Towards circular economy: Sustainable valorization of municipal solid waste incineration fly ash for recovery of high-purity chlorides and calcium, and separation of heavy metals.

Incineration is an effective method for handling the increasing volume of municipal solid waste, but the resulting fly ash presents a significant problem that needs to be addressed. Municipal solid waste incineration fly ash (MSWI FA) contains toxic and hazardous substances, including heavy metals, dioxins, and chlorides, and is classified as hazardous waste. This paper analyzes the current situation of MSWI FA and summarizes the main treatment methods, including solidification/stabilization, thermal treatment, and chemical separation/resource recovery. The review critically evaluates research on the chemical separation/resource recovery of MSWI FA, covering chlorides removal and resource utilization, heavy metals recovery through hydrometallurgy, thermal separation, and electrochemical methods, as well as calcium extraction and CaCO3 production by CO2 mineralization. It highlights innovative chemical separation/resource recovery technologies and future prospects to promote the development of MSWI FA valorization technologies and achieve sustainable management of MSWI FA.