Management of acid mine drainage (AMD) in Indian coal mines

Abstract

Mining practices, present and past, contribute towards environmental degradation affecting the ecosystems and human health. The unscientific coal mining in the tertiary North Eastern Region (NER) Indian coal mines poses a serious threat to the environment. Dumping of waste rocks including mine rejects generated during mining adds to the problem by aqueous weathering and discharge of acidic effluents. The coal mining in Meghalaya causes large-scale destruction and degradation of the environment. Coal extraction in the state is done by primitive sub-surface mining methods commonly known as ‘rat hole’ mining. The indiscriminate and unscientific mining, absence of post mining treatment and management of mined areas are making the fragile ecosystems more vulnerable to environmental degradation and leading to land use changes. The main problems in Meghalaya are the production of Acid Mine Drainage (AMD) in nearby areas by continuous leaching of acidic waste from the coal mining sectors. An Environmental Management Plan (EMP), has been developed for management of AMD in high sulphur coalmines by simulation of AMD from weathered coals and mine rejects. Sequential alkalinity producing (SAP) coupled with biological processes found effective in controlling AMD and reducing TDS, Conductivity, SO4 and toxic elements. In this paper, the state of art for AMD and the processes suitable for the management of AMD are discussed.