Dissolution of tungsten carbide and valence analysis of tungsten ions in chloride-fluoride molten salts

The main obstacles to the production of metals such as tungsten are the multi-step reaction processes and disproportionation reactions. Tungsten has more metastable valence states in molten salt and is more likely to undergo side reactions. To implement the low-valence reduction of tungsten, the composition of the molten salt system was changed. The influence of fluoride ions on the valence states of tungsten ions was determined by experiments and simulation analysis. The preliminary results suggested that a one-step direct reduction to metallic tungsten could be achieved by selecting a proper [Cl-]/[F-] ratio. This change of the valence state, which is the primary issue for tungsten reduction, was overcome by understanding the interactions between the ions and the coordination form. More specific details related to the variation of the reaction process and coordination form were provided by simulations. The simulation results showed that low-valence tungsten ions were dissolved from tungsten carbide at appropriate [Cl-]/[F-] ratios, and the change of the coordination form of the tungsten ions affected the reduction process of these ions with various valence states. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The main obstacles to the production of metals like tungsten are the complex reaction processes and disproportionation reactions. To overcome these obstacles, the composition of the molten salt system was modified to achieve the low-valence reduction of tungsten. Experiments and simulation analysis showed that the presence of fluoride ions influenced the valence states of tungsten ions. Simulation results demonstrated that by selecting a proper [Cl-]/[F-] ratio, a one-step direct reduction to metallic tungsten could be achieved, and the coordination form of tungsten ions had an impact on the reduction process.