煤及其燃烧产物中稀土元素地球化学特征

发布时间：2018-04-07 17:47

本文选题：燃煤产物　切入点：有机组分　出处：《中国矿业大学》2017年硕士论文

【摘要】：论文首先基于数理统计方法归纳总结了华北、华南部分地区石炭-二叠纪煤中REE在不同沉积环境下的分布特征,在此基础上,以华南贵州无烟煤和华北徐州气煤为研究对象,通过酸处理分离出煤有机组分,同时使用马弗炉燃烧和电厂采样获取煤的无机燃烧产物,再通过磁选方法获得燃烧产物中的磁性矿物;使用红外光谱、X射线衍射、X射线荧光光谱、电感耦合等离子质谱、环境磁学和电子探针等研究手段,分析煤有机组分和燃烧产物的化学组成、稀土元素含量及磁学参数,以揭示不同沉积环境煤中稀土元素的地球化学特征,阐明煤在燃烧过程中稀土元素的迁移特征及磁学响应。取得如下主要成果和创新性认识:(1)探明华北和华南地区石炭-二叠纪不同沉积环境煤中REE的分布规律同一地区不同沉积环境下的煤中REE分布特征整体相似,不同地区相同沉积环境下REE分布特征各具差异。接近陆相沉积环境,煤中REE总含量就越高;越接近海相沉积环境,煤中轻、重稀土元素分馏就越大,Eu元素的亏损程度会增强,Ce的富集程度相对降低,直至亏损。煤中REE分布形态主要受控于陆源物质,岩浆活动会造成煤中REE相对富集,轻、重稀土元素分馏程度变高。(2)揭示了煤及其有机组分中REE的地球化学差异性特征在成煤阶段,煤中有机和无机组分均继承了物源中REE赋存特征,但无机组分比有机组分更容易受水体环境的影响。煤样经过酸处理后,无机矿物被溶蚀而有机质基团基本未被破坏,且REE的有机复合物稳定性较高,酸处理后有机组分中REE得以保留,其分布特征与有机基团种类和相对含量有关,表现为含碳基团较含氢基团越多,轻、重稀土元素分馏程度越明显。煤中有机和无机组分的含量差异是煤样经过酸处理后REE分布差异的主要原因。(3)探索了原煤及其燃烧产物中REE迁移分配特征燃煤产物基本保留了原煤中REE的分布特征,均为左高右低的Eu元素负异常的宽缓“V”型曲线,其REE富集程度远高于原煤,燃煤产物的底灰中REE富集程度和轻、重稀土元素分馏程度均相对大于飞灰。原煤中REE向灰分中迁移富集情况各异:原煤中硅酸盐矿物细颗粒比重越大,逸散率越高,燃煤产物底灰中轻、重稀土元素分馏程度则越低;原煤中硅酸盐矿物含量及其细颗粒比重越大,燃煤产物中无水石膏、方解石等矿物含量相对就越高,随着燃烧温度升高(700℃→800℃),飞灰中细颗粒及细颗粒中Si、Fe、S和P等主量元素含量增加;底灰中无水石膏等矿物含量相对降低,硅铝酸盐矿物含量相对升高,REE相对富集。(4)揭示了燃煤产物中磁性矿物与REE的响应关系燃煤产物中的磁性矿物并非以颗粒分散状态出现,而是与玻璃质矿物相胶结。磁性矿物在燃烧温度较低的底灰中形状不规则,在高温飞灰中则显示为磁珠状。受“镧系收缩”效应影响,燃煤产物中REE与其低频磁化率χlf的相关系数随REE的正三价离子半径减小而增大。随着燃烧温度的升高(700℃→800℃),控温燃煤产物中Fe元素的逸散率增加,由于Fe元素与REE呈正相关关系,其中与HREE的相关性系数较高,Fe元素的逸散造成了底灰的磁性矿物中HREE含量的相对亏损;三价REE可以置换磁性矿物中的二价Fe,在磁性矿物中REE含量与二价Fe含量变化相反,随着温度的升高(700℃→1500℃),三价Fe离子含量降低,二价Fe离子含量升高,磁性矿物中REE含量相对降低,其中HREE较原灰分尤其亏损。
[Abstract]:Firstly, based on the method of mathematical statistics summarized in North China, the distribution characteristics of Carboniferous Permian coal in some areas of Southern China - REE in different sedimentary environment, on the basis of this, to Southern China and North Xuzhou Guizhou anthracite coal as the research object, through the acid treatment of isolated coal organic components, at the same time using muffle furnace combustion and power plant sampling the inorganic coal combustion products, to obtain magnetic minerals in combustion products by magnetic separation method; using infrared spectroscopy, X ray diffraction, X ray fluorescence spectrometry, inductively coupled plasma mass spectrometry, environmental magnetism and electronic probe and other research methods, analysis of coal combustion products and organic chemical composition, REE contents and magnetic parameters. In order to reveal the geochemical characteristics of rare earth elements in different sedimentary environment in the coal, migration characteristics and magnetic elucidate coal in the combustion process of rare earth elements in response to the following. The main achievements and innovation of knowledge: (1) study of Carboniferous in Southern China and Northern China in different sedimentary environments of Permian distribution of different sedimentary environment of coal REE in the same area of the coal distribution characteristics of REE are similar, with the same REE distribution characteristics of sedimentary environment in different areas of difference. Close to the continental sedimentary environment in coal REE the total content is higher; more close to the marine sedimentary environment in coal, light, heavy REE fractionation is larger and the degree of loss of Eu element will be enhanced, the enrichment degree of Ce decreased, until the loss. REE in coal distribution is mainly controlled by the source material, magmatic activity will cause the relative enrichment of REE in coal, light and heavy REE fractionation degree becomes higher. (2) the coal and geochemical characteristics of fractions of REE in the coal forming stage, coal in organic and inorganic components were inherited the occurrence characteristics of REE source, but no unit than Set points are more easily affected by water environment. Coal samples after acid treatment, inorganic mineral dissolution and organic groups without destruction, high stability and organic compound REE, after acid treatment of organic components in REE are retained, the distribution and relative content of organic groups and types, performance carbon containing groups containing hydrogen groups is more light and heavy REE fractionation degree is obvious. The organic and inorganic components in coal is the main reason for differences in the content of coal samples after acid treatment REE distribution. (3) to explore the raw coal and its combustion products REE migration distribution characteristics of combustion products to retain the basic distribution characteristics REE in the raw coal, all Eu elements left high right low negative anomaly relief "V" curve, the REE concentration is much higher than that of raw coal, REE enrichment degree of bottom ash combustion products in light and heavy rare earth elements, the degree of fractionation are relatively large To fly ash in coal ash. The migration to REE enrichment in different situations: coal in silicate mineral fine particles of the larger proportion of dissipation rate is high, the product of coal bottom ash light, heavy REE fractionation degree is low; silicate mineral contents in raw coal and fine particles of the larger proportion of anhydrous gypsum coal products. Calcite content is relatively higher, with the increasing of combustion temperature (700 DEG to 800 DEG C), fly ash particles and fine particles of Si, Fe, S and P increased the contents of major elements; the bottom ash and anhydrous gypsum mineral content is relatively low, aluminosilicate mineral salt content increased relatively. The relative enrichment of REE. (4) revealed that magnetic minerals not response between the combustion products of magnetic minerals and REE in the residues in particle dispersion state, phase but with vitreous mineral cementation. The magnetic minerals in the bottom ash low combustion temperature in irregular shape in The high temperature in the fly ash is bead shape. Influenced by the "contraction" effect of lanthanide, Cr3 + ion radius correlation coefficient X LF REE and low frequency magnetic susceptibility in the residues with REE decreases. With the increase of combustion temperature (700 DEG to 800 DEG C), emission of Fe element increased temperature control coal products, because Fe elements are positively correlated with REE, HREE and the correlation coefficient is higher, Fe emission caused by the relative loss of elements of bottom ash in magnetic mineral content of HREE; REE two Fe price of trivalent replacement in magnetic minerals, in magnetic mineral content change of REE and two Fe were opposite price and with the increase of temperature (700 DEG to 1500 DEG C), reduce the content of trivalent Fe ion, Fe ion content increased two relative price, reduce the content of REE in magnetic minerals, which is especially HREE ash loss.

【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ534;P618.11

【参考文献】