Rudniev Ye. On the dependence of the gas capacity of fossil coals on the degree of metamorphic transformation of coal seams
- Details
- Parent Category: Geo-Technical Mechanics, 2025
- Category: Geo-Technical Mechanics, 2025, Issue 172
Geoteсh. meh. 2025, 172, 143-157
ON THE DEPENDENCE OF THE GAS CAPACITY OF FOSSIL COALS ON THE DEGREE OF METAMORPHIC TRANSFORMATION OF COAL SEAMS
Volodymyr Dahl East Ukrainian National University
UDC 622.8
Language: English
Abstract. Purpose: To determine the correlation strength between the sorption methane capacity of hard (bituminous) coals and anthracites and the degree of metamorphic transformation of coal seams with changes in pressure and temperature conditions.
Methodology: The research methodology involves statistical processing by the least squares method of the experimentally established values of the methane capacity (a) of hard (bituminous) coals and anthracites, from the indicator of the yield of volatile matter during thermal decomposition of coals without air access (Vdaf). The values of pressure (P) during laboratory experiments and temperature (t), corresponding to the depth of occurrence of coal seams, are considered as additional influencing factors.
Results. When changing the pressure in the range from 0.1 MPa to 5.0 MPa, a high correlation dependence of the sorption methane capacity of hard coals and anthracites (a) on the yield of volatile matter was obtained in all cases. High pressure (5 MPa and more) causes not only an increase in the standard deviations from the averaging curves, but also leads to a change in the type (character) of the dependence of the sorption methane capacity on the yield of volatile matter. At atmospheric pressure (P=0.1 MPa), with an increase in the degree of metamorphic processes (further decrease in the Vdaf values), only a one-sided increase in the sorption methane capacity of fossil coals is observed. The sigmoid more reliably reflects the one-sided nature of the change in the sorption methane capacity of hard (bituminous) coals and anthracites with an increase in the degree of metamorphic transformations of coal seams and a relatively low (atmospheric) gas pressure of 0.1 MPa. This advantage is lost at a pressure of 5 MPa. At high gas pressure (in the range of 1.0÷5.0 MPa), the dependence of sorption isotherms on the yield of volatile matter is most reliably described by a second-order polynomial. At a gas pressure of 0.1÷1.0 MPa, these dependencies are most realistically described by empirical equations of the sigmoid type.
Scientific novelty. For the first time, based on statistical processing of experimental data, it was established that with pressure changes within the range from 0.1 MPa to 5.0 MPa, a high correlation dependence of the sorption methane capacity of hard (bituminous) coals and anthracites on the yield of volatile matter at all stages of metamorphic transformations of coal seams was obtained. With an increase in pressure from 0.1 MPa to 5.0 MPa, an increase of four and more times in the standard deviations from the averaging curves is observed.
Practical value. The results of the research allow us to develop proposals for improving the regulatory framework in terms of forecasting the hazardous properties of coal seams during mining operations.
Keywords: coal, gas capacity, metamorphism, coal seams, safety.
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About the authors:
Rudniev Yevhen, Doctor of Technical Sciences (D.Sc.), Associate Professor, Professor of the Department of Electrical Engineering, Professor of the Department of Pharmacy, Production and Technology, Volodymyr Dahl East Ukrainian National University (VDEUNU), Ukraine, Kyiv, This email address is being protected from spambots. You need JavaScript enabled to view it. (Corresponding author), ORCID 0000-0002-4236-8407