燃烧过程中碱/碱土金属对重金属迁移转化影响的研究进展

A review on the migration and transformation of heavy metals influence by alkali/alkaline earth metals during combustion

  • 摘要: 碱/碱土金属广泛存在于各种固体燃料中,在燃烧过程中碱/碱土金属与燃料中重金属及其他矿物发生复杂的物理化学反应,从而影响重金属的迁移和转化。本研究主要介绍了碱/碱土金属对As、Se、Pb和Cr四种重金属迁移转化的影响规律,包括碱金属和碱土金属对重金属迁移转化的影响,颗粒物团聚与黏结对重金属排放的影响三个方面。碱/碱土金属能够抑制重金属的挥发:碱金属与Cl元素的结合,降低了PbCl2的生成;碱金属的存在有利于提升高岭土对Pb的吸附效率;碱/碱土金属可以与As和Se形成稳定的化合物。但同时需要注意碱/碱土金属与Cr的部分结合产物中,Cr以六价态存在,具有较高的毒性。碱/碱土金属对于团聚现象发生,分别起到了促进和抑制作用,适当含量的碱金属有利于减少重金属的释放。通过总结碱/碱土金属对重金属迁移转化的影响规律,以期为降低重金属的危害提供思路。

     

    Abstract: Alkali/alkaline earth metals(AAEMs) are widely present in various solid fuels. During the combustion process, the AAEMs undergo complex physical and chemical reactions with heavy metals and other minerals in the fuel, thereby affecting the migration and transformation of heavy metals. This paper mainly introduced the influence of AAEMs on the migration and transformation of As, Se, Pb and Cr, including the influence of alkali metals and alkaline earth metals on the migration and transformation of heavy metals, and the influence of particle agglomeration and coherence on heavy metal emissions. AAEMs can inhibit the volatilization of heavy metals. The combination of alkali metals and Cl elements reduces the production of PbCl2. The presence of alkali metals is beneficial to improve the adsorption efficiency of kaolin for Pb. AAEMs can form stable compounds with As and Se. However, at the same time, it should be noted that in the partial combination products of AAEMs and Cr, Cr exists in a hexavalent state and has high toxicity. AAEMs play a role in promoting and inhibiting the occurrence of agglomeration, respectively. An appropriate content of alkali metals is beneficial to reduce the release of heavy metals. By summarizing the influence of AAEMs on the migration and transformation of heavy metals, it is hoped to provide ideas for reducing the harm of heavy metals.

     

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