US Patent 7686866 Recovery of copper from chalcopyrite

A process for recovering copper from chalcopyrite is disclosed. The process includes oxidising sulphur in chalcopyrite with a solution under predetermined contact conditions and thereby releasing at least part of the copper in the chalcopyrite into the solution as copper ions. The process includes a subsequent step of reducing sulphur in a solid product from step (a) to a minus two, ie. sulphide, valence state with a solution under predetermined contact conditions. The process further includes a subsequent step of oxidising sulphur in a solid product from step (b) with a solution under predetermined contact conditions and thereby releasing at least part of the remaining copper in the solid product into the solution as copper ions. The process further includes recovering copper from one or more of the solutions from steps (a) and (c).