Molybdenite flotation

A process for recovering molybdenite from copper sulfide flotation concentrates containing minor amounts of iron sulfide comprising (1) preparing an aqueous pulp comprising the concentrate and about 0.2 to 1 pound of activated carbon per ton of concentrate, (2) injecting steam into the pulp in an amount and for a time sufficient to raise the temperature to about 70.degree. to 100.degree. C. and to maintain the pulp at this temperature for a period of about 10 to 60 minutes, (3) continuing steam injection while adding to the hot pulp an amount of soluble sulfide reagent sufficient to depress copper and iron sulfides, and conditioning the mixture for a period of about 0.5 to 3 minutes with continued steam injection, and (4) injecting a mixture of steam and air into the hot pulp in an amount sufficient for continued maintenance of the temperature of about 70.degree. to 100.degree. C. and to float a rougher molybdenite concentrate.