Electrochemical Extraction of Tungsten Derived from WC Scrap and Electrochemical Properties of Tungsten Ion in LiCl-KCl Molten Salt

Abstract

Tungsten carbide (WC) scrap was used as a consumable anode to produce metallic tungsten in LiCl-KCl molten salts at 773 K. The feasibility of direct electrochemical dissolution of the WC anode to metallic tungsten was analyzed by thermodynamic calculations and experimental verifications. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were applied to investigate the dissolution of the WC anode, and the electrochemical properties of the issued tungsten ions in LiCl-KCl melts were studied by cyclic voltammetry (CV), square wave voltammetry, and chronopotentiometry. The results revealed that the WC anode could be used as a consumed anode to produce tungsten powder and the electroreduction of tungsten ions in the melts was achieved through a one-step reaction involving four exchanged electrons. Furthermore, it was found that the reaction was limited by the diffusion of tungsten ions in the solution with a diffusion coefficient estimated as 5.9 × 10−7 cm2/s at 773 K. Finally, analysis of the cathode products using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and energy dispersive spectroscopy (EDS) showed that tungsten powders could be prepared from a molten salt bath.