On Methods of Determination of Real Coal Density to Forecast Outburst Hazard of Coal Seams

It is required to establish the advisability of determining real coal density using empirical dependences obtained based on statistical processing of technical analysis indices and their compliance with results obtained by the standard method. The methodology is based on the comparative analysis of design values’ compliance with real coal density for each mine seam, in accordance with empirical equations, with their values obtained by the standard method. The reliable determination of actual coal density values is required to identify mine seam tendency to spontaneous coal and gas outbursts during mining operations and to forecast and control gas emissions during coal production at coal mines. A significant mean square deviation from average curve, exceeding up to ten times the accuracy of the determination of actual coal density by the standard method has been established, which excludes a practical possibility of using design values by empirical equations to forecast mine seam tendency to spontaneous coal and gas outbursts and to control gas emissions during mining operations. Real coal density is a strictly individual property of a specific mine seam. It can be reliably determined only by the standard method. Average empirical dependences provide only a tendency of change of real coal density under metamorphic transformations of mine seams. For the first time, based on statistical processing of coal density experimental data and indices of technical analysis for 590 mine seams of the Donbass and Lviv-Volyn basins, the unacceptability of the use of design values in accordance with empirical equations to forecast mine seam tendency to spontaneous coal and gas outbursts has been proved. The results of the studies help develop proposals for the improvement of the regulatory framework for the forecast of coal seam outburst hazard.