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In coal mining, the problem of particular importance is the occurrence of endogenous fires and explosions of the methane-air mixture, which lead to the death of people. The aim of the study is to establish indicators that directly characterize the change in the elemental composition in the process of metamorphic transformations of coals and determine them tendency to spontaneous combustion. Statistical multivariate analysis showed that the degree of metamorphism is the most significant characteristic of the propensity of coal to oxidize. The sum of the content of the main components decreases inversely to the increase in carbon content over the entire range of coal conversion from a small degree of their metamorphism from coal to anthracites. The dependence of decrease in oxygen content with increased carbon is nonlinear. With carbon content of more than 88%, there is a slight decrease in the rate of oxygen reduction in comparison to its decrease at earlier stages of metamorphism. A significant correlation of carbon with oxygen and hydrogen is observed. A characteristic feature of coals containing up to 75% carbon is a wide range of changes in formation moisture and oxygen content in organic matter. It indicates minor transformations of coals at the early stages of metamorphism. One of the signs of an increase in the influence of metamorphic processes is a one-sided increase in the carbon content in organic matter and a functional decrease in the sum of the remaining components - hydrogen, nitrogen, sulfur and oxygen.

Metamorphism Indicators for Establishing the Endogenic Fire Hazard of Coal Mining Plants in Mining