An investigation into electrochemical reduction of TiO2 pellet

Abstract

The electrolytic reduction of solid TiO2 directly to the solid metal is a promising alternative to the current Kroll process. The products of electrochemical reduction of TiO2 in the present work were examined by SEM, EDX and XRD, which showed that TiO2 was reduced progressively from outside to inside of a pellet and from a high valence oxide to a lower one until the metallic state was achieved. From the analysis of anode gases and the measurement of current during the electrolysis, it was observed that the average current efficiency was relatively low and decreased with electrolysis time. Secondary reaction between Ca and CO, CO2 evolution at the anode and a short circuit caused by the black carbon product were considered as the main reasons for low current efficiency. There are two methods to improve the current efficiency. One is to separate the anode region from the cathode region to limit the secondary reaction. The other is to drain the molten salt containing black carbon at the surface continuously or to cut off the short circuit caused by black carbon bridging between anode and cathode.