Determination of High Concentration of Fluorine in Lithium Mica by X-ray Fluorescence Spectrometry with Pressed-Powder Pellets

Abstract

BACKGROUND The fluorine content in lithium mica is very high (1.36% to 8.71%), and the leaching rate of lithium during roasting lithium mica minerals decreases gradually with the increase of fluorine content. With increased defluorination of lithium mica, the leaching rate of lithium is also increased accordingly. Therefore, accurate determination of fluorine in lithium mica and control of fluorine content can provide a basis for determining the process conditions, equipment parameters and cost of roasting process. At present, the most common used method for determination of fluorine is the ion selective electrode method. However, the process is complex, the analysis time is long and the blank value is high. X-ray Fluorescence Spectrometry (XRF) is a green and pollution-free method, which is simple, fast and accurate. OBJECTIVES To determine the fluorine content in lithium mica. METHODS The fluorine content in lithium mica was determined by XRF with pressed-powder pellets. The working curve was made from standard material lithium ore and manually prepared calibration material, and the experience coefficient was used to correct the matrix effect and spectral interference. RESULTS The method precision(RSD, n=10) is 1.03% and the detection limit of fluorine is 46±4μg/g. Analytical results of samples synthesized from standard samples acquired by this method are in good agreement with theoretical values. It is demonstrated by actual samples that the determination results are consistent with those of the ion selective electrode method. CONCLUSIONS This method is suitable for determining fluorine in lithium mica with contents ranging from 0.68% to 9.14%.

Keywords

• lithium mica
• fluorine
• experience coefficient correction
• pressed-powder pellets
• x-ray fluorescence spectrometry