APPROVAL

Surface coal mining and hard rock mining operations often expose iron sulfide minerals (e.g. pyritic sulfur) and organic sulfur containing substances to a new oxidizing environment. Acid generation from the oxidation of these materials often inhibits the revegetation of mine spoils. A total lime requirement must be determined to mitigate existing acidity and prevent re-acidification from the continued oxidation of sulfide and organic sulfur containing materials. Traditional agricultural lime rate determination methods are not appropriate for mined land situations where the majority of acid production is from the weathering of relatively insoluble minerals such as pyrite. Because of this limitation, acid-base accounting has become the standard in the reclamation industry for the estimation of lime requirements for acid mine spoils. This method, however, has technical limitations and frequently leads to erroneous results. Thus, there is a need for the development of a reliable methodology to determine the total lime requirement for acid mine wastes. In this study, simulated weathering chambers were designed to examine acid production potential of mine waste materials under weathering conditions similar to the natural mine site. This methodology eliminated errors in interpretation of acid-base account data and provided a more accurate lime rate recommendation for acid mine spoils