A microscopic and quantitative analysis on the separation of chloride ion by fly ash washing: Effect of liquid-to-solid ratio, washing time and temperature

In order to understand the removal characteristics of Cl- (chloride ion) in the fly ash from municipal solid waste incineration, so as to realize the harmless treatment of fly ash. The fly ash washing treatment experimental system was designed and built. The single factor experiments were used to explore the effect of liquid-to-solid ratio, washing time and temperature on the leaching rate of Cl- in the fly ash. The best experimental parameters of fly ash washing were obtained. At the same time, the microscopic morphology and crystal phase composition of fly ash before and after washing were explored. The results showed that the maximum removal rate of Cl- in the fly ash was 88.72% when the liquid-to-solid ratio was 8:1, the washing time was 5 min and the washing temperature was 70 ℃. It can be seen from the scanning electron microscope (SEM) image that most of the irregularly shaped square fly ash particles gradually transformed into regular spherical or elliptical shapes after washing. The X-ray diffractometer (XRD) results proved that the chlorine salt content in the fly ash after washing was significantly reduced, and the CaSO4•2(H2O), SiO2, CaCO3 and other substances were formed.