Study on Environmental Safety of Thermal Treatment of MSWI Fly Ash

摘要

MSWI fly ash requires safe handling due to existence of heavy metals which pose potential threat to people’s health and the environment. In this work, the fly ash went through thermal treatment at different temperatures, and its environmental safety was studied by means of leaching toxicity and specification analysis of heavy metals in sintered fly ash and volatilization analysis of heavy metals during the treatment process. It is found that between 400 and 1,200 °C , increase of temperature is conducive to stabilization of Zn, Cu, Pb, Cd, Ni, As and Hg. However, increase of temperature, between 900 °C and 1200 °C, facilitates leaching of Cr into the environment. Leaching toxicity of heavy metals meet requi °C rements of the relevant standard on environment safety only when the sintering temperature is no lower than 1100. Waste gas from the treatment process contains a lot of volatilized Hg, Pb, As, Cd and Zn, and °C thus requires further safe handling.