铜污泥中重金属形态分布及浸出毒性分析

结合目前有色冶金工业上普遍采用的石灰铁盐法工艺特点，首次采用改进的BCR连续提取法与毒性浸出实验相结合的方法对铜污泥（中和渣与铁砷渣污泥）的重金属形态分布与浸出毒性进行了系统的研究。结果表明：采用改进的BCR方法对铜冶炼污泥重金属元素形态进行提取，形态提取具有较高的回收率；As、Zn、Pb与Cd为中和渣与铁砷渣污泥中主要的重金属元素（质量含量As＞Zn＞Pb＞Cd），其中中和渣含As高达58 566 mg/kg（折合5.85%），铁砷渣含As为12 582 mg/kg（折合1.26%）；两种重金属形态分布差异主要体现在As的形态分布上，铁砷渣污泥中重金属稳定性较好，特别是砷的稳定性较中和渣高；中和渣污泥中，As主要以弱酸态形式存在（占68.01%），Zn、Pb与Cd主要以残渣态存在；铁砷渣污泥中，As、Zn、Pb与Cd主要以残渣态存在，其中残渣态As占59.21%；浸出毒性结果显示两种污泥中砷的浸出毒性都远远超过国标GB 5085.3-2007规定值，因此铜冶炼厂污泥属于含高砷危险废弃物，而以弱酸态As为主的中和渣污泥浸出毒性较高，而主要以残渣态As存在的铁砷渣污泥浸出毒性较低。

Chemical speciation of heavy metals and leaching toxicity analysis of sludge in copper metallurgy plant

According to the lime-iron salt method commonly used in recent non-ferrous metallurgy industry，the modified sequential extraction procedure proposed by BCR (Community Bureau of Reference of the European Commission，now the Standards，Measuring and Testing Programme) was used and leaching toxicity test was performed to investigate sludge (neutralization sludge and iron-arsenic sludge) in a copper metallurgy plant for the first time. It was found that recovery of heavy metals in the BCR process was high. As，Zn，Pb and Cd were the main heavy metals in those two sludges，following the weight content order of As > Zn > Pb > Cd. The weight contents of neutralization sludge and iron-arsenic sludge were high up to 58 566 mg/kg (5.85%) and 12 582 mg/kg (1.26%)，respectively. There was a big difference of As chemical speciation in the chemical speciation of heavy metals for two sludges. The stability of heavy metals in iron-arsenic sludge was higher than that of neutralization sludge，especially for As. For neutralization sludge，As acid-soluble fraction (68.01%)，Zn，Pb and Cd mostly existed as residual fraction. For iron-arsenic sludge，As，Zn，Pb and Cd mostly existed as residual fraction，and the residual fraction of As was 59.21%. Leaching toxicity test results showed that leaching toxicity of As for both sludges was much higher than that of GB 5085.3-2007. Therefore，the sludge in the copper metallurgy plant belonged to hazardous waste containing high arsenic. It was also found that neutralization sludge with higher acid-soluble fraction of As had higher leaching toxicity while iron-arsenic sludge with lower acid-soluble fraction of As had lower leaching toxicity.