MICROBIAL REMOVAL OF RESIDUAL METALS FROM MINE TAILINGS AND DUMP WASTES

MILLIONS OF TONS OF MINE TAILINGS AND DUMP WASTES CONTAIN RESIDUAL METALS OF BOTH COMMERCIAL AND ENVIRONMENTAL INTEREST. MANY OF THESE MATERIALS CONTAIN ECONOMIC CONCENTRATIONS OF COPPER, SILVER, AND OTHER METALS. OTHER HEAVY METALS SUCH AS LEAD, ZINC, AND CADMIUM ARE FOUND IN THESE MATERIALS THAT MAY LEACH INTO SURFACE AND GROUNDWATER SUPPLIES. MANY OF THESE TAILINGS AND DUMPS HAVE BEEN ON-SITE FOR MANY YEARS AND HAVE BEEN WEATHERED OR OXIDIZED. THEREFORE, CLASSICAL BIOOXIDATIVE LEACHING IS NOT APPROPRIATE FOR THESE MATERIALS. RESEARCH SHOWS THAT BIOREDUCTIVE NONACID-GENERATING BACTERIA CAN SOLUBILIZE METALS FROM OXIDE MINERALS. MINE SPOILS CAN BE BIOLOGICALLY REPROCESSED RECOVERING MARKETABLE METALS TO SUPPORT THE OPERATIONS WHILE, AT THE SAME TIME, REMOVING OTHER METALS THAT ARE TOXIC TO THE ENVIRONMENT.