Abstract: A hydrometallurgical method is provided for recovering copper from particulate copper sulfide flotation concentrate containing at least about 20% copper by weight as cuprous and cupric sulfide, a significant portion of the copper in the copper sulfide concentrate being in the cuprous state. The flotation concentrate in the finely divided state is subjected to leaching with an alkaline solution of ammonia plus ammonium sulfate at a temperature ranging from about 10.degree. C. to 95.degree. C., preferably about 20.degree. C. to 40.degree. C. the amount of concentrate being proportioned at least stoichiometrically to the ammonia concentration of the leaching solution.