Using Ammonia to neutralize low pH Acid Mine Water

[GWJPE]

Could someone out there provide me with the stoichiometric equation for the reaction between Anhydrous Ammonia & Acid mine water developed from pyrite?

I recently read about using to neutralize low pH acid mine water. The literature I read indicates NH3 is a good reagent, but it does not speak about the development of nitrates in the treated water.

With a balanced equation, I think I could calculate the amount of nitrates produced. This is important because the treated water gets disharged into a nearby stream. If the nitrates become to high, discharging becomes prohibited.

 

[bimr]

NH3 + H20 -> NH4 + OH

2NH3 + H2SO4 -> (NH4)2SO4

http://www.wvu.edu/~agexten/landrec/AMD_using_ammonia_to_treat_mine_water_W91.pdf

Anhydrous ammonia is effective in treating Acid Mine Drainage having a high ferrous iron and/or manganese content. Ammonia costs less than caustic soda and has many of the same advantages. However, ammonia is difficult and dangerous to use and can affect biological conditions downstream from the mining operation. The possible off-site impacts are toxicity to fish and other aquatic life forms, eutrophication and nitrification. Fish species generally exhibit low tolerance to unionized ammonia and toxicity levels can be affected by Ph, temperature, dissolved oxygen and other factors. A more complete review of ammonia treatment of mine drainage is given by Faulkner (1991). Ammonia use is not allowed in all States and, where permitted, additional monitoring is required.

http://ammoniapro.com/Ammonia Library/Water Treatment/National Ammonia_Acid Mine Drainage.pdf

http://wvmdtaskforce.com/proceedings/86/whi/86whi.htm

http://www.wvu.edu/.../AMD_special_chemicals_for_treating_AMD_Su93.pdf