Pyritic coal wastes produced by a coal beneficiation plant in the State of Santa Catarina in southern Brazil are acid generating. In this paper, we report the results from the first phase of a study evaluating the performance of dry covers for minimizing generation of acid mine drainage and its release to the environment. The first phase includes our investigation of locally available materials for dry covers. Numerical modeling led to four configurations being selected for testing: a dry cover using a double capillary barrier with bottom ash, a dry cover with a single layer of clay, a dry cover with mixed waste, and waste with no cover. Modeling also showed that the best position for the lysimeter was at the bottom of the excavation, where it would not interfere with the water flux in the waste. A subsequent paper will describe the construction of the experimental unit and the results of the geotechnical and geochemical studies.

Pyritic coal wastes produced by a coal beneficiation plant in the state of Santa Catarina in Southern Brazil are acid generating. Here we report the second part of a study evaluating the use of a dry cover to minimize acid mine drainage generation and its release into the environment. This part encompasses the construction and initial monitoring of an experimental pilot-scale unit. Local clays and ash from a power station were used as cover materials. Monitoring started in October 2007 and will extend for at least 4 years. Initial results of the dry cover system constructed using compacted locally available clay and ash look promising. The pH of the drainage ranged from 6.0 to 7.0, within the legal limits for discharge into the environment.