Assessment of heavy hydrocarbons influence on aerological risks in coal mines

Abstract

Introduction. An analysis of the dynamics of the increase in the number of functioning coal mines in the Russian Federation shows that over the past 22 years, the maximum number of new mines has increased dramatically and amounted to (over a decade) 11, which is 1.6 times more than the same maximum value of 7 (new mines commis-sioned over previous decades), for the entire period from 1910 to 2000. The largest number of mine seams currently being developed in the Russian Federation is represented by grades: D, G, GZh, Zh. It has been established that the content of heavy hydrocarbons in the residual gases of Kuzbass and Donbass coals is more than 80%, reaching 98% for Zh and KZh grades. Heavy hydrocarbons pose a great explosion and fire threat to coal mines, which necessitates the study of their composition and content and taking into account the impact on the aerological risks of mines. Objective. Study of the composition and content of heavy hydrocarbons in the residual gases of coal and coal dust and assessment of their impact on the aerological risks of accidents in coal mines. Methodology. To assess the impact of heavy hydrocarbons on the aerological risks of coal mines, the methodology developed by the authors was used to find the area of intersection of hazardous factors in mining and the vulner-abilities of ventilation schemes and methods, characterized by the proportion of probabilities of undesirable events. This methodology has been further developed in assessing and taking into account the impact of heavy hydrocarbons on aerological risks in excavation areas and development workings. The previously assessed mining hazards were supplemented by taking into account the high methane content of the seams, the presence of a critical content of heavy hydrocarbons, and the depth of mining operations. The vulnerability of the schemes and methods of ventilation of the working areas and development workings was manifested at high loads on the stopes, high values of the absolute methane content of the working areas, high speeds of advancement of the working and development faces. Results and discussion. A general pattern has been obtained for the two basins, consisting in the fact that the content of heavy hydrocarbons in the residual gases of coal is more than 80%, reaching 98% for Zh and KZh grades. It was determined that the residual gases of coal dust contain a greater amount of heavy hydrocarbons (up to 91%) compared to the residual gases of coals (87%), with propane and butane predominating. The presence of heavy hydrocarbons in the residual gases of coals under favorable conditions for mining coal seams increases aerological risks by 3.3 times; for the worst conditions, aerological risks due to the influence of heavy hydrocarbons increase only 1.7 times, which is due to the large influence on risk assessment of such factors as the load on the stope, absolute methane abundance, the rate of advance of the face, the depth of mining operations. For development workings, aerological risks due to the influence of heavy hydrocarbons are 1.5 times greater than for extraction areas. The research results can be useful in assessing the impact of heavy hydrocarbons on the aerological risks of coal mines. Conclusions. Heavy hydrocarbons contained in the residual gases of coal and coal dust, under certain conditions, increase the explosion and fire hazard of coal mines. It is possible to imagine the following scheme of methane ignition processes followed by an explosion of coal dust: methane ignition, heating of coal dust, release of combustible components from dust, ignition of combustible components, combustion of coal dust, explosion.