Enhancing the degradation of dioxins during the process of iron ore sintering co-disposing municipal solid waste incineration fly ash

Iron ore sintering is a promising thermal method for co-disposing the municipal solid waste incineration (MSWI) fly ash. To reduce the increased dioxins in flue gas caused by adding fly ash powder, pelletizing was used as a pre-treatment for fly ash to enhance the degradation of dioxins. High specific surface area (5380 cm2 g−1) made the fly ash balls easier to be prepared. Mechanical strength of dried fly ash balls was qualified for further sintering co-disposal as crushing strength reached 145 N P−1 and cracking temperature reached 600 °C. The concentration of dioxins in the flue gas were 4.50 ng I-TEQ m−3 (fly ash balls added) and 4.32 ng I-TEQ m−3 (fly ash balls containing solid fuel added), respectively, both of which were less than 5.61 ng I-TEQ m−3 (fly ash powder added). The degradation rate of dioxins was improved from 93.03% (fly ash powder added) to 96.10% (fly ash balls added) and 96.61% (fly ash balls containing solid fuel added), correspondingly. The improvement of dioxins degradation was realized by reducing the dispersed distribution of the chlorine-containing material, by inhibiting the volatilizing of dioxins before degradation, and by utilizing the suppressing functions of sulfur and calcium compounds from CaSO4 decomposing in the fly ash balls. The method of degrading more dioxins in fly ash during the co-disposing process proved to be feasible.