Study On Microstructure And Ultra-microstructure Characteristics Of Tectonic Coal

A large number of tectonic and primary structure coal samples collected from major coalfield of China have been studied by means of scanning electron microscope(SEM), x-ray diffraction(XRD) and electron paramagnetic resonance(EPR), The difference of the microstructure of tectonic coals formed under different tectonic stress and deformation environment conditions and the evolution law of macromolecular structure of tectonic coals with the variation of coal rank or the tectonic stress are analyzed, and The chemical mechanism and controlling factors which result in changing the structure of tectonic coals are discussed in this thesis.Through the observation of scanning electron microscope for tectonic coals, on the basis of the difference of the property, magnitude, primary-secondary and condition of the tectonic stresses, the structure of the tectonic coal at the micro size is subdivided into brittle-deformed series and ductile-deformed series. The former includes brittle crack and micro-breccia structure; the latter includes lentoid, squamose structure and mirror-like friction plane. The analysis of X-ray diffraction for tectonic coals indicates that the crystal structure of the tectonic coal is alternated along with the decrease of the tectonic stress, and the influence range of tectonic stress on the chemical structure of coal is limited, usually within 2m away from the stress concentration zone. It is expounded that the tectonic stress has a strong role in promoting the accumulation height of aromatic nucleus, and has a relatively weak effect on the expansion of aromatic nucleus. The result of electron paramagnetic resonance analysis shows that the free radical concentration of tectonic coals is elevated with the increase of coal rank in the bituminous coal stage, and has reduced tendency when the coal rank reach into the anthracite stage. The tectonic stress promotes the aromatizating process of the aromatic ring polymerization. In the bituminous coal stage,with the decrease of tectonic stress, the free radical concentration reduces rapidly within 1m away from the tectonic position,and is almost no changed in the farther position. Various chemical mechanisms causing regional metamorphism are the main controlling factors that result in the variety of the free radical concentration of tectonic coals, and the dynamic metamorphism caused by the tectonic stress is relatively minor controlling factors.