Role of Air Leaks in Causes of Methane Explosions in Coal Mines and Improving Calculation Methods

Valeriy Vitalievich Smirniakov and Victoria Vladimirovna Smirniakova

National Mineral Resources University "Mining University" Russian Federation, 199106, St. Petersburg, 21st line, 2.

DOI : http://dx.doi.org/10.13005/bbra/2019

ABSTRACT: The authors performed the analysis of the circumstances and causes of accidents associated with gas and dust explosions for the last twenty-five years. The conducted research has shown that there is a steady tendency of the stabilization of the number of accidents (associated with impaired stope ventilation) at present time. Most accidents occur at the excavation sites, working off benches of low gradient by the layout systems with flanking pillars and complete roof collapse. As a result of the evaluation of the reasons thereof, conducted by statistical methods and methods of technical analysis, it was found that most excavation sites were provided with the calculated air amount during the accident, while the explosive concentration of methane was observed in the breakage headings and adjacent workings. The main reason for gas normalization violations, according to the authors, is the leakage of supplied air into the collapsed area, the negative role of which lies in the fact that its amount varies continuously in space and time. Currently, all schemes for the ventilation of excavation sites and some coal mines (with gas explosion hazard) are divided into a number of known determinant classification characteristics; the path of air leaks differs respectively. Therefore, the main goal of this research is the development of scientific methods for the calculation of leakage (with the practical use value). This problem is of particular importance during the working of gas seams with the development systems which produce the substantial amounts of worked-out areas. Based on the conducted research, new methods for calculating leaks in the collapse zone were introduced, which allow to determine the air flow amount along the face length on the basis of the minimum input data, and extend the air distribution control capabilities at the excavation site, significantly increasing the safety of mining operations by the gas factor.

KEYWORDS: gas explosions; methane; air leaks; mined-out area; underground accident; causes of explosions; accident analysis

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