№67-04

Coal grade as an indicator of metamorphism and hazardous properties of coal seams

Ye. Rudniev¹, V. Galchenko¹, Е. Filatieva¹, М. Antoshchenko¹

¹Volodymyr Dahl East Ukrainian National University, Sevierodonetsk, Ukraine

Coll.res.pap.nat.min.univ. 2021, 67:40-52

https://doi.org/10.33271/crpnmu/67.040

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ABSTRACT

Purpose. To establish the accuracy of the correspondence between the grade identity of coals and their elemental composition of the organic (combustible) mass.

Methodology. The research methodology provides for the use of official data on the elemental composition of the combustible mass of more than a thousand coal seams of the Donetsk and Lvov-Volyn basins. This information made it possible to develop statistical models of the main components of the combustible mass of coal for each grade and to analyze the changes in the boundaries of the considered components. Based on the relative position of these boundaries, conclusions were drawn about the accuracy of determining the grade of coal by the elemental composition of their combustible mass.

Findings. The carbon content functionally controls the sum of the content of other main components of coal (hydrogen, sulfur, nitrogen and oxygen), but this does not apply to changes in the content of individual components of the combustible mass under the influence of metamorphic transformations of coal mines. Coals of the same grade with the same carbon content can have different properties, which in different ways can characterize both their consumer characteristics and the manifestation of the hazardous properties of coal seams during mining. The content of each of the main components of the combustible (organic) mass in different ways reflects one of the sides of the change in the elemental composition, therefore, the individual content of carbon, oxygen, hydrogen and nitrogen refers to the metamorphic indicators of the transformation of organic matter. When predicting the hazardous properties of coal seams, in addition to them, it is necessary to take into account the sulfur content. An increased individual content of oxygen, hydrogen, sulfur, or some combination of them, can provoke the manifestation of one of the dangerous properties of coal seams during mining operations.

Originality. For the first time, on the basis of statistical models based on the change in the average values of hydrogen, nitrogen, oxygen and their nonlinear dependences as the degree of metamorphism increases (increase in carbon content), it is proved that they should be considered when predicting the hazardous properties of coal seams as indicators of the degree of metamorphic transformations. The sulfur content cannot be considered a criterion for assessing the degree of metamorphic transformations, but the sulfur content affects the change in the ratio between other main components of the organic (combustible) mass and, in addition, sulfur itself can provoke the manifestation of the hazardous properties of coal seams.

Practical implications. The research results make it possible to develop proposals for improving the regulatory framework in terms of forecasting hazardous phenomena that arise during mining operations.

Key words: grade, coal, coal seams, metamorphism, indicator, definition, error, properties, hazard, mining, regulatory framework, improvement.

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