锡林郭勒褐煤提质改性过程及其提质褐煤低温氧化性能的研究

In view of the increasing of spontaneous combustion tends results in serious harm to Upgrading Process and Upgraded Lignite in Xilin Gol. The project committed to coal sample from specific chemical structure and composition by sequential chemical extraction, ion exchange, organic solvent extraction and other methods, combined with the FTIR,XPS,XRD,RAMAN和NMR and other characterization methods were adopted to Processing and characterization ShengLi lignite, the aim is to determine the type of inherent minerals, and oxygen-containing functional groups, side chain of aromatic structure, the bridge bond and the low molecular weight organic compounds qualitative and quantitative analysis. The reactivity performance as well as the formation and evolution mechanism of various period products of upgrading process, low temperature oxidation and spontaneous combustion tends were studied with the thermal analysis, Fixed bed micro-reactor and situ surface chemical reaction. To make sure the intrinsic relationship of the low temperature oxidation characteristics,，dynamics and side chain of aromatic structure, the bridge bond, the low molecular weight organic compounds and other structure units, the key oxidation reaction and its mechanism which occur in the incubation period of spontaneous combustion and self-heating period ,the law of effect on low temperature characteristics and spontaneous combustion tends by the mineral compositions. To achieve low temperature characteristics and spontaneous combustion tends in the upgrading process of Xilin Gol. Effective measures of inhibiting the spontaneous combustion of Xilin Gol will be formulated based on the above analysis. It provides scientific foundation for upgrading process optimization of Xilin Gol lignite, process control and inhibiting spontaneous combustion.

鉴于锡林郭勒褐煤提质过程及提质褐煤自燃倾向大幅增加对褐煤产业的严重危害，本项目从锡林郭勒褐煤特定的组成和化学结构入手，采用逐级化学提取分离、离子交换、有机溶剂抽提等方法对煤样进行处理，结合 FTIR、XPS、XRD、RAMAN和核磁等手段，对褐煤固有矿物质及芳香结构侧链、桥键、含氧官能团以及低分子有机化合物进行分析，应用热分析、微反固定床及原位表面化学反应等方法考察其反应性能，对提质过程各阶段产物的生成演变机制、低温氧化特性及自燃倾向进行研究。确定其低温氧化性能、动力学与芳香结构侧链、桥键以及低分子有机化合物等结构单元的内在关系，自燃潜伏期和自热期所发生的关键氧化反应及机理，矿物质成分对其低温氧化和自燃倾向的影响规律，获得锡林郭勒褐煤提质过程与其低温氧化性能及自燃倾向规律，并据此制定可抑制锡林郭勒提质褐煤发生自燃的有效措施，为锡林郭勒褐煤提质工艺优化、过程控制及抑制自燃的发生奠定科学基础。

本项目针对锡林郭勒地区胜利褐煤反应性高、着火温度低以及易自燃等特点进行了系统的研究。首先考察了胜利褐煤提质前后芳香结构侧链、桥键以及低分子有机化合物等易燃结构单元的变化规律，在此基础上进一步研究了胜利褐煤低温氧化/燃烧特性与微结构转化特性的关系，同时分析了主要矿物质成分对胜利褐煤低温氧化/燃烧性能及其微结构的影响。研究结果表明：（1）热解提质温度对胜利褐煤易燃结构单元具有显著的影响，随热解提质温度的升高，煤焦微晶结构有序度增加，其中羟基、甲基、亚甲基、羧基和羰基等有机官能团减少，表明易燃结构单元随热解提质温度的升高而减少。酸处理改善了褐煤中侧链的数量，增加了着火温度和表观活化能；（2）温度对胜利褐煤的低温氧化性能影响较大，氧化温度低于220 C时，煤样的质量变化很小，在220-230 C温区内，煤样的质量发生突变，由220 C时的5.8%突变为230 C时的42.6%，而脱矿掺铁褐煤质量发生突变的温度范围分别较原煤和脱矿煤降低约10 C和20 C，说明铁物种对褐煤低温氧化性能有明显的促进作用，同时确定了褐煤在起始突变温度下有类醌结构形成，且类醌结构的氧化分解导致褐煤的质量发生突变，而高度分散的铁物种使褐煤质量的突变温度下降；（3）碱氧氧化处理温度对褐煤微结构和燃烧性能有显著的影响，经碱氧氧化处理后的褐煤其着火温度均升高，尤以150-200C时最为明显，表征结果表明芳族核上的脂族侧链和羧基官能团含量降低，芳族层尺寸和有序度增加；（4）NaOH处理对褐煤的燃烧性能具有明显的抑制作用，NaOH处理后的褐煤出现两个失重温区，且最大燃烧反应速率对应的温度高出原煤350-400C，FTIR和XPS分析确定了在NaOH处理煤样中有类多元羧酸钠结构出现，其源于褐煤中的羧基官能团与NaOH的交联组合，类多元羧酸钠结构较高的稳定性导致褐煤的主燃温度显著提高。本项目的研究结果为抑制褐煤的自燃提供了理论基础，对于工业上褐煤的安全运输和有效利用具有重要意义。