SEM-EDS analysis of fly ash from one Shanghai municipal solid waste incineration plant during heating process

摘要

This study aims to explore microstructure and elementary variation of fly ash from one Shanghai municipal solid waste incineration (MSWI) plant on the one hand and analyze leaching toxicity of Zn, Pb, Cd and Cu during heating process. SEM-EDS was performed on fly ash of room temperature and those sintered at 700°C, 800°C, 900°C, 1, 000°C, and 1, 100°C respectively, and leaching toxicity of four heavy metals analyzed by horizontal vibration extraction procedure (HVEP). It is found that structure of fly ash is strengthened with increase of temperature, which is conducive to stabilization of heavy metals. Crystal content increases from room temperature to 800°C and then decreases in the heating process, while content of glass phases has a reverse trend. Ca and O content variation has a similar trend, while Cl has a reverse trend with them. Their leaching toxicity in fly ash sintered at temperatures over 900°C is lower than the limit value described in "Identification Standard of Hazardous Waste - Identification of Leaching Toxicity". Finally, 1000°C is recommended to treat MSWI fly ash.