Acid Mine Drainage :: science

Acid Mine waste pipeFor hundreds, even thousands of years, human beings have mined for metals and st superstars, and with the advent of greater applied science as well as greater needs, the demands for these resources continue to grow. While these resources value our lives in many ways, the effects of mining nooky be detrimental, and one such effect is the topic of this essay, acid mine drain (A.M.D.). The causes of A.M.D. exit be discussed, along with some of the physical and biological problems associated with it. Some bar and remediation treatments allow for also be considered. Acid mine drainage refers to body of urine (leachate, drainage or seepage) that has come into speck with oxidised rocks or overburden that contains sulphide material ( coal, zinc, copper, lead). (Keller, 2000 U.S.G.S. U.S.E.P.A., 2002). A common sulphide is pyrite, or iron disulfide (FeS2), and throughout this essay it pull up stakes be pyrite that will be the primary sulphide considered. Acid m ine drainage is non a new phenomenon, early mining techniques utilized gravity to block water pooling, resulting in the water becoming foul by acid, iron, second and aluminium (U.S.E.P.A., 2002). It is most commonly associated with coal mining, especially with soft coal, coal that has high sulphur content. The pyrite that is present in coal seams will be portalible after surface mining when the overlying surfaces ar removed or in deep mines that allow oxygen access to the previously inaccessible pyrite-containing coal (D.E.P. 1, 1997). After pyrite is exposed to send and water, sulphuric acid and iron hydroxide are formed, creating an acidic outpouring (D.E.P. 1, 1997 2 2002). When the water comes into contact with the pyrite, the chemical reactions that take place causes the water to increase in pH which will dissolve heavy metals which taking into custody in solution. However, when the pH levels reach a certain stage, the iron can then precipitate out, coating sediments with the characteristic yellow, red or orangeness colourings (D.E.P. 2, 2002 U.S.G.S. U.S.E.P.A., 2002). The rate that A.M.D. advances is also influenced by the presence of certain bacteria (Doyle U.S.G.S). A.M.D that has turn heavy metals such as copper, lead and mercury can stain ground and surface water. Especially at risk are mines that are located above the water table (Keller, 2000 D.E.P. 2, 2002). The sources of water that get polluted can be surface water that permeates into the mine, shallow ground water flowing through the mine or any water that comes into contact with the waste tailings produced by mines.