[Heavy metal stabilization in municipal solid waste incineration fly ash using soluble phosphate]

The physico-chemical characteristics of municipal solid waste incineration fly ashes was analyzed. It indicated that the main elements of fly ashes are Ca, Cl, K, S and Si, and many heavy metals such as Pb, Zn, Cu, Mn and Cr can be found in fly ashes, and the heavy metal leaching toxicity such as Pb, Cu, Zn and Cd is much higher than the standards. A new kind of stabilization agent-soluble phosphate is chosen to treat with fly ash, different influence factors including agent dosage, curing time and pH are taken into consideration to test its stabilization for the stabilized fly ash. The experimental results indicate that fly ash treated with soluble phosphate can have excellent stabilization effect, and the leaching toxicity for Pb, Cd and Zn can be reduced by 97.5%, 91.6% and 95.5% at a phosphate dosage of 3%; curing time can not influence its stabilization; and, stabilized fly ash using soluble phosphate can keep long-term stabilization at a broad pH value.