【作者】 吴代赦；

【导师】 郑宝山；

【作者基本信息】 中国科学院研究生院（地球化学研究所） ， 地球化学， 2004， 博士

【摘要】 氟是煤中含量较高的微量元素，大多在20-500mg/kg，平均值为150mg/kg左右。煤在燃烧时，其中的氟化物将发生分解，大部分以HF、SiF₄等气态污染物形式排入大气，不仅严重腐蚀锅炉和烟气净化设备，而且造成大气氟污染和生态环境的破坏。氟是人体所必需的微量元素，但摄入过量则会罹患氟斑牙和氟骨症。燃煤污染型氟中毒为我国所独有，导致了近1500万患者，这是人类有史以来最严重的环境污染导致的健康危害事件。因此，根据目前国内外对煤中氟的研究进展，研究中国煤中氟的含量、分布及其影响因素；燃煤型氟中毒的环境地球化学特征；选煤脱氟的机理；粮食中氟的分析方法既有理论意义又有现实价值。 通过本文的研究，得出以下几点认识： 1、通过在全国有计划的系统取样。统一采用当前最有效的分析方法——高温热水解—离子选择性电极法来获得中国煤炭的平均氟含量。与世界煤相比，中国煤含氟量正常，绝大部分（90％）煤的含氟范围为47～347mg/kg，全国煤氟平均含量为136mg/kg。澄清了长期以来关于中国煤炭高氟的错误认识，为正确计算燃煤的氟排放通量并评价其环境影响提供了较准确的基础资料。 2、中国煤中氟含量与灰分显著正相关，表明煤中氟主要以无机矿物形式赋存。 3、在本批样品中按变质程度的不同，煤含氟量由低到高依次为贫煤、长焰煤、无烟煤、气煤、焦煤、肥煤、瘦煤和褐煤。煤中的氟主要赋存于无机矿物中，以无机形态赋存的氟不受煤变质程度的影响。从褐煤到无烟煤，煤中的氟含量和煤变质程度之间没有必然的关系，在讨论煤氟含量与变质程度的关系时要考虑氟的赋存形态的影响，以统计分析的方法来研究其间的相互关系时要慎下结论，某些变化趋势不一定就是必然的规律。 4、在本批样品中按地质时代的不同，煤中氟含量由低到高依次为早石炭世、中侏罗世、早侏罗世、早二叠世、晚石炭世、中石炭世、晚侏罗世、第三纪和晚三叠世。煤中的氟含量受物质来源、成煤环境、后期地质地球化学作用等多种因素的影响，而我国幅员辽阔、成煤期多、煤田分布广，而且同地质时中国科学院博_t学位论文 代的不同煤矿区（或者地质单元）可以具有相同条件，也可具有不同条件， 致使影响含氟量的各种因素大多只具有局部性，造成成煤时代等单一因素的 作用可能为其它各种因素的作用所掩盖，对此有必要进行更深入具体的研究。5、拌煤的粘土取自土壤的淀积层，其氟含量非常高。中国煤氟的含量不高，远 低于徒识层粘土的氟含量。在燃煤型氟中毒病区通常用粉煤与粘土加水搅拌 制成湿的煤泥在无烟囱的炉灶内燃烧。使用烟煤和无烟煤的燃煤型氟病区的 氟主要来自于拌煤的粘土。我们突破了长期以来关于氟源是高氟煤的错误认 识，这为正确、有效地防治燃煤型地氟病提供了新的思路。6、在石煤污染型氟病区石煤的风化淋溶对水环境、粮食作物的含氟量影响不 大，但其燃烧后释放出的的气态、气溶胶态和尘态氟会污染室内空气、粮食、 蔬菜和饮水从而导致人体摄氟过量而中毒。改良炉灶，改变在厨房烘烤、存 放辣椒的陋习，经常清扫室内，尤其是室内上部灰尘，防止灰尘坠落污染食 物、饮水等，对预防氟中毒有重要意义。7、选煤可降低灰分、硫分，同时还能有效脱除煤中的氟及其他有害微量元素， 从而可减少运输成本，降低粉煤灰的收集、处理和处置与有害微量元素的排 放控制费用，提高燃烧热效率，符合以预防为主的国家环保政策，要大力倡 导。8、我们采集的病区玉米第二次酸浸时浸出液含氟量低于检测限;而辣椒由于含 油较多，辣椒油阻碍了氟的浸出，这导致浸泡两、三次后在浸出液中还能检 测出氟。在地氟病区采用酸浸一离子选择性电极法测定氟含量时，玉米浸泡 一次即可满足研究需要，而对于辣椒则宜进行多次浸泡。一次或多次未浸出 的氟含量基本为一个定值，在研究地氟病时不用对此作太多考虑，但在制订 粮食的含氟量及人体的摄氟量标准时要将这一部分氟考虑进去。更多还原

【Abstract】 With a concentration scope of 20-500 mg/kg and an average value at 150 mg/kg, fluorine is one of the abundant trace elements in coal. Because of its presence in the daily diet at varying levels, fluorine often has an extraordinary significance in health and environments. During the combustion of coal, fluorine is released into the fume in the form of HF, most of which enters the atmosphere. Statistical data collected by the Chinese Ministry of Health in 2001 from 201 counties of 14 provinces, autonomous regions, and municipalities in China indicates that coal-burning fluorosis led to 18,138,780 cases of dental fluorosis and 1,594,799 cases of skeletal fluorosis. Coal-burning fluorosis in China is therefore one of the most serious health problems resulting from environmental pollution anywhere in the world.Based on the progress of study on fluorine in coals, this dissertation mainly studies the fluorine content and its distribution in Chinese coals, the environmental geochemistry of coal-burning endemic fluorosis, the fluorine reduction by coal cleaning and the determination of fluoride in corn and chili.Based on the study, some conclusions can be drawn:1. Fluorine contents in Chinese coalc are achieved through a designed nationwide samples collecting and consistently determining by the most effective method i.e. pyrohydrolysis. The contents of fluorine in Chinese coals show logarithm normal frequency distributions. The estimate of the most probable fluorine concentration for Chinese coals can be designated as 136 ppmw with the range for most of the Chinese coals of 47-347 ppmw.2. The concentration of fluorine versus ash content in 288 coal samples was studied. A significant positive correlation is inferred from this data, showing that fluorine increases in the samples studied, as does the ash content, suggesting that the fluorine compounds present in the Chinese coals aremainly of an inorganic nature.3. Fluorine in coal is predominantly associated with the inorganic constituents, and it is not affected when coal developed from lignite coal to anthracite. The fluorine content varying from lignite coal to anthracite can’t be attributed to the coal-rank’s varying.4. Fluorine contents in coal increase from C1, J2, J1, P1, C3, C2, P2, J3, R to T3. The concentration of fluorine in coal is strongly influenced by geological factors such as sedimentary environment, character of source rock, tectonic setting, and hydrogeological conditions. Most of these parameters have regional characteristics, whereas China’s abundant coal resources are spread over widely distributed coal fields with large variations in coal-forming periods. Therefore, it is difficult to get any consistent relationship between the fluorine content and the coal-forming period for the nation as a whole.5. The clay mixed with the coal to make coal-clay is derived from illuvial lower soil and has a high fluorine level. The fluorine content of most coals in China is relatively low. Because of the similar geochemistry and the essentially identical habits of coal-clay usage in coal-burning endemic fluorosis areas, clay remains a major source of endemic fluorosis in China.6. Little fluorine pollution of surface water and plant is deduced from the stone-like coal’s weathering and leaching. Fluorine released from stone-like coal combustion results in serious fluorosis. To improve stove and abandon the traditional backward habit of food baking and improve the room sanitation to avoid the contamination of dust is effective in get rid of fluorosis.7. Physical coal cleaning techniques are effective in fluorine reduction. At the same time,coal cleaning offers numerous benefits. It reduses the ash-forming mineral content of coal and increases the heating value, reducing transportation costs and increasing boiler efficiency. Coal cleaning also provides environmental benefits by reducing the sulfur dioxide andother HAPs emissions potential of the coal and the amount of ash for collection and disposal.8.更多还原