A process for winning copper and zinc from brass mill waste products containing oxidic copper and zinc, iron, nickel, or cobalt. The feed material is leached in sulfuric acid, neutralized to a pH between about 2.5 and 3.0, and treated with zinc metal to precipitate copper. After separation of the copper product, residual copper as well as iron and cobalt are removed in a second, oxygen-free, cementation on zinc metal. The liquor is then raised to about pH 4.0 or greater and flushed with oxygen to precipitate iron. Lastly, the purified electrolyte is subjected to zinc electrowinning wherein acceptably pure zinc cathode is produced and sulfuric acid is regenerated.