(3) the exposure, usually as a result of mining, of sulfide bearing minerals to air and water, forming sulfuric acid. This acid dissolves metals such as lead, zinc, copper, arsenic, selenium, mercury, and cadmium into ground and surface water. Acid rock/mine drainage can poison ground and drinking water and destroy aquatic life and habitat. Commonly mined ore bodies that pose the risk of acid rock drainage include gold, silver, copper, iron, zinc and lead. (4) low pH drainage derived from materials with an insufficient capacity to neutralize the acidic products of sulfide and elemental sulfur oxidation and the dissolution products of acidic minerals and amorphous materials. ARD is produced when the neutralization potential is no longer capable of maintaining neutral pH conditions. In the context of mining, may be referred to as acid mine drainage (AMD).
Acidic, heavy-metals-laden stream contamination resulting from the drainage of water that contains acidic soils and tailings (residues) from the mining process. Usually associated with surface and underground coal mining.
Low pH drainage water from certain mines usually caused by the oxidation of sulphides to sulphuric acid. Mine drainage can also contain high concentration of metal ions.
Water leaving a surface or underground mine enriched in acid, usually surfuric acid.
Water mixed with sulfuric acid and having a pH of 6.0, due to minerals containing sulfides, etc. The sulfuric acid mixes with water and flows out of the mine into surrounding areas as acid mine drainage.
Liquid drainage from bituminous coal mines containing a high concentration of acidic sulfates, especially ferrous sulfate.
AMD is formed through a series of chemical and biological reactions that occur when a pyrite found in rock strata is disturbed and exposed to oxygen and moisture as a result of mining operations. AMD may contaminate surface and ground water.
The general term applied to water being discharged from a mine, a tailings pond or leaching through a mine spoil dump. Most mine drainage is acidic, but can also be either neutral or even alkaline. Mine drainage can carry a significant level of metals in solution.
Drainage of water from areas that have been mined for coal or other mineral ores. The water has a low pH because of its contact with sulfur-bearing material and is harmful to aquatic organisms.
(AMD) water draining out of surface or subsurface mines that has an extremely low pH ( i.e. high concentration of hydrogen ions); it often contains high concentrations of sulfur, aluminum, and heavy metals such as iron.
Acidic run-off water from mine waste dumps and mill tailings ponds containing sulphide minerals. Also refers to ground water pumped to surface from mines.
Drainage of water from areas that have been mined for coal or other mineral ores. Because of its contact with sulfur-bearing material, the water may have a very low pH and be harmful to aquatic organisms.
The term AMD is used, in this context, to refer to any pollutional discharge emanating from a mining operation. Many of these discharges are, in fact, alkaline with high levels of metals.
water which is affected by passage through, or alteration by, coal or abandoned coal mine environments. Acid mine drainage can have acceptable water quality, but often it is contaminated. Contaminated MD lowers water quality and kills aquatic life (fish, insects, etc.). Contaminated acid mine drainage most often has these characteristics: 1) Low pH (high acidity) 2) High metals concentrations 3) Elevated sulfate levels 4) Excessive sediment and siltation Acid concentrations in streams can kill many life forms and stunt the growth of others. Acidic water also can break down the metallic compounds of iron, sulfur, manganese and aluminum found in nearby rock or earthen waste piles.
Acid Mine Drainage (AMD), a form of Acid Rock Drainage, usually has a pH of 2.0 to 4.5 and is produced through the disturbance and exposure of large quantities of sulfide-bearing rocks by mining activities. The products of AMD formation, acidity and iron plus other heavy metals, can devastate watercourses by lowering the pH and coating stream bottoms with iron and aluminum hydroxides. These form the familiar orange-colored "yellow boy" common in areas with abandoned mine drainage, and (as at Molycorp) a bluish-white aluminum precipitate which destroys invertebrate populations and prevents trout spawning. "Acid mine drainage (AMD) is the number one environmental problem facing the mining industry. AMD is virtually impossible to reverse with existing technology once it starts." - Mineral Policy Center. See also: Acid Rock Drainage (ARD).
Acid mine drainage occurs when abandoned mine sites are drained by water whose pH lowers as it passes through the mine.
Drainage of water from areas that have been mined for coal or other mineral ores; the water has low pH, sometimes less than 2.0 (is acid), because of its contact with sulfur-bearing material.
Acid mine drainage (AMD), or acid rock drainage (ARD), refers to the outflow of acidic water from (usually) abandoned metal mines or coal mines. However, other areas where the earth has been disturbed (e.g. construction sites, subdivisions, transportation corridors, etc.) may also contribute acid rock drainage to the environment. In many localities the liquid that drains from coal stocks, coal handling facilities, coal washeries, and even coal waste tips can be highly acidic, and in such cases it is treated as acid rock drainage.