水热法外加硅铝添加剂稳定垃圾焚烧飞灰中的重金属

Hydrothermal process for stabilization of heavy metals in MSW incineration fly ash with external silicon-aluminum additive

研究了在碱性水热条件下添加粉煤灰、膨润土、高岭土等以提供硅铝元素稳定生活垃圾焚烧飞灰中的重金属。实验结果表明,水热反应中添加粉煤灰、膨润土合成了雪硅钙石和水钙铝榴石,添加高岭土合成了雪硅钙石和加藤石。水热反应中添加粉煤灰、膨润土、高岭土对降低飞灰中Pb、Zn等重金属的浸出毒性均具有显著效果,水热产物中Pb、Zn和Cu的浸出浓度与飞灰相比分别降低了87%~96%、87%~94%和57%~78%。硅铝添加剂还能抑制飞灰中Pb、Zn等在碱性水热条件下向液相的转移,使重金属稳定在固相中。

Coal fly ash,bentonite,or kaolin was used as a silicon-aluminum additive in an alkali-assisted hydrothermal process to stabilize heavy metals from municipal solid waste incinerator fly ash. Tobermorite and hibschite were found to be the main secondary products when coal fly ash and bentonite,respectively,were used as additives. When kaolin was used as the additive,tobermorite and katoite were primarily synthesized. When coal fly ash,bentonite,or kaolin were added,the alkali-assisted hydrothermal process reduced the leaching toxicity of heavy metals（ Pb,Zn,etc.） in the fly ash. Compared with fly ash,the alkali-assisted hydrothermal products＇ leaching concentrations of Pb,Zn,and Cu were reduced from 87% to 96%,87% to 94%,and 57% to78%,respectively. The additives also effectively inhibited heavy metals transfer to the alkali in liquid phase during the hydrothermal process.