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Column leaching tests of coal combustion by-products.
Kim AG; Sharp FA
Coal - Energy and the environment, proceedings of 12th Annual International Pittsburgh Coal Conference, September 11-15,1995, Pittsburgh, Pennsylvania. Chiang S-H, ed. Pittsburgh, PA: University of Pittsburgh, 1995 Sep; :126-131
Coal combustion by-products (fly ash, bottom ash, and flue gas desulfurization sludge) are classified as residual wastes, and their disposal is regulated by the states. When coal combustion by-products are placed in abandoned or inactive surface and underground coal mines, they may react chemically with naturally occurring fluids, such as rain, ground water and acid mine drainage. The U.S. Bureau of Mines is investigating possible reactions with a series of column leaching tests. Approximately 1 kg of material is placed in each of seven 5-cm by 1 m acrylic columns. The material is leached at a nominal rate of 250 mL/d for 60 days. Lixiviants include deionized water, artificial ground water, synthetic precipitation, and dilute solutions of acetic acid, ammonium hydroxide, sulfuric acid, and ferric chloride. Leachate is analyzed for pH, acidity/alkalinity, iron, calcium, aluminum, manganese, magnesium and heavy metals. Leaching tests have so far been completed on four fly ash samples. Eleven heavy metals were detected in at least 1% of the leachate samples; the average dissolution rate varied between 0.1 and 70 ppb per day.
Ann G. Kim, Pittsburgh Research Center, U.S. Bureau of Mines, P.O. Box 18070, Pittsburgh, PA 15236, USA
Coal - Energy and the environment, proceedings of 12th Annual International Pittsburgh Coal Conference, September 11-15,1995, Pittsburgh, Pennsylvania
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division