Determination of Major and Minor Components in High-Cr Red Mud by X-ray Fluorescence Spectrometry with Fusion Sample Preparation

Cr and other valuable metals are enriched in red mud (Cr₂O₃: 3%-30%) after high-Cr red clay type Al-Fe composite ores are comprehensively utilized by sodium reduction roasting-magnetic separation-leaching. High-Cr red mud belongs to refractory ore whose analysis methods are dominated by chemical analysis, which is a well-established but complicated procedure. High-Cr red mud can also be analyzed by X-ray Fluorescence Spectrometry (XRF). However, a use of sodium flux and a high dilution ratio are not conducive to sodium and low content elements. In this paper, a method of XRF analysis is developed for the determination of the major and minor components (Cr, Si, Al, Fe, Mg, Ca, Na, K, S, P, Ti, Mn and V) in high-Cr red mud by fused bead preparation with Li₂B₄O₇-LiBO₂ (67:33) flux, NH₄NO₃ oxidizer and saturated LiBr solution parting medium. When the dilution ratio of the melting sample is lower than 24:1, the lower dilution ratio, the more serious is the corrosion on the Pt-Au crucible; the RSD (n=10) of the sample preparation method is at a minimum when the dilution ratio is 24:1; the longer the melting time and the higher the melting temperature, the RSD becomes lower. The optimization conditions of fused bead are obtained when the dilution ratio is 24:1, the melting temperature is 1100℃ and the melting time is 15 min. The working curve was established by chromite, bauxite, clay, ferrous standards and manual preparation standard materials. The matrix effect and spectrum line overlap interference were corrected by a fundamental parameter method and standard regression. The results are consistent with certified values and the RSD (n=10) range from 0.3% to 3.9%. Compared with domestic and foreign XRF methods for chromium containing minerals, this method uses no sodium salt, a fuse piece, conventional sample melting temperature (1100℃), low dilution ratio (24:1) for sample preparation, and the sampling precision and analysis precision are low. The problem with XRF analysis of high-Cr red mud has been solved by this method, which can be used to analyze Cr, Al, Si and Fe in roasting, concentrates and tailings and other ores processed by sodium.