| Abstract
| - An increasingly common practice for metallurgical plantsis to discard their wastes by combining them with minetailings prior to disposing the blended material to acontainment facility. This practice has occurred since1985 at the Kidd Creek tailings impoundment, wherenatrojarosite, a waste produced from the adjacent Znrefinery, is combined with mine tailings and is depositedin a single impoundment. To assess the environmental impactof the co-disposal, a laboratory column experiment wasconducted. The column material was flotation tailings fromthe Kidd Creek site containing 3 wt % natrojarositeresidue. Dilute sulfuric acid was passed through thecolumn to simulate the acid generated in the unsaturatedzone of the tailings impoundment. The results of thisexperiment were compared to the results of a previousexperiment conducted on unamended flotation tailings. Theresults showed that the effluent from the column containingthe natrojarosite-bearing mixture had a faster decreasein pH, earlier increases in the concentrations of dissolvedmetals such as Pb and Cd, and a greater persistence ineffluent metal concentrations such as Pb, Zn and Ni. Toprevent the observed enhanced release of dissolved metalsfrom mine waste disposal areas, natrojarosite should notbe co-disposed with tailings.
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