Abstract
Incineration fly ash is a hazardous solid waste with the risk of heavy metal leaching and dioxin overload. A large amount of chloride limits its application in the cement industry. The water-washing process can enhance resourceization of waste in the cement industry. In this paper, the effects of water washing on the physicochemical properties of incineration fly ash, its toxic leaching characteristics, and its performance as a cement admixture were investigated. The results showed that water washing could remove more than 90% of chlorine and some soluble substances, However, in the water washing process, heavy metals and dioxins could accumulate, and heavy metals might be leached from raw and washed ash. In cement preparation, washed ash could reduce the water requirement and prolong the setting time compared with the cement prepared by raw ash, meet the requirement of >42.5 MPa at <15% and improve the mechanical properties of cement at 5%. Washed ash and raw ash could promote cement hydration, during which, however, Friedel salts generated. Incineration fly ash could improve the pore structure of cement and enhance its mechanical properties. Cement could solidify heavy metals well, and there was no risk of heavy metal leaching. Water washing was unable to remove dioxins. Thus, to reuse the water-washed incineration fly ash as a resource, it is necessary to dispose of dioxins and chlorides in it.
Published Version
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