Research on the release characteristics of heavy metals and chlorine during the co-combustion of aged refuse

Aged refuse (AR), with high combustible content, high lower heating value (dry basis), and low moisture, is well suited for energy recovery. These properties make AR a major feedstock for co-combustion in refuse-to-energy facilities. However, AR poses environmental safety concerns due to its high contents of heavy metals and chlorine, accumulated through long-term landfilling. This study investigated the release of heavy metals (Cd, Cr, Zn, Ni, Cu, Pb, Mn) and HCl during co-combustion of AR and MSW in a tube furnace, aiming for clean co-disposal. The effects of refuse sorting, AR age, blending ratio, temperature, N2/O2 ratio, and additives on the release of HCl and heavy metals during combustion were investigated. Results show that Cr and Mn are more volatile in AR. Increased AR age enhances the volatilization of Cd and Cr. Cu and Zn showed the highest release at 30% and 20% AR blending ratios, respectively, and were most affected by temperature. HCl release reached saturation at 950°C. Higher N2/O2 ratios increased the release of Ni, Pb, Zn, and Cr but reduced the release of Cd, Mn, Cu, and HCl. The three additives inhibited HCl and most heavy metal release, with overall adsorptivity: CaO > CaCO3 > Ca(OH)2.