Electrochemical dissolution of cemented carbide scrap and electrochemical preparation of tungsten and cobalt metals

Abstract

In this study, WC and WC-6 wt% Co scraps were utilized in molten salt state as two consumable anodes to circulate tungsten and cobalt during electrolysis. Because of poor dissolution of cemented carbide scrap in NaCl-KCl salt, tungsten trioxide was added to NaCl-KCl salt as active substance to improve the dissolution of the anode. Therefore, dissolutions of WC and WC-6 wt% Co anodes were studied at different tungsten trioxide contents. It was shown that addition of tungsten trioxide significantly increased dissolution of the anode. The addition of tungsten trioxide drastically reduced charge transfer impedance and accelerated the dissolution. The electrolyte resistance also reduced slightly. The electrolysis of WC anode was investigated at optimal tungsten trioxide content. Tungsten with single phase was obtained at current density of 0.1 A·cm−2 for 8 h. The electrolysis of WC-6 wt% Co anode was also explored using same tungsten trioxide content. The data suggested that electrolysis time and current density greatly influenced the composition of cathode product. The preliminary conditions were determined for separation of tungsten and cobalt. Overall, the electrochemical preparations of cobalt and tungsten metal were achieved by two-step electrolysis processes.