Optimal Underground Extraction of Coal at Shallow Cover Beneath Surface/Subsurface Objects: Indian Practices

Summary  Considering ground instability problems of underground coal mines at shallow covers, this paper reviews and describes problems of optimal extraction of coal stuck below surface/subsurface constraints at Indian coal fields. Importance of thickness and quality of inter-burden between the working horizon and surface/subsurface constraints is discussed from a ground movement point of view during optimisation of coal recovery by underground mining beneath the constraints. A CIMFR, formerly CMRI idea, known as Wide Stall Method, was found suitable to overcome the limitations of non-effective-width based optimisation of recovery of coal, trapped in pillars below surface/subsurface objects, at shallow cover. The involved rock mechanics concept and three successful field trials of the Wide Stall Method under three different geo-mining conditions of the country are also briefly given in this paper. Author’s address: Rajendra Singh, Central Institute of Mining and Fuel Research (CIMFR, formerly CMRI), Barwa Road, Dhanbad, 826001 Jharkhand, India