Tungsten is recovered from refractory ores by roasting, rapidly quenching, and leaching. Thus, a w ore containing 1.63 pct wo3, particle size 65 pct -325 mesh, was heated at 800 deg c for 2 h and immediately poured into a rapidly agitated aqueous solution of naoh 2.5 and na2co3 2.5 pct. The mixture was transferred to an autoclave and leached at 200 deg c and 200 psi for 2 h. The mixture was cooled and filtered, and 95 pct of the w was extracted from the ore. Chem. Abstr. 91:161,036K (see also chem. Abstr. 90:190,325P) tungsten is recovered from hot-springs tungsten ores (blanketlike deposits and veins underlying beds of calcareous tufa). The ores are calcined at 800 deg-950 deg c, quenched in a solution of naoh and na2co3, and leached in an autoclave at 180 deg-300 deg c and 200- 500 psi. Thus, w ore was calcined at 900 deg c for 2 h and quenched in a solution of naoh 2.5 and na2co3 2.5 Wt pct. The mixture was transferred to an autoclave and reacted at 200 deg c and 300 psi for 2 h. After filtering and washing, the leach solution contained 95 pct of the initial wo3.
U.S. Pat. 4,167,555; Sept. 11, 1979; Chem. Abstr. 90:190,325P