ACID COAL MINE DRAINAGE: AN OVERVIEW

Mining of coal is carried out in many parts of the world because of its large demand as an important industrial commodity. Exposure of coal and the associated minerals to the atmosphere because of mining results in the weathering of some of the constituent minerals contaminating the water regime in and around the mining area by the weathering products. The weathering of different sulfide minerals particularly pyrite, a common metallic mineral constituent in coal deposits, leads to the generation of acid which can contaminate mine drainage water and adversely affect the environment in the long run. Assessment of the acid generation phenomenon and prediction of mine drainage characteristics are helpful in deciding suitable mitigation measures to combat the environmental effects. This paper attempts to present a comprehensive picture of acid coal mine drainage phenomenon with respect to the genesis of the problem, assessment and prediction of mine drainage quality and, the approaches towards prevention and mitigation of the problem.