A NEW CONCEPT OF SPONGE TITANIUM PRODUCTION BY CALCIOTHERMIC REDUCTION OF TITANIUM OXIDE IN THE MOLTEN CaCl_2

摘要

A new cell concept for calciothermic reduction of titanium dioxide and an ongoing test program for its experimental verification are presented. The thermo-chemical background of this concept and new cell designs are described. The reduction system consists in a single cell, where both the thermochemical reaction and the electrochemical reaction for recovery of reducing agent coexist in the same molten CaCl_2 bath. A few mol%Ca dissolves in the melt, which constitutes the media with a strong reducing power. Separated experiments on calciothermic reduction showed that 3.6 ks were enough to reduce TiO_2 powder at 1173 K, where the oxygen content was lowered below 1000 mass ppm, The optimum concentration of CaO in the molten CaCl_2 was lower than 5 mol%. Combining carbon anode and titanium net cathode, titanium sponge containing 2000 ppm oxygen was produced from anatase-type TiO_2 powder.