Water-washing pretreatment enhanced co-smelting of MSWI fly ash and copper slag: Metals extraction, slag vitrification and silicate network evolution mechanism.

Municipal solid waste incineration fly ash (MSWI FA) is a typical hazardous waste that needs urgent detoxification and resource utilization. However, existing treatment methods typically suffer from high energy consumption, low metal yield, and unclear microstructure evolution mechanisms. This study proposes a novel, energy-efficient water-washing pretreatment enhanced co-smelting strategy utilizing copper slag (CS) as a co-treatment feedstock to simultaneously recover high-value Cu/Zn and achieve slag vitrification. A water-washing pretreatment was implemented to mitigate chlorination-induced Cu volatilization. Under optimal conditions, Cu and Zn extraction ratios reach 96.41% and 85.84%, respectively, with 91.40% glass content in the residual slag. Crucially, molecular dynamics (MD) simulations were performed to quantitatively decode the microstructural evolution of the silicate network. The results establish a precise multiscale linkage between atomic-level [SiO4]4- depolymerization, melt fluidity, and macroscopic metal-slag separation. This co-treatment strategy offers an efficient and economical solution for simultaneous resource extraction and hazardous waste detoxification.