Static Coal Storage - Chemical Effects on the Aquatic Environment

The aqueous leaching of heavy metals from soft coal has been examined under a variety of conditions. Variables examined were pH, particle size, rate of flow, time of contact and oxygen or nitrogen atmosphere. Simple leaching of coal from Western mines with pure water does not remove large amounts of metal. Metal removed was in most cases about 0.1% to 0.5% of the total metal in the coal. Extended, successive leaches (of about one week duration) and leaches in a mildly acid (acetic acid-acetate buffer; pH%4.7) tended to remove larger amounts of some metals. Leaching with a strong com­plexing agent removes relatively larger amounts of metal. When placed in contact with water previously spiked with metal ions, the coal actually re­ duces the aqueous concentration of many metal ions. Continuous flow and simple shaker experiments correlate qualitatively with each other. Considerable variation was found between Eastern and Western coal and also between different samples of Western coal.US EP