焦煤镜质组热解过程中胶质体的结构演化特性研究

Structure evolutions of plastic phase derived from vitrinite in coking coal during pyrolysis process

研究炼焦煤热解成焦过程中胶质体阶段的结构对于认识成焦机理和指导配煤炼焦具有重要作用。采用基氏流动度测定仪对炼焦煤中镜质组进行热解实验以探究热解过程中胶质体的结构演化,并对特征温度点(T_(p)、T_(m)、T_(k))产物进行X射线衍射(XRD)、拉曼光谱(Raman)、^(13)C NMR结构表征。结果表明:随着热解温度的增加,微晶结构参数中的堆垛高度(L_(c))、芳香度(f_(a))增加,石墨片层间距(d_(002))、碳微晶尺寸(L_(a))减小;Raman结构参数中的碳结构石墨化程度(A_(G)/A_(all))增加,而热解产物中碳结构的缺陷结构和无序结构逐渐减小;核磁中芳香族碳含量逐渐增加,脂肪族含量减小。镜质组热解过程中胶质体流动度的变化分为胶质体发展过程与胶质体固化过程2个阶段,且2个阶段热解产物的结构演化速度存在明显差异,产物的结构参数在胶质体的发展过程中均演化较慢,而在胶质体的固化阶段演化较快。

It is important to study the structures of the plastic phase(metaplast)derived from coking coals during pyrolysis and coking process for understanding the coking mechanism and guiding coal blending and coking.The pyrolysis of the vitrinite in a coking coal was carried out by a Gieseler plastometer to investigate the structure evolutions of the metaplast during pyrolysis process,and the products at characteristic temperature(T_(p),T_(m),T_(k))were studied by X-ray diffraction(XRD),Raman spectroscopy(Raman),carbon-13 nuclear magnetic resonance(^(13)C NMR).The results show that with the increase of pyrolysis temperature,the stacking height(L_(c))and aromaticity(f_(a))of the metaplast increased,and the graphite interlayer spacing(d_(002))and microcrystal size(L_(a))of the metaplast decreased;the graphitizing degree of the carbon structure(A_(G)/A_(all))for the metaplast increased,and the defective and disordered carbon structures of the metaplast gradually decreased;the aromatic carbon content in the metaplast increased,and the aliphatic content in the metaplast decreased.The fluidity of metaplast derived from the vitrinite during pyrolysis process was divided into two stages:the development and solidification of the metaplast.Furthermore,there was a great difference for the structure evolution rate of the metaplast between the two stages.The change rates for the structural parameters of the metaplast were slower in the development stage and faster in the solidification stage.