不同毒性浸出标准下飞灰的铅浸出率研究

Study on Lead Leaching Rate of Fly Ash under Different Toxicity Leaching Standards

选取中国、美国、日本施行的5种典型毒性浸出标准,以飞灰中最易超标的重金属元素铅为研究对象,对国内不同季节、焚烧工艺、地域分布的24个代表性飞灰样本进行浸出pH值、铅浸出量和铅总量的关联性研究。结果表明:飞灰中铅总量受焚烧工艺、地域分布、季节变迁的影响而波动,炉排炉飞灰的铅总量明显高于流化床飞灰;与美国TCLP、日本盐酸法、国内硫酸硝酸法、水平法相比,国内现行飞灰填埋标准HJ/T 300醋酸缓冲溶液法浸提剂酸度最高;飞灰中碱性物质和浸提剂酸度相互作用中和后,受浸出液pH值的影响,飞灰样本中40%的铅几乎不溶出,无法真实呈现飞灰的污染程度,容易形成二次污染。

Taking China,USA,Japan as reference,five typical toxicity leaching standards were selected.Taking lead,the most easily over-standard heavy metal element in fly ash,as the research object.24 representative fly ash samples from different seasons,incineration processes,geographical distribution and investment groups in China were studied for the correlation of leaching pH,lead leaching amount and total lead.The results show that the total amount of lead in fly ash fluctuates due to the influence of incineration process,regional distribution and seasonal changes,and the total amount of lead in grate furnace fly ash is significantly higher than that in fluidized bed fly ash;Compared with TCLP horizontal method in America,hydrochloric acid method in Japan,sulfuric acid and nitric acid method in China,the current domestic standard for fly ash filling is HJ/T 300 acetic acid buffer solution method,the acidity of the extractant is the highest.After neutralization by the interaction between the alkaline substances in fly ash and the acidity of the extractant,the lead in 40%of fly ash samples can hardly be dissolved due to the influence of pH value of the leaching solution,which can not truly reflect the pollution degree of fly ash and is easy to cause secondary pollution.