Study on the air atmosphere molten salt electrolytic extraction of tungsten and cobalt from cemented carbide scrap

Abstract

In this study, tungsten and cobalt were extracted from cemented carbide scrap by three-stage electrodeposition in Na2WO4 molten salt at 900 °C in air atmosphere. The cemented carbide scrap was used as the consumable anode, while the cemented carbide calcined material was used as the electrolytically active substance additive. The composition of the cemented carbide calcined material was determined by thermodynamic calculations combined with XRD phase analysis. The study investigated the promoting effect of air atmosphere on anode oxidation and the effect of varying the molar ratio of tungsten to cobalt in the molten salt on product composition. Cyclic voltammetry was used to analysed the cathodic reduction behaviour of tungsten and cobalt. The nucleation mechanism of tungsten and cobalt was determined to be instantaneous by chronoamperometry. Finally, metallic tungsten and cobalt were successfully separated and extracted by three-stage constant current electrolysis.