Effect of Acid Mine Drainage on Aluminum Release from Clay Minerals

Aluminum is an environmentally toxic material found in some acid mine drainage (AMD) locations. Data reported from over 150 different mine drainage samples across USA showed that over 30% of these locations presented minimum dissolved aluminum concentrations of 50 mg/L, elucidating that aluminum pollution must be taken seriously. Research underway at the University of Pittsburgh involves an AMD site where a former trout fishery stream has been ruined. The evolution of the aluminum in this AMD, released from a subsurface environment, suggested a first stage dominated by first order kinetics of exchange reactions on clay surfaces, followed by a second stage dominated by dissolution processes with lower rates that exist over a long term. Results from a batch experiment involving synthetic AMD and kaolin minerals were in concordance with this analysis.