Abstract: The feasibility of co-melting municipal solid waste incineration (MSWI) fly ash with red mud and its synergistic effects on heavy metal immobilization were systematically investigated. Through analysis of the chemical composition, co-melting characteristics of fly ash and red mud, and the compositions of the melting products and its leaching toxicity, the effects of high-temperature co-melting treatment on both melting temperature reduction and heavy metal stabilization were evaluated. The experimental results demonstrated that the co-melting process could significantly reduce the flow temperature from above 1 500 ℃ to approximately 1 250 ℃ and shorten the melting process of fly ash. The main molten products were complex silicate minerals, including Alinite, Wadalite, and double perovskite. Leaching tests conducted that the molten treatment had a significant solidification effect on most heavy metals, and the leaching concentrations were all below the relevant standard limits. These findings collectively suggest that the co-melting treatment of MSWI fly ash with red mud represents an effective approach for waste treatment, providing a innovative pathway for achieving “waste treatment with waste”.

Key words: domestic waste incineration fly ash, red mud, melting treatment, collaborative disposal, ash melting characteristics