Influence of bath composition on Ti metal deposition in molten CaCl₂ containing calcium titanate

¹ Kansai University, Suita 564-8680, Japan

^* ttakenak@kansai-u.ac.jp

Abstract

The dependence of the cathodic behavior of a Ti ion on the molar ratio of CaO to TiO₂ (R_CaO/TiO2) was investigated in molten CaCl₂ above 1373 K, and the influence of R_CaO/TiO2 on Ti metal deposition was discussed. The reduction mechanism changed at R_CaO/TiO2 = 1.5; a three-step reduction of Ti was suggested in the melt of R_CaO/TiO2 < 1.5, while a two-step reduction seemed to occur above R_CaO/TiO2 = 1.5. Titanium metal deposition was also affected by R_CaO/TiO2 as well as by the cathode potential, and the suitable R_CaO/TiO2 was likely 1.5. Since this value was the same as the suitable value in the molten fluoride system, Ti metal was thought to be obtained only from Ti₂O₇^6-. Silicon and Al metal were obtained electrochemically in molten CaCl₂ containing calcium silicate and aluminate more easily than Ti metal. The difficulty of the Ti metal deposition is likely to be caused by the so-called shuttle reaction; the shuttle reaction can occur in the Ti metal electrolysis because some ionic states of Ti are stable in the bath. To realize better Ti metal deposition, the control of the shuttle reaction should be important.