Experimental study on the stabilization of heavy metals in fly ash from municipal solid waste incineration by N-30 alkaline silica sol

Abstract

The disposal of municipal solid waste incineration fly ash is a key environmental issue in China. The high content of heavy metals in fly ash makes ash disposal extremely difficult. A new method which binds N-30 alkaline silica sol and temperature was proposed for the first time in this study. The crystal composition and the patterns of heavy metal leaching concentration and speciation in fly ash were obtained via experiments. The results showed that adsorption of the self-made curing agent and the formation of metal silicate and phosphate promotes the migration of heavy metals from an unstable acid state to a stable residue state, thus improves the stability of heavy metals. The optimum temperature of self-made N-30 alkaline silica sol during treating process is about 700℃. Moreover, the risk assessment of heavy metal emission has proved that, the leaching amount of heavy metals after treatment reaches a risk-free level.