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

The 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)WO(4 )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 ?. Similar thermal reduction in the presence of carbon result in the production of tungsten carbides, WC and W2C, obtained at around 1250 ?. 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.