铋试金-电感耦合等离子体质谱法测定贫铂矿石中痕量金铂钯

Determination of trace gold,platinum and palladium in leanplatinum ore by bismuth fire assaying-inductively coupled plasma mass spectrometry

为解决传统铅试金法中所存在的污染问题,通过理论计算、优化操作流程等方式建立了针对贫铂矿石中痕量金、铂、钯的铋试金-电感耦合等离子体质谱测定方法。结果表明,选用40.0g氧化铋、30.0g硼酸、20.0g无水碳酸钠和2.0g面粉作为试金配料的组分,贵金属的选择性好,排除重金属的能力强,可基本满足贫铂矿石样品(20.0g)中痕量金、铂、钯的测定需要。实验还针对铋扣难以完全回收的问题,采用了在出炉时趁热倾倒熔渣,使铋扣于空气中自然冷却然后取出的方法。在进行质谱测定时,选择197 Au、195Pt、105Pd分别作为金、铂、钯的测定同位素,以185Re、115In作为校正基体效应与信号漂移的内标元素。方法检出限(ng/g,以20.0g取样量计)分别为:0.51(Au)、0.43(Pt)、0.50(Pd),Pt、Pd、Au测定结果的相对标准偏差(RSD,n=5)分别为4.7%、5.4%、9.7%。对GBW07291和GBW07293铂族元素地球化学标准物质中Pt、Pd、Au进行测定,测定值与认定值基本一致。方法可用于地质样品中痕量Au、Pt、Pd的准确测定。

In order to solve the pollution problem in traditional lead fire assaying method, the determi- nation method of trace gold, platinum and palladium in lean-platinum ore by bismuth fire assaying-in- ductively coupled plasma mass spectrometry was established through theoretical calculation and opti- mization of operation procedures. The results showed that, the selectivity of precious metal by fire as- saying 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, ]97 Au, 195 Pt and 10Spd was used as the determi- nation isotope for Au, Pt and Pd, respectively. 18s Re and 11s In 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） ofPt, PdandAuwas4.7%, 5.4% and 9.7%, respectively. Pt, PdandAuin geochemical reference materials of platinum family element （GBW07291 and GBW07293） were deter- mined, 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.