尾渣中砷的精细化学结构、赋存形态

The fine chemical structure and occurrence patterns of arsenic in tailings

本文以安徽某有色金属冶炼厂排放的尾渣为研究对象,利用扫描电镜(SEM)、X射线衍射仪(XRD)、X射线荧光光谱分析仪(XRF)和X射线光电子能谱仪(XPS)等方法对尾渣中As的精细结构进行分析,并结合Tessier提取法研究As在尾渣中的赋存形态。结果表明,尾渣中As主要与O共生以As(Ⅴ)-O金属砷酸盐形式存在,含砷矿物为砷酸铁FeAsO_(4)和拉砷铜石Cu(AsO_(4))_(2),伴有少量砷酸铝和硫化砷;总砷含量范围为0.11%—0.17%,赋存形态以残渣态为主,占90%—95%,不同形态As含量大小依次为残渣态>Fe-Mn氧化态>碳酸盐结合态>可交换态>有机结合态;pH是影响As迁移转化的重要因素之一,在环境中会积累一定水平的潜在As释放风险。

In this study,the tailings around Nonferrous Metals Smelter in Anhui Province was the main research object.The fine chemical structure of arsenic in tailings were analyzed by using multiple analytical technologies such as scanning electron microscope(SEM),X-ray diffraction(XRD),X-ray fluorescence spectrometer(XRF)and X-ray photoelectron spectroscopy(XPS)and the occurrence patterns of arsenic in tailings were discussed by sequential extraction method(Tessier).The results indicated that arsenic in the tailings was mainly symbiosis with O and exists in the form of As(Ⅴ)-O arsenate.The arsenic-containing minerals were Iron arsenate(FeAsO_(4))and Lammerite(Cu(AsO_(4))_(2)),accompanied by a small amount of aluminum arsenate and arsenic sulfide.The content of total arsenic ranged from 0.11%to 0.17%,and the occurrence patterns of arsenic were mainly in the residual fraction,accounting for 90%to 95%.The content of arsenic in different fractions followed the order of residual>Fe-Mn oxide>carbonate>exchangeable>organic.pH was one of the important factors influencing the migration and transformation of arsenic,and there might be an accumulation of potential release risk in the environment.