Washington, DC: U.S. Department of the Interior, Bureau of Mines, Bulletin 20, 1911 Jan; :1-204
This bulletin traces the growth in the belief in the explosibility of coal dust, summarizes the experiments and mine investigations that have established this belief, and gives the present status of preventive measures. It has been prepared in accordance with the provisions of the acts of Congress authorizing investigations relating to the causes of mine explosions, and contains references to and descriptions of experiments made at the Federal testing station at Pittsburg, Pa. This station was inaugurated under the United States Geological Survey, and was transferred to the Bureau of Mines on the establishment of the latter on July 1, 1910. Only within comparatively few years has the dry dust of bituminous and lignitic coals been generally recognized as an explosive agent more insidious, threatening, and deadly to the miner than fire damp. Fire damp carries its own flag of warning-the "cap" in the safety lamp-but coal dust, though visible, does not attract attention until present in large quantities. Fire damp is of local occurrence, and except in notable and very exceptional cases is controllable by careful manipulation of ventilating currents. If by mischance a body of fire damp is ignited in a mine, the force of the explosion may be terrific, but the effect is local unless dry coal dust is present, or unless (as it very rarely happens) an explosible mixture of methane gas and air extends through large areas of the mine. In a dry mine dust accumulates everywhere, and the blast from the ignition and combustion of bituminous dust may traverse miles of rooms and entries and wreck structures at the entrance to the mine. The comparative potential destructiveness of gas and of bituminous dust is strikingly shown by the history of the Pennsylvania anthracite mines. These mines not infrequently have large inflows of gas, and the resulting mixtures of gas and air have sometimes been ignited, yet no such wide-sweeping explosions have taken place, despite the presence of dry anthracite dust, as have happened in excellently ventilated bituminous mines. This bulletin, as is emphasized in the body of it, should be regarded as a preliminary study of the coal-dust problem. The pressure of other work and the almost continuous use of the explosives-testing apparatus at the Pittsburg station for the important work of investigating the relative safety of explosives for use in coal mines have limited the experiments that could be made dealing with methods of lessening the danger from coal dust. However, it is expected that opportunity will be afforded in the future to take up systematic testing in an experimental mine or underground gallery near Pittsburg.
Washington, DC: U.S. Department of the Interior, Bureau of Mines, Bulletin 20