锡试金-电感耦合等离子体质谱法测定铅精矿中贵金属元素

铅精矿中金、银分析报道较多,而铂族元素分析难度大,常用的铅试金和镍锍试金不能满足铅精矿中贵金属8元素同时分析的要求。实验采用锡试金富集,盐酸溶解锡扣,王水溶解所得贵金属沉淀物,用电感耦合等离子体质谱法(ICP-MS)同时测定铅精矿中铂、钯、锇、铱、钌、铑、金和银8种贵金属元素。选择试金配料组分条件为20g锡粉、10g铁粉、20g碳酸钠、25g碳酸钾、5g二氧化硅、30g硼砂、3g面粉、10g 硝酸钠、5g 氟化钙,1100℃熔矿温度时,获得良好的锡扣,且硝酸钠可以调整试金熔剂体系的氧化还原反应,铁粉的加入减少了铅进入锡扣的比重。选择¹⁹⁵Pt、¹⁰⁵Pd、¹⁸⁹Os、¹⁹³Ir、¹⁰¹Ru、¹⁰³Rh(需要测定铅进行元素校正)、¹⁹⁷Au和¹⁰⁹Ag为待测元素同位素,同时选择镥(20ng/mL)为内标元素,可消除基体效应和信号漂移的影响;铂族元素在一定的质量范围内与其光谱强度呈线性关系,检出限为0.028~98ng/g。对铅精矿实验样品进行准确度考察,各元素测定结果的相对标准偏差(RSD,n=6)为1.4%~5.4%,加标回收率为96%~104%。实验方法测定铅精矿样品的结果与其他方法的对照结果一致性较好。

Determination of precious metal elements in lead concentrate by inductively coupled plasma mass spectrometry with tin fire assay

There are many reports on the analysis of Au and Ag in lead concentrate. But the analysis of platinum group elements is very difficult. At present, the commonly used lead fire assay and nickel matte fire assay cannot meet the requirements of simultaneous analysis of 8 precious metal elements in lead concentrate. Tin fire assay enrichment was adopted. The Sn buckle was dissolved with hydrochloric acid. The precious metal precipitates were dissolved with aqua regia, and eight precious metal elements including Pt, Pd, Os, Ir, Ru, Rh, Au and Ag in lead concentrate were simultaneously analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The components for assaying in experiments included 20g of Sn powder, 10g of Fe powder, 20g of Na₂CO₃, 20g of K₂CO₃, 5g of SiO₂, 30g of borax, 3g of flour, 10g of NaNO₃ and 5g of CaF₂. The Sn buckle obtained was good when the melting temperature was 1100℃. Moreover, NaNO₃ could adjust the redox reaction of assaying flux system, and the Fe powder could reduce the proportion of lead into Sn buckle. ¹⁹⁵Pt, ¹⁰⁵Pd, ¹⁸⁹Os, ¹⁹³Ir, ¹⁰¹Ru, ¹⁰³Rh (the determination of Pb was required for the elemental correction), ¹⁹⁷Au and ¹⁰⁹Ag were selected as the analyte isotopes. Meanwhile, Lu (20ng/mL) was employed as the internal standard element to eliminate the influence of matrix effect and signal drift. The mass concentration of platinum group elements in certain range had good linear relationship with the corresponding spectral intensity. The limit of detection was 0.028-98ng/g. The accuracy tests were conducted using actual sample of lead concentrate. The relative standard deviations (RSD, n=6) of determination results were between 1.4% and 5.4%. The spiked recoveries were between 96% and 104%. The determination results of lead concentrate sample according to experimental method were in good agreement with those obtained by other methods.