The Impact of Pyrite on Acid Mine Drainage
Formation of Acid Mine Drainage
Pyrite (FeS2) is a mineral that is commonly found in coal deposits and metal ores. When pyrite is exposed to air and water, it undergoes a chemical reaction known as oxidation. This process leads to the formation of sulfuric acid (H2SO4) and dissolved iron (Fe2+).
Reaction with Air and Water
When pyrite comes into contact with oxygen from the air and water, the following reaction occurs:
FeS2 + 7/2 O2 + H2O â Fe2+ + 2SO4^2- + 2H+
Formation of Mine Drainage
The sulfuric acid generated from the oxidation of pyrite lowers the pH of the surrounding water, making it highly acidic. This acidic water, along with dissolved iron, flows out of the mine and creates what is known as acid mine drainage.
Environmental Impact
Acid mine drainage can have devastating effects on aquatic ecosystems. The acidic water can harm fish, plants, and other organisms by disrupting their normal biological processes. The iron precipitates formed in the streams can also smother habitats and degrade water quality.
Prevention and Treatment
Effective management practices, such as covering exposed pyrite-containing rocks and properly treating mine drainage before it enters water bodies, can help mitigate the impact of acid mine drainage on the environment.