【作者】 郑刘根；

【导师】 刘桂建；

【作者基本信息】 中国科学技术大学 ， 环境科学与工程， 2008， 博士

【摘要】 汞是煤中有害微量元素之一,具有较强的挥发性,几乎所有的汞在煤燃烧过程中都会释放进入大气,对环境和人体健康造成影响。本次研究在充分调研国内、外文献及相关科学研究领域的基础上,通过精密仪器测试、化学实验以及微区分析等手段,对中国煤样品中的汞进行了分析和研究,并充分运用煤地球化学、煤田地质学、煤化学、环境地球化学、环境科学等交叉理论知识,系统探讨了煤中汞的环境地球化学特征。通过研究得出:(1)中国煤中汞的含量多在0.1mg╱kg到0.3mg╱kg,平均含量为0.19mg╱kg,并根据其含量特征将中国煤中汞划分为低含量汞区、中等含量汞区和典型富汞区等三个区域;由于沉积环境及成煤过程中各种地质因素的综合影响,中国不同成煤时代以及不同变质程度煤中汞的含量差别较大;(2)探索性研究了中国低硫煤中汞的浓度分布和赋存特征,研究结果表明,硫化物结合态的汞和有机结合态的汞在低硫煤中占共同的支配方式;(3)重点系统研究了淮北煤田低硫煤中汞的含量、赋存状态及影响因素,研究结果表明,岩浆侵入导致了煤层中汞的重新分配,硅酸盐结合态的汞是岩浆侵入煤层中汞的主要赋存方式;(4)对比研究了不同煤级、高氯、高硫以及风化煤和非风化煤等典型煤样中汞的赋存特征,发现了煤中汞在不同类型的典型煤中赋存方式明显不同;(5)对淮北煤田和兖州煤田煤中汞的地球化学形成与演化进行了详细研究,分析了成煤植物、陆源母岩性质、沉积环境、岩浆热液作用以及其它一些因素对煤中汞分布和富集的影响机理;(6)在对洗选、淋滤以及矿区水环境中汞的浓度分布特征分析的基础上,探讨了煤中汞在环境中的迁移和分配规律,评价了1980到2007年间我国燃煤过程中汞的大气排放量,结果表明,煤炭资源的开采利用,导致煤中的汞对中国部分地区环境(特别是典型矿区的环境)造成了污染,控制燃煤过程中汞的排放仍是今后研究的重要内容之一。更多还原

【Abstract】 Mercury (Hg) is a toxic, persistent, and globally distributed pollutant due to its characteristic properties such as low melting and boiling points, conversion between chemical forms and participation in biological cycles. During combustion Hg in coal is almost totally emitted to the atmosphere and result in environmental contamination and human health problem. Combining with the knowledge of coal geochemistry, coal geology, coal chemistry and environmental geochemistry, the environmental geochemistry of Hg in coals was investigated using instrument analysis, chemical experiments, and microprobe analysis, and the results indicate as follows.(1) By combining our results with the literature values, we have a database of Hg content in 1,712 samples of Chinese coals, and using this database, the variation of Hg in Chinese coals was investigated according to coal basins, geological ages and coal ranks. The results show most Chinese coals have Hg content in the range of 0.1 to 0.3 mg/kg, with an average of 0.19 mg/kg, and the Hg content in coals varies in different coal basins, geological ages and coal ranks.(2) The author groping investigated abundance and mode of occurrence of Hg in low sulfur coals, and the original results indicates that the organic-bound and sulfide-bound Hg are the main forms in most low-sulfur coals;(3) Hg in the Huaibei Coalfield, Anhui Province was systematically studied, especially on distribution, modes of occurrence, and enrichment of Hg in coals influence by magmatic intrusion. The results indicates that magmatic intrusion not only results in enrichment of Hg in coals but also influences modes of occurrence of Hg in coals, silicate-bound Hg is the main form in coals intruded by magmatic;(4) Hg in coals of different coal ranks, high-Cl, high-sulfur, weathered and unweathered were selected to determine their forms, and the results indicates that modes of occurrence of Hg are different in these special coals.(5) The Huaibei Coalfield in Anhui Province and the Yanzhou Coalfield in Shandong Province were selected as studied areas. Hg enrichment in these coals were investigated according to factors such as coal-forming plants, character of source rock, sedimentary environment, hydrotherm such as magmatism and others, and the results indicates that Hg enriched in coals are formed in multiphase and multigenesis.(6) Character of Hg distribution and migration during coal mining, accumulation and utilization has been investigated in this study, and the results shows:①Physical coal cleaning techniques such as coal washing is not effective in Hg reduction;②Leaching experiment indicates migration of Hg varies with conditions of pH values, times and temperatures;③Dump accumulation has resulted in water contamination in coal mining area. Mercury emission to atmosphere during coal combustion increased from 1980 to 2007, and has resulted in serious environmental contamination in China, particularly in the northeastern and southwestern China, where a high Hg content in the atmosphere occurs.更多还原