Generation of titania-rich slag and iron from ilmenite concentrate by carbothermic reduction and magnetic separation in the presence of Na2CO3

Abstract

ABSTRACT The carbothermic reduction of an ilmenite concentrate, followed by wet magnetic separation, was performed with varying additions of Na2CO3 to generate metallic iron and a titanium-rich slag. The size of the metallic iron particles correlated positively with increasing graphite addition up to a C/O (O bound to Fe) molar ratio of 1.4; further increases beyond this level decreased the particle size. The size of these metallic iron particles also increased with greater addition of Na2CO3. The addition of Na2CO3 to the ilmenite concentrate enhances the carbothermic reduction by promoting the gasification of C and fluxing the slag phase, lowering its melting point and increasing fluidity; a 5.97 wt% addition of Na2CO3 decreased the reduction onset temperature from 1020 to 900°C. This fluxing of the slag with Na2CO3 also allows for much lower concentrations of FeO than the 10–12% concentration typically required to ensure adequate fluidity in conventional EAF smelting operations. With the addition of Na2CO3, the recovery of Fe to the magnetic fraction, following magnetic separation, was over 97% and the non-magnetic fraction contained more than 74% TiO2. Within the range of conditions considered in this study, the highest recovery of TiO2 to the non-magnetic fraction (89%) was achieved for material reduced at 1450°C.