X射线荧光光谱法用于粗铜中铜和13种杂质元素的测定

铜冶炼过程的中间产品粗铜中铜质量分数在97.5%以上,常含有砷、锑、铁、铅、锌、锡等杂质元素。使用X射线荧光光谱法(XRF)测定粗铜中铜时,铜元素含量过高导致其X射线荧光强度与铜含量的线性度变差,而且试样的光洁度和密度的差异等因素也导致铜含量测定值偏离真实值。试验首先选取各元素含量均具有梯度的粗铜生产样品,使用多种化学湿法对各元素进行定值。在对XRF测定条件优化的前提下,通过车床加工制样,建立了X射线荧光光谱法(XRF)测定粗铜中13种杂质元素(硫、铁、锑、铋、砷、铅、锌、镍、硒、锡、银、钴、碲)的方法。结合测氧仪提供的氧含量值,通过差减法可计算出粗铜中的铜含量。实验方法用于测定1个粗铜样品中铜和13种杂质元素,测定结果的相对标准偏差(RSD,n=11)小于5%。按照实验方法测定4个铜块中铜和13种杂质元素,测定结果与化学湿法值进行比对,结果表明各杂质元素测定值与湿法测定结果相吻合;而使用差减法计算的铜含量(质量分数均大于97.5%)和化学湿法测定结果差值很小,完全满足生产需要。

Application of X-ray fluorescence spectrometry on the determination of copper and thirteen impurity elements in crude copper

The mass fraction of copper in intermediate product of copper smelting (i.e., crude copper) is more than 97.5%. Moreover, the crude copper usually contains several impurity elements such as arsenic, antimony, iron, lead, zinc and tin. During the determination of copper in crude copper by X-ray fluorescence spectrometry (XRF), too high content of copper will lead to the deterioration of linearity between XRF intensity and copper content. Meanwhile, the difference of sample in finish degree and density can also cause the determination results of copper content to deviate from the true value. The crude copper production samples with content gradient of each element were firstly selected, and various chemical wet methods were used to determine the content of each element. On the premise of optimizing the determination conditions of XRF, the determination method of copper and 13 kinds of impurity elements (sulfur, iron, antimony, bismuth, arsenic, lead, zinc, nickel, selenium, tin, silver, cobalt and tellurium) in crude copper by XRF was established after preparing samples by the means of lathes. The content of oxygen was provided by oxygen meter. Then the content of copper in crude copper could be calculated by subtraction method. The proposed method was applied for the determination of copper and 13 impurity elements in one crude copper sample. The relative standard deviations (RSD, n=11) of determination results were less than 5%. The contents of copper and 13 impurity elements in four copper samples were determined according to the experimental method, and the found results were compared with those obtained by chemical wet method. It was found that the determination results of impurities were consistent with those obtained by wet method. The calculated content of copper (the mass fractions were all higher than 97.5%) by subtraction method had little difference with those obtained by chemical wet method, which could fully meet the production requirements.