Acid and toxic drainage prevention and treatment
|
|
Photo Library: Acid and toxic drainage prevention and treatment |
| |
Before reclamation this Illinois mine site contained three slurry disposal impoundments. During the coal washing process acid materials were disposed of in the impoundments. Operating under special "Experimental Practice" guidelines of the Surface Mining Law, this reclaimed site is now free of acid and is a productive wetland habitat. During reclamation agricultural limestone and four feet of nontoxic soil material were spread on the old disposal areas then the entire area was fertilized and wetland vegetation planted.
Enlarged Photo (30 KB file)
Toxic elements and sulfur-bearing compounds, especially pyrite, may be present in certain coal beds, overburden, and soils. These materials can pollute water and kill vegetation if not handled and disposed properly. The sulfur in pyrite can oxidize to form sulfuric acid when exposed to air and moisture, and if present in sufficient quantity, will result in acid mine drainage. Acid mine drainage kills fish and vegetation and can create high concentrations of toxic elements that make surface and ground water generally unusable for livestock, domestic purposes, or irrigation. This acid seep is running out of overburden at a Pennsylvania abandoned coal mine. Enlarged Photo (40 KB file)
Rock layers identified as being acid forming (black color rock in the photo) have been segregated and are being buried high in the backfill of this Ohio mine. This "high-and-dry" approach seeks to minimize acid drainage production by keeping the material out of the water accumulating part of the backfill near the pit floor. Without water, acid drainage is prevented.
Enlarged Photo (30 KB file)