Abstract: The slowly cooling copper smelting slag of flash furnace contains 1.01% copper.Main valuable minerals are bornite，chalcocite and chalcopyrite.Main gangue minerals are pyroxene，glass and magnetite.In order to achieve high efficiently recovery of copper，copper flotation experiment was carried out on basis of process mineralogy research.Results indicated that，at the grinding fineness of 90% passing 0.045 mm，via two roughing(one roughing scavenging to obtain high grade copper concentrate)，three cleaning，two scavenging process.First roughing preferential quickly flotation with collector BK-908 dosage of 20 g/t，foaming agent 2# oil dosage of 20 g/t，second sulfide roughing scavenging with collector EP dosage of 40 g/t，pH adjusting agent lime dosage of 500 g/t，vulcanizing agent sodium sulfide dosage of 250 g/t，foaming agent 2# oil dosage of 30 g/t，finally，copper concentrate with copper grade of 17.77% and recovery of 89.38% were obtained.

Key words: Slow cooling copper smelting slag, Asynchronous flotation, Copper oxide, Sodium sulfide