Influence of Microwave Radiation on the Pyrogenetic Transformation of Coal Grains

Resumo

As for other dielectrics, the heating of coal by microwave radiation is based on polarization of its organic mass. This is probably because the heating of coal by microwave radiation is the result of polarization of macromolecules in coal’s organic mass, facilitating oscillatory, pulsational, and rotary motion of electrical dipoles, charges, and electrons. In such conditions, the microwave radiation changes the polarity of the particles, which begin reciprocating motion at the same frequency. Accordingly, the temperature increases over the whole coal volume. In each coal grain, as a result, the coal’s organic mass undergoes pyrogenetic transformation. Solid, liquid, and gas phases are formed as a result of primary pyrolysis. The gaseous phases are volatile aromatic hydrocarbons, which are the main components of the primary coal tar and create pressure at the internal surface of the coal grain. The results permit analysis of the destructive processes within the coal grains, which permit more profound intramolecular changes in the organic mass on account of polarization. That facilitates oscillatory, pulsational, and rotary motion of the electrical dipoles, charges, and electrons, which, in turn, is responsible for heat liberation. Microwave heating of a coal grain increases the temperature by more than 500°C. That facilitates the formation of plastic mass and the sintering of the coal grains.