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LIME TREATMENT LAGOONS TECHNOLOGY FOR TREATING ACID MINE DRAINAGE FROM TWO MINING SITES
Citation:
AlAbed*, S R., D Allen*, E R. Bates*, AND D. J. Reisman. LIME TREATMENT LAGOONS TECHNOLOGY FOR TREATING ACID MINE DRAINAGE FROM TWO MINING SITES. Presented at Hardrock Mining 2002 Conferences "Issues Shaping the Industry", Westminster, CO, 5/7-9/2002.
Description:
Runoff and drainage from active and inactive mines are someof the most environmentally damaging land uses i the US. Acid Mine drainage (AMD) from mining sites across the country requires treatment because of high metal concentrations that exceed regulatory standards for safe discharge to the environment. The purpose of this study is to provide an initial, bench scale, evaluation for the use of "lime treatment lagoons" as a possible treatment technology for contaminated acidic surface water from two sites (Copper Basin, Tennessee, and Leviathan, Nevada). Lime treatment lagoon technology uses well documented chemical pH dependent ractions to precipitate metal contaminants in mine drainage water. An alkaline reagent is used to raise the pH of the mine drainage to the required pH causing contaminant metals (As, Cd, Cu, and Zn) to precipitate as a sludge. We conducted bench scale (jar tests) on AMD samples obtained from both sites. Several alkaline reagents were evaluated in addition to CaO. All performed essentially the same as CaO except for limestone which failed to achieve the optimum pH of 8.5. Thus, the choise of alkaline reagent was based on cost and ease of use. Results show that CaO would be the reagent of choice based on cost and would be as easy to use as any other reagant. The Jars were treated with CaO to increase the pH and to precipitate the metals. The data obtained from treating AMD with CaO from the two sites consistently show that metal concentration levels can be reduced to less than 0.2 mg/L when the pH is raised to 8.5. Thus, this technology may represent the lowest cost treatment approach, and should be further investigated by means of a larger scale test in both sites.