Technology News 465 - method for predicting methane emissions on extended longwall faces.
NIOSH 1997 Nov; :1-2
A method for predicting methane (74828) emissions on extended longwall faces in coal mines was developed. Methane emissions at the active faces of two coal mines were measured by sensors attached to the shields over the pass line while a continuous mining machine made three 76 meter (m) passes at the faces. One sensor was placed near the headgate and the other close to the tailgate. Air flows at the methane monitoring sites at the faces were also measured with a handheld anemometer. The methane monitoring data were analyzed by logistic regression techniques to develop an empirical equation that could be used to predict methane emissions at coal faces that were extended to 305m. A power curve which expressed the average methane release rate as a function of each 76m pass made by the continuous miner raised to the 0.179889th power fit the measured emission data best at the first coal mine. Projecting the regression curve to a fourth 76m longwall pass predicted that methane would be released at an average rate of 0.14 cubic meters per second (m3/sec). This was equivalent to a 7% increase in methane emission for a 305m wide coal face. A linear regression curve fit the data obtained at the second mine the best. Projecting the regression curve to a fourth 76m pass predicted that methane would be released at an average rate of 0.27m3/sec, equivalent to a 13% increase in methane emission for a 305m wide face. It was noted that the relatively low predicted increase in methane emission at the face of the first mine should not result in additional methane control problems. The predicted methane emission at the face of the second mine falls within the general range where methane control problems have been experienced. Larger, 305m wide, face widths have not been developed at the first mine. Panels with 305m wide panels have been developed at the second mine. The measured methane emissions were less than those predicted by the empirical formula. This was attributed to an improved methane drainage program that had been implemented at the mine.
NIOSH-Author; Flammable-gases; Coal-mining; Explosive-hazards; Occupational-hazards; Industrial-safety; Mathematical-models; Underground-mining; Safety-research
National Institute for Occupational Safety and Health