A novel process to prepare high-titanium slag by carbothermic reduction of pre-oxidized ilmenite concentrate with the addition of Na2SO4

In this paper, a novel process was studied for the recovery of iron and titanium from ilmenite concentrate. The ilmenite powders first underwent an oxidation pretreatment and were reduced isothermally at 1350-1450 °C by graphite with the addition of Na2SO4. The influence of temperature, C/O molar ratio and the dosage of the added Na2SO4 on the metallization ratio, phase transformation and titanium grade were studied. The results demonstrated that Na2SO4 not only significantly promotes the aggregation and growth of metallic iron-grain particles but also enhances the reduction ability. Under the promotion of added Na2SO4, the highest metallization ratio reached 94%, and the theoretical calculation of the highest grade of titanium dioxide is approximately 75%. The Na2SO4 additive decreases the melting point of the slag and metal, resulting in the effect of semi-melting reduction. The carbothermic reduction order of phase transitions of pre-oxidized ilmenite concentrate was also discussed.