粉煤灰中微量重金属元素的溶出研究

Study on Leaching of Trace Heavy Metals in Fly Ash

以不同来源的粉煤灰为研究对象,采用水平振荡试验,研究不同溶出试验条件对粉煤灰中微量重金属元素溶出量的影响规律,并结合SEM与XRD分析其溶出机理.结果表明:振荡时间、浸提液pH值、液固比、颗粒细度对重金属元素的溶出都有一定的影响.不同来源的粉煤灰在相同时间内Cr和Zn溶出量较大,其次是Cu.Cu,Cr,Zn均呈两性溶出趋势,即在pH=7～10内溶出量最低而强酸碱条件下容易溶出.溶出后粉煤灰的主要物相种类未发生变化,重金属元素的溶出是部分矿物发生溶解、结构解体所致.

The effects of various leaching conditions on the leachability of heavy metals in fly ash were investigated by horizontal oscillatory test with different sources of fly ash. The leaching mechanism was analyzed by SEM and XRD. The test results show that the oscillation time, the pH value of the extract, the ratio of liquid to solid and the fineness of fly ash had a certain influence on the leachability of heavy metals in fly ash. The leachability of Cr and Zn was the larger in the same time, and followed by Cu. Cu, Cr and Zn showing amphoteric leaching trends,which areat the lowest leachabilityin pH =7 ~10 and easy to leach under strong acid and alkali conditions. There was no significant change in the kinds of major minerals after leaching. The leaching of heavy metal elements was caused by the dissolution of some minerals and the disintegration of their structure.