垃圾焚烧飞灰磷酸洗涤对重金属的固定效应研究
Effects of phosphoric acid washing on immobilization of heavy metals in municipal solid waste incineration fly ash
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摘要: 重金属的固定是垃圾焚烧飞灰资源化技术的核心问题。通过系统试验，研究了垃圾焚烧飞灰磷酸洗涤对重金属溶出、后续烧结过程中重金属挥发，以及重金属化学形态变迁的影响。试验结果表明，磷酸洗涤在有效洗脱飞灰中氯盐的情况下，能够显著减少洗涤过程中重金属的溶出，抑制烧结过程中重金属的挥发，从而避免了飞灰处理过程的二次污染；同时，磷酸洗涤使飞灰中的重金属在烧结前后均向更为稳定的化学形态转化，烧结产物中重金属主要以残留态存在，从而提高了烧结产物资源化利用的长期环境安全性。Abstract: The influences of phosphoric acid washing municipal solid waste incineration (MSWI) fly ash on the leaching of heavy metals during the washing, the evaporation of heavy metals during the subsequent sintering, and the chemical speciation of heavy metals were discussed. It is showed that in the case of eluting the chloride salts in the fly ash effectively, phosphate pretreatment can reduce the leaching of heavy metals during the washing remarkably, and inhibit the evaporation of heavy metals during the sintering, such that the secondary pollution can be avoided during the disposal of fly ash. At the same time, phosphoric acid washing causes heavy metals in the fly ash to transform into a more stable chemical form both before and after the sintering, and the heavy metals in the sintered products exit in the residual state, such that the longterm environmental security for the resource reuse of the sintered products can be improved.
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Key words:
- MSWI fly ash /
- heavy metal /
- phosphoric acid washing /
- immobilization /
- chemical speciation
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