Determination of silicon dioxide,aluminium oxide and iron trioxide in bauxite by X-ray fluorescence spectrometry with fusion sample preparation

      The determination of components in bauxite was very important to guide the actual production of steelmaking.The mixture of 

lithium tetraborate with mass fraction of 35.3%and lithium metaborate with mass fraction of 64.7%was used as mixed flux.The 

ammonium iodide solution was used as release agent.The bauxite sample was prepared as sample fused bead by fusion method 

in platinum-gold crucible.The absorption-enhancement effect was corrected by theoretical coefficient method and empirical 

coefficient method.Thus,a determination method of silicon dioxide,aluminum oxide and iron trioxide in bauxite was established by 

X-ray fluorescence spectrometry(XRF).The dilution ratio of sample to flux,the fusion temperature,the type and dosage of release 

agent were optimized.The results showed that the prepared sample slice was uniform and transparent without bubbles,which 

could meet the determination requirements,under the following conditions:the dilution ratio of sample to flux was 1∶10;13-15 

drops of 300 g/L potassium iodide solution was selected as the release agent;the sample was fused at 1080℃ for 16 min.In order 

to guarantee enough wide content range and proper content gradient of three components(silicon dioxide,aluminum oxide and iron 

trioxide)in calibration curves,three certified reference materials of alumina(YSS066-2013,YSS067-2013 and YSS068-2013)and the

 artificially synthesized calibration sample prepared with the above three certified reference materials according to certain mass 

ratio were employed to draw the calibration curve.The results showed that the linear correlation coefficients of calibration curves for test components were all higher than 0.998.The limit of detection of silicon dioxide,aluminum oxide and iron trioxide were 

0.004%,0.15%and 0.0026%,respectively.The proposed method was applied for the determination of silicon dioxide,aluminum oxide

 and iron trioxide in bauxite actual sample.The relative standard deviations(RSD,n=12)of determination results were between 

0.41% and 1.2%.