Determination of Major and Rare Earth Elements in Rare Earth Ores by X-ray Fluorescence Spectrometry with Fusion Sample Preparation

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.