Quantitative Analysis of Mineral Composition of Kyanite by X-ray Diffraction with Rietveld Refinement Method

Abstract

BACKGROUND The content of minerals in kyanite can be analyzed by chemical phase method, but the analytical process is very tedious. Moreover, the existence of heteromorphism and refractory minerals can affect the accuracy of analysis results. An internal standard method by X-ray diffraction (XRD) for direct determination of kyanite requires the use of pure mineral to draw a standard curve, but it is extremely challenging to purify minerals due to the inclusion. The differences between the mineral components of kyanite in different mining areas makes the above two methods applicable only to the quantitative analysis of minerals in the same mining area. OBJECTIVES To simplify analysis the process of mineral composition of kyanite and improve efficiency. METHODS The content of minerals in kyanite was studied by X-ray diffraction. The X-ray diffraction Rietveld refinement method was used to analyze the secondary standard materials and field samples of kyanite, and the results were compared with the diffraction quantitative method and chemical analysis results including RIR method, adiabatic method and K-value method. RESULTS Rietveld refinement method was simple and effective in correcting the diffraction intensity error caused by the preferred orientation. Accurate results can be obtained by Rietveld refinement method more than other methods of X-ray quantitative phase analysis, such as RIR method, adiabatic method, K-value method. The analytic absolute error of minerals with content greater than 5% was less 1%, and significantly lower than the allowable error. The results obtained by Highscore agree well with results measured by Jade, and the double difference of results was less than 0.8%. The relative standard deviation was less than 2.5%. The spiked recoveries of kyanite were 95.3%-101.0%. CONCLUSIONS X-ray diffraction with Rietveld refinement method is simple, and can be used to determine the content of all minerals in kyanite from different mining areas.

Keywords

• kyanite
• phase composition
• x-ray diffraction
• rietveld refinement method
• preferred orientation