Phase-separated resource utilization of municipal solid waste incineration fly ash and iron ore tailings via a...

The large production volume of municipal solid waste incineration fly ash (MSWI-FA), which is rich in dioxins and potentially toxic metals, poses a potential threat to the environment, thereby imposing higher requirements on treatment and resource utilization technologies. To address this issue, this study proposed and validated a synergistic co-treatment process, which combined MSWI-FA with iron ore tailings (IOTs) to achieve the harmless treatment and resource utilization of MSWI-FA. This process utilized the Si and Al components in IOTs to lower the melting point of the SiO₂-CaO-Fe₂O₃·(Al₂O₃)_1.7 system from > 1400°C to ∼1200°C. Simultaneously, it leveraged the C and Ca in the MSWI-FA to achieve the in-situ reduction of metal oxides and regulated the viscosity of the molten glass phase, thereby promoting the enrichment of siderophile elements into the metallic phase and enabling efficient separation of slag and alloy. Under optimized conditions of 1250°C and a holding time of 2.5 h, this process could simultaneously produce a vitrified slag with a dense structure and leaching toxicity below standard limits, as well as an Fe-rich (>80 wt%) alloy enriched with siderophile elements such as Cu and Ni. Moreover, the distinct interface between the two phases facilitated separation and utilization. The research indicates that this process not only achieves synergistic resource utilization and environmental risk reduction for two types of solid waste but also offers significant environmental benefits. Furthermore, it provides a new pathway with potential for promotion for the green and efficient disposal of MSWI-FA.