Migration, solidification/stabilization mechanism of heavy metal in lightweight ceramisite from co-sintering fly ash and electrolytic manganese residue

Municipal solid waste incineration (MSWI) fly ash and electrolytic manganese residue, as hazardous waste, were roasted into lightweight ceramisite with coal fly ash. The migration, transformation and stabilization/solidification mechanism of heavy metals during ceramisite formation process was explored. Heavy metals in ceramisite pellet were concentrated and experienced the transportation among solids below 710 ℃, then heavy metals were prone to flue gas in the form of chlorides above 710 ℃, in particular for Pb, Cd and Cu. Heavy metal chlorides depended on the generation of HCl and Cl2, which needs co-existence of silicon oxide and aluminum oxide. Note that gibbs free energy change of copper chlorides generation reaction decreased with temperature, resulting in higher volatilization rate compared with Mn, Zn and Cr. Remained heavy metals in the solid phase like Cu, Zn and Cr were prone to ion-exchange, balance-charge and specific-adsorb with calcium-bearing minerals (Ca(Mg,Al)(Si,Al)2O6 and (Ca,Fe)SiO3) in ceramisite based on mineral analysis and principle component analysis at 1160 ℃.