The electric arc furnace (EAF) smelting process, which produces titanium slag, is the most popular method for utilizing Panzhihua ilmenite concentrate. However, the EAF process involves high energy consumption, high pollution, and low efficiency due to the high smelting temperature, the large amount of dust produced, and the long smelting period. An economical and clean method for semi-molten reduction followed by magnetic separation to produce titanium slag from Panzhihua ilmenite concentrate was presented. In this paper, the semi-molten reduction process was studied and the effect of reduction temperature, C/O molar ratio, and the addition dosage of Na2SO4 on the metallization ratio, phase transformation, and size of metallic iron grain was discussed. The results showed that Na2SO4 and its subsidiary products can function as fluxing agent for decreasing the melting point of metal and slag, thus promoting the growth of metal particles, and achieving high efficiency and clean reduction of ilmenite concentrate. The action mechanism of Na2SO4 addition is also discussed. (C) 2018 Elsevier B.V. All rights reserved.