The behaviour of selected heavy metals in MSW incineration electrostatic precipitator ash during roasting with chlorination agents

The thermal behaviour from 500-1050 degrees C of selected heavy metals (Pb, Zn, Cu and Cd) in the electrostatic precipitator (ESP) ash from a municipal solid waste (MSW) incinerator was studied on a laboratory scale. The parameters studied included temperature, reaction time, type of chlorination agent, and amount of chlorination agent. The vaporization and removal of these metals are characterized by the formation and volatilization of the metal chlorides, and are dependent on temperature and time. As a result of volatilization, approximate to 90% of Pb, Zn, Cu and Cd can be removed from the ESP ash under the conditions studied. The fraction of metal removed is determined mainly by the relative stabilities of the metal chloride and oxide. The results provide a basis for the development of a thermal treatment process to convert the ESP-ash from potentially hazardous into non-hazardous material and to recover the selected metals from the ash.