Abstract：In order to solve the pollution problem in traditional lead fire assaying method, the determination method of trace gold, platinum and palladium in lean-platinum ore by bismuth fire assaying-inductively coupled plasma mass spectrometry was established through theoretical calculation and optimization of operation procedures. The results showed that, the selectivity of precious metal by fire assaying formula containing 40.0 g of bismuth oxide, 30.0 g of boric acid, 20.0 g of anhydrous sodium carbonate and 2.0 g of flour was good. This formula had strong exclusion ability to precious metals and could meet the determination requirements of trace gold, platinum and palladium in lean-platinum ore samples (20.0 g). Aiming at the problem that bismuth button was hardly recovered, the melt slag was poured while hot. The bismuth button was naturally cooled in air, thus it could be easily taken out. During the determination by mass spectrometry, 197Au, 195Pt and 105Pd was used as the determination isotope for Au, Pt and Pd, respectively. 185Re and 115In were used as internal standard elements to correct matrix effect and signal drifting. The detection limit of method (sampling amount of 20.0 g) was 0.51 ng/g for Au, 0.43 ng/g for Pt and 0.50 ng/g for Pd, respectively. The relative standard deviation (RSD, n=5) of Pt, Pd and Au was 4.7%, 5.4% and 9.7%, respectively. Pt, Pd and Au in geochemical reference materials of platinum family element (GBW07291 and GBW07293) were determined, and the results were consistent with the certified values. The proposed method could be used for the accurate determination of trace Au, Pt and Pd in geological samples.
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LI Ke-ji,ZHAO Chao-hui,FAN Jian-xiong. Determination of trace gold, platinum and palladium in lean-platinum ore by bismuth fire assaying-inductively coupled plasma mass spectrometry. , 2013, 33(8): 19-23.
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