添加剂能抑制湿法烟气脱硫(WFGD)系统汞释放,被添加剂富集到石膏的汞在石膏热处理过程会再释放.实验研究了3 种WFGD 抑制汞释放添加剂对汞在石膏中富集的促进作用、石膏中汞化合物变化和石膏热处理过程汞稳定性的影响.结果表明,NaHS、TMT 和DTCR 的添加使石膏汞含量显著升高,使石膏中汞分别以HgS、Hg3(TMT)2 和Hg(DTCR)2 形式存在,其分解峰值温度与分解温度范围依次减小;在200℃热处理2,h 后石膏的剩余汞含量也依次降低,最低汞质量分数为182.0ng/g,而且DTCR使汞释放率增加到90%.
Additives can inhibit Hg0 re-emission in WFGD and cause mercury enrichment in gypsum,but mercuryin gypsum will be released in heat treatment processes.Experiments were conducted to study the effect of three additiveson the promotion of mercury content in gypsum,the thermal stability of mercury in heat treatment processes,and the change of mercury compound species in gypsum.The results showed that when NaHS,TMT and DTCRwere added to gypsum slurry,the mercury content in gypsum was significantly increased,and that mercury mainlyexisited in the form of HgS,Hg3(TMT)2 and Hg(DTCR)2. The peak of decomposition temperature and the range ofdecomposition temperature gradually decreased in the order of HgS,Hg3(TMT)2 and Hg(DTCR)2.The residualmercury content in gypsum was gradually reduced with the addition of adding NaHS,TMT and DTCR after heated at200,℃ for 2h.The lowest residual mercury content in gypsum was 182.0 ng/g,and the mercury release rate wasincreased to 90% with the addition of DTCR.