干法烟气脱硫副产物中汞的形态分布

通过分析干法烟气脱硫副产物中不同形态汞的含量,研究干法脱硫灰中汞的环境稳定性.利用逐级化学提取法,分析了锅炉底灰、锅炉飞灰、脱硫塔底灰和除尘器灰中水溶态、酸溶态、过氧化氢溶态及王水溶残渣态汞的含量,研究了不同形态汞含量的变化规律.结果表明,锅炉底灰、锅炉飞灰、脱硫塔底灰和除尘器灰中w(总汞)分别为0.23,0.36,0.46和1.22 mg/kg,且随着脱硫除尘时间的延长w(总汞)呈增加的趋势,其中,以氯化物、硝酸盐和硫酸盐存在的水溶态汞变化明显,除尘器灰中w(水溶态汞)高达0.72 mg/kg.分析认为,干法烟气脱硫灰吸附的大部分汞蒸气转化为可溶性的氯化物、硝酸盐和硫酸盐等,另外还有少量汞以单质状态存在.

Mercury Speciation Distribution in Dry Flue Gas Desulfurization Byproduct

Environmental stabilization of mercury in dry flue gas desulfurization(FGD) residue was studied by analyzing the contents of different species of mercury in dry FGD byproduct.The sequential extraction method was used to analyze the contents of mercury in different forms(water-soluble,acid extractable,H2 O2 soluble and residue) in boiler bottom ash,fly ash,FGD tower bottom ash and precipitator ash.The content variation characteristics of different forms of mercury were studied.Experimental results showed that the total mercury in boiler bottom ash,fly ash,FGD tower bottom ash and precipitator ash was 0.23,0.36,0.46 and 1.22 mg /kg,respectively.Total mercury concentration increased with the increase of adsorption time of the four solid samples.The results indicate that recovery of water soluble mercury compound in precipitator ash was observed as high as 0.72 mg /kg,where the mercury compound with speciation of chloride,nitrate and sulfate were obtained.It was concluded that mercury vapor adsorbed by fly ash and lime were mainly formed into chloride,nitrate and sulfate,while the other was elemental mercury.