Pore morphology in pressurized lignite coal: A small angle x-ray scattering investigation

The morphological changes in lignite coal at two different pressures, using small angle x-ray scattering, have been investigated. All the scattering profiles are interpreted in terms of surface fractal morphology. It is observed that the surface fractal dimension does not change appreciably under the experimental pressure range, while the volume of micro-cracks and inter-particle pore space is reduced with increasing pressure. By and large, the constant value of the surface fractal dimension of all the specimens, as calculated from the scattering profiles, indicates that the roughness on the pore coal interface remains almost unaffected under the experimental pressure range. The validity of single scattering approximation for this experiment has also been confirmed by the observation of the identical nature of the small angle scattering profiles with respect to change of wave lengths, namely, 0.154 nm. (Cu Kα) and 0.072 nm (Mo Kα), of the probing radiation.