How Underground Mining Works | HowStuffWorks
Underground mines are the alternative to surface mines. Surface mines excavate from the top down, a method that can become inefficient at depths greater than about 200 feet (60 meters) [sources: Illinois Coal Association, De Beers].Undergrounds coal mines can drive 2,500 feet (750 meters) into the Earth and other types even deeper -- uranium mines can reach 6,500 feet, or 2 kilometers.Appendix:Dictionary of Mining, Mineral, and Related,c. Applied generally to track mining as opposed to conveyor mining, although belt conveyor systems are sometimes referred to as belt haulage. d. The system of hauling coal out of a mine. e. S. Afr. A drive used for mechanical transport. haulage boss. In bituminous coal mining, a foreperson who supervises mine haulage operations underground or,Appendix:Dictionary of Mining, Mineral, and Related,The exploitation of coal or mineral deposits by underground mining methods. "Deep" is often interpreted as meaning 5,000 ft (1.5 km) or more, where stresses are high enough to cause sloughing of development openings, not to mention walls and faces in stopes.