Iron Dynamics in Acid Mine Drainage

The oxidation of iron sulfides in mine wastes is the main cause of acidic, sulfate, and trace element-rich acid mine drainage (AMD). However, the suite of reactions that transform iron from one species to another is quite complex. A reasonable strategy for controlling AMD production is to identify and further slow the slowest, rate-determining step (RDS) in the overall process. This paper provides an overall quantitative comparison of iron transformation rates in the AMD process using data from the literature and this comparison allows us to confirm that pyrite oxidation is the RDS for overall acid production over the entire pH range. ______________________ 1 Paper presented at the 7 International Conference on Acid Rock Drainage (ICARD), March 26-30, 2006, St. Louis MO. R.I. Barnhisel (ed.) Published by the American Society of Mining and Reclamation (ASMR), 3134 Montavesta Road, Lexington, KY 40502 2 Mark A. Williamson is Senior Geochemist for MFG, Inc., Applied & Environmental Geochemistry Group, 3801 Automation Way, Fort Collins, CO 80525; Carl S. Kirby is Assistant Professor of Geology, Department of Geology, Bucknell University, Lewisburg, PA 17837; J. Donald Rimstidt is Professor of Geology Department of Geosciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061