Characterics of heavy metals during melting and solidification of MSWI fly ash

To investigate the characteristic of heavy metal during the vitrification of municipal solid waste incineration (MSWI) fly ash, a pilot scale experiment was carried out to treat MSWI fly ash from a MSWI plant in Hangzhou City using a diesel oil furnace for more than 6 months. The effects of vitrification processing parameters such as the temperature, the additive (glass dust as a substitute for SiO2) and the cooling mode on the chemical composition, microstructure and phases of MSWI fly ahs and molten slag were investigated by inductively coupled plasma mass spectrometry, X-ray fluorescence spectrometer and X-ray diffraction. The results indicate that: comparing with Pb, Cd and Cr, the residual fractions of Cu and Zn are enhanced greatly with the increase of temperature and the additives proportion; under water cooling, the residual fractions of all heavy metals are slightly higher than those under the air cooling; during the vitrification, the concentration of the pollutants and dioxin and furans (PCDD/Fs) in flue gas meets the national standard.