煤灰中微量重金属元素的迁移性实验研究

为了解煤灰中部分微量重金属元素的迁移性，用去离子水、含有机酸及含无机酸三种滤液，对煤的灰化灰和循环流化床燃烧灰进行了长期的浸取实验，实验结果表明，不同淋滤液浸取率明显不同，煤灰中Cr,Ni和Zn的浸取率，含无机酸的淋滤液高于含有机酸的，含有机酸的淋滤液又高于去离子水，不同燃烧方式产生的为煤灰中，微量重金属元素的浸取率不同，高温灰化灰中As,Cr,Ni和Zn的浸取率基本上都高于循环流化床灰中的浸取率。As在中性和弱碱性条件下容易迁移，但是As和CaCO3在弱碱性条件下发生协同作用，共沉淀加脱硫剂CaO燃烧的煤灰中，残余的CaO转化为CaCO3，因此As的迁移性降低，煤灰中部分微量重金属元素发生迁移对周围水体会造成一定的污染。

The leachability of trace metal elements in coal ash

The mobility of four trace metal elements As, Cr,Ni and Zn in high temperature ash (HTA) and circulating fluided bed combustion ash (CFBCA) of two Guizhou coals was investigated through leaching experiments by using the de ionized water, inorganic acid solution, and organic acid solution. The mobility of the trace metal elements was obviously different in different leaching solutions. The leachability of Cr,Ni and Zn in organic acid solution was lower than that in inorganic acid solution but higher than that in de ionized water. The mobility of the trace metal elements was different in HTA and CFBCA. The leachability of As, Cr,Ni and Zn in HTA was a little higher than that in CFBCA. Arsenic compounds in coal ash are easy to be mobile in neutral to moderately alkaline pH range. Plus CaO in coal combustion, arsenic compounds co precipitate with CaCO 3 and the mobility of As in coal ash decreased in neutral to moderately alkaline pH range.