Geochemical characterization of acid mine drainage associated with the Makum Coalfield, Assam, India

摘要

The Makum coalfield is the largest producing Tertiary coalfield in India. Several collieries are highly affected by acid mine drainage (AMD) problems. Two types of mine drainage water were recognized, namely nearly neutral and highly acidic. Both types are characterized by high concentration of SO<,4>, Fe, Al, Mn, and Ni while concentrations of Zn, Cr, Cu, Cd and Hg are lower. Tikak, Tirap and Tipong collieries were found to be highly affected where as Ledo and Baragolai collieries are less affected by AMD. There is a systematic decrease in concentration of metals and increase in pH away from the point of discharge of mine water. This may be due to adsorption of metals on to the secondary minerals precipitated from solution. X-ray diffraction indicates the presence of jarosite, goethite and schwertmannite in the ochreous precipitates.