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Acid Mine Drainage

Acid Mine Drainage. What is it?. Refers to the leaching of acidic waters from previously mined metal or coal sources. Sulfuric acid (acid rock drainage) comes from natural oxidation of sulfide minerals causing the formation. . How is it formed?.

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Acid Mine Drainage

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  1. Acid Mine Drainage

  2. What is it? • Refers to the leaching of acidic waters from previously mined metal or coal sources. • Sulfuric acid (acid rock drainage) comes from natural oxidation of sulfide minerals causing the formation.

  3. How is it formed? • When sulfide minerals are brought to the surface and exposed to oxygen or meteoric waters, sulfuric acid is formed. Contaminating water sources for surrounding environment and communities. • Although this process occurs naturally mining and construction can cause it to occur at an accelerated rate

  4. In Colorado • 1,300 miles of streams and 20,00 inactive mines are affected by acid mine drainage (general) • Lack clean drinking water and the survival of local flora and fauna • Silverton, Colorado- Mineral Creek has a pH of 3 and is laden in heavy metals. • Silverton has a history of mining for gold and silver which causes excess sulfide minerals to oxidize, creating acid runoff.

  5. Steps of Acid Mine Drainage • The sulfide mineral is oxidized when expose to air and water. 2FeS2 + 7O2 + 2H2O = 2FeSO4 + 2H2SO • The iron goes into solution and oxidizes from ferrous to ferric iron. 2Fe2+ + 1/2O2 +2H+ = 2Fe3+ + H2O • The ferric iron precipitates ferric hydroxide. Fe3+ + 3H2O = Fe(OH)3 + 3H+ • Sulfuric acid is created (Acid) FeS2(s) + 15/4 O2 + 7/2 H2O = 4H+ +2SO4-+Fe(OH)3(s)

  6. Acid Mine Drainage

  7. Discoloration • As ferrous iron precipitates as ferric hydroxide and is combined with fresh water, a yellow-orange solid known as yellow boy is formed. • Other types of iron precipitates may occur and contribute to the discoloration and toxicity of the water source.

  8. Angle • The angle of repose of a mine waste pile is about 45° • Waste piles of this angle are prone to excessive erosion, preventing the accumulation of biomass • In order for mine waste to be reclaimed, the overall biomass must be increased.

  9. Angle/Waste Pile

  10. Biochar • Shown to improve water retention, stabilize heavy metals, and raise the pH of contaminated soils. • Biochar is a sustainable material that is created through the carbonization of lodge pole pine which ahs been decimated by the mountain pine beetle of Colorado. • Simulates the effects of pyroysis, or thermochemical decomposition, on soil productivity (Fire) • Biochar helps amend soil and promote soil revegatation

  11. Biochar

  12. Biochar & Alternative Energy • Cooking stoves which produce biochar as a by-product • Industrial models capable of producing biochar • Bio-oils • Replacing fuel oil. • Fuel gasses • Reacts in a similar manner like coal.

  13. Why use biochar? • Reduces nitrogen oxide (green house gases) one of many causes of global warming. • Increases pH, stabilized heavy metals, and improves water retention of soil • Can be used as a bio-fuel

  14. Bibliography • http://www.biochar-international.org/biochar/faqs#q5 • http://www.biochar-international.org/biochar • http://kerrcenter.com/publications/intern-reports/biochar_factsheet.pdf • http://www.biocharproducts.com/bio-oil.html • http://www.diacarbon.com/bio-fuel

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