Russian State Geological Prospecting University, Moscow, Russia:

V. S. Lebedev, Professor, Doctor of Geologo-Mineralogical Sciences, vslebedev@mtu_net.ru

College of Mining, National University of Science and Technology – MISIS, Moscow, Russia:
O. V. Skopintseva, Professor, Doctor of Engineering Sciences

Down to recent time, the main lines in the research and practice in the field of underground coal mining safety are prevention of methane outbursts and explosions of dust–methane–air mixtures in mines. Far less attention is paid to the issues related with the residual gas content of coalbeds. At the same time, coal extraction can induce release of residual hydrocarbons and create fire-and-explosion hazards in mines. The authors have compared gas contents of residual hydrocarbons in coal reserves under mining in Kuzbass and eastern Donbass fields and revealed a general regularity of change in the content and composition of hydrocarbons under carbonization. As compared to methane, residual hydrocarbons have lower ignition temperature and explosive range and higher calorific power. That is where potential hazard of residual hydrocarbons occurs as coal is subjected to high temperatures in the course of many production processes during extraction (for instance, under coal cutting, temperature at the cutter bits and coal interface goes up to 500–600 °С and higher). It is found that residual hydrocarbons are mostly composed of heavy components (propane, butane, etc.). The intra-component content of residual hydrocarbons differ per ranks of coal, while it is almost identical within the ranks in all searched mines in Kuzbass and eastern Donbass, which has allowed stating averaged indexes of content of residual hydrocarbons for each rank of coal in these basins. Despite the difference in actual percentage of residual hydrocarbons in coal in the studied coal fields, the ratios of heavy components and methane in residual hydrocarbons are similar in the same ranks of coal. The maximum content of С2–С6 in coals of the mentioned basins is found in fat and coking fat ranks of coal; the relative percentage of heavy components in these ranks is 94–98.6%, and portion of methane is insignifi cant against this background. This fact is relevant for development of general preventive control of explosion risk of residual hydrocarbons. The large-scale research into residual hydrocarbons in the specific coal fields has shown that the contents and compositions of residual hydrocarbons obey general regularity.

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