Understanding the electro-deoxidation of titanium dioxide to titanium metal via the FFC-Cambridge process

Abstract

The FFC-Cambridge process, invented at the Department of Materials Science and Metallurgy of the University of Cambridge approximately 10 years ago, offers a novel and rather universal approach in the field of electro-winning of metals. In this process, metals and alloys can be produced directly from their oxides by polarising the oxide cathodically in a molten salt electrolyte based on calcium chloride. The winning of titanium metal from titanium dioxide has been the first and the main goal of the FFC-Cambridge process. This article summarises the key results of a series of in-depth studies performed at Cambridge with the aim of understanding the fundamentals that the process rests upon. Subjects of discussion are the pathway of electro-deoxidation in the cathode, the validation of a molten salt compatible pseudo-reference electrode, and the investigation of the reactions at the anode. A particular emphasis is on the importance of the composition of the electrolyte and its interplay with the other components of the electrolytic cell. The knowledge gained has enabled optimisation of the process and scale-up to the pilot plant level.