Study On Separation Of Metal Elements In Municipal Solid Waste Incineration Fly Ash

The metallurgic, physical and chemical theories and methods have been used to study on the physical and chemical characteristic of the fly ash gathered under fabric filter in Tongxing Municipal Solid Waste Incineration (MSWI) plant, Chongqing city. Meanwhile, the existing forms and characteristics of metallic elements in the fly ash have also been researched.The properties of fly ash including humidity, water absorption, microstructure, chemical composition, particular size distributing, heavy-metal content and effects of heavy-metal leaching characteristic by pH value are studied by experiments. The results show that the concentration of zinc, lead and cadmium exceed Solid Waste Leaching Character Standard. With pH value of leaching liquid increasing, the concentration of heavy-metal in leaching liquid decrease. When the pH value is 4.5~7.5, the concentration of heavy-metal changes largely.Adding the different binders in different period will affect the shaping properties and compressive strength of fly ash. The optimal technology of shaping has been attained in this paper. Adding cement as binder, the compressive strength of fly ash pellets will rise with cement content and curing period increasing. The suitable cement content is about 6% and curing period is about 8 days while the compressive strength is 500-550N/bellet. The hydrated lime has good solidifying capability. The suitable The hydrated lime content is about 7% and curing period is about 12 days. In the experimental conditions, the optimal technology is adding 3% hydrated lime and 1% industrial syrup and its curing period is about 11 days while the compressive strength is 550-600N/bellet. Adding 6% cement or 3% hydrated lime and 1% industrial syrup as binders, its compressive strength can satisfy melting strength. Moreover, that two kinds of pellets have been tested for the leaching characteristic. The results show that the value of leaching concentration is smaller than Chinese Standard, and that the fly ash was solidified well.The metals in fly ash pellets separating effects are studied by experiments. How the melting temperature, period, metal melting bath proporsition and basicity affect heavy-metal separating are studied and analysed, which provide a technological method and parameter for metal in MSWI fly ash disposing. The results indicated that the removal rate of heavy metal in the fly ash increased along with the temperature...