Clean separation of vanadium from NaVO3 in NaF-KF-AlF3 molten salt by electrochemical reduction

Abstract

Aluminum-vanadium intermediate alloy is a significant raw material for the fabrication of high-performance titanium alloys. In the present study, the electrochemical behavior of NaVO3 on a solid molybdenum and liquid aluminum electrode is systematically investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) in the NaF-KF-AlF3 molten salt and the formation mechanism of Al-V intermetallic compounds is emphatically analyzed. The results show that the electrochemical reduction of VO3− on the solid molybdenum electrode is a multi-step process and low-valence vanadium oxide (V2O3) is obtained. In contrast, the electrochemical reduction of VO3− to V2O3 on liquid aluminum electrode is through one-step process and the deposition potential is more positive than that on molybdenum electrode owing to the depolarization effect of the liquid aluminum electrode. In addition, Al-V intermetallic compounds are obtained on the liquid aluminum electrode by potentiostatic electrolysis. The reduction process of VO3− on the liquid aluminum electrode is described as: the electrochemical process is started by the direct electro-reduction of VO3− to V2O3, which is further converted to Al-V intermetallic compounds under the combined effect of electrochemical and aluminothermic reduction, with the latter playing a dominant role.