British Columbia Mine Reclamation Symposium

The effectivesness of vegetation in controlling acid generation in base metal tailings Veldhuizen, Hennie; Blowes, David, 1956-; Siwik, Richard S.

Abstract

Noranda, Inc., which currently owns 18 mines in Canada and the United States, maintains a high degree of commitment to environmental protection. Reclamation research in the early 1970’s at Noranda Waite Amulet site led to a successful vegetation program. However, the expected benefits of vegetation in reducing acid generation at Waite Amulet have not been realized. Further research efforts have been undertaken at Heath Steele Mines Ltd., Newcastle, N.B., Waite Amulet, Rouyn-Noranda, P.Q., and a high carbonates tailings site in Ontario. The program involves a characterization of the geochemistry and hydrogeology and an evaluation of the parameters which control oxidation. Modelling tools will be evaluated for predicting the geochemical behaviour of these tailings with time and under varying reclamation scenarios. Direct vegetation of reactive tailings has not restricted oxygen diffusion nor has it limited water infiltration. Consequently, oxidation of sulphide tailings is occurring, acid water containing heavy metals is being generated and complex geochemical processes of neutralization, precipitation, co-precipitation and absorption are raking place to ameliorate pore water quality. The upper 1 to 2 m zone of oxidation is influenced by such factors as the water table and the sulphide content and particle sizing of the tailings. Infiltrating water due to precipitation and snowmelt transports pore water containing dissolved metals through the tailings and into the groundwater and surface seepage systems.

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