Novel fluidised cathode approach for the electrochemical reduction of tungsten oxide in molten LiCl–KCl eutectic

Abstract

The electrochemical reduction of metal oxides is an important step in refractory metal production and in the pyroprocessing of spent nuclear materials. The FFC Cambridge process has revolutionised molten salt electrolysis; however, it has quite a low efficiency and has diffusion and oxide build-up issues. The fluidised cathode approach eliminates some of these issues. To illustrate the process, the electroreduction of tungsten oxide particles from a LiCl–KCl eutectic is demonstrated. Cyclic voltammetric measurements were taken and show the main reduction peak for WO3 to W to be at −2.135V (vs. Ag/Ag+) at an operating temperature of 450°C. Chronoamperometry shows an increase in current associated with an increasing current collector size and the spalling of deposited W from the surface. SEM and EDS analyses of the product reveal the deposit to be pure W.