Study on Microstructure and Elements in the Sandstone of the Shendong Coal Field, Inner Mongolia by SEM-EDX

The sandstone strata in the Shendong coal field have lots of structural planes, which has a significant influence on the mechanical properties, ultrasonic wave propagation, failure mode and force transfer of the strata. The structural plane in the sandstone strata of the Buertai, Daliuta, Bulianta mine was chosen as the research object, and their microstructure and element characteristics were studied by using FEI-SEM and Energy Dispersive X-ray Fluorescence Spectrometer (EDXRF). Results show that the structural planes in sandstone of the Shendong coal field can be divided into two types (Ⅰ and Ⅱ), with Ⅰ being further divided into three subgroups (Ⅰ₁, Ⅰ₂, Ⅰ₃). TypeⅠ mainly contains coal, whereas typeⅡ mainly contains muscovite. TypesⅠ₁ and Ⅱ structural plane particles are not obvious and the particle boundaries are not clear. But the particles of typeⅠ₂ and Ⅰ₃ structure planes are more obvious with much clearer particle boundaries. The pore diameter and fracture length of typeⅠ₁ structure plane are 2.1 μm and 81.8 μm, respectively, whereas those for typeⅠ₂ structure plane are 8.9 μm and 38.8 μm, respectively. The pore diameter and fracture length of typeⅠ₃ structure plane are 4.5 μm and 143.7 μm, whereas those for typeⅡ structure plane were 3.8 μm and 13.8 μm, respectively. The main elements of typeⅠ₁ structure plane are C, O, Si, Al, K, Ti and Fe, whereas the main elements of Ⅰ₂ structure plane is C. The main elements of Ⅰ₃ structural plane are C, O, Si, Al, K and Mg. The main elements of typeⅡ structural plane are C, O, Si, Al, K and Ti. Therefore, C and O are the main elements of the structural planes in the strata of the Shendong coal field. The microstructures of the two types of structural planes are different. The results are helpful to further reveal the roof dynamic disaster and step subsidence in the Shendong coal field.