Effects of Na2CO3 on the carbothermic reduction and magnetic separation of ilmenite concentrate

Ilmenite concentrates are the raw material used for the production of titania pigment and metallic titanium. This work studies the effect of the addition of Na2CO3 in direct carbothermic reduction of ilmenite concentrate to enhance the separation of metallic iron from titanium components. The effects of temperature, Na2CO3 content and C/O molar ratio on the mineral phases, metallization degree of iron, and iron grain size of the reduced product are evaluated. The optimal conditions for the direct reduction of ilmenite concentrate are 1300 °C, a C/O molar ratio of 1.1, and 5 wt% Na2CO3. Under these optimal reduction conditions, the metallization of iron reaches the maximum of 96.8%, and the average iron grain size is 20.1 μm. After grinding and magnetic separation, the direct reduced iron product (magnetic component) contains 93.9 wt% of iron and 4.66 wt% of TiO2, with an iron recovery of 93.9%, while the non-magnetic product contains 69.9 wt% of TiO2 and 7.61 wt% of iron, with a TiO2 recovery of 93.5%. The results show that an appropriate amount of Na2CO3 effectively promotes the reduction of ilmenite. However, excessive Na2CO3 adversely affects ilmenite reduction. The phase transition patterns of Na2CO3 in the direct reduction of ilmenite is investigated.