协同处理药渣过程飞灰重金属分布及浸出特性

Distribution and Leaching Characteristics of Heavy Metals in Fly Ash During Co-processing of Pharmaceutical Residues

为评估燃煤锅炉协同处理药渣过程中飞灰重金属的环境风险,该文对不同粒径飞灰重金属的分布及浸出特性进行研究。结果表明:Pb、Zn在整体飞灰中的分配率均达到了95%以上,Cd、Cu、As在整体飞灰中的分配率均达到75%以上,而Mn在整体飞灰中的分配率仅40%。沿着烟气流程,除尘器不同电场捕获的飞灰中值粒径逐渐减小,飞灰颗粒表面更加光滑。随飞灰粒径的减小,飞灰中Pb、Zn、Cd、Cu的质量分数逐渐增大,而As的质量分数逐渐减小;不同粒径飞灰中Mn的质量分数在300 mg/kg上下波动。随飞灰粒径的减小,Pb、Cd、Cu的浸出浓度逐渐增大;飞灰中值粒径由20.2μm减小到5.0μm,Zn的浸出浓度增大了687%,环境风险急剧提高;不同粒径飞灰中As的浸出浓度均小于0.05μg/L,Mn的浸出浓度均小于0.01μg/L。协同处理药渣过程中,随着飞灰粒径减小,Pb、Zn、Cd、Cu、Mn的环境风险逐渐升高,该试验中不同粒径飞灰样品重金属的环境风险均满足环保要求。

In order to evaluate the environmental risk of heavy metals in fly ash during the co-processing of pharmaceutical residues in coal-fired boilers,the distribution and leaching characteristics of heavy metals in fly ash with different particle sizes were investigated.The results showed that the distribution rates of Pb and Zn in the overall fly ash all reached more than 95%,and the distribution rates of Cd,Cu and As in the overall fly ash all reached more than 75%,while the distribution rate of Mn in the overall fly ash was only 40%.Along the flue gas flow,the median particle size of the fly ash captured by different electric fields of the dust collector gradually decreased,and the surface of the fly ash particles was smoother.With the decrease of the fly ash particle size,the mass fraction of Pb,Zn,Cd and Cu in the fly ash gradually increased,while the mass fraction of As gradually decreased.The mass fraction of Mn in the fly ash of different particle sizes fluctuated above and below 300 mg/kg.The leaching concentration of Pb,Cd and Cu gradually increased as the particle size of fly ash decreased.The median particle size of fly ash decreased from 20.2μm to 5.0μm,and the leaching concentration of Zn increased by 687%,the environmental risk increases sharply;the leaching concentration of As in different particle sizes of fly ash is less than 0.05μg/L,and the leaching concentration of Mn is less than 0.01μg/L.In the process of co-processing of pharmaceutical residues,the environmental risk of Pb,Zn,Cd,Cu,Mn gradually increases as the particle size of fly ash decreases,but the environmental risk of heavy metals in different particle sizes of fly ash samples in this test meets the environmental requirements.