was probably incorporated into the Ti_nO_2n-1 lattice only for n > 3, forming mixed oxides of uncertain composition. The formation of TiC was evident at temperatures as low as 1100 °C, but the rate of reaction was extremely slow, presumably due to a solid-state diffusion limitation. Increasing the temperature gave increasing conversion of TiO₂ to TiC until it was the only confirmed product. The effect of iron on the later stages of reduction was removed by examining the reduction of pure rutile. It was found that the reduction of Ti₃O₅ was enhanced by the presence of iron. The separation of iron from the titanium product proved to be high, with >90 pet of iron removed after the initial reduction. The iron removal increased slowly to almost 100 pet when elemental iron and titanium carbide were the products.