Towards the Stability of Low-Temperature Aluminum Electrolysis

The results of several different tests related to the low-temperature aluminum electrolysis were considered in this work. The role of mass transfer processes in the anode-cathode space was recommended to be significant during electrolysis in the low-temperature KF-AlF₃ and NaF-AlF₃-based melts. The stationary polarization and voltammetry methods were applied in order to study the kinetics of the electrode processes on the carbon and metal electrodes in the KF-AlF₃-Al₂O₃ melts and to select the electrolysis parameters. The schemes of electrode processes were suggested on the basis of electrochemical tests, the flows of substances in the anode-cathode distance were analyzed and the main reasons of the cathode current efficiency decrease during the low-temperature electrolysis in the KF-AlF₃-Al₂O₃ and KF-NaF-AlF₃-Al₂O₃ melts were discussed. It was revealed that the cathode current density should not exceed 0.4–0.55 A cm⁻² during the electrolysis at 750 °C–800 °C.