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 and 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.

Electrochemical studies of chemical reactions in molten salts

“…При содержании фторида калия более 60 мас. % наступал анодный эффект[273].Результаты этих экспериментов, представленные на рис. 8.11, показывают некоторое уменьшение выхода по току ниобия от 55 % в расплаве KCl − K 2 NbF 7 до 47 % в расплаве KCl − KF − K 2 NbF 7 , когда содержание KF в электролите достигает ~ 60 мас.…”

Electrodeposition of Niobium Coatings on the Cryogyroscope Rotor

“…The electrochemical behavior of niobium was investigated in melts of different composition and with utilization of different working electrode. [36][37][38][39][40][41][42][43] To the best of our knowledge, the usage of working electrode made from carbopyroceram has not been previously reported. In the present study, the electrochemical behavior of niobium in chloride-fluoride melt with utilization of working electrode from carbopyroceram was investigated.…”