Material balance of metamorphic transformations of coal seams and their dangerous properties

Purpose: To establish empirical relationships during coalification of coal seams between the main components of the organic (combustible) mass, moisture content and mineral impurities using experimental data on the consumer qualities of solid fuels obtained by generally accepted standard methods. Reliably established relationships between these main components make it possible to scientifically substantiate and reveal the nature of the occurrence of dangerous properties of coal seams during mining operations due to the factor of metamorphic transformations and the generation of gaseous and liquid products. The research methodology was developed based on the results of a preliminary analysis of the change in the ratio between the main components of organic (combustible) mass, the content of moisture and mineral impurities during coal formation, starting from the processes of peat formation and subsequent coalification. Experimental data on the consumer qualities of solid fuels determined by generally accepted standard methods were used. Results: At all stages of metamorphic transformations of coal seams, with an increase in carbon content, a unilateral reduction in the elemental oxygen content in the organic (combustible) mass has been established. This indicates the formation of gaseous products at all stages of metamorphism with the participation of carbon and oxygen of the organic (combustible) mass. The reduction in the elemental content of hydrogen, nitrogen and organic sulfur in the later stages of metamorphism indicates the participation of these components in the generation of gaseous products. The reliability of the empirical dependence of carbon content on the average reflectivity of vitrinite was tested. The generation of moisture at the stage of metamorphic transformations of coals was not fully confirmed by the direction of trends in the average content of moisture, oxygen and hydrogen at successive stages of the processes of peat formation, diagenesis and metamorphism up to the transition from hard coals to anthracites. A significant excess (up to two times) of the yield of volatile substances was established compared to the content of the sum of the main components of the organic (combustible) mass at fixed values of carbon content. Scientific novelty: Based on changes in the ratio of the elemental content of the main components of the organic (combustible) mass (solid residue), their participation in the formation of gaseous products at all metamorphic stages of transformation of coal seams has been established. The obtained results of the formation of the material balance make it possible to introduce appropriate clarifications into the scheme of coal formation processes in terms of the generation of specific gaseous products at each stage. Practical value: The practical significance lies in the need and possibility of improving the regulatory framework for the safety of mining operations when forecast the hazardous properties of coal seams.