Influence of oxygen content on the manifestation of hazardous properties of coal seams

Abstract

Purpose. To improve the regulatory framework for the safe conduct of mining operations, to establish the effect of mineral impurities and moisture on the accuracy of determining the oxygen content, under conditions close to those of coal seams. Methodology is based on the fact that practically for all coal seams of Donbass and the Lvov-Volyn basin indicators of consumer qualities of solid fuels have been established, but they characterize only one organic (combustible) part per dry ash-free state. In this case, the effect of mineral impurities (their content for many reservoirs exceeds 30-40%) and moisture on the change in oxygen content is not taken into account. The manifestation of many hazardous properties of coal seams depends on the ratio of oxygen content with other components of the organic mass and mineral impurities. To bring the quality indicators of coals to a state close to the conditions of mining operations, they were recalculated for each coal seams, taking into account the actual yield of ash and total moisture. Findings. The indicator of the release of volatile substances used in the normative documents for the safe conduct of mining operations for assessing the metamorphic transformations of coal seams does not determine the type of coal by their reduction. Restorability determines the properties of the organic mass based on the ratio of oxygen to its other main components. In addition to the organic mass in the dry ash-free state, the composition of solid fuels includes mineral impurities and moisture. They significantly affect the change in the ratio between the main components. The carbon content in the organic (combustible) mass is more informative in comparison with the yield of volatile substances, an indicator. It functionally controls the sum of the remaining components - hydrogen, nitrogen, sulfur and oxygen. To a lesser extent, but rather high, the closeness of the correlation interdependence was established between the content of oxygen and carbon in the dry ash-free state of the fuel. Such interdependence is completely eliminated when considering the fuel for its working condition, which indicates the random nature of the relationship between the main components of the organic mass and mineral impurities, including moisture, for each considered coal seams. Originality. For the first time, on the basis of statistical processing of experimental data on the quality of coals for almost all coal seams of the Donbass and the Lviv-Volyn basins, the possible limits of the oxygen content for the working state of the fuel were established, which makes it possible to individually consider for each coal seam the ratio between the main components of the organic mass and mineral impurities, including the presence of moisture. Practical implications. The research results make it possible to develop proposals for improving the regulatory framework in terms of predicting the hazardous properties of coal seams during mining operations.

Influence of the natural content of mineral impurities and moisture on the manifestation of hazardous properties of coal seams

“…The weakening of this dependence is caused by the partial enrichment of coals (the presence of a random residue of mineral impurities) and total moisture's presence, which are individually different for each mine. Consideration of the ratio between the components after they have been brought to working condition on the basis of the actual ash content and total humidity has led to an unpredictable redistribution of the influence of factors on oxygen content [15]. The natural accidental presence of mineral impurities and the different values of total moisture in the seam's samples have eliminated the monopolistic metamorphic ratio of oxygen in the organic, dry, ash-free mass to carbon.…”