Underground mining involves opening one or more portals or shafts into the earth that follow or intercept coal seams that are too deep for surface mining methods. Method of Work is Bord & Pillar method & longwall method for extraction of coal.
There are two stages of board & pillar mining i.e Development & Depillaring
Development: It is a method of making drivage of the gallery by drilling and blasting for establishing & extending ventilation, traveling roadway, haulage roadway for material flow, making sump area, panel making (sectionalisation), etc.
Depillaring: Final extraction of coal from pillars
Depillaring is Two Method: 1. Caving 2. Stowing
Caving: Allowed roof to cave in after final extraction of coal pillar in slices in a sequence manner, Permitted when no surface feature. In the caving process development of crack/subsidence up to surface thus danger of fire- Air flowing through cracks developing conditions of Spontaneous heating of coal, the inrush of water from upper seam-inundation, the release of gas. It required landfilling & degradation, reclamation, and plantation/vegetation.
Stowing: Filling of Sand, Other Incombustible Material- Flyash, LD Slag in de-coaled area, Sand on Lease- Collection of sand at the river.
Followed all legal requirements subjected to the method of working.
In this course, you will learn about the underground mine planning process & the coal winning process. All methods for extraction of coal from underground. Formation of coal & their rank, types & grade of coal. All statutory requirements of Working Under Railway, Public Road, etc. Working near Mining Boundary, Working underwater body &. Multi Seam or Section Working.