Online Monitoring of Metal Oxides in Molten Fluoride Electrolytes

Reliable monitoring of oxide concentrations in electrowinningElectrowinning of metals in fluoride-based electrolytes is very important for avoiding unwanted reactions, notably perfluorocarbonsPerfluorocarbons emissions which are very potent greenhouse gasesGreenhouse gases. A probe, consisting of a working electrode and a counter electrode, has been developed for online monitoringOnline monitoring of metal oxide concentrations in molten fluoride electrolytesMolten fluoride electrolyte. During measurements, the immersed probe in the electrolyte is subject to fast anodic polarisation sweeps while the electric current response is recorded. During anodic polarisation, oxide species in the electrolyte are rapidly depleted at the probe, resulting in a response called anode effectAnode effect on the probe tipTips, triggering a rapid voltage increase and current drop. The rate of oxide depletion and the consequent anode effectAnode effect is proportional to the dissolved oxide concentration. This allows to correlate voltage-current–time curves to the oxide concentration. Measurements in cryolite melts with different oxide concentrations showed different voltages at which anode effectAnode effect occurs.