Characteristics of MSWI fly ash solidified by clinker- activated semi-dry flue gas desulfurization residue

This paper investigates to assess the characteristics of municipal solid waste incineration (MSWI) fly ash solidified by clinker-activated semi-dry flue gas desulfurization residues which is unsuitable as a concrete admixture due to its high amounts of f-CaO, CaSO3, and CaSO4. The solidification process was conducted on samples preparing with MSWI fly ash, binders (clinker- activated semi-dry FGD residues) and water (water / solid weight ratio = 0.38), among which the MSWI fly ash replace the binder at the ratio of 0%, 20%, 40%, 60% and 80% in dry weight. The compressive strength tests and toxicity leaching test results show that all solidified MSWI fly ash can meet the landfill standard after 7 days of curing. Sequential chemical extractions results also show that the chemical forms of heavy metals transform more stably after solidification. All characteristics of solidified product show a possibility to achieve an effective and cheaper solution for MSWI fly ash disposal and useful resource way for semi-thy FGD residues.