西藏某矿厂铁尾矿中重金属形态及迁移潜力分析

Analysis on the Form and Migration Potential of Heavy Metals in Iron Tailings of a Mine in Tibet

以西藏某矿厂中两个尾矿库的铁尾矿(TW-1、TW-2)为研究对象,采用《浸出毒性浸出方法硫酸硝酸法》HJ/T 299—2007研究铁尾矿的浸出毒性,以改进的BCR法探讨铁尾矿中9种重金属的形态分布。结果表明:铁尾矿属于一般固体废弃物,铁尾矿中重金属含量较高的是Fe、Mn、Zn和Cu,其中铁尾矿中As含量超出一类用地风险筛选值2倍。TW-1中Cd的浸出浓度超出Ⅱ类水标准。铁尾矿中TW-1重金属活性系数大小为Pb>Cd>Ni>Zn>Cu>Mn>Cr>Fe>As,TW-2重金属活性系数大小为Pb>Zn>Ni>Cd>Mn>Cu>Cr>Fe>As。综合9种重金属的迁移能力,结果为TW-1重金属迁移能力大于TW-2。铁尾矿中的Pb、Cu、Cd和Zn的易于迁出态占比超过60%,对环境有潜在的风险,其中Pb主要以还原态为主,Cu、Cd和Zn以氧化态为主。

Taking the iron tailings from two tailings ponds in a mine in Tibet as the research object,the leaching toxicity of the tailings was studied using the"Leaching Toxicity Leaching Method Sulfuric Acid Nitric Acid Method"HJ/T 299—2007,and the improved BCR method was used to investigate the distribution of 9 kinds of heavy metals.The results show that iron tailings are general solid wastes.The content of Fe,Mn,Zn and Cu is high in iron tailings.The content of As in iron tailings exceeds the risk screening value of the first type of land by 2 times.The leaching concentration of Cd in TW-1 exceeds the standard of ClassⅡwater.The activity coefficient of TW-1 heavy metal in iron tailings is Pb>Cd>Ni>Zn>Cu>Mn>Cr>Fe>As,and the activity coefficient of TW-2 heavy metal is Pb>Zn>Ni>Cd>Mn>Cu>Cr>Fe>As.Integrating the migration capacity of 9 kinds of heavy metals,the result is that the migration capacity of TW-1 is greater than that of TW-2.Pb,Cu,Cd,and Zn in iron tailings account for more than 60%of their easy-to-exit states,which pose a potential risk to the environment.Among them,Pb is mainly in the reduced state,and Cu,Cd and Zn are mainly in the oxidized state.