焚烧飞灰结构表征及烧结固化体重金属稳定化

The MSWI fly ash was finely characterized by element analysis, XRD, DSC and TG-MS, SEM and TEM respectively. The solidification mechanism of heavy metals Pb, Cd and Zn in MSWI fly ash was studied through theoretical modelling and experiment by using the mixture of MSWI fly ash, fly ash and water glass with certain proportion of composition control sintering. The energy simulation calculation carried out by Materials Studio instructed that Pb, Cd, and Zn could replace Ca in the cell structure of wollastonite, the main phase in the final products, with energy benefit. The cell parameters of wollastonite were altered accordingly, which was confirmed by XRD analysis. The results of the Tessier extraction test elucidated that the sintered products have significantly large amount of the residue lattice phases, comparing with untreated MSWI fly ash, indicating the substantial improvement of the heavy metals stability in the sintered products. The study also found that the heavy metals had less volatilization ability in the solidified products than in the MSWI fly ash during heat treatment process. The MSWI fly ash ceramists, with satisfying mechanical features, were finally obtained with an optimal ratio of the MSWI fly ash, coal fly ash and sodium silicate solutions after a relatively low temperature treatment (900℃), which provides a feasible process to use MSWI fly ash as building materials.