On the issue of determining the accuracy of the apparent density of coals to establishingthe outburst hazard of coal seams

Abstract

The article considers the possibility of determining the apparent density for the prediction of the tendency of coal seams to the manifestation of sudden emissions using the empirical dependence obtained on the basis of statistical processing of indicators of technical analysis of coal. The methodology is based on a comparative analysis of the compliance between the calculated values of the apparent density of coal and the values established by the standard method for each coal seam. According to the results of research, there is a practical absence of correlational interdependence between the calculated values of the apparent density and its values, which are experimentally determined according to the methodology of generally accepted standards. This indicates a complete discrepancy between the accuracy of determining the apparent density of coal in accordance with the empirical dependence of its values established by the standard method. The closeness of the obtained calculated values of the apparent density of coal in accordance with the empirical dependences, using, respectively, one index of volatile matter output (V^daf) and three (volatile output, moisture and ash output) influencing factors, gives reason to analyze the apparent density of coal only from V^daf. Depending on V^daf, a second-order polynomial with high correlation density characterizes the apparent density of coal determined by the standard method. A reliable determination of the apparent density of coal is possible only by standard methods, excluding the use of empirical dependencies with the use of indicators of technical analysis, which is confirmed by a significant root mean square deviation, which exceeds the accuracy of the determination by 1.5 times. For the first time, on the basis of statistical processing of experimental data given on the apparent density of coal and indicators of technical analysis for 592 coal seams of the Donbass and Lviv-Volyn basins, the inadmissibility of using calculated values according to empirical equations for predicting the susceptibility of mine layers to sudden emissions of coal and gas during mining operations was proven. The research results make it possible to develop proposals for improving the regulatory framework in terms of forecasting the outbursts hazard of coal seams.