Abstract: A process for the recovery of copper from a copper sulphide concentrate in slurry form. The slurry is subjected to a biological oxidation turning the copper sulphide to soluble copper sulphate. The liquid containing the copper sulphate is separated from the slurry and treated with an oxime solvent extraction reagent so that copper ions are exchanged by the reagent for hydrogen ions to produce a raffmate which is high in sulphuric acid and low in copper sulphate. The solvent extraction reagent is then stripped from the raffinate with a sulphuric acid solution. Copper is electrically harvested from the sulphuric acid solution and the copper depleted raffinate can be returned to again form a slurry with additional ore for subsequent biological oxidation. The preferred bacterium is one of Thiobacillus Ferro-oxidans, Thiobacillus Thio-oxidans, Leptospirrilum Ferro-oxidans, Thiobacillum Caldus, and Sulpholobus.