Mining Publication: Using Site Case Histories of Multiple Seam Coal Mining to Advance Mine Design

The nature of competition in the coal market tends to deplete the most favorable coal reserves first and forces subsequent development of mines in more extreme ground conditions, such as those associated with multiple-seam mining. In fact, 70% of U.S. coal reserves are in multiple-seam situations. The National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop mine design algorithms that will result in safer multiple-seam mines. This paper presents an overview of multiple-seam issues in the central Appalachian coalfields. To date, more than 50 case histories have been analyzed from 20 operating mines in eastern Kentucky, western Virginia, and southern West Virginia. Each case history is classified according to the degree of multiple-seam interaction, ranging from no apparent interaction to severe interaction with direct impacts on mine safety and resource recovery. The case histories are also examined with regard to amount and geologic characteristics of interburden and overburden, and design stability factors. The sequence of mining has also been found to be critical when the lower seam is fully extracted. This paper compares current case histories to traditional rules of thumb. In addition, two situations were modeled using LAMODEL software. LAMODEL has been upgraded to import pillar grids and topographic data from AutoCAD files. The cases presented demonstrate vertical stress capabilities of LAMODEL.