垃圾焚烧飞灰熔融无害化及资源化研究现状

垃圾焚烧飞灰因含二噁英和重金属被列为危险废物（HW18），存在环境污染风险，2020年全国生活垃圾焚烧量高达14607.6万吨，以焚烧量5%（质量分数）计算，全国垃圾焚烧飞灰的产生量为730.4万吨。目前垃圾焚烧飞灰以固化填埋为主，占用土地资源，且堆存量与处理量严重失衡，无法实现资源化，因此垃圾焚烧飞灰的无害化及资源化已成为绿色发展的瓶颈课题。本文详细介绍了垃圾焚烧飞灰经熔融无害化及资源化的研究现状，阐述了熔融处理垃圾焚烧飞灰的重金属固化、二噁英降解机理，结合熔融形成的玻璃渣分析了制备微晶玻璃、泡沫微晶玻璃、胶凝材料的资源化技术，并指出现有玻璃化虽能固化重金属，但在后续资源化以及产品服役过程，重金属的迁移规律、浸出性需要进一步研究，为垃圾焚烧飞灰的综合利用提供了参考。 

Current state of the harmless melting and recycling of municipal solid waste incinerator fly ash

In 2020, the municipal solid waste removal and transportation volume reached 235.117 million tons, of which 146.076 million tons were incinerated in China. Because it can reduce the harmfulness of waste and recycle energy, municipal solid waste incineration (MSWI) technology has become the primary method for the disposal treatment of urban domestic waste in China. However, this method produces MSWI fly ash, which is defined as a hazardous waste rich in dioxins and heavy metals. Calculated based on 5% (mass fraction) of the original waste, the output of MSWI fly ash in China nearly reached 7.304 million tons in 2020. Moreover, the stockpile management and treatment capacities are seriously out of balance. At present, the main disposal method of MSWI fly ash is landfilling, which consumes land resources and poses an environmental hazard. As a result, the harmlessness and recyclability of MSWI fly ash have become a bottleneck for green development. In this review, the harmless melting and recycling of MSWI fly ash are introduced in detail. The mechanisms of heavy metal solidification and dioxin degradation during MSWI fly ash melting have been explained. MSWI fly ash can be transformed into glass slag containing CaO?SiO₂?Al₂O₃ after co-melting with other solid wastes rich in silicon aluminum oxide. Heavy metals in MSWI fly ash can be solidified at the atomic scale in the silicate network of glass. More importantly, as the temperature increases beyond 800 °C, dioxins undergo dechlorination and degradation, reducing the harmfulness and revealing the harmlessness of MSWI fly ash. This review also describes how to deal with the glass slag that forms because of co-melting. The glass slag has low added value and poor mechanical properties. Future disposal trends for vitrified slag from MSWI fly ash, including glass–ceramic, glass–ceramic foam, and cementitious materials, have been proposed. Given that vitrification can solidify heavy metals in the process of subsequent resource usage and product service, the migration and leaching characteristics of heavy metals need to be further investigated. This study provides a reference for the comprehensive usage of MSWI fly ash.