Molten Salts

A new sodiothermic reduction process of TiO₂ in CaCl₂ melt was proposed aimed at fine Ti powder preparation. The chemical analysis and direct potentiometric methods were used to investigate the reaction pathway of sodiothermic reduction in CaCl₂ melt. The as-prepared samples were characterized by X-ray diffraction and scanning electron microscopy. It was found that when reductant of Na was added into the CaCl₂ melt, Ca²⁺ was reduced to Ca by Na and Ca dissolved in the CaCl₂ melt. The whole melt would have the reducing power with dissolved Ca. Using this melt as a reaction medium, fine and uniform Ti powder with a purity of around 99 mass pct was successfully produced at 1173 K (900 °C). In addition, as the CaCl₂ melt could dissolve about 20 mol pct CaO, it was found that the molar ratio of TiO₂ and CaCl₂ should be 1:20 to eliminate the by-product CaO from the reaction interface within the experimental period to continue the reduction.