On Determining the Coal Carbonization Indicator for Establishment of Mine Fire Hazard Groups

Abstract

The article analyzes the dependence of endogenous fire hazards on the following factors: the degree of coalification, the total sulfur content, the thickness of the developed formations and their structure, the presence of tectonic disturbances. By the genetic propensity of coals to spontaneous combustion, three groups of coal sites are distinguished: І – Vdaf ≥ 41%, Сп ≤ 7, coals of marks D and partially G; ІІ – Vdaf = 40-30%, Сп ≤ 8, coals of marks D and partially F; ІІІ – Vdaf < 36%, Сп >8, coals of marks Zh, K, OS, T. Studies have shown that individual dependences of the decrease in the content of each component (Оo, Нo, No) significantly differ from each other. Decrease in oxygen content, as well as the sum of the main components, occurs with an increase in carbon content. 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 (Со ≈ 70%) to anthracites (Со ≈ 98%). 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. Data analysis showed an almost functional dependence between the sum of the main components of the organic mass (0.995). A significant correlation of carbon with oxygen and hydrogen is observed. A significant scatter of points in experimental data is due to the diversity of composition of the source material, the conditions of its accumulation and transformation for different coal basins and individual coal sites. Studies have shown that the relationships between all the main components of the organic mass of coal during metamorphic transformations change significantly at different stages of these processes. The established dependence of the carbonization index on the carbon content at different stages of coalification allowed us to develop an engineering method for calculating the carbonization index for the entire range of coal metamorphism. The proposed method significantly clarifies the determination of the carbonization index, which is necessary not only for establishing the fire hazard of mine layers, but also for establishing other manifestations of the dangerous properties of coal sites during mining operations. Keywords: carbonization index, endogenous fire hazard, elemental composition, organic mass, metamorphism, coalification.