机械力活化固硫灰固化处理生活垃圾焚烧飞灰

Solidification/Stabilization of MSWI fly ash with CFBC fly ash activated by mechanochemical method

为实现城市生活垃圾焚烧飞灰的安全处理,通过机械力化学法活化循环流化床燃煤固硫灰,探讨了球磨样品制备固化体的参数。并采用X射线衍射仪(XRD)和傅里叶变换红外光谱仪(FTIR)手段对垃圾焚烧飞灰中重金属的固化机制进行了研究。结果表明,当垃圾焚烧飞灰掺加比为60%,球磨转速为600 r·min^(-1),球磨时间为5 h,养护温度60℃时的固化体28 d和56 d抗压强度分别达到15.6 MPa和17.9 MPa,采用原子吸收光谱仪(AAS)测得固化体中Zn、Pb、Cu、Cd和Cr重金属浸出量均低于GB 5085.3-2007规定限值。XRD和FTIR表征结果表明,在水化过程中,该混合体系生成了水化硅酸钙(C—S—H)、斜方钙沸石和钙矾石(AFt)等水化产物,并且C—S—H凝胶可通过物理包裹的形式固化垃圾焚烧飞灰中重金属;斜方钙沸石和钙矾石以化学吸附的方式使垃圾焚烧飞灰中的重金属离子达到固化/稳定化效果,实现了垃圾焚烧飞灰中重金属的安全处理。

To safely dispose municipal solid waste incineration（ MSWI） fly ash,circulating fluidized bed combustion（ CFBC） fly ash was substantially activated by a mechanochemical method to immobilize the MSWI fly ash. The present research explored the effect on the performance of the solidified waste that immobilized the MSWI fly ash. Furthermore,the solidification mechanism of heavy metals from MSWI fly ash was investigated using X-ray diffraction（ XRD） and Fourier transform infrared（ FTIR） spectroscopy. The research showed,under these conditions that MSWI fly ash mixing ratio was 60%,velocity of milling was 600 r·min^-1,milling time was 5 h,by curing after 28 d and 56 d at 60 ℃,the compressive strength of solidified wastes were 15. 6 MPa and 17. 9 MPa respectively. Meanwhile,the leaching amounts of Zn、Pb、Cu、Cd、and Cr metals,which were detected by atomic absorption spectroscopy（ AAS） in the solidified waste,were much lower than the national standard value（ GB 5085. 3-2007）. The XRD and FTIR analysis indicated that the hydration products of the solidified waste were calcium silicate hydrate（ C—S—H）,gismondine,ettringite（ AFt）,etc. Moreover,the heavy metals from the MSWI fly ash mainly were physically encapsulated in the C—S—H and chemically absorbed in the structures of the gismondine and AFt.