Fluoride-Promoted Recovery of Tungsten from Scrap in Na2WO4 Molten Salt: A Mechanistic Study

Tungsten is widely applied in aerospace materials and precision machinery, but due to its high price and scarce resources, realizing the recovery and reuse of tungsten is urgent. The extraction of tungsten by Na₂WO₄ molten salt electrolysis is an emerging industrial route. In this study, the effect of fluoride on tungsten deposition is further investigated by adding NaF to the electrolysis system. The products of the cathodic attachment are characterized as tungsten monomers. Raman spectroscopic characterization verifies that the addition of fluoride enables the formation of the O–W–F bonds in the molten salt structure. The deposition potential of tungsten ions becomes lower with the increase of fluoride content, as demonstrated, and the reduction step is gradually turned from 3 steps to 1 step. Meanwhile, the deposition impedance of tungsten ions also decreases gradually, indicating that the fluoride can promote the deposition of tungsten at the cathode. DFT calculations and in situ Raman spectroscopy further verified the promotion of fluoride on the deposition of tungsten ions. This study provides theoretical support for the electrolytic recovery and recycling of tungsten.