Prediction of longwall methane emissions and the associated consequences of increasing longwall face lengths: a case study in the Pittsburgh Coalbed

In an effort to increase productivity, many longwall mining operations in the U.S. have continually increased face lengths. Unfortunately, the mining of larger panels may increase methane emissions. The National Institute for Occupational Safety and Health (NIOSH) conducted a mine safety research study to characterize and quantify the methane emissions resulting from increasing face lengths in the Pittsburgh Coalbed. The goal of this research effort was to provide the mine operator with a method to predict the increase in methane emissions from the longer faces for incorporation of additional methane control capacity into the mine planning process, if necessary. Based on measured methane emission rates of 0.066 m/s (140 cfm) for a 315 m (1032 ft) face, projected longwall face methane emission rates were 0.090 m/s (191 cfm) for a 366 m (1200 ft) face, 0.106 m/s (225 cfm) for a 426 m (1400 ft) face, and 0.124 m/s (263 cfm) 488 m (1600 ft) face.