Direct electrolytic separation of tungsten and cobalt from waste cemented carbide and electrochemical behavior of tungsten and cobalt ions in NaF-KF molten salts

摘要

In this study, WC-10Co cemented carbide scrap was used as a consumable anode to separate and prepare tungsten and cobalt powders in NaF-KF melts at 1073 K. The feasibility of direct electrochemical dissolution of WC main phase to produce metallic tungsten was analyzed by thermodynamic calculations and experimental verifications. Furthermore, a series of electrolysis experiments were performed under constant cell voltage for selective preparation of tungsten and cobalt powders. The results show that metal cobalt powder was obtained at <= 0.6 V whereas metal tungsten powder was produced between 0.6 V and 1.2 V. The analysis of cathode products using scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) show that tungsten and cobalt powders can be prepared in NaF-KF melts. Finally, linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were used to investigate the dissolution of WC-10Co anode. The electrochemical properties of tungsten and cobalt ions in NaF-KF melts were studied by cyclic voltammetry (CV) and square wave voltammetry (SWV). The results show that WC-10Co anode could be used to produce tungsten and cobalt powders and the electroreduction of tungsten and cobalt ions in NaF-KF melts was achieved through a one-step reaction involving the transfer of two electrons.