Characterization and analysis of Zouzhuang tectonic coal with different degree of demineralization

To investigate the effects of acid washing on coal quality properties, and tectonic coal from Zouzhuang was pretreated by hydrochloric acid solutions of different concentrations. Coal samples were extracted with chloroform solvent using fractionated samples in ultrasound-microwave extractor. Structure characteristics of the extracts were studied in detail by means of FTIR analysis and the extracts were separated by column chromatography and fluorescence characteristics of the group components were also analyzed. The results show that the removal ratio and extraction rate of coal increased with the degree of acid treatment; FTIR absorption spectra showed increasingly evident intermittent trend. The content of saturated hydrocarbon and aromatic hydrocarbon in column chromatography groups increased gradually, whereas asphaltenes content decreased stepwise. The structural dynamic action makes the coal molecular structure have polycondensation and aromatization, speeding up the evolution of the macromolecular hydrocarbons (asphaltenes). The coal extracts of maximum fluorescence intensity changes into "U" shape. The fluorescence intensity of aromatics is obviously higher than that of extraction, the hydrocarbon and asphaltenes, which may be caused by the size of molecular weight.