Mechano-thermic reduction of low-grade titanium ore for high-grade TiO₂ synthesis

A systematic study on the mechano-thermic reduction of low-grade ilmenite concentrate for the production of high-grade TiO₂ powder used in the production of non-oxide ceramics for cutting tool applications has been successfully carried out. Samples were prepared via planetary ball milling and carbothermic reduction processes, and the as-reduced product was subsequently leached in order to improve the synthesized TiO₂ by removing the metallic iron in it and other minor soluble impurities dissolved in the iron. The mechano-thermic reduction was achieved by milling a representative mixture of ilmenite and carbon in a molar ratio of 1:1, followed by carbothermic reduction at 1000 °C in a laboratory high-temperature furnace for 60 min. The as-reduced product was subsequently leached at 80 °C for 6 h in a hydrochloric acid solution. It was found that there was a complete reduction of ilmenite to metallic iron and TiO₂ at 1000 °C. The results of the FESEM showed there were only two distinct regions of metallic iron (bright region) and titanium dioxide (grey region) with minor traces of unreacted carbon (dark spots), although there was clear regional demarcation between these regions. However, the iron dissolution during the acid treatment was almost 100% as there were no peaks of iron in the as-leached powder. The results of these analyses confirmed the synthesis of high-grade TiO₂, which finds application in cutting tool applications and other areas such as in reflective pigment production.