These sites are examples of an "externality", a cost that is not borne by either the mining company or the purchaser of the minerals see our article on "True Cost". For example, metal at the historic Kennecott Copper Mine in Alaska was found in conjunction with large amounts of carbonate that neutralized any acid-forming compounds.
Carbonate rocks limestone are a typical alkali mineral sometimes associated with sulfides. Isolating very large quantities of acid-generating waste and rock is difficult, either above or below ground, and in many cases is effectively impossible.
Copyright held by photographer Summary Acid mine drainage AMD refers to the outflow of acidic water from a mining site. In addition to the direct effects of this acidity, acid water leaches toxic heavy metals such as lead and arsenic from the surrounding rocks into the water.
However, evidence suggests that reclamation bonds are seldom or never adequate to cover the actual costs. As the water becomes less acidic, metals and other solids come out of solution.
As with all acid mine drainage sites, the rocks will remain capable of generating sulfuric acid for an unknown number of years, perhaps throughout the entire future human habitation of the region.
However, in many cases, the water flowing out from waste ponds still needs to be treated to neutralize acidity before it is released into the environment. Historically, however, costs have been borne by the government when the mining companies responsible for the original mine go defunct.
Extracting valuable metals from ore usually involves crushing the ore rock into a mud slurry, where each particle can be less than 50 millionths of a meter across.
The sulfuric acid produced in sulfide mine tailings makes the surrounding water more acidic, sometimes dramatically so. These systems are far less costly to build, but are also less efficient i.
Additionally, heightened acidity reduces the ability of streams to buffer against further chemical changes. Roman-era mines have been identified which are still producing acid mine drainage. Microbes and drug discovery[ edit ] Scientists have recently begun to explore acid mine drainage and mine reclamation sites for unique soil bacteria capable of producing new pharmaceutical leads.
A significant number of coal mines also suffer from acid mine drainage. Each alone is caustic, but combined they neutralize each other, like baking soda a base and vinegar an acid.
Ion exchange[ edit ] Cation exchange processes have previously been investigated as a potential treatment for acid mine drainage. The potential impacts of acid mine drainage on Bristol Bay fisheries is the primary source of opposition to the proposed Pebble Mine in southwestern Alaska and also a concern at the proposed Donlin Gold Mine.
Precipitation of metal sulfides[ edit ] Most base metals in acidic solution precipitate in contact with free sulfide, e. Extracting the valuable metals from these rocks, however, involves extracting and crushing the ore.
Theoretically, acid formation is neutralized where sulfide ores occur alongside more alkali minerals, since alkali a.
They are isolated from the atmosphere and surface waters by their depth, providing relatively little surface area for them to react with water and oxygen.
Soil microbes have long been a source for effective drugs  and new research, such as that conducted at the Center for Pharmaceutical Research and Innovationsuggests these extreme environments to be an untapped source for new discovery."ARD causes a crushing effect on the nature of the ground or surface water it releases to.
(Ellison & Hutchison)" Corrosive MINE DRAINAGE Inside the mining.
Acid mine drainage is a problem at a number of active Alaskan metal mines including Red Dog, Greens Creek, and Kensington Mine. The potential impacts of acid mine drainage on Bristol Bay fisheries is the primary source of opposition to the proposed Pebble Mine in southwestern Alaska and also a concern at the proposed Donlin Gold Mine.
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Get started now! Chemical Stability of Acid Rock Drainage Treatment Sludge and Implications for Sludge Management DANNY M. MCDONALD* AND JOHN A. WEBB Environmental Geoscience, La Trobe University. A Study of the Cause, Effects and Treatment of Acid Rock Drainage PAGES 2. WORDS 1, View Full Essay. More essays like this: Not sure what I'd do without @Kibin Sign up to view the complete essay.
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Show me the full essay. View Full Essay. This is the end of the preview. Sign up to view the rest of the essay. Acid rock drainage is the term used to describe leachate, seepage, or drainage that has been affected by the natural oxidation of sulfur minerals contained in rock which is exposed to air and water.
The major components of ARD formation are reactive sulfide minerals, oxygen, and water.Download