Sodium chloride and sodium silicate containing a tungsten ore (scheelite or wolframite) are melted, and the melt is sparged with methane or natural gas at 900 deg-1,100 deg c to form tungsten carbide, wc. Thus, wolframite containing wo3, fe2o3, and mno was mixed with nacl and na2sio3 and the mixture melted at 1,075 deg c. A very fluid halide phase containing 31.4 pct wo3 was formed and separated from the highly viscous silicate phase. The halide phase was treated with ch4 at 1,100 deg c by sparging. The recovery of w as wc was 81 pct, and the wc contained al 0.005, Cu 0.007, Fe 0.10, Mgo 0.005, Mn 0.05, Mo <0.001, Si 0.07, Sn 0.009, Ti 0.01, V 0.006, O 0.34, and c 6.19 pct. The specifications for commercial wc are: free c 0.10, Fe 0.15, Mo 0.10, Wt pct maximum, and the stoichiometric carbon content of wc is 6.13 pct.
U.S. Pat. 4,489,044, Dec. 18, 1984; Chem. Abstr. 102:187,435K