Modeling of Zn Migration during the Co-Processing of MSWI Fly Ash with Cement Kiln

The migration characteristic of Zn during the co-processing of municipal solid waste incinerator (MSWI) fly ash with cement kiln was investigated. The statistical analysis of emission data of Zn from cement kiln which co-processed waste materials was conducted to investigate the effect of total Zn input or total chloride input. An equilibrium analysis of Zn was performed using the thermodynamic equilibrium software CHEMKIN. The results show the exchangeable, water and acid-soluble phase, the easily reduced phase and the oxidizable phase of Zn in MSWI fly ash was 0.72%, 21.1% and 8.63% respectively according to the BCR sequential extraction procedure. Chloride has small effect on the migration of Zn under the sintering process, when the HCl level was high, the percentage of ZnCl2 (g) began to increase, but was only about 5% of the total. The simulated stabilization rate of Zn during the single sintering process was compared with experimental value, which showed the simulated value was in good agreement with the experimental values.