LEACHING CHARACTERISTICS OF HEAVY METALS IN FLY ASH FROM DIFFERENT ESPS OF COAL-FIRED POWER PLANT

摘要

China has become the largest ash producer of the world. Most coal fired power plants in China are still using hydraulic transmission for wet storage. These lead to serious leaching pollution for water, especially groundwater environment. Batch leaching tests have been performed on fly ashes collected from three electrostatic precipitators(ESP) of 2# furnace in a coal-fired power plant in order to study the leaching characteristics of Cd、Cr、Pb、V in fly ashes. Leaching solutions are chosen with HCl solution of initial pH=4 and NaOH solution of pH=10, liquid/solid=4:1；forteen leaching times are chosen, different from 15 minutes to 7days. The results show that under the experimental conditions, Cr has a relatively high leachability in acid leaching solution, while Pb has a high leachability in alkaline solution. Besides, with the accumulating of leaching time, the leachability of Cr has obviously increased, and the leachability in three coal ashes shows a tendency as follows: LCr3>LCr2>LCr1.