Multiple seam longwall mining in the United States: lessons for ground control.
Proceedings: New Technology for Ground Control in Multiple-Seam Mining. Mark C; Tuchman RJ, eds., Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 2007 May; :45-53
Relatively few longwall mines in the U.S. operate under multiple seam conditions where the two seams are less than 200 ft apart. This paper describes the experience of six that do. These operations are located in PA, WV and UT, and include examples of both undermining and overmining. Some operate above or beneath their own workings, others are in historic mining districts and must contend with abandoned mines that are decades old. The lessons that these mines have learned cover a broad range of topics, including: 1. Whether to stack gateroads or place them under old gob areas; 2. How to size pillars and select artificial support to cross longwall stop lines; 3. How to use yield pillars to minimize multiple seam stresses and coal bump potential, and; 4. When to anticipate the creation of pathways for gas, water, or oxygen between current and abandoned gobs.
Mining-industry; Underground-mining; Safety-research; Longwall-mining; Geology; Coal-mining
Proceedings: New Technology for Ground Control in Multiple-Seam Mining