The vaporization of fly ash from municipal waste incinerators during vitrification by plasma is the result of the complex interaction of 02, Cl2, H20 with a multicompounds molten bath at different temperatures.
It is shown theoretically that vaporization rate decreases with 02 partial pressure and that H20 affects mainly the equilibrium pressure of alkali (Na,K). The influence of Cl2, is proved to be temperature dependent. At low temperature (1500K) the Cl2 pressure increase causes the enhancement
of the heavy metals vaporization (Pb and Zn), whereas the effect is negligible at high temperature. The main part of chlorine is associated with Na and K in the fumes.
Concerning the interest of chlorine elimination by ash washing, the theoretical analysis shows the possible decrease of heavy metal evaporation, but it is not observed experimentally due to the modification of electric arc
characteristics and bath temperature with and without chlorine.