Underground Extraction of Locked-Up Coal

In most of the coalfields in India, there are many mines where the seams are only developed by extracting 15-20% of coal but the pillars could not be extracted due to different constraints like presence of surface/subsurface features, forest area, danger of subsidence, lack of proper methodology, scarcity of suitable filling material, environmental issues, etc. As a result, a huge quantity of quality coal (around 3000 million tonnes) is locked-up in pillars for many years. This may lead to spontaneous heating and fire, accumulation of poisonous gases, severe stability problem leading to unsafe working and environmental problems. Even, after stowing by sand, due to compaction there may be chances of strata movement or subsidence which may damage delicate surface/sub-surface structures. So, there is a pressing need of a technology to extract this huge amount of locked-up coal. In this book, the locked-up coal is proposed to be extracted either by artificial pillar or by strengthening the rib pillars with FRP. Several extraction methodologies are designed and studied through numerical modelling for its stability analysis to evaluate its suitability of application in underground.