医疗垃圾焚烧飞灰的重金属浸出特性及其稳定化处理研究

Leaching and Stabilization of Heavy Metal in the Fly Ash of Medical Wastes

通过对医疗垃圾飞灰的浸出特性和高温熔融处理实验,研究了浸出时间、液固比、pH值和颗粒尺寸对重金属浸出特性的影响以及飞灰熔融对重金属稳定化处理效果.结果表明,随着浸出时间的增加,飞灰绝大部分重金属的浸出浓度增高,浸出毒性增强;液固比（L/S）增加,大部分重金属的浸出率大大提高,其中重金属Cd的浸出率最大,在液固比为90时,飞灰中的Cd的浸出率达到70%以上;pH为中性左右的时候,医疗垃圾飞灰中的大部分重金属的浸出液浓度最低;颗粒尺寸在较大或者较小时,医疗垃圾飞灰中的大部分重金属浸出浓度较小,大部分重金属在颗粒尺寸250-900μm时,重金属的浸出浓度较高;飞灰高温熔融后,重金属的浸出毒性大大降低,说明熔融对重金属有很好的固化效果.

Through the experiments of leaching and melting on the fly ash of medical wastes,the influence of leaching time,L/S,pH and grain size on the leaching characteristics of heavy metal and the effect of melting on the stabilization of fly ash are studied.Results show that,following the leaching time extending,the leaching concentrations of heavy metals and lixiviate toxicity of heavy metals increase in the fly ash.When the ratio of liquid and solid add,the leaching concentrations of heavy metals obviously become big,and the Cd＇s leaching concentration is the biggest,when the ratio of liquid and solid is 90,the Cd＇s leaching ratio exceed the percent of 70.At the time pH is about 7,the leaching concentrations of heavy metals are the lowest.When the grain size is the bigger or little,the leaching concentrations of heavy metals are lower,however when the grain size is 250-900 μm,the concentrations are higher.After fly ash melt in the high temperature,the lixiviate toxicity of heavy metals greatly reduce,which explains that the effect of melting on heavy metals＇ stabilization is very good.