Abstract:

Fly ash from waste incineration is rich in heavy metals, dioxins and other pollutants, which is a hazardous waste and needs to be treated in an environmentally sound manner. At present, the solidification/stabilization + landfill method is widely used in domestic waste incineration plants to dispose of fly ash. In this paper, we sampled the domestic grate furnace waste fly ash and fluidized bed fly ash, and their chelated products. We compared and analyzed the characteristics of two types of fly ash, the leaching characteristics of heavy metals before and after chelation, and analyzed the effects of the differences between fly ash before and after chelation on the stabilization of heavy metals using XRD, XRF, and SEM methods. It was found that chelation can bring the heavy metal problem of fluidized bed fly ash under control and the leaching concentrations of Cd in the fly ash of grate furnace after chelation were still exceeded, pointing out the shortcomings of the current solidification/stabilization method for fly ash treatment. This method can make the fly ash surface dense by cement wrapping, which can reduce the leaching of heavy metals to a certain extent, but the effect of stabilizing heavy metals with chemicals was not obvious. Therefore it was not easy to achieve long-term stabilization of heavy metals and had no sustainable development potential. This paper can provide a reference for further research on new waste incineration fly ash disposal technologies in a targeted manner.

Key words: waste incineration fly ash, heavy metals, solidification/stabilization, chelation

摘要：

垃圾焚烧飞灰富含重金属、二英等污染物，属于危险废物，需进行无害化处理。目前国内生活垃圾焚烧厂广泛采用固化/稳定化+填埋的方式处置飞灰。对国内的炉排炉飞灰和流化床飞灰，以及两者的螯合产物进行取样，对比分析两种飞灰的特性、螯合前后的重金属浸出特性，利用X射线衍射（XRD）、X射线荧光光谱分析（XRF）、场发射扫描电子显微镜（SEM）等方法分析飞灰螯合前后差异对重金属稳定化的影响。研究发现，螯合可使流化床飞灰的重金属问题得到控制，而炉排炉螯合后飞灰中Cd重金属的浸出浓度仍存在超标问题，指出当前固化/稳定化方法处理飞灰存在不足，这种方法可通过水泥包裹使飞灰表面致密，一定程度上降低重金属的浸出，但化学药剂稳定重金属的效果不明显，不易于实现重金属的长期稳定，没有可持续发展潜力，为进一步有针对性地开展新型垃圾焚烧飞灰处置技术研究提供借鉴参考。

关键词: 垃圾焚烧飞灰, 重金属, 固化/稳定化, 螯合