酸洗污泥与煤共燃烧过程中重金属的迁移分布研究

采用高温管式炉系统进行酸洗污泥与煤共燃烧实验。对共燃烧后As、Cr、Ni、Cd、Cu、Mn、Pb、Zn、Sb、Se重金属元素在烟气、飞灰及炉渣中的分配率进行分析。结果表明,Cd、Se、Zn是易挥发重金属,主要分布在烟气和飞灰中。Cd在烟气中的最大分配率为61%;Se在烟气中的分配率为38.58%~94.612%;Zn在低、高温段分别主要分布在烟气和飞灰中。As、Cu、Pb、Sb是半挥发重金属,Pb在炉渣中的分配率较稳定,分配率为42.67%~64.76%,在烟气和飞灰中的分配率波动较大,其分配率分别是14.176%~45.79%和9.78%~32.55%;Sb在烟气中的最大分配率为37.64%;温度升高反而会抑制As、Cu挥发,这与高温下As、Cu易与矿物质反应生成络合物有关。Ni、Cr、Mn属于难挥发重金属,绝大部分残留在炉渣中,且分配率对温度变化不敏感。赋存于炉渣中的Cr、Ni分别超过95%和97%;随着温度升高,Mn在炉渣中的分配率由71.46%增加到96.89%。

Migration and distribution of heavy metals during co-combustion of pickling sludge and coal

The experiment on co-combustion of pickling sludge and coal was carried out under different temperatures in a high-temperature tubular furnace. The distribution of ten heavy metals (HMs) including As, Cr, Ni, Cd, Cu, Mn, Pb, Zn, Sb and Se in flue gas, fly ash and bottom slag was analyzed. The results indicate that Cd, Se, and Zn are volatile HMs, which predominate in gas phase and fly ash. As to Cd, the maximum proportion in gas phase reaches 61%, while the proportion of Se in flue gas ranges from 38.58% to 94.612%. When the temperature increases, a large amount of Zn is transferred from flue gas to fly ash. As, Cu, Pb, and Sb are semi-volatile HMs. The distribution rate of Pb in bottom slag changes slightly. However, its percentage in flue gas and fly ash swings from 14.176% to 45.79% and from 9.78% to 32.55%, respectively. The peak distribution rate of Sb in flue gas is 37.64%. On the contrary, the temperature increment inhibits the volatilization of As and Cu. This phenomenon is closely relevant to the reaction between As or Cu and some mineral matter. Ni, Cr, and Mn are anti-volatile HMs. The majority of them enrich in bottom slag; in addition, their distributions are insensitive to the temperature change. The enrichment of Cr and Ni in bottom slag is more than 95% and 97%, respectively. The percentage of Mn in bottom slag is boosted from 71.46% to 96.89% as the temperature rises.