Electrochemical treatment of pyrrhotite-rich tailings-a laboratory study

Many sulphide minerals are semiconductors and are therefore amenable to electrochemical manipulation. Large scale massive sulphide bodies can act as solitary electrodes in electrochemical cells. In mill tailings, however, sulphide minerals occur as silt- to sand-sized particles. The present study wasconducted to determine if the same in-situ electrochemical treatment system used for sulphide bodies might work on a tailings deposit that is greater than 75% pyrrhotite. The objective was achieved by determining two key factors: (1) the mechanism of charge transfer within tailings: electronic vs electrolytic and (2) where cathodic reductions reactions occur, i.e., on the surface or within the tailings body. Results showed that electronic conduction predominated over electrolytic conduction in the tailings sample. Most of the reduction reactions took place at the outer surface of the tailings mass rather than within the tailings matrix. This study confirmed that the identified tailings deposit behaves as a single conductive body and is therefore a potential site for installation of an in-situ electrochemical treatment system. © IMWA Springer-Verlag 2001.