A Study on Heavy Metal Solidification and Migration in Co-Vitrification of Fly Ash and Furnace Bottom Ash from Hazardous Waste

Safe and efficient disposal of hazardous waste fly ash (HFA) has become a worldwide problem.Hazardous waste and furnace slag contain various heavy metals such as Mn, Cu, Zn, and Cr, posing significant threats to both the environment and human health.co-vitrification of fly ash and bottom slag has the advantages of low consumption and green, and has the potential for large-scale disposal of hazardous waste. On this basis, the co-vitrification of hazardous waste fly ash with bottom slag (HBA) was realised using waste glass (WG) as a flux. A new method for HFA/HBA co-vitrification was proposed. The effects of HFA/HBA ratios on glass conversion rate, heavy metal solidification, and melting mechanism were investigated. The results showed that at 1300°C, with the increase of HBA doping, Ca/Al was basically unchanged, SiO2 increased, and the glass conversion rate increased up to 98.71%. In addition, the effects of Fe, S, Cl and other elements content and valence changes on the glass melting and heavy metal solidification were investigated, and it was proved that Fe, S, Cl and other elements have different effects on the stabilisation of different heavy metals.The presence of iron in particular leads to the formation of spinel phases, which play a significant role in heavy metal immobilisation.By adjusting the HFA/HBA ratio, the overall solidification rate of raw ash can reach 94.6%,while ensuring a glass transition rate exceeding 85%, the HFA/HBA-WG system effectively cures a significant quantity of heavy metals. The HFA/HBA-WG system effectively cured a large amount of heavy metals, which provided a reference for the migration law of HFA/HBA-WG glass melting and heavy metal solidification.