Biotechnological processing of slag and tailings

摘要

It has been shown in the past that biological treatment can be used to clean up slag and tailings. However, for a long time it was not economically viable to apply these biological processes due to very slow conversion rates thus resulting in large applications at high investment and operational costs. With high rate biotechnology that was developed during the 1990's, there is now a possibility to apply the biological processes in a cost efficient manner. In this paper, full-scale installations and other applications will be discussed for the treatment of tailings. At the Caribou Mine in New Brunswick, Canada, acid mine drainage is treated with bio-genie sulphide. This plant is situated upstream of a conventional lime neutralization plant. As a result, saleable ZnS is produced to offset lime treatment costs, the volume of the sludge (gypsum and hydroxides) from the lime plant is reduced significantly, the sludge is free of heavy metals and the final effluent concentration of heavy metals meets current discharge criteria for all metals. In the second phase of this project, metals will also be recovered from stored tailings, resulting in significant revenues.