(Reissue of Pat. 4,489,044). Formation of Tungsten Monocarbide from a Molten Tungstate-halide Phase by Gas Sparging.
Nacl and na 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 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% 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%, and the wc contained al 0.005, Cu 0.007, Fe 0.10, Mg 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%. The specifications for commercial wc are free c 0.01, Fe 0.15, Mo 0.10 Wt % max and stoichiometric c content of wc 6.13%.