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Electrochemical Tailings Cover
Primary Issue Addressed: Source Control
Secondary Issue Addressed: None
Project Site: MSE’s Mike Mansfield Advanced Technology Center in Butte, Montana
Collaborating Entities: MSE, Enpar Technologies, Inc., Placer Dome’s Golden Sunlight Mine
Cost Share: In-kind services provided by Golden Sunlight Mine.
Project Description
This project is being conducted at the MSE Technology Applications, Inc. (MSE) test facility in Butte, Montana. The purpose of the demonstration is to gather performance information for the electrochemical cover technology developed by Enpar Technologies, Inc., of Guelph, Ontario, Canada.
Fresh, nonoxidized tailings along with soil cover were transported from the Golden Sunlight Mine (GSM) near Whitehall, Montana. Lined, in-ground test cells, each equipped with a leachate collection system, along with a common sprinkler system, were constructed at MSE’s test facility. Two test cells, loaded with tailings and capped with soil cover, were constructed as identical control cells, receiving no electrochemical cover treatment. Two additional test cells, loaded with tailings and capped with soil cover, were constructed as identical test cells and were equipped with the electrochemical enhancement. Equal amounts of water were applied to all four test cells through the summers of 2004 and 2005, since their installation in September 2003. Leachate was pumped from each test cell to maintain an artificial water table and to provide water for analytical purposes. Leachate water quality was monitored by regular sampling and analyses. Oxidation of the acid-generating tailings in all four cells is being assessed primarily by monitoring sulfate concentrations, along with specific conductance measurements. Sulfate mass produced by the two cells equipped with electrochemical cover treatment will be compared to that produced by the two control cells with no electrochemical cover treatment. It is anticipated that the two control cells will show higher sulfate concentrations and higher specific conductance, resulting from tailings oxidation. The field installation was to be monitored for 2?years, at which time, it will be dismantled and the tailings returned to GSM.
Status
Accomplishments in fiscal year (FY) 2005 included resuming irrigation and leachate collection in the spring of 2005, conducting multiple sampling events, and regularly checking the functional health of the electrochemical covers. Leachate analytical results were inconclusive at the end of FY05; data from all four cells indicated that soluble salts were still being flushed from the tailings with no noticeable indications of tailings oxidation. Dismantling of the field system was scheduled for early FY06, with the tailings to be returned to the Golden Sunlight Mine, and tailings samples obtained for acid-base accounting analysis to assess the effect of the electrochemical cover. It is anticipated that the acid-base accounting analyses will provide an indication of the performance of the electrochemical cover relative to the control cells.