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Comparative tests to remove manganese from acid mine drainage.
Control of acid mine drainage: proceedings of a technology transfer seminar. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, IC 9027, 1985 Jan; :41-47
The Surface Mining Control and Reclamation Act of 1977 mandates that mine drainage discharge water meet quality standards for pH, iron, manganese, and total suspended solids. These standards are shown in table 1. Typical treatment of acid mine drainage involves addition of an alkaline material (such as lime or sodium hydroxide), natural or mechanical aeration, and settling. When mine drainage is neutralized to a pH near 7, the ferrous iron oxidizes and forms an iron sludge, Fe(OH)3. This treatment satisfies the effluent standards for pH and iron, but may not remove much manganese from the water. Typical acid mine drainage contains 1 to 8 mg/L manganese, but concentrations of 50 to 100 mg/L are not uncommon. At present, most mine operators with manganese problems are using excess alkalinity to raise pH of the mine water to about 10.0 to precipitate manganese. During the precipitation of manganese, as MnO2, acid is produced and the pH of the water decreases. Whether or not the pH will fall below 9.0 depends on individual mine water characteristics. If the pH remains above 9.0 the mine operator has two options: apply to State authorities for a variance to discharge high-pH water, or reacidify the high-pH water. An alternative to excess alkalinity is the use of chemical oxidants such as chlorine gas, hypochlorite salts (sodium and calcium), ozone, potassium permanganate, or hydrogen peroxide. These oxidants can oxidize soluble manganese to insoluble Mn0 2 at pH values within the regulatory criteria. Based on a review of the literature on manganese removal, three chemical treatments were selected for field testing: excess alkalinity, sodium hypochlorite, and potassium permanganate. The selection of these treatment methods was based on ease of use, costs (capital and operating), availability, effectiveness, and likelihood of acceptance by the mining industry.
Acid mine drainage; Mining; Mining industry; Waste treatment; Waste abatement
IH; Conference/Symposia Proceedings
Control of acid mine drainage: proceedings of a technology transfer seminar
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division