Mineralogy Associated With Acid Mine Seepage as Determined Using Fourier Transform Infrared Spectroscopy and Relations to Acid Base Accounting

Abstract

Over 7,000 km of streams in the eastern United States are negatively affected by acid drainage from coal mines (U.S. Environmental Protection Agency, 1994). Pyrite (FeS2) is known to be the primary cause of acid formation, but analytical measurements to quickly and accurately detect trace pyrite content and predict acid drainage are lacking. This study analyzed sedimentary samples from a reclaimed east Texas lignite mine using Fourier Transform Infrared spectroscopy (FTIR) to detect the pyrite responsible for the environmental degradation of surface waters and the water table due to low (~2.5) pH. Subsequently, acid base accounting (ABA) was used to determine net acid forming potential of the mineralogy and determine FTIR utility. In conjunction with X-Ray Diffraction data, FTIR spectra and experiments and scanning electron microscopy (SEM) have semi-quantitatively detected the FeS2 which has and will release the H+ responsible for the low pH in the surface water bodies. Analytical techniques were used to develop a concept of how acid-formation from mine tailings can be predicted relatively accurately and quickly using FTIR.