Quantitative investigation on the structural characteristics of thermally metamorphosed coal: evidence from multi-spectral analysis technology

摘要

The macromolecule structural characteristics of thermally metamorphosed bituminous coals (TMBC) are very significant to understand the thermal evolution history of coal basin and coal organic maturation. However, the relevant information is still limited. Here, four TMBC, selected from Daxing coal mine, Liaoning province, China, were investigated by using varied modern tools including Fourier transform infrared spectroscopy, X-ray diffraction and Raman spectroscopy to expound the effect of igneous intrusions on their chemical structures. Results indicate that the studied TMBC are characterized as turbostratic structures, composing of crystalline carbon assorted with varying amounts of disordered amorphous carbon. An increase in agglomeration degree of molecular structure in TMBC was observed with the increase in coal ranks. In addition, the strong contact metamorphism imposed on indigenous coal has created new pores and fractures examined by scanning electron microscope, which facilitate the drainage of coal bed methane in coal mines.