An all-in-one strategy for municipal solid waste incineration fly ash full resource utilization by heat treatment with added kaolin

Resourcization has become a popular research topic for the final disposal of municipal solid waste incineration fly ash (MSWI FA). However, the current research is limited to building material preparation or valuable chloride recovery, which may cause resource waste and secondary pollution. A unique process, heat treatment with the addition of kaolin (KL), was presented to achieve complete resource utilization of MSWI FA. The physical properties of ceramsite could be improved by adding KL, and dioxin removal, heavy metals, and valuable chloride separation could be achieved via sintering at 1150 degrees C. The separation and purification of dust carried by the flue gas during thermal treatment (secondary fly ash) was achieved via wet separation. A building ceramsite with a compressive strength of 24.8 MPa was obtained, whereas dioxin and heavy metal toxicity were far below the standard limits. Heavy metal content was enriched by 12 times, approximately 59.6%, achieved after sec-ondary fly ash separation and purification. A heavy metal product containing 39.5% Zn, 19.1% Pb, and chloride salt containing 41.8% KCl were obtained. This showed a high potential for the developed process to separate multiple valuable elements from ashes. This novel process will further promote the development and application of harmless and resourceful technologies for MSWI FA.

Automated summary

Research has shown that complete resource utilization of municipal solid waste incineration fly ash (MSWI FA) can be achieved through heat treatment with the addition of kaolin. This process can improve the physical properties of ceramsite and separate and recover dioxins, heavy metals, and valuable chloride. Wet separation can effectively separate and purify the dust carried by the flue gas. Ceramsite with a compressive strength of 24.8 MPa was obtained, while dioxin and heavy metal toxicity were below the standard limits. Enrichment of heavy metals by 12 times and the recovery of valuable chloride were achieved through secondary fly ash separation and purification. The developed process shows a high potential for separating multiple valuable elements from ashes.