Anodic Processes during the Electrowinning of Niobium from Chloride-Fluoride Melts and the Influence of Oxide Ions on Them

Abstract

Anodic processes were studied in chloride-fluoride, fluoride melts by voltammetry and gas chromatography mass spectrometry method. It was found that the reason for the occurrence of the anodic effect during the electrolysis of the KCl-KF-K2NbF7 melt is the formation of the compound CxFy on the electrode surface, which has electrical insulating properties. Influence of oxide ions on the anodic processes in the KCl-KF-K2NbF7 melt was investigated. It was determined that oxide ions and oxofluoride complexes of niobium oxidize at a glassy carbon electrode at more negative potentials than fluoride ions. The anodic effect in the chloride-fluoride melt containing oxide ions and oxofluoride complexes of niobium can be reached if the anodic current density will be higher than the limiting current density of electrooxidation of oxide ions and niobium oxofluoride complexes.