Rapid ferrous sulfate biooxidation

Disclosed is an improved process for using iron-oxidizing bacteria to reactivate the raffinate ferrous sulfate solution in chemical leach operations. The process uses a biological raffinate converter, or BRC, as a key feature of the process. The invention process provides enhanced efficiency and commercial utility over the best known biological process for converting raffinate ferrous sulfate. The resulting ferric sulfate then can be recycled back into the bioleaching process of, for example, copper from chalcocite.