Co-disposal of MSWI fly ash and lead-zinc smelting slag through alkali-activation technology

MSWI fly ash and lead-zinc smelting slag (LZSS) are solid wastes containing heavy metals and negatively impact the environment. This study synthesized MSWI fly ash-LZSS based alkali-activated cementitious material (AAFL) material for their co-disposal. The experimental results revealed that the compressive strength of AAFL raised as the SiO2/Na2O molar ratio and alkali content increased but decreased as the liquid-solid ratio and initial curing temperature increased. The immobilization ratios of Zn, Pb and Cu in AAFL were above 97%. Heavy metal speciation, XRD, FTIR, SEM and EDS analysis indicated that the main reaction products were calcium silicate hydrate (C-S-H) and amorphous aluminosilicate gels, and heavy metals were mainly immobilized through physical encapsulation.