水热法稳定垃圾焚烧飞灰重金属研究

Research on stabilization of heavy metals in MSWI fly ash by hydrothermal treatement

水热法是生活垃圾焚烧飞灰无害化处置新方法,在飞灰重金属稳定化方面具有显著能力.在前期研究基础上,提出利用水热法耦合化学添加剂方法实现重金属的深度稳定化,设计正交实验研究各参数对重金属浸出毒性的影响.结果表明:实验的较优工况为以空气为气氛,碳酸钠为添加剂,在300℃下水热并保持1h;同时可通过增大添加剂使用量来降低飞灰的浸出毒性,达到生活垃圾填埋场的飞灰进场标准.水热法可有效改变飞灰微观结构,降低颗粒粒径;水热后重金属是以一种稳定的、难以离子交换的形式存在,从而实现稳定化;水热反应中有部分微、中孔向大孔转变,改善了孔隙结构,具有更大的比表面积,飞灰利用价值也得到了提升.

Hydrothermal method is a new method for the disposal of waste incinerttion fly ash , and has significant ability in the stabilizttion of fly ash heavy mttals. On the basis of previousstudies , the coupling of chemical additives with hydrothermal method is presented to realize thedeep stabilization of heavy metals , the orthogonal experiment was used to study the effects ofdifferent parameters on heavy metal leaching toxicity. Results show that ： the optimum experimental conditions for air atmosphere, sodium carbonate as additive, hydrothermal at 300 O and keep 1 hour. At the same time,by increasing the amount of additives , the leaching toxicity is reduced , and meet the demand of the standard of domestic landfill. Hydrothermal method caneffectively change the microstructure of fly ash, reducing particle size; the heavy metal is in a stable and difficult form of ion exchange after hydrothermal, so as to realize the stabilization. Meantime,some micro and mesopores change to the macroporous, improve the pore structure, the fly ash has larger specific surface area and utilization value.