熔融制样-X射线荧光光谱法测定稀土矿石中的主量元素和稀土元素

摘要

应用熔融制样-X射线荧光光谱法(XRF)分析矿石样品具有定量准确、试剂用量少、重现性好等优点,但由于目前稀土标准物质较少,不能满足复杂稀土矿石类样品的准确定量要求.本文采用配置人工标准样品,解决了现有稀土标准物质较少的问题,加入高纯稀土氧化物La2O3、CeO2、Y2O3扩展了La、Ce、Y的线性范围,利用人工标准样品和现有稀土标准物质、碳酸盐标准物质制作工作曲线,建立了XRF测定稀土矿石、矿化样品中25 种主量元素和稀土元素的分析方法.针对主量元素采用理论α系数法校准,稀土元素采用经验系数法校准,对有谱线重叠的元素进行干扰校正,使绝大多数主量元素的相对标准偏差(RSD,n＝13)小于1.5%,稀土元素含量在300 μg／g以上时RSD(n＝13)在0.69%～6.94%之间.通过未知样品考核,主量元素、稀土元素和烧失量的加和结果为99.41%～100.63%,满足《地质矿产实验室测试质量管理规范》的一级标准.%BACKGROUND:The analysis of ore samples by X-ray Fluorescence Spectrometry (XRF)has the advantages of quantitative accuracy,less reagent and good reproducibility.However,due to the lack of rare earth standard materials at present,the accurate quantitative requirements for complex rare earth ore samples cannot be met. OBJECTIVES:To establish the analysis method for XRF determination of 25 major elements and rare earth elements in rare earth ores and mineralized samples. METHODS:The use of artificial standard samples solved the problem of lack of standard materials.The linear ranges of La,Ce and Y were extended by adding high purity rare earth oxides La2O3,CeO2and Y2O3. A calibration line was produced using artificial standard samples,existing standard materials of rare earth and carbonate.The major elements were calibrated by a theoretical alpha coefficient method,whereas the rare earth elements were calibrated by an empirical coefficient method.Interference correction was used for elements with overlapping spectral lines. RESULTS:The relative standard deviations (RSD,n ＝13 )of most major elements were less than 1.5%, whereas the RSDs of rare earth elements were 0.69%-6.94% when their concentrations were above 300 μg／g. CONCLUSIONS:The method was evaluated by unknown samples and the sums of major elements,rare earth elements and loss of ignition were 99.41% -100.63%.The method satisfies the first criterion of Geology and Minerals Laboratory Testing Quality Management Standards.