Design, Test and Theoretical Assessments for Reduction of Titanium Oxide to Produce Titanium in Molten Salt

摘要

We have investigated the details of the calciothermic reduction of TiO2 in CaCl2-CaO-Ca molten salt electrolyte and developed a process for Ti production that is proceeding toward commercialization. In this process, when a potential of 3 V is applied between the carbon anode and the stainless steel cathode, the electrolytic decomposition of CaO occurs such that Ca deposits at the cathode and immediately dissolves into the molten salt. This Ca attacks the TiO2 powders fed into the bath and reduce them to metallic titanium. The engineering aspects of the new reactor have been considered according to the following items; (1) the simplest possible cell structure, (2) permanent inside wall lining, (3) open cell and (4) surface protection layer. The 10 days campaign using a reactor with 2 tons of molten salt and current of 4000 A has been conducted. As a result of the test, we came to propose a definitive model of open reactor body. We have theoretically examined the possibility of prebaked soluble titanium dioxide anode. Application of the oxygen-ion deficient titanium dioxide anode to this process will contribute to achieving the high productivity of titanium as well as the commercial level of oxygen in titanium.