A new approach for the study of processes at the atomic-molecular level occurring in the current situation in fossil carbonized organics was proposed. A new phenomenological model of physicochemical transformations in a metastable coal substance with the emission of fluids has been developed. The proposed physic/chemical model is based on the genetic connection of coal methane with fossil organic matter and determines the conditions for the activation of structural transformations in coalmines. This model describes the possible options for the coal/gas system development in the current situation. The accumulation of thermal and mechanical energy by coal in the form of structural stresses in an amount, sufficient to activate free-radical reactions, was experimentally established. In the undisturbed coalrock massif the processes of the coal molecular structure transformation have the relaxation character. The result of relaxation of the accumulated energy in the conditions of a gas-saturated coalrock massif is the methane generation by coal. Gas generation in the process of coalification, in its essence, is the energy response of the system to the action of external geomechanical options (temperature and pressure), by the way of releasing the accumulated additional energy with the emission of gaseous products and the destruction of the solid phase in the organic matter of the coal.
Purpose. To establish the regularities of the influence of magnetic fields on the peculiarities of changing the chemical and structural characteristics of the coal substance according to the size of microparticles enriched with vitrinite. To formulate a new system of views on the mechanisms of structural and functional transformations of coal substance under the influence of weak external fields. Methodology. The authors used an electric furnace heating up to 320 K that creates a pulsation magnetic field with a strength of up to 4,000 A/m to process dispersed samples of hard coal with a weak magnetic field. The methods of infrared spectroscopy and electron paramagnetic resonance were used in the research. Findings. Experimental works were carried out to estimate the impact of weak fields on the state and properties of coal substance. It is shown that weak energy fields, and the electromagnetic one in particular, are able to reduce the energy barriers of reactions in coal substance due to spin-spin interaction, which leads to the activation of processes at the atomic-molecular level and interfacial interaction. Originality.It is experimentallyestablished that for coal micro-particles with sizes from 0.16 to 0.1 m, enriched with vitrinite, the coupling coefficient decreases after exposure to an external magnetic field, and for micro-particles with sizes less than 0.63 m, this indicator increases. Such changes are caused by the redistribution of hydrogen between aromatic and aliphatic components during free-radical reactions. Changes in the spectrum on vitrinite (0.160.10 mm), are more significant than on inertinite (0.063<0.05 mm). At the same time, the external action of the electromagnetic field has caused the opposite consequences. It is shownthat magnetically stimulated chemical reactions occurring in the coal substance are aimed at the recombination of free radicals with active surface states of the organic mass of coal into stable gas molecules. The results of laboratory studies using the methods of electron magnetic resonance and infrared spectroscopy and infrared spectroscopy allow assuming that the changes in structural characteristics recorded during experiments with low-energy impacts can be considered as intermediatorsfor the matter transformation or changes in the state of coal in preparation for structural and functional transformations.For example, to the sorption interaction or destructive processes with methane generation. Practical values.The magnetic field effect can be used to develop new research methods for the study on elementary processes by electron spin resonance; control spin-dependent phase transitions. The use of magnetic resonance methods allows the usage of magnetically field effects in the form of basic tools for the research on structural defects. The results obtained will be a scientific ground for the development of methods for estimating the parameters of electromagnetic processes in coal to develop new technologies for the extraction and processing of hydrocarbon energy carriers.
The molecular structure of coal is estimated by 13 parameters of infrared spectra, electron paramagnetic resonance, volatile yield and ash content. A new criterion of hydrophobicity is applied, which has shown its informativeness in analyzing the molecular structure of coals of various ranks. It is more sensitive to changes in coal rank than the standard index of volatile yield. The coalification process leads to a significant increase in this index due to the water release and other hydroxyl-containing compounds from the substance of coal. Two-way analysis of variance showed that the influence of the metamorphism factor is significant for 9 molecular parameters. The strongest effects are manifested in the sorption capacity, the criterion of hydrophobicity and the number of paramagnetic centers. The stratigraphic factor does not have a significant impact on one of the molecular parameters. Factor analysis by the method of principal components of the molecular structure of coal showed that the most significant independent factors are metamorphism and sedimentation conditions, the latter ones include independent processes: accumulation of mineral components, decomposition of biomass and geochemical environment during the sedimentation period.
The article focuses on a quasistable electrical potential registered on samples of highly-metamorphic and high-ash coal in normal laboratory conditions. The purpose of the study is to determine the possible conditions for the appearance of their effect in the coal and carbon-like argillite and the parameters of its structure. The appearance of an uncompensated charge is not associated with thermoelectric and electrokinetic phenomena and it has not been previously described. Most samples are characterized by an uneven distribution of charges along the surface in the form of a polydomain structure. Polarized samples have a layered coal-mineral structure. The charge magnitude depends on the thickness and density of the layers. In heterogeneous and heterophase substances the Maxwell-Wagner polarization is realized, arising on the boundary layers of dielectric micrograins of various substances, as well as between the areas of one dielectric with an amorphous and crystalline phase. Microinclusions and anthracite layers, which increase the potential ability of mineral components to their own polarization, can be conductors. Charged samples may have a stable, non-compensated monodomain residual charge under constant external conditions, which is characteristic of the electrets. The detected effect can be useful when creating alternative devices accumulating electricity.
At present, based on the research of the conditions and factors of outburst hazard of coal beds, various predicting methods have been developed grounded on contemporary views concerning the nature and mechanism of gas-dynamic phenomena. One of the main factors affecting the outburst hazard of coals is gas saturation, which is determined by the sorption capacity of coals. The sorption properties of coal matter are significantly determined by the degree of coal transformation (metamorphism). Therefore, the analysis of the data obtained for a coal matter of the same rank makes it possible to reveal the role and importance of factors that have formed the parameters of the signals observed by EPR (electron paramagnetic resonance) spectroscopy. These signals define the features of the sorption coal-gas interaction for a particular sample. It is established that the average values of the concentration of paramagnetic centers are (2.29 ± 0.36) and of contingency - (0.476 ± 0.02), and the calculated value of the sorption capacity of coals (24.3 ± 0.29) can be considered basic for gas and fat ranks of coals in the Krasnoarmeyskiy district. Minor deviations from the basic parameters can be caused by various geological and technological factors. Significant deviations of the average values for the sorption capacity of coals can be caused by tectonic processes. The purposeis to research the impact of geological factors on the sorption properties of gas and fat ranks of coals determined by the EPR method in the mines of the Krasnoarmeyskiy district. During the research, the following parameters were defined: 1) the integrated intensity of the EPR spectrum - the concentration of paramagnetic centers (Na) in the matter under research, which characterizes the conjoint impact of external factors on the coal matter, and 2) the contingency coefficient (Ksc), i.e. the number and status of the conjugate system in the molecular structure of a matter, which characterizes the transmitting depth of structural transformations (a degree of structuredness) of fossil organics at the nanolevel. As a result, it is found that various factors acting in different directions affect the calculated value of the sorption methane capacity of coals. The average sorption capacity of gas and fat ranks of coals from the Krasnoarmeyskiy district is 24.3 ± 0.29 and mainly depends on the deformation conditions. The average concentrations of paramagnetic centers are (2.29 ± 0.36), and of contingency (0.476 ± 0.02). The calculated value of the sorption capacity of coals (24.3 ± 0.29) can be considered as the base one for the gas and fat ranks of coals in the Krasnoarmeyskiy district. Minor deviations from the basic parameters can be caused by various geological and technological factors. Significant deviations in the average values of the coals sorption capacity can be caused by tectonic processes.
The research of redistribution and realization of energy at different scale-hierarchical levels at the Donbas coalrock massif based on the parameters of faultings and gas-dynamic phenomena has been conducted. It is proved that the energy transfer, incoming by impulses in post-inversion time of the geological development in Donbas, occurs throughout the whole structure of coal, due to the formation of energy connection between individual elements of the molecular structure. This process is accompanied by transition of free energy into a bound state with increase in ordering of the molecular structure and aromaticity of the coal substance (local increase in the degree of catagenetic transformations). The conditions of energy accumulation and realization depend on the peculiarities of molecular processes occurring in dislocations of different types. Less energy is accumulated in tensile zones than in compression zones, which is confirmed by the intensity of coal and gas outbursts. It has been established that the energy entering the multifractal geological environment in Donbas from external sources is also redistributed fractionally by the system, causing the formation of multiscale discrete inhomogeneities, which provides the massif with specific properties and ability to self-organization. A fractal model of the structure of the coalrock massif is proposed.
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