氟作为煤中有害元素之一，探究氟在电厂煤及燃烧产物中的迁移、赋存与浸出特征，对控制燃煤过程中氟的迁移行为和固体废弃物的潜在风险至关重要。以燃煤电厂煤及燃烧产物为研究对象，基于氟的质量平衡研究了氟在燃煤电厂中的分布，采用扫描电镜-能谱（SEM-EDS）、逐级化学提取试验分析了燃煤电厂煤及燃烧产物中氟的赋存状态，在此基础上采用标准毒性浸出方法TCLP和HJ/T 300—2007《固体废物 浸出毒性浸出方法 醋酸缓冲溶液法》浸出试验研究了氟的浸出特征。结果表明，氟属于易挥发元素，煤中氟经过燃烧主要分布在燃煤烟气中并被脱硫石膏捕获，其次分布在飞灰中，只有很少一部分高温稳定性较好的氟化物残留在炉渣中；煤和炉渣中的氟主要为铝硅酸盐类矿物中的残渣态氟，燃烧过程中残渣态氟的转化以及飞灰对烟气中氟的吸附使得飞灰中活性氟的比例增加，飞灰中活性氟比例为63%～68%，脱硫石膏以残渣态氟为主，活性氟比例为38%～50%；浸出试验结果表明燃煤电厂中不同样品的浸出量在0.12～27.31 μg/mL，均低于危险废物浸出液中氟浓度限值；氟的浸出主要与氟的赋存状态和所处环境有关，在环境较温和的情况下主要是固体样品中离子可交换态氟会影响环境，在酸性较强的环境下，离子可交换态和碳酸盐结合态氟则是产生氟污染的主要原因。

As one of the harmful elements in coal,it is essential to investigate the migration,occurrence and leaching characteristics of fluorine in power plant coal and combustion products to control the migration behavior of fluorine during coal combustion and the potential risk of solid waste. This paper took the coal and combustion products of coal-fired power plant as the research object,the distribution of fluorine in coal-fired power plants was studied through the mass balance of fluorine,the occurrence of fluorine in coal and combustion products of coal-fired power plant was analyzed  by scanning electron microscope-energy spectrum (SEM-EDS) and step-by-step chemical extraction test. On this basis,the leaching characteristics of fluorine were studied by standard toxicity leaching method TCLP and HJ/T300—2007"Solidwaste-Extraction procedure for leaching toxicity-Acetic acid buffer solution method" leaching test. The results show that fluorine is a volatile element. After combustion,fluorine in coal is mainly distributed in flue gas and captured by desulphurization gypsum,followed by fly ash,and only a small part of fluoride with good high temperature stability remains in slag. Fluorine in coal and slag is dominated by residual fluorine existing in aluminosilicate minerals. The transformation of residual fluorine during combustion and the adsorption of fluorine in flue gas by fly ash increase the proportion of active fluorine in fly ash,and the proportion of active fluorine in fly ash is 63%-68%. Desulphurization gypsum is mainly residual fluorine,and the proportion of active fluorine is 38%-50%. The leaching test results show that the leaching amounts of different samples in coal-fired power plant is between 0.12-27.31 μg/mL,which is lower than the limit of fluorine concentration in hazardous waste leaching solution. The leaching of fluorine is mainly related to the occurrence state and environment of fluorine. In the mild environment,the ion exchangeable fluorine in the solid sample will affect the environment,and in the acidic environment,ion exchangeable fluorine and carbonate bound fluorine are the main reasons that affect the fluorine pollution in the environment.

0 引言

1 样品与方法

   1.1 试验样品

   1.2 元素分析和样品表征

   1.3 逐级化学提取试验

   1.4 浸出试验

2 结果与分析

   2.1 燃煤电厂中氟的迁移行为

   2.2 扫描电镜-能谱分析

   2.3 电厂煤及燃烧产物中氟的形态

   2.4 电厂煤及燃烧产物中氟的浸出特征

3 结论