某铅锌矿区矿渣重金属Pb和Zn浸出影响分析

Analysis of Leaching of Heavy Metals Pb and Zn from Slag in a Lead-zinc Mine Area

以三峡库区某废弃铅锌矿区矿渣为研究对象,采用优化的连续化学提取(SCE)-微波消解-ICP-MS法分析了矿渣中Pb和Zn的水溶态、弱酸态、还原态、氧化态及残渣态的分布特性,研究了不同pH值与反应时间对重金属Pb和Zn浸出的影响,分析了Pb和Zn的迁移能力和浸出能力。研究表明,Pb主要以氧化态和弱酸态形式存在,Zn以还原态和弱酸态为主,有效态含量Pb<Zn,Pb的污染风险更低;酸性或碱性环境能促进Pb的浸出,中性环境对Pb的浸出量最低;在酸性环境中,Pb和Zn的浸出过程大体相似,浸出能力Pb>Zn,最大浸出量Pb>Zn,碱性环境对Zn的稳定有利。当环境条件发生改变时,如pH值或降水改变时,均可能造成矿区中包括Pb和Zn在内的重金属浸出和迁移,造成严重的二次污染。

The waste residue from an abandoned lead zinc mining area in the Three Gorges Reservoir area as the research object.Optimized species chemical extraction(SCE)-microwave digestion-ICP-MS method was adopted.Effects of different pH value and reaction time on leaching of heavy metals Pb and Zn were studied.Mobility and leaching ability of Pb and Zn were analyzed.The results showed that Pb mainly exists in the form of oxidation and weak acids.Zn was mainly composed of reduced and weak acids.Effective content was Pb<Zn,and Pb has lower pollution risk.Acid or alkaline environment could promote the leaching of Pb.In neutral environment,the leaching amount of Pb was the lowest.In acidic environment,the leaching process of Pb and Zn is similar,the leaching capacity is Pb>Zn,and the maximum leaching amount is Pb>Zn.Alkaline environment is beneficial to the stability of Zn.If environmental conditions change(such as pH value or precipitation),the possibility of leaching and migration of heavy metals including Pb and Zn in the mining area will increase,and even cause serious secondary pollution.