Characteristics of coal re-oxidation based on microstructural and spectral observation

In order to investigate the characteristics of re-oxidation of residual coal in goafs in close coal seam mining, scanning electron microscope and infrared spectrometer are used to study the changes of coal microstructure and chemical reaction of functional groups of eight coal samples at different ranks. Result shows that after initial oxidation, the surface morphology of pore are different, and the porosity of coal is increased and the oxygen adsorption capacity of coal is improved. The change of coal molecular structure and presence of a large amount of active oxygen-containing functional groups lead to increasing tendency of coal to further oxidation. In addition, the higher lever of the initial oxidation is, the easier the re-oxidation occurs.