ABSTRACT
Metal separation processes directly applicable to solid wastes consist of biological processes, flotation, magnetic separations, pyrometallurgical processes, and solvent partition. These processes are most successful for metal wastes with minimal amounts of secondary contaminant metals and here provide potential opportunities for dewatering and/or concentration if not separation. Biological processes can also play a role in the separation of metals. One type of process arises from the solubilization effect of organisms, such as certain bacteria, on minerals and various solid wastes. The leaching of copper sulfide ores with Thiobacillus ferrooxidans has been used for some time as a commercial process for copper recovery. Another type of separation process that has been considered is the accumulation by adsorption-ion exchange of metal cations in aqueous solution onto organic substrates, notably algae such as Chlorella pyrenoidosa, Spirulina, Penicillium, and Cladosporium. Practical success with the biological separation processes requires coping with large volume reaction systems and the patience needed for low-temperature reaction kinetics.
