Chapter18FossilFuelsandtheEnvironment-Sarasota.ppt

Coal Classified according to its energy and sulfur content Anthracite Bituminous Subbituminous Lignite Energy content greatest in anthracite and lowest in lignite Lower sulfur coal emits less sulfur dioxide Coal Mining and the Environment In US thousands of sq miles disturbed by coal mining Only about half reclaimed The process of restoring and improving disturbed land, often by reforming the surface and replanting vegetation. Strip Mining A surface process in which overlying layers of soil and rock is stripped off to reach the coal. Over half of the coal in US mined this way One serious problem is acid mine drainage The drainage of acidic water from mine sites Happens in eastern US where there is abundant rain fall Strip Mining Acid mine drainage occurs where surface water infiltrates spoil banks Water reacts with sulfide minerals to produce sulfuric acid. The acid then pollutes streams and groundwater Strip Mining In arid and semiarid regions the land may be more sensitive to activities related to mining Exploration and road building Soils thin and water scarce Makes reclamation more difficult Reclamation can minimize damage Laws vary by site Strip Mining Appalachian Mountain’s of West Virginia Technique known as “mountaintop removal” Strip-mining levels tops of mountains and fills valleys w/ mining waste Flood hazard increases as valleys filled w/ mine waste and toxic waste water is stored behind coal waste sludge dams Also produces voluminous amounts of coal dust Strip Mining Surface Mining Control Act of 1977 US government has required that mined land restored to support pre-mining use Prohibit mining on prime ag land Reclamation includes Disposing of wastes Contouring the land Replanting vegetation Underground Mining Accounts for 40% of coal mined in the US Some of the environmental problems: Acid mine drainage from the mines and waste piles has polluted thousands of kilometers of streams. Land subsidence can occur over mines. Coal fires in underground mines