A new cell concept for calciothermic reduction is proposed that titanium dioxide
instead of TiCl4 is used as the raw material for reduction. Metallic
calcium is needed as the reductant of the thermochemically stable oxide such as
TiO2. CaCl2 is selected as the solvent of Ca, and simultaneously as
the solvent of CaO.
The reduction system consists in a single cell, where both the reduction
reaction and the electrolytic reaction for recovery of reducing agent coexist in
the same molten CaCl2 bath. A few mol%Ca dissolves in the melt, and it
makes the media with a strong reducing power. Sufficiently deoxidized titanium
metal 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 CaCl2 has a relatively large
solubility for CaO. Some cell designs and modifications are proposed for
industrial applications.