Abstract: In the deacidification of MSW incineration flue gas， it was difficult to control the pH of subsequent fly ash by controlling the amount of injection calcium deacidifying agent. So the feasibility of using mixed deacidifying agent substitute calcium deacidifying agent in the deacidification of MSW incineration flue gas was expounded. The deacidification effects of mixed deacidifying agent， impact on the pH of simulated fly ash leaching solution， impact on the heavy metals leaching concentration of fly ash， impact on the deacidification process， as well as the material cost were analyzed respectively. The results showed that in the process of deacidification of flue gas， when the mass ratio of hydrated lime and buffering agent were 1∶1， 2∶1， 3∶1 and 4∶1， by changing the adding amount of mixed deacidifying agent，good deacidification effect could be achieved and the components of fly ash could be controlled from the source， which made the pH of fly ash leaching solution to be slightly alkaline. In this way， the heavy metals leaching concentration of fly ash was reduced and the subsequent stabilization disposal cost of fly ash was reduced.

Key words: waste incineration fly ash, mixed deacidifying agent, slaked lime, heavy metals