Progress in Plasma Processing of Materials, 1997

ISBN Print: 1-56700-093-2

COMBINED EFFECTS OF OXYGEN, CHWRINE AND WATER VAPOR ON THE VAPORIZATION OF HEAVY METALS DURING FLY ASHES VITRIFICATION BY PLASMA

DOI: 10.1615/ITPPC-1996.530
pages 447-454

Аннотация

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.