Identification of toxicity in the Laronde Mine final effluent
Symposium Rouyn-Noranda 2002
Laronde Mine has been working since a few years to identify the substances that contribute to the toxicity of the process water and to search for an effective treatment system. The first studies had identified ammonia, nitrate, cyanide and thiocyanides, cyanates, dissolved organic carbon, copper and zinc as potential substances for the origin of the toxicity. Laboratory tests were carried out with the help of Lakefield Research in order to find an effective treatment to eliminate water toxicity. Nine types of treatment were assessed: 1) treatment with granular activated carbon followed by a zeolite treatment, 2) a zeolite treatment followed by a treatment with granulated activated carbon, 3) aeration followed by a treatment with granulated activated carbon, 4) granulated activated carbon in stages, 5) chlorination followed by dechlorination, 6) addition of bentonite-based polymers, 7) treatment with peroxide followed by an ultraviolet treatment, 8) treatment by the addition of carbon powder and zeolite powder, 9) treatment with bacteria.
This article summarizes the test results and the special problems associated with choosing a technology to treat the toxicity.