Self-ignition of dust and gas-air mixtures in the atmosphere of mine workings

Abstract

The underground mining of coal deposits is usually accompanied by manifestation of a number of negative factors, one of which is the presence of dust and gas-air mixtures consisting of fine coal dust, methane released from the broken coal and the air of the mine atmosphere. Despite modern methods and means of dust suppression and dust collection, it has not yet been possible to achieve complete neutralization of dust and gas-air mixtures in the atmosphere of mine workings. The negative effects of dust and gas-air mixtures can manifest themselves in different ways. On the one hand, deposits of coal dust in the worked-out spaces, under certain conditions, form foci of spontaneous combustion, which are the causes of endogenous fires. On the other hand, dust and gas-air mixtures are predisposed to ignition from external sources or to spontaneous ignition followed by combustion in the form of deflagration, which, under certain conditions, turns into detonation, spreading in the atmosphere of mine workings at supersonic speed. This article considers a nonstationary one-dimensional problem of selfignition of dust and gas-air mixtures in the air flows of mine workings. The temperature and the period of spontaneous ignition of dust-gas-air mixtures are found based on the solution of this problem, expressed numerically using the Geer method. An analysis of the mixture self-ignition process is performed and some patterns of the influence of the parameters of mixtures on the period of their self-ignition are revealed.