Physical Kinetics of Coal-Methane System: Mass Transfer, Pre-Outburst Events
E. P. FEL’DMAN, T. A. VASILENKO, N. A. KALUGINA
Institute of Physics of Mining Processes, National Academy of Sciences of Ukraine, ul. Rozy Lyuksemburg 72, Donetsk, 83114 Ukraine
Keywords: thermodynamic potential, filtration diffusion, gas-filled fracture, Griffiths criterion, bearing pressure, coal bed
Abstract
The article gives the review of the present-day development in the physical kinetics of coal-methane system. The Gibbs thermodynamic potential is derived for this system as the function of methane density (persisting order parameter) and coal jointing (non-persisting order parameter). The authors put forward diffusion-filtration mechanism of gas mass transfer in porous material on two time scales and substantiate the concept of “quick” and “slow” methane. Based on the nonequilibrium thermodynamic potential, kinetic equations are derived for gas pressure and jointing in coal (bed). The first equation solution explains the physical effect of temporal gas pressure growth at the maximum of the external rock (bearing) pressure, the second equation enables generalization of the Griffiths failure criterion for a set of gas-filled fractures. Mechanism of pre-outburst spalling of gas-saturated coal is analyzed.
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