Determination of Major and Rare Earth Elements in Rare Earth Ores by X-ray Fluorescence Spectrometry with Fusion Sample Preparation
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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300μg/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。Abstract:
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. BAOBJECTIVES 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, CeO2 and 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. -
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表 1 仪器分析条件
Table 1. Working conditions of the elements by XRF
元素及谱线 分晶体 准直器
(μm)探测器 电压
(kV)电流
(mA)2θ(°) PHD范围 峰值 背景1 背景2 Si Kα PE 002 550 FL 32 100 109.14 -2.3160 1.7938 26~76 K Kα LiF 200 150 FL 32 100 136.73 -1.1730 2.2190 26~74 Ti Kα LiF 200 150 FL 40 90 86.215 -0.6320 0.8640 26~75 Mn Kα LiF 200 150 DUP 55 66 62.998 -0.7190 0.7868 13~72 Na Kα PX1 550 FL 32 100 27.895 -1.8910 2.1214 22~82 Mg Kα PX1 550 FL 32 100 23.077 -1.8760 2.1788 20~78 Al Kα PE 002 550 FL 32 100 144.98 2.9372 -1.2490 21~76 P Kα Ge 111 550 FL 32 100 141.02 -1.3960 2.8040 23~78 S Kα Ge 111 550 FL 32 100 110.74 -1.5160 1.4708 16~74 Ca Kα LiF 200 150 FL 32 100 113.16 -0.8730 1.6258 28~70 Fe Kα LiF 200 150 DUP 55 66 57.530 -0.7130 0.8854 16~69 Cr Kα LiF 200 150 DUP 55 66 69.365 -0.6450 0.7386 12~73 Ni Kα LiF 200 150 DUP 55 66 48.658 -0.5890 0.8294 18~70 Y Kα LiF 200 150 SC 55 66 23.767 0.7668 -0.7400 23~78 Rb Kα LiF 200 150 SC 55 66 26.581 0.7720 -0.5110 22~78 Sr Kα LiF 200 150 SC 55 66 25.121 -0.5610 0.7542 22~78 Zr Kα LiF 200 150 SC 55 66 22.470 -0.7750 0.8758 24~78 Nb Kα LiF 200 150 SC 55 66 21.372 -0.5870 0.4690 24~78 Cu Kα LiF 200 150 DUP 55 66 45.010 -0.6960 0.9256 20~69 Zn Kα LiF 200 150 SC 55 66 41.796 -0.7050 0.6534 15~78 Ba Kα LiF 200 150 FL 40 90 87.204 0.6376 - 33~71 Rh Kαc LiF 200 150 SC 55 66 18.447 - - 26~78 V Kα LiF 200 150 DUP 40 90 76.929 -0.6230 - 15~74 Br Kα LiF 200 150 SC 55 66 29.940 -0.6830 0.9706 20~78 La Lα LiF 200 150 FL 40 90 82.938 -0.9010 24~78 Ce Lα LiF 200 150 DUP 40 90 79.047 -0.8740 - 26~78 Pr Lα LiF 200 150 DUP 55 66 75.379 -0.8580 - 15~74 Nd Lα LiF 200 150 DUP 55 66 72.141 -0.9860 - 13~74 Sm Lα LiF 200 150 DUP 55 66 66.237 0.9598 - 15~73 Tb Lα LiF 200 150 DUP 55 66 58.800 0.3626 - 15~72 Dy Lα LiF 200 150 DUP 55 66 56.600 -0.8020 - 15~71 Ho Lα LiF 200 150 DUP 55 66 54.575 -0.6550 - 16~71 Er Lα LiF 200 150 DUP 55 66 52.605 0.7728 - 17~71 Yb Lα LiF 200 150 DUP 55 66 49.038 0.8474 - 18~70 Lu Lα LiF 200 150 DUP 55 66 47.417 -0.4030 - 19~70 Ta Lα LiF 200 150 DUP 55 66 44.403 0.9066 - 20~69 Eu Lα LiF 200 150 DUP 55 66 63.591 0.4858 - 15~73 Gd Lα LiF 200 150 DUP 55 66 61.115 -0.8880 - 15~72 注: FL为流气式正比计数器, SC为闪烁计数器。DUP为流气式正比计数器和封闭式正比计数器串联使用,以提高探测效率。PHD为脉冲高度分析器。 表 2 人工标准样品的配制
Table 2. Preparation of artificial standard samples
人工标准样品编号 La2O3加入量
(g)CeO2加入量
(g)Y2O3加入量
(g)国家标准物质编号 标准物质称样量
(g)HC-XT-1 0.0400 0.0500 - GBW07159 0.5600 HC-XT-2 0.0300 0.0400 - GBW07160 0.5800 HC-XT-3 0.0200 0.0300 - GBW07187 0.6000 HC-XT-4 0.0100 0.0200 - GBW07158 0.6200 HC-XT-5 - 0.0100 - GBW07188 0.6400 HC-XT-6 - - - GBW07187 0.3250 HC-XT-7 - - 0.0200 GBW07188 0.3250 HC-XT-8 0.0050 0.0050 - GBW07161 0.6300 GBW07188 0.6400 表 3 各元素工作曲线浓度范围
Table 3. Working range of elements concentration
主量元素 含量范围(%) 稀土元素 含量范围(μg/g) SiO2 0.3~74.55 Pr6O11 5.43~890 Al2O3 0.1~19.04 Sm2O3 13.53~2000 TFe2O3 0.07~3.49 Eu2O3 0.31~75 FeO 0.007~0.49 Gd2O3 27.91~2500 TiO2 0.003~0.537 Tb4O7 5.15~550 CaO 0.0224~55.49 Dy2O3 26.04~3700 Na2O 0.014~0.66 Tm2O3 2.29~310 MnO 0.004~0.1 Yb2O3 13.45~2100 P2O5 0.0022~0.124 La2O3* 0.002~6.16 MgO 0.066~20.15 CeO2* 0.0022~7.69 K2O 0.01~5.52 Y2O3* 0.017~3.2 Nd2O3* 0.0024~0.4 Lu2O3 1.91~300 Ho2O3 5.44~640 Er2O3 15.26~2000 Σ RExOy* 0.085~13.92 注:标记“*”的元素含量单位为%。 表 4 稀土元素的重叠谱线和影响元素
Table 4. Overlapping spectral lines and influencing elements of rare earth elements
待测元素 重叠谱线 校正基体元素 Y Rb Kβ1 Al,Si,Ba,Sr,Ni,Cr,Fe,Ca La Cs Lβ1 Si,Fe,Nd Nd Ce Lβ1 La,Sm,Al Ce Ba Lβ2 - Sm Ce Lβ2 - Tb Sm Lβ1 La,Ce Ho Gd Lβ1 Er,Yb Er Tb Lβ1,Co Kα La,Ce,Fe Yb Ni Kα Y Lu Dy Lβ2,Ni Kβ1 La Pr La Lβ1 La,Ce Eu - La,Ce Gd Ce Lγ1 La,Nd,Dy P Y Lβ1 - 表 5 分析元素的检出限
Table 5. Detection limits of elements
元素 方法检出限
(μg/g)Na2O 56.44 MgO 44.34 Al2O3 15.82 SiO2 96.03 P2O5 18.59 K2O 25.36 CaO 30.37 TiO2 20.04 MnO 8.32 Fe2O3 6.69 Y2O3 4.52 La2O3 42.6 Nd2O3 52.85 Sm2O3 42.74 CeO2 38.11 Tb4O7 44.83 Dy2O3 39.23 Ho2O3 8.86 Er2O3 27.19 Yb2O3 30.10 Lu2O3 13.41 Pr6O11 58.19 Eu2O3 6.14 Gd2O3 29.25 表 6 方法准确度和精密度
Table 6. Accuracy and precision tests of the method
元素 GBW07188 HC-XT-8 测定平均值
(%)标准值
(%)相对误差
(%)RSD
(%)测定平均值
(%)标准值
(%)相对误差
(%)RSD
(%)Na2O 0.62 0.66 5.30 2.35 0.121 0.156 3.54 5.45 MgO 0.13 0.11 11.82 4.07 0.074 0.076 25.0 4.37 Al2O3 13.8 14.26 2.52 0.27 14.51 14.47 2.14 0.213 SiO2 66.8 66.9 0.01 0.19 73.5 73.4 0.15 0.17 K2O 5.56 5.52 1.09 0.32 4.861 4.9 0.86 0.27 CaO 0.29 0.29 0.69 1.40 0.021 0.026 2.80 16.3 TiO2 0.18 0.17 4.12 1.09 0.034 0.022 3.59 7.07 MnO 0.05 0.052 7.69 1.40 0.017 0.017 7.84 2.89 Fe2O3 2.28 2.24 2.05 0.30 1.13 1.13 1.90 0.14 Y2O3 2.14 2.16 0.93 0.71 0.054 0.056 1.78 0.98 La2O3 0.21 0.23 7.83 1.64 0.768 0.771 8.85 0.49 Nd2O3 0.41 0.4 2.50 0.88 0.003 0.003 5.57 69.5 Sm2O3* 2006 2000 0.05 2.92 30 15.5 3.40 34.7 CeO2 0.0619 0.053 26.42 5.39 0.728 0.771 2.26 2.30 Tb4O7* 652 550 16.55 6.94 7.93 8.07 24.17 46.2 Dy2O3* 3645 3700 2.38 0.69 未检出 55.4 6.64 - Ho2O3* 655 640 5.16 2.05 10.8 11.8 7.30 26.9 Er2O3* 1989 2000 1.95 1.94 25.45 35.8 13.71 38.8 Lu2O3* 306 300 5.60 4.13 2.57 5.4 1.02 48.1 Pr6O11* 863 890 8.58 5.40 99.5 6.2 18.49 55.2 Yb2O3* 2063 2100 2.72 0.79 13.55 36 8.95 33.0 Gd2O3* 2536 2500 0.80 1.16 111.9 31.9 7.47 13.4 加和 99.8 - - 0.12 99.6 - - 0.14 注:标记“*”的元素含量单位为μg/g。 表 7 全分析加和结果
Table 7. Analytical results of sam additivity
标准物质和样品编号 烧失量 主量元素和稀土元素测定值(%) 加和
(%)GBW07187 5.42 94.51 99.93 GBW07188 5.53 94.36 99.89 GBW07158 6.73 93.00 99.73 GBW07159 3.70 96.39 100.09 GBW07160 3.77 96.08 99.85 GBW07161 6.80 92.61 99.41 HC-XT-1 3.19 96.58 99.77 HC-XT-2 3.36 96.18 99.55 HC-XT-3 5.00 94.90 99.90 HC-XT-4 6.42 93.21 99.63 HC-XT-5 5.35 94.52 99.87 HC-XT-6 5.43 94.70 100.13 HC-XT-7 6.59 93.00 99.59 HC-XT-8 3.64 95.93 99.57 GX-TC-F2 7.48 93.15 100.63 GX-TC-F4 5.38 94.76 100.14 GX-DB-F1 5.85 94.27 100.12 GX-DB-F2 6.02 94.59 100.61 GX-DB-F3 3.55 96.55 100.10 GX-DB-F4 3.57 96.29 99.86 GX-DB-F5 3.65 96.53 100.18 XF-WX-F3 7.13 93.28 100.41 -
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