Production of Tungsten by Pulse Current Reduction of CaWO_4

摘要

Tungsten is mainly produced by H_2 reduction of WO_3 which makes its production difficult and costly. A promising method was recently reported for direct electrochemical production of tungsten from CaWO_4 (scheelite) which is estimated as the seventy percent of the all tungsten reserves of the world. This paper investigates the application of pulse current in the electrochemical reduction of CaWO_4 pellets attached to a current collector. The electrolyte was composed of calcium chloride and sodium chloride salts at eutectic composition (48 pct mol NaCl at 873 K). The reduced samples were cleaned with dilute hydrochloric acid solutions and characterized by X-ray diffraction and scanning electron microscopy. Examination of the results revealed that metallic tungsten was obtained by pulse current reduction.