燃煤飞灰中汞在渗滤过程中的迁移规律研究

燃煤飞灰在堆放、填埋过程中，固定于灰中的汞可能被再次释放，而带来二次污染。为研究飞灰中汞对环境的影响，本研究参照国标规定的渗滤方法和美国毒性特征浸出程序，对飞灰中汞的渗滤特性进行研究，即研究不同类型酸浸取液、浸取液pH值以及液固比对汞渗滤特性的影响。不同酸的浸取试验结果表明：硝酸的汞渗出浓度最大，硫酸最小，经化学动力学分析是由于不同类型酸对于玻璃体中各种氧化物溶解能力的差异性所致。采用硫酸渗滤时，出现反常的渗滤特征，并发现该现象与飞灰二次相生成物有关。滤液汞浓度随浸取液pH的增大成指数曲线下降趋势；随液固比增加，滤液汞浓度呈单峰分布，经化学动力学分析表明氢离子与硅铝玻璃体的配比是产生这一现象的主要原因；本研究对于燃煤汞污染的深度控制及治理方面有指导意义。

Transportation Behavior of Mercury in Fly Ash in Leaching Process

Mercury which fixed in fly ash is likely to be released again in disposal,storage or utilization process.The releasing behavior of mercury probably results in second pollution sequentially.The leaching characteristic of mercury in fly ash was studied in this paper by consulting leaching methods of GB and the toxicity characteristic leaching procedure(TCLP)of U.S.EPA.The impacts of different types of acid,pH value of leaching liquor,liquid-to-solid ratio on leaching characterization of mercury are studied carefully.It was found that mercury concentration in nitric acid is maximal;otherwise mercury concentration in sulfuric acid is minimal.This phenomenon can be explained by chemidynamics analysis that the solubility of oxides in fly ash glass is diversity to different kinds of acid leachate.Abnormal leaching behavior was appeared when leached by sulfuric acid.Second-phase-resultant was found having the relationship to this phenomenon.It was found in the experiment that the mercury concentration in leachate descended in exponential curve with the decrease of pH value.The impact of liquid-to-solid ratio on mercury concentration in leachate was presented in single peak distribution.The ratio of hydrogen ion to silialuminium glass has the close relationship to this phenomenon through chemidynamics analysis.This study was important and meaningful to the profound control of mercury pollution in coal combustion area.