超低排放燃煤机组Se、Hg在固相产物中的赋存形态和浸出特性研究

Study on the Occurrence Speciation and Leaching Characteristics of Se and Hg in the Solid Phase Products of Ultra-low Emission Coal-fired Units

煤燃烧会产生大量污染物,研究燃煤固相产物中有害痕量元素的含量分布和赋存形态具有深远意义。本文依托Se和Hg两种元素,探讨了其在燃煤电厂超低排放机组固相产物中的含量分布、结合形态及浸出特性。结果表明,飞灰中Se含量高于底渣;底渣中Se和Hg的主要存在形态为较为稳定的残渣态,4#机组底渣中残渣态含量最低;飞灰中Se和Hg的主要存在形态为可氧化态;四台机组底渣和飞灰中Se和Hg浸出量均低于《危险废物鉴别标准-浸出毒性鉴别》(GB5085.3-2007)规定排放限值;4#机组飞灰中Se对环境的潜在风险更低,Hg在底渣和飞灰中的浸出量几乎为0,不存在浸出风险。

Coal combustion will produce a large amount of pollutants,and it is of far-reaching significance to study the content distribution and occurrence speciation of harmful trace elements in the solid phase products of coal combustion.Based on the two elements Se and Hg,the content distribution,binding speciation and leaching characteristics of these elements in the solid phase products of ultra-low emission units of coal-fired power plants were discussed.The results show that the Se content in fly ash is higher than that in bottom slag.The main forms of Se and Hg in the bottom slag are relatively stable residue state,and the content of residue state in the bottom slag of 4# unit is the lowest.The main forms of Se and Hg in fly ash are oxidizable states.The leaching amount of Se and Hg in the bottom slag and fly ash of the four units was lower than the emission limit stipulated in“Hazardous Waste Identification Standard-Identification of Leaching Toxicity”(GB5085.3-2007).The potential risk of Se in the fly ash of Unit 4#to the environment is lower,the leaching amount of Hg in the bottom slag and fly ash is almost zero,and there is no leaching risk.