溶剂萃取后构造煤的微晶及化学结构参数变化特征
Change characteristics of microcrystalline and chemical structure parameters of tectonic coals under solvents extraction
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摘要: 以山东腾南煤田金源矿为研究区,采集不同煤体破坏程度的煤样,通过溶剂分级萃取实验,利用X射线衍射(XRD)和核磁共振(NMR)测试技术,对比分析了萃取前后煤样的微晶结构参数,探讨了化学结构特征参数的变化规律。研究表明:(1)在不同溶剂的分级萃取下,不同煤体结构煤的累计萃取率从小到大依次为原生结构煤、碎裂煤、碎粒煤、糜棱煤,其中THF溶剂对各类煤样的萃取率最大;(2)溶剂萃取后,各类煤样的碳原子网面间距(d002)、堆砌度(Lc)和延展度(La)均大于原煤。随着萃取级数的增加,各煤样的碳原子网面间距(d002)呈现较复杂的变化趋势,BSU的堆砌度(Lc)除了糜棱煤随着萃取的深入有略微减小外,总体上随着萃取级数的增加呈现增大的趋势;(3)随着构造变形的增强,构造煤的芳碳率呈增大的趋势,而脂碳率的数值变化有明显减小的趋势。溶剂的萃取作用中,脂族类的小分子化合物更容易溶出,芳香环上的小分子化合物萃取率较低。Abstract: 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.