垃圾焚烧飞灰高温热处理技术研究进展

Research progress on high temperature heat treatment technology of municipal soild waste incineration fly ash

垃圾焚烧飞灰高温热处理可有效固定重金属和彻底分解二噁英,实现飞灰的无害化、减量化和资源化再利用,其为最具前景的飞灰处置技术之一。在热处理过程中,飞灰中大部分难挥发重金属Cr、Ni固定在飞灰熔渣中,而易挥发的重金属Pb、Cd则大量迁移至二次飞灰中。飞灰熔渣无毒性,可直接进行资源化利用;而二次飞灰属富含重金属的危险废弃物,常采用化学稳定化+填埋进行处理,也可通过回收二次飞灰中的重金属和可溶性氯盐以达到对飞灰的资源化利用。结合垃圾焚烧炉的主要技术特点以及垃圾焚烧过程中重金属的迁移过程,总结飞灰中重金属及其存在形式、飞灰组成成分、热处理条件和添加剂等因素对飞灰热处理过程中重金属固定及迁移特性的影响规律,梳理我国垃圾焚烧飞灰高温热处理技术中的烧结、熔融和水泥窑协同处置之最新进展,剖析我国回转窑飞灰烧结工艺、旋流式燃料熔融炉中试系统及等离子体气化熔融工艺路线、水泥窑协同处置垃圾焚烧飞灰流程及其相关项目。指出水泥窑协同处置飞灰已成为我国除化学稳定化+填埋之外最主要的飞灰处置方式,且随着相关技术规范和标准的完善及相应政策的支持,水泥窑协同处置飞灰会得到更大范围的推广和应用。

High-temperature heat treatment is usually regarded as one of the most promising methods of waste incineration fly ash detoxification and reuse as it allows for effective heavy metal immobilization,dioxin decomposition,and environmentally stable material production.During the heat treatment process,most of the hard-to-volatile heavy metals Cr and Ni in the fly ash will be fixed in the fly ash slag,while the volatile heavy metals Pb and Cd will migrate to the secondary fly ash in large quantities.The fly ash slag is non-toxic and can be directly used for resource utilization.The secondary fly ash is a hazardous waste rich in heavy metals,which is often treated by chemical stabilization and landfill,and can also recycle heavy metals and soluble chloride salts in the secondary fly ash to achieve the resource utilization of fly ash.Combining the main technical characteristics of waste incinerators and the migration process of heavy metals in the process of waste incineration,this article summarizes the influence of characteristics of heavy metals in fly ash,fly ash composition,heat treatment conditions and additives on the immobilization/migration of heavy metals during the heat treatment of fly ash.Finally,reviewing the latest developments in the co-processing of sintering,melting and cement kilns in the high-temperature heat treatment technology of waste incineration fly ash in China,the paper analysis of rotary kiln fly ash sintering process,swirling fuel melting furnace pilot system and plasma gasification melting process route,cement kiln co-processing waste incineration fly ash process and related projects.It is pointed out that cement kiln co-processing fly ash has become the most important fly ash disposal method in China besides chemical stabilization and landfilling.With the improvement of relevant technical specifications and standards and the support of corresponding policies,cement kiln co-processing fly ash will be get a wider range of promotion and application.