Removal of iron from ilmenite through selective chlorination using CO-Cl₂ gas mixture

Titanium is usually produced from rutile. However, as the amount of rutile ore is exhausted, ilmenite ore could be an alternative resource of titanium extraction. There are various kinds of methods to remove iron and produce rutile from ilmenite ore such as reduction, leaching and selective chlorination. In this study, the removal of iron from ilmenite through selective chlorination using CO-Cl₂ gas mixture was carried out. The effect of the experimental temperature, the gas flow ratio and the particle size distribution of ilmenite were investigated. 10 g of ilmenite powder was used during the experiment and the removal ratio of iron was calculated after the experiment. Pseudo-brookite was discovered at the beginning of the experiment, and it gradually disappeared with the reaction process. The removal ratio of iron increased linearly at the initial stage of the reaction and reached 98% after the reaction for 1 h when the flow rates of both CO and Cl₂ were 5 cm³/s at 1173 K. After reacting with CO-Cl₂ gas mixture, pores formed on the surface of ilmenite particles, which were caused by the removal of iron and the gas mixture further diffused into the central portion of ilmenite particles through the pores. It was found that the removal ratio of iron increased with temperature and the flow ratio of CO/Cl₂, but was hardly affected by the particle size distribution. The chlorination of titanium also occurred and was suppressed by reducing the flow ratio of CO/Cl₂. Metallic chlorides such as FeCl₃ were discovered in the condensate after the experiment.