利用管式高温炉研究了医疗垃圾焚烧飞灰中重金属的蒸发特性,以确定飞灰中重金属的有效热分离参数.结果表明,停留时间20与60min时的重金属蒸发率差别不大,其影响程度取决于温度;布袋飞灰中高含量Cl的存在对重金属的蒸发有促进作用;在1000℃时,飞灰中Pb和Cd的蒸发率已达90%以上;气氛对Zn的蒸发效果影响显著,Zn在1000℃空气气氛下蒸发率仅为67%,但在N2气氛下蒸发率高达92%;若考虑Cd,Pb,Zn等挥发性重金属有效分离和二噁英分解两方面的需求,医疗垃圾焚烧飞灰的最低热处理温度宜控制在1000℃左右.
The evaporation characteristics of heavy metals in hospital waste incineration fly ash were studied on a laboratory scale to obtain the effective separation parameters of heavy metals. The results show that their evaporation rates in 20 and 60 min of residence time have no obvious distinction, they depend on temperature. The abundant NaCl in the bag fly ash induces the formation of volatile chloride salts of heavy metals and enhances their evaporation. Evaporation rates of Pb and Cd in the bag fly ash are over 90% at 1000 ℃. Atmosphere has the significant effect on evaporation of Zn. The evaporation rate of Zn in the bag fly ash is only 67% at 1000℃ and air atmosphere, but it reaches 92% in N2 atmosphere. So, the lowest temperature of heat treatment should be controlled at about 1000 ℃ in view of effective separation of volatile heavy metals, such as Pb, Cd and Zn, and drastical decomposition of dioxins and furan.