Change characteristics of microcrystalline and chemical structure parameters of tectonic coals under solvents extraction

Based on the coal samples with different coal body structures in Jinyuan mine,Shandong Province,the ex- periment of coal extraction has achieved by different solvent fractionated extractions. Also,the microcrystalline struc- ture parameters of coal samples were analyzed by means of X-ray diffraction (XRD) and the variation characteristics of chemical structure of tectonic coal and residues were studied with the nuclear magnetic resonance (NMR) technolo- gy. The research shows that under the fractional extraction by different solvents,the extraction rates of coal samples with different coal body structures ( from low to high) are as follows:raw coal,cataclastic coal,granulated coal,and mylonitic coal. Meanwhile the extraction rate by tetrahydrofuran (THF) is the largest. After the extraction,the parame- ters of d002 ,La and Lc of coal samples are larger. As the deformation degree of coal body structures increases,the aro- matic lamellae spacing (d002 ) in aromatic fused ring of coal shows a complicated trend,but the stack height (Lc ) appears an increasing trend except the Lc of mylonitic coal decreases slightly. And the aromatic-carbon ratio (fa ) also in- creases,but the aliphatic carbon ratio ( fal ) shows a decreasing trend. Furthermore,the research concludes that the small molecular compounds of aliphatic strip easily,the extraction rate of small molecular compounds of aromatic rings is low during the process of extraction.