Simulation analysis on optimization of tungsten carbide recovery efficiency by molten salt electrolysis

The molten salt electrochemical method is an efficient one-step process to extract tungsten from tungsten carbide (WC). Owing to the limitation of molten salt electrochemical experiments and the number of data points, determining the optimal process conditions is challenging. In addition, the mechanism that affects the current efficiency is difficult to obtain intuitively. In this study, simulations of tungsten carbide anode electrolysis were obtained using the COMSOL Multiphysics 5.3, and the results were compared to the dissolution experiment of tungsten carbide with varying content of sodium tungstate (Fig. 1). The experimental data fitted well with the theoretical current efficiency of 75%. At concentrations below 0.5 wt% of sodium tungstate, the anode dissolution showed a linear relationship against the concentration of sodium tungstate. At a constant concentration of sodium tungstate, the anodic dissolution decreased with increasing immersion depth, consistent with the variation of cell voltage difference before and after electrolysis. The optimal immersion depth and effective area of the anode estimated by simulations were 2.5 mm and 0.465 mm2, respectively (Fig. 2). Under the optimum electrolysis conditions simulated by COMSOL, the nano tungsten powder was obtained.