Investigation of the larger scale tungsten production by the electrochemical reduction technique

Hydrogen reduction of WO3 is the major industrial process in tungsten production. A promising cost and energy efficient method was recently reported [1-3] for direct electrochemical production of tungsten from CaWO4 (scheelite) which is estimated as the two third of the all tungsten reserves of the world. Following the above mentioned patent, several studies verified the production of metallic tungsten by electrochemical reduction of calcium tungstate in the laboratory. This study investigates the application of electrochemical reduction technique to produce larger amount of metallic tungsten as compared to laboratory experiments. The electrolyte was composed of calcium chloride and sodium chloride salts at eutectic composition (48 % mol NaCl at 873 K). The reduced samples were cleaned with dilute hydrochloric acid solutions and characterized by XRD and SEM. Examination of the results revealed that there are several problems against pilot-scale production, the biggest of which was observed as the electronic conduction provided by the graphite powders dispersed in the molten salt