The influence of the pre-addition of semi-dry and dry slaked lime during the purification of flue gas on the subsequent chelation and solidification treatment of MSWI fly ash

Incineration is a main way to dispose the municipal solid waste (MSW) in China, but municipal solid waste incineration (MSWI) fly ash will negatively impact the environment and human health as containing high content of heavy metals. This study aimed to investigate the influence of the pre-addition of dry/semi-dry slaked lime during the purification of flue gas on the subsequent chelation and solidification treatment of fly ash. This study has found that semi-dry slaked lime had more effect on the solidification rate of heavy metals in MSWI fly ash compared to the pre-addition of the dry slaked lime. As the dosage of semi-dry slaked lime increased, the solidification rate of Zn and Ba increased to 100%, while the solidification rate of Cr decreased to as low as 0%. However, the effect of the dosage of semi-dry slaked lime on the other heavy metals (Cu, Pb, Cd, Ni) showed a complex trend. This study underscores the importance of the pre-addition of slaked lime during the purification of flue gas in influencing subsequent chelation and solidification treatment of MSWI fly ash. It provides valuable insights into optimizing lime dosage to enhance heavy metal stabilization, contributing to more effective and sustainable waste management practices.