Analysis of metamorphism and tendency of coal seams and their hazardous properties

Abstract

The object of this study is coals of different stages of metamorphism. Currently, a situation has arisen when indicators developed to establish the consumer qualities of coal are used to predict the manifestation of hazardous properties of mine seams during mining operations. The need to consider the fuel for its working condition is due to different end goals between the establishment of consumer qualities of coal and the manifestation of the hazardous properties of mine seams. The condition and quality of coal after its preparation for use is significantly different from the condition in the mining area. Appropriate sample preparation changes the physical and chemical properties of coals, which determine the manifestation of the hazardous properties of mine layers during mining. To eliminate such a discrepancy, the quality indicators of coals were recalculated for their working condition, taking into account the yield of ash and moisture content for the mined mine seams, followed by an analysis of changes in the correlations be-tween the indicators. The indicators of the manifestation of the hazardous proper-ties of mine layers are borrowed from the characteristics of the quality of the fuel, reduced to a dry, ash-free state. Using these indicators, additional errors are introduced in advance into the accuracy of the prediction of the manifestation of hazardous properties during mining operations. The values of the indicators of the organic (combustible) part of the fuel serve as general reliable characteristics of its quality for the entire set of mine seams, but they cannot be used to predict the hazardous properties of a particular mine seam due to a decrease in the accuracy of their determination due to the unpredictable content of mineral impurities and moisture. The initial experimental data, which have been accumulated over several decades based on the experience of using coal for industrial purposes, are analyzed. On the basis of the conducted researches the peculiarities of the choice of indicators of metamorphic transformations of coal, which are used in parallel respectively to establish the quality of fuel and forecast the dangerous properties of coal seams, have been established. The discrepancies between the indicators of the degree of metamorphism used in the current regulatory framework for the safe conduct of mining operations, the state of fuel during mining operations in underground conditions.