In view of treatment efficiency and stability about stabilization treatment of fly ash from municipal solid waste incineration

a stabilization technology was developed for treating heavy metals in fly ash using organic heavy metal chelator ammonium dipropyl dithiophosphate(ADD).The effect of pH on heavy metal leached amount from stabilized fly ash was studied.The contents of different forms of heavy metals in fly ash were compared before and after stabilization treatment with ADD chelator

and the stabilization effect was analyzed with different amounts of ADD chelator.The result showed that stabilization rate against Pb

Zn

and Cd of 1.5% ADD chelator reached 95.6%

85.5% and 93.4% respectively

and the amounts of Pb

Zn

and Cd in the leachate met the Pollution Control Standards for Hazardous Waste Landfill(GB 18598-2001)at pH values exceeding 3.The contents of Pb

Zn and Cd bound to carbonates in fly ash after ADD chelator treatment was significantly decreased with significantly increased contents bound to organic matter.The Pb

Zn and Cd stable form contents increased by 15.4%

17.1% and 24.3% respectively

and accordingly reduced the risk of secondary pollution of stabilized products under environment change.The stabilization effect of ADD chelator on heavy metals in fly ash was apparently better than that of inorganic stabilizing agent lime and sodium sulfide.