OS PROCESS - THERMOCHEMICAL APPROACH TO REDUCE TITANIUM OXIDE IN THE MOLTEN CaCl_2

摘要

A new cell concept for calciothermic reduction is proposed in which the titanium dioxide instead of TiCl_4 is used as the raw material for reduction. Metallic calcium is needed as the reductant of a thermochemically stable oxide, such as TiO_2. CaCl_2, is selected as the solvent of Ca and simultaneously as the solvent of CaO. The reduction system consists of a single cell where both the reduction reaction and the electrolytic reaction for recovery of reducing agent coexist in the same molten CaCl_2 bath. A few mol%Ca dissolves in the melt and gives the media a strong reducing power. Sufficiently deoxidized metallic titanium deposits and forms a slightly sintered granular sponge. Both mechanisms of the halide flux deoxidation and the electrochemical deoxidation work efficiently for these fine precipitates. The reducing agent is in situ recovered by electrolysis of CaO because the molten CaCl_2 has a relatively large solubility for CaO. Some cell designs and modifications are proposed for industrial applications.