水洗—热处理过程对飞灰中Pb、Zn、Cu固化和长期浸出影响研究  

Study on the Influence of Washing-Thermal Treatment on the Stabilization and Long-term Leaching of Pb,Zn,Cu in Fly Ash

作　　者：吕中 夏运雪 张健帅 唐圆圆 LYU Zhong;XIA Yunxue;ZHANG Jianshuai;TANG Yuanyuan(School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen Guangdong 518055)

机构地区：[1]南方科技大学环境科学与工程学院,广东深圳518055

出　　处：《环境卫生工程》2022年第6期46-57,共12页Environmental Sanitation Engineering

基　　金：科技部国家重点研发计划项目(2018YFC1902904);国家自然科学基金面上项目(41977329);广东省自然科学基金杰出青年项目(2021B1515020041)。

摘　　要：水洗预处理与热处理相结合具有同时实现飞灰安全处置与资源化利用的前景。然而,研究仍未明确水洗对重金属迁移转化的影响,且由于飞灰极强的缓冲性能,常用浸出方法低估了处置后飞灰的浸出风险。针对上述问题,对飞灰中Pb、Zn、Cu的固化机制进行研究,探讨水洗预处理对重金属固化行为的影响。并设计恒定pH长期浸出装置,以评估处置后飞灰的长期浸出行为。结果表明,水洗-热处理飞灰烧结后主要含Pb、Zn、Cu物相为铅铝硅酸盐、氧化铅钙、硅酸锌、锌铝硅酸盐等,热处理飞灰均生成了前述物相,并同时生成氧化铅氯化物、铅铝氧化物、硅酸铅、氯化锌、钙铜氧化物等,经过水洗-热处理的飞灰中Pb、Zn、Cu物相种类受烧结温度和重金属含量影响更小。水洗-热处理比直接热处理对飞灰Pb固化效率更高,为94.59%~99.60%;恒定pH长期浸出中,两种浸提液对应浸出液pH保持在2.91~3.63和4.91~5.36,Pb、Zn、Cu浸出浓度基本在前600 min内达到最大值,随后降低并保持较低浓度,依次为0~0.09、0.01~0.92、0.03~0.22 mg/L(水洗-热处理)和0.03~0.31、0.07~0.94、0~0.11 mg/L(热处理)。本研究提出的长期浸出方法可评估飞灰在极端条件下长期浸出风险,揭示了水洗-热处理过程中重金属迁移转化机制,为飞灰安全处置与资源化利用提供参考。A combination of water washing pretreatment and thermal treatment may become a strategy for safe disposal and resource utilization of the MSW incineration fly ash.However,the influence of water washing on the migration and transformation of heavy metals has not been clearly studied,and the leaching risk of fly ash after disposal was underestimated by common leaching methods due to the strong buffering performance of fly ash.In view of the above problems,the curing mechanism of Pb,Zn and Cu in fly ash was studied,the influence of water pretreatment on the curing behavior of heavy metals was discussed.And a long-term leaching device with constant pH was designed to evaluate the longterm leaching behavior of fly ash after disposal.The results showed that the major product phases of Pb,Zn,Cu after the washing-thermal treatment were identified as lead-aluminosilicate,lead-calcium oxide,zinc silicate,zinc-aluminosilicate,etc.Meanwhile,the aforementioned phases were also detected in the scheme of only thermal treatment but with additional lead oxide chloride,lead aluminum oxide,lead silicate,zinc chloride and calcium copper oxide,etc.The types of Pb,Zn and Cu phases in fly ash after washing-thermal treatment were less affected by the sintering temperature and metal content.A higher Pb stabilization efficiency was obtained after washing-thermal treatment compared with only thermal treatmeat,with the value ranged from 94.59%to 99.60%.In the long-term leaching experiments with constant pH,the corresponding leachate pH of the two solutions were maintained in the range of 2.91~3.63 and 4.91~5.36.Leaching concentrations of Pb,Zn,Cu concentrations basically reached the maximum value after 600 mins,then decreased and maintained a low concentration at 0~0.09,0.01~0.92,0.03~0.22 mg/L(washing-thermal)and 0.03~0.31,0.07~0.94,0~0.11 mg/L(only thermal)respectively.The long-term leaching method proposed in this study could evaluate the long-term leaching risk of fly ash under extreme conditions,reveal the migration and transformation

关 键 词：城市垃圾焚烧飞灰 重金属 水洗预处理 热稳定化 长期浸出行为 

分 类 号：X799.3[环境科学与工程—环境工程]