Production of Metallic Tungsten and Tungsten Carbide from Natural Wolframite and Scheelite via Sulfide Chemistry

Abstract

AbstractThe development of sulfide-based chemistry and physical separation in the last decade opens new processes to produce metals at the industrial scale. Herein, a new route to produce metallic tungsten and tungsten carbides particles from natural wolframite (Fe,Mn)WO4 and scheelite CaWO4 is presented. Sulfidation of mineral concentrates breaks the tungstate crystal structure into a mix of sulfides, in particular tungsten disulfide WS2. The thermal instability of WS2 at high temperature allows for its subsequent, selective, thermal reduction to tungsten particles at around 1500 °C. Similar thermal reduction in the presence of carbon result in the production of tungsten carbides, WC and W2C, obtained at around 1250 °C. The other major components of the sulfidized concentrate remain un-reduced under the proposed conditions, demonstrating selective reduction of WS2 as a possible new route for W recovery. Similar findings are reported for the carburization of WS2.