INFLUENCE OF MICROWAVE ACTIVATION OF COAL ON ITS PETROGRAPH-IC PROPERTIES

Despite the development of renewable sources, coal occupies an important place in the energy balance of many countries, especially those with large reserves. One of the ways to influence the characteristics of coal and add specified properties to it is its preliminary microwave activation. As a result of the studies, it was found that with microwave activation with an electromagnetic field power of 750 W for 240 s, an ambiguous effect on the characteristics of coal samples is observed, namely, coal with R0 greater than 1.16 before activation, microwave activation occurs faster, while the vitrinite reflectivity increases to 1.58 %, the yield of volatile substances and the thickness of the plastic layer decrease. Coals of a high stage of metamorphism are activated faster due to a denser structure. The presence of a more ordered structure than less metamorphosed coals, during the activation process, the condensed carbon layers come closer together, which ultimately increases their metamorphism stage. On the contrary, for coal with R0 less than 1.03 before activation, microwave activation is slower, while the vitrinite reflectance index decreases to 0.75 %, the yield of volatile substances and the thickness of the plastic layer increase. Obviously, this is due to the fact that coal of a low metamorphism stage is characterized by a less dense structure and more time is needed for its activation. Also, to increase the metamorphism stage, it is necessary to apply more energy so that the formed radicals and structural units connect with each other and form an ordered aromatic structure. Therefore, for coals of a low metamorphism stage, the activation time should be longer. The research results indicate the possibility of changing the coal metamorphism stage, which will increase the efficiency of coal processing processes, reduce energy costs and minimize harmful emissions due to the use of microwave technologies. In addition, the use of microwave activation can expand the raw material base for various coal technologies, especially in conditions of fuel shortage.