Molybdenite concentrate from cu-mo ores is purified by heating in an aqueous slurry containing 5-15 pct solids at 100 deg.-150 Deg. C and 200-600 psi o2 for 30-60 min to oxidize cu and s and dissolve them as cuso4. If the temperature, pressure, or time is exceeded, mo is also dissolved, with lower recovery and no better purification. Thus, 45 g of concentrate containing mos2 75.4, Cu 2.84, and fe 6.1 pct was treated with 450 ml of h2o with 30 min agitation at 150 deg. C and 245 psi o2, to give a 95.3 pct recovery of mos2 in a filter cake analyzing mos2 86.2, Cu 0.06, and fe 3.1 pct. When the reaction time was 2 h, the mos2 recovery was 60.2 pct; and when the o2 pressure was no more than 650 psi at 100 deg. C, the treated and filtered residue contained 79.9 pct mos2 and 6 pct cu.
U.S. Pat. 3,714,325; Jan. 30, 1973; Chem. Abstr. 79:44,644Y