Effect of electrolysis voltage on electrochemical reduction of titanium oxide to titanium in molten calcium chloride

The electrochemical reduction of solid TiO2 directly to solid metal is a promising alternative to the current Kroll process. The present work is aimed at studying the effect of electrolysis voltage on the rate of electrochemical reduction. The products of electrochemical reduction of TiO2 and Ti2O were examined using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The results show that Ti2O was reduced to low valent titanium oxide at 1.5-1.7 V, which was the result of ionization of oxygen. TiO2 and Ti2O were reduced to titanium metal at 2.1-3.1 V, which was the co-action of ionization of oxygen and calciothermic reduction. The oxygen content decreased rapidly with voltage increasing from 2.1 to 2.6 V, while it changed little from 2.6 to 3.1 V. The optimized cell voltage was 2.6-3.1 V.