垃圾焚烧飞灰的二噁英热裂解解毒及氯固化机理

The output of municipal solid waste incineration (MSWI) fly ash was about 1.066 million tons in China in 2014. For containing dioxins and heavy metals, MSWI fly ash is belonging to dangerous solid. The existing landfill method, the cement solidification method and the melting solidification method can not eliminate MSWI fly ash in the dioxin pollution. The glass-ceramic method invented by the applicant will be applied for preparing non-toxic, high added value glass ceramics using MSWI fly ash. CaO and MgO will be used as outside the body a glass network, while SiO2 and Al2O3 as the body a glass network. Oxides of Cr, Ni, Pb and Zn will be used as a nucleating agent. Dioxins can be reduced or avoided through the deployment of CaO for glass-ceramic. The mechanism is not clear, such as the decomposition of dioxin and the solidification of chlorine atoms. We will be intensively investigated adsorption and desorption behaviour of MSWI fly ash for dioxins, pyrolysis of dioxins, immobilization for chlorine atoms etc. We will clarify synthesis mechanism of dioxins by catalysis heavy metals from chlorobenzene. We will analyse the stability vs temperature of oxygen bond linked benzene ring structure. We will indicate detoxification mechanism of pyrolysis of dioxins. We will show migration path of Cl in preparing glass-ceramic. We will also calculate reaction barrier of Cl replacing O crystal sites and the binding energies of M-Cl. We will give the scientific reason of Cl mobilized in glass-ceramic. The results can put an end to the pollution of containing dioxins MSWI fly ash, as well as non-toxic high value of glass-ceramic.

2014年我国垃圾焚烧飞灰约106.6万吨，因含二噁英和重金属被列为危险固废。现有的填埋法、水泥固化法和熔融固化法无法消除垃圾焚烧飞灰中的二噁英污染。采用申请人发明的微晶玻璃法，利用垃圾焚烧飞灰的CaO和MgO作玻璃网络外体、SiO2和Al2O3作玻璃网络体，Cr、Ni、Pb、Zn等氧化作形核剂，制备出无毒、高值的微晶玻璃。通过调配CaO实现二噁英减排或避免其合成，但二噁英裂解及氯原子固化等机理不清。因此，深入研究二噁英与垃圾焚烧飞灰吸附-解吸、二噁英高温裂解、氯原子固化等，阐明氯苯重金属催化合成二噁英机理；分析氧键连结苯环结构稳定性及其与温度关系，揭示二噁英的裂解解毒机理；描绘Cl的迁移轨迹，计算Cl取代O晶位反应势垒和M-Cl结合能，解释微晶玻璃稳定固化Cl机理。本研究为含二噁英垃圾焚烧飞灰无害化处置资源化提供全新的思路，不仅避免二噁英污染，而且将其制备成无毒、高值的微晶玻璃。

2020年我国垃圾焚烧（MSWI）飞灰约1000万吨，因含二噁英和重金属被列为危险固废。现有的填埋法、水泥固化法和熔融固化法无法消除垃圾焚烧飞灰中的二噁英和重金属污染。采用项目主持人发明的微晶玻璃法，利用垃圾焚烧飞灰的CaO和MgO作玻璃网络外体、SiO2和Al2O3作玻璃网络体，重金属氧化物作形核剂，制备出无毒、高值的微晶玻璃，构建了氯和重金属的迁移模型和稳定机制，主要结论如下：. (1)以MSWI飞灰、酸洗污泥和废玻璃原料一步法制备微晶玻璃。酸洗污泥含Cr2O3、Fe2O3和CaF2等形核剂，导致玻璃网络Si-O键断裂，产生非桥连氧，降低了玻璃的稳定性，增强了晶化能力；. (2)对比研究了玻璃和微晶玻璃固化重金属机理。结果表明：微晶玻璃固化重金属的效果优于玻璃，其原因是重金属形成稳定微晶态的化合物，重金属固化性能与结晶度呈正相关；. (3)揭示了Cl的迁移轨迹和赋存状态，阐明了Cl的微晶玻璃稳定化机制。部分Cl在MSWI飞灰制备玻璃升温过程挥发，残余Cl弥散分布于微晶玻璃，表现出良好的稳定性；. (4)研究了MSWI飞灰添加量对微晶玻璃性能的影响。研究表明：微晶玻璃消纳MSWI飞灰上限比例为50wt.%。50wt.% MSWI飞灰、28wt.%废玻璃和22wt.%酸洗污泥制备的微晶玻璃综合性能最佳，其维氏硬度为7.97GPa，抗弯强度为114.86Mpa，达到工业微晶玻璃板 (JC/T2097-2011)行标的要求。. 本研究为含二噁英垃圾焚烧飞灰无害化处置资源化提供全新的思路，不仅避免二噁英污染，而且将其制备成无毒、高值的微晶玻璃。