Insight into the clean and sustainable co-treatment of hazardous municipal solid waste incineration fly ash and metallurgical iron-bearing waste

Municipal solid waste incineration fly ash (FA) is a hazardous solid waste that primarily comprises calcium- and chlorine-containing compounds, heavy metals, and dioxins. A novel approach has been proposed to achieve the reuse of valuable components and control of hazardous constituents by leveraging the deep interactive effects of multiple elements during the co-disposal of FA with typical metallurgical iron-bearing wastes. To achieve the desired objective, blast furnace dust (BFD) and converter sludge (CS) were selected to combine with FA to form a system rich in calcium, carbon, chlorine and iron. In this system, the calcium-containing components from FA facilitated the phase transformation of ferrites (such as ZnFe2O4 and PbFe10O16) and sulfates (including ZnSO4, PbSO4, Na2SO4, and K2SO4) into oxides (such as ZnO and PbO). Subsequently, the removal of hazardous elements was enhanced by converting these oxides into chlorides, aided by the chlorine-containing components from FA and the carbon provided by BFD. The removal rates of K, Na, Pb and Zn were 93.81 %, 91.22 %, 94.87 % and 94.83 %, respectively. Additionally, under conditions of high calcium content and a low-oxidation atmosphere, 98.40 % of dioxins were degraded. Consequently, a clean raw material suitable for ironmaking was successfully obtained. This method offers both theoretical insights and technical guidance for the co-treatment of wastes from various industries.