Pluvial percolation in pyrite-bearing coal stockpiles

acid mine drainage is a main environmental problem linked to coal and sulfide ore mining. its treatment usually involves alkalinization and subsequent precipitation and immobilization of the dissolved species. rainfalls over stockpiles can cause a very similar phenomenon. this work aimed to study the effluents from such a leaching process in steam-coal stockpiles brazilian coal with a high pyrite content was used. the effluents have been chemically characterized. effluent clarification by aggregation and settling in an attempt to simultaneously deplete heavy metal content was studied. settling experiments were carried out with coal suspensions, in order to evaluate the efficiency of inorganic and polymeric reagents in the process.