广东省典型生活垃圾焚烧飞灰的物化及固化特性

Physicochemical and solidification characteristics of municipal solid wastes incineration (MSWI) fly ash from Guangdong Province

对佛山某垃圾焚烧发电厂飞灰的化学、矿物组成、粒径分布及浸出毒性进行了分析,采用水泥蒸养固化技术处理垃圾焚烧飞灰,研究了不同飞灰掺量及混合原料的Ca/Si比对垃圾焚烧飞灰固化试块中重金属Pb、Ni、Cu、Cr、Cd和Ba浸出浓度的影响,并对不同Ca/Si比情况下的固化试块进行了相应的物相分析.结果表明,飞灰中重金属Pb、Cd的浸出浓度均超过《危险废物鉴别标准-浸出毒性鉴别》(GB 5085.3—2007)的限定,因此被列为危险废弃物,需进行固化/稳定化处理.飞灰掺量的增加不利于重金属Cu、Pb、Cd及Ni的固化,在Ca/Si比为0.53的情况下,虽然所有固化体均不属于危险废物,但是重金属Pb、Cd的浸出浓度仍然不满足《生活垃圾填埋场污染控制标准》(GB16889—2008)的限定.随着Ca/Si比的增加,重金属Pb、Cd的浸出浓度越来越低,当飞灰掺量为43.75%且Ca/Si增至1.24时,固化体中重金属Pb、Cd的浸出浓度分别为0.09、0.03 mol·L-1,完全满足填埋标准,甚至在一定条件下可用作工程用料.

The characteristics of municipal solid wastes incineration （MSWI） fly ash and leaching toxicity were analyzed. The MSWI fly ash was treated using the method of cement steam curing stabilization. Bench experiments were carried out to investigate the effect of the ratio of fly ash to mixed stocks and Ca/Si ratio on the leaching concentration of heavy metals including Pb,Ni,Cu,Cr, Cd and Ba, and the phases of solidification bodies with different Ca/Si ratio were checked. The results show that it is necessary to solidify the heavy metals in the original MSWI fly ash since uncontrolled leaching of its heavy metals constituent, especially Pb and Cd would be a potential hazard. The increase in ratio of fly ash to mixed stocks is unfavorable for the solidification of Cu, Pb, Cd and Ni. When the Ca/Si ratio is 0.53, all solidified bodies with different ratio of fly ash to mixed stocks are not hazardous wastes, but the leaching concentration of Pb and Cd in these solidified bodies still exceeded the control standard of pollution in landfill （GB16889-2008）. With the increase of Ca/Si ratio, the leaching concentration of Pb and Cd decreased gradually, and their Value decreased to 0.09 mol· L^-1 and 0.03 mol· L^-1 respectively when the ratio of fly ash to mixed stocks was 43.75% and Ca/Si ratio increased to 1.24. In this case, the solidified bodies can satisfy the landfill standard, and can even be used as engineering materials under certain conditions.