Abstract

Nearly two-thirds of all underground U.S. coal tonnage is extracted using continuous mining machines in room-and-pillar mining operations¹. As a result of the Mine and Safety act of 1960² and various state laws, present practice in the room-and-pillar mine is to stop mining every twenty minutes to measure the concentration of methane gas within one foot of the working face. After the mining machine is withdrawn, temporary roof supports are installed to the working face so that a miner can approach the face and measure the methane concentration with a hand-held catalytic combustion methane detector and/or flame safety lamp³. When the measurement is completed, the temporary roof supports are removed and the mining machine begins working again. Obviously, this procedure reduces productivity and is in itself a safety hazard as temporary roof supports can well be dangerous.

© 1985 Optical Society of America