铅锌尾矿中重金属形态分布与毒性浸出特征研究

Characteristics of speciation distribution and toxicity leaching of heavy metals in Pb-Zn tailings

以铅锌尾矿为研究对象,用改进BCR法探讨Pb、Zn、Cd、Cr、Cu五种重金属形态分布特征,TCLP法研究重金属毒性浸出特征,并将金属形态含量与浸出含量做相关分析。结果表明:表层尾矿金属含量低于下层尾矿,Zn、Cd、Cu、Cr主要以残渣态为主,Pb主要以弱酸提取态为主,表层尾矿中Pb、Zn、Cd的弱酸提取态比例系数高于下层尾矿;下层尾矿浸出含量均高于表层,Zn、Pb、Cd浸出含量均超标;在本文既定的实验条件下,不考虑重金属性质、含量差异的情况下,重金属弱酸提取态和可还原态与浸出含量呈极显著正相关;铅锌尾矿应重点关注Pb、Zn、Cd的环境污染,尾矿堆积过程中会造成下层尾矿中重金属含量增加和金属Zn、Pb、Cd活性降低,以弱酸提取态和可还原态之和评价尾矿重金属有效性较合理。

Taking Pb - Zn tailings as research object, speciation distribution and toxicity leaching characteristics of five heavy metals （Pb, Zn, Cd, Cu and Cr） were investigated by using modified BCR method and TCLP method. Correlation between speciation and leaching content was analyzed. Results showed that metals contents in surface tailings were less than those in lower tailings. Zn, Cd, Cu, Cr mainly existed in residual fraction, while Pb mainly existed in acid extractable fraction, and the ratio coefficient of acid extractable fraction of Pb, Zn, Cd in surface tailings were larger than those in lower tailings. Leaching contents of metals in surface tailings were less than those in lower tailing , and leaching contents of Pb, Zn, Cd exceeded standard. Under the experi- mental conditions, the nature of heavy metals and the difference of the content of heavy metals were not consid- ered. Acid extractable fraction and reducible fraction of heavy metals were significantly positively correlated with leaching contents, respectively. Pb -Zn tailings should focus on Pb, Zn, Cd pollution. Heavy metal contents of lower railings increased, and the activity of Pb, Zn and Cd decreased during the accumulation process. Metal availability evaluation of tailings could be carried out by the sum of the two fractions.