【作者】 徐蕾；

【导师】 王文峰；

【作者基本信息】 中国矿业大学 ， 矿产普查与勘探， 2018， 硕士

【摘要】 煤主要由矿物和有机质组成,但在其形成过程中矿物受到了有机质的影响,使得它们的物理化学性质与非煤源的矿物存在一定差异。为了探究此科学问题,本文利用扫描电子显微镜和X射线衍射分析了大同煤田石炭-二叠纪煤层及夹矸中常见的矿物种类和它们的赋存特征。在此基础上,以大同煤田煤层样、夹矸样、煤中剥离出的黄铁矿以及非煤源的高岭石和黄铁矿为研究对象,通过X射线荧光、X射线衍射和红外光谱等研究方法以及燃烧实验等,对比研究了煤源高岭石与非煤源高岭石的晶形差异,探究了有机质含量与晶形的关系;通过双比重瓶法、磁化率测试和黄铁矿的热解实验,对比研究了煤源黄铁矿与非煤源黄铁矿在密度、磁性及热稳定性方面的差异,并运用有机质萃取实验结合红外光谱法、煤样的热解实验,阐明了有机质对煤中黄铁矿的影响。主要得到以下成果和认识:(1)揭示了大同煤田石炭-二叠纪煤层及夹矸中常见的矿物种类和它们的赋存特征。大同煤田煤中的矿物主要为硅酸盐矿物、硫化物矿物、碳酸盐矿物、氧化物矿物,另外还有少量的卤化物矿物及硫酸盐矿物,其中硅酸盐中的高岭石为含量最高的矿物,其次为硫化物中的黄铁矿。高岭石以梭状、条带状和蠕虫状分布于煤中;黄铁矿则主要呈自形粒状、鱼子状、结核状、滚圆球形状、他型及裂隙充填状。煤层夹矸中的矿物主要为硅酸盐中的高岭石,主要呈片状和蠕虫状分布。(2)明确了煤源与非煤源高岭石的物性差异。煤源高岭石的烧失量均大于非煤源高岭石的烧失量,表明煤源高岭石中有机质的含量高于非煤源高岭石。煤源高岭石的OI结晶指数和Hi指数均高于非煤源高岭石,表明煤源高岭石的结晶度高于非煤源高岭石。相关性分析表明,有机质含量与高岭石结晶度有很好的相关性,可能是有机质的存在为高岭石的生长结晶提供了更加有利的环境。在煤源高岭石中,有机质含量越高、高岭石与有机质结合的程度越紧密、高岭石颗粒越小,则煤源高岭石的结晶度越好。(3)揭示了煤源与非煤源黄铁矿的物性差异特征。煤源黄铁矿的密度(3.5253 g/cm~3~3.6729 g/cm~3)远小于非煤源黄铁矿(4.8435 g/cm~3~4.9226 g/cm~3),碳峰的强度高于非煤源黄铁矿,S/Fe原子比小于非煤源黄铁矿,这可能是有机质对煤源黄铁矿产生了影响。煤源黄铁矿在500℃时磁性达到最大,非煤源黄铁矿在550℃时磁性达到最大,此温度高于煤源黄铁矿磁性最大点的温度,但最大失重量要低于煤源黄铁矿。煤源黄铁矿发生热解时的温度低于非煤源黄铁矿,最大失重量大于非煤源黄铁矿,这些都说明了有机质可能参与了煤源黄铁矿的作用。(4)探究了煤中黄铁矿与煤有机质间的相互作用,揭示了煤源与非煤源矿物的物性差异机理。原煤样的THF萃取液中全部为有机质,并且含有更高的硫成分,除此之外,在有机质中还发现有较高含量的噻吩类杂环化合物,这说明了黄铁矿可能与有机质之间存在一定的作用。热解实验表明掺入黄铁矿的混合煤样的最大失重量大于原煤,即黄铁矿的存在加快了煤的热解,对煤的热解产生一定的催化作用;而且混合煤样中黄铁矿热解时的温度比纯黄铁矿分解时的温度低,表明了有机质对黄铁矿的分解也有一定的促进作用。但通过对比煤源黄铁矿与非煤源黄铁矿对煤热解产生的影响,得出了原煤样最大失重率大于混合煤样,最大失重温度小于混合煤样,即煤源黄铁矿具有更强的催化能力。更多还原

【Abstract】 Coal is mainly composed of minerals and organic matter,but minerals are affected by organic matter in the process of their formation,making their physical and chemical properties different from non-coal minerals.In order to explore this scientific problem,the common mineral species and their occurrence characteristics in the Carboniferous-Permian coal seams and partings of Datong coalfield were analyzed using scanning electron microscopy and X-ray diffraction.On this basis,the study focused on the coal seam samples of Datong coalfield,the helium samples,pyrite stripped from coal,and kaolinite and pyrite from non-coal sources.By means of X-ray fluorescence,X-ray diffraction,infrared spectroscopy,and combustion experiments,the difference in crystal shape between coal-derived kaolinite and non-coalogenic kaolinite was compared.The relationship between organic matter content and crystal shape has been explored.The differences in the density,magnetic properties,and thermal stability of coal-derived pyrite and non-coal-derived pyrite were compared using the double pycnometer method,susceptibility testing,and pyrolysis experiments of pyrite.Using organic matter extraction experiments combined with infrared spectroscopy and coal pyrolysis experiments,the effect of organic matter on pyrite in coal was clarified.The main results and understandings are as follows:(1)It reveals the common mineral species and their occurrence characteristics in the Carboniferous-Permian coal seams of the Datong coalfield.The minerals in Datong coalfield coal are mainly silicate minerals,sulfide minerals,carbonate minerals,and oxide minerals.In addition,there are a small amount of halide minerals and sulfate minerals.Among them,kaolinite in silicate is the highest content of minerals,followed by pyrite in sulfides.Kaolinite is distributed in coals as fusiform,stripe and worm-like.The pyrite is mainly in the form of self-granular,crescent-like,nodular,round ball,histogram and fissure-filled.The minerals in coal seams are mainly kaolinite in silicate,mainly in the form of flakes and worms.(2)The differences in the physical properties of coal and non-coal kaolinite are clarified.The loss of ignition of coal-sourced kaolinite is greater than that of non-coal kaolinite,indicating that the content of organic matter in coal-sourced kaolinite is higher than that of non-coal kaolinite.The OI and Hi index of coal-sourced kaolinite are higher than that of non-coal kaolinite,indicating that the crystallinity of coal-derived kaolinite is higher than that of non-coal kaolinite.The correlation analysis shows that the organic matter content has a good correlation with the kaolinite crystallinity.It may be that the presence of organic matter provides a more favorable environment for the growth and crystallization of kaolinite.In coal-sourced kaolinite,the higher the organic matter content,the more closely the kaolinite and organic matter are combined,and the smaller the kaolinite particles,the better the crystallinity of the coalescent kaolinite.(3)The characteristics of the difference in physical properties between coal and non-coal-derived pyrite are revealed.The density of coal-derived pyrite(3.5253g/cm~3~3.6729g/cm~3)ismuchsmallerthannon-coal-derivedpyrite(4.8435g/cm~3~4.9226g/cm~3),and the intensity of carbon peak is higher than that of non-coal-derived pyrite.The atomic ratio of S/Fe is lower than that of non-coal-derived pyrite.This may be due to the influence of organic matter on the pyrite.Coal-derived pyrite has the highest magnetic properties at 500°C.Non-coal-derived pyrite has the highest magnetic properties at 550°C.This temperature is higher than the temperature at the maximum magnetic point of coal-derived pyrite,but the maximum lost weight is lower than that of coal.The pyrolysis temperature of coal-derived pyrite is lower than that of non-coal-derived pyrite,and the maximum loss weight is greater than that of non-coal-origin pyrite.These indicate that organic matter may be involved in the role of coal-derived pyrite.(4)The interaction between pyrite and coal organic matter in coal was explored,and the mechanism of physical differences between coal and non-coal minerals was revealed.The raw coal-like THF extracts are all organic and contain higher sulfur components.In addition,high levels of thiophene-type heterocyclic compounds are also found in organic matter,indicating that pyrite may have a certain role with organic matter.The pyrolysis experiments show that the maximum lost weight of the mixed coal sample mixed with pyrite is greater than that of the raw coal,that is,the presence of pyrite accelerates the pyrolysis of the coal and produces a certain catalytic effect on the pyrolysis of the coal.The temperature of pyrite pyrolysis in mixed coal samples is lower than that of pyrolysis,indicating that organic matter also contributes to the decomposition of pyrite.However,by comparing the influence of coal-derived pyrite and non-coal-derived pyrite on coal pyrolysis,it is concluded that the maximum weight loss rate of raw coal samples is greater than that of mixed coal samples,and the maximum weight loss temperature is lower than that of mixed coal samples.That is,coal-derived pyrite has a stronger catalytic ability.更多还原