锍镍试金-电感耦合等离子体质谱法测定分金渣中铑和铱

建立测定分金渣中铑和铱含量的检测方法,对实现分金渣中铑和铱的有效提取、铑和铱冶炼新工艺开发及提高铜阳极泥的综合回收利用率具有重大意义。分金渣经锍镍试金预处理,用6 mol/L盐酸溶解锍镍扣使得含铑和铱的沉淀与其他杂质元素分离,趁热过滤,沉淀经王水(1+1)密封消解,以¹⁰³Rh和¹⁹³Ir为测定同位素,实现了电感耦合等离子体质谱法(ICP-MS)对分金渣中铑和铱的测定。对锍镍试金配料、溶解锍镍扣的盐酸浓度、封闭消解温度和时间等条件进行了考察。通过选择合适的测定同位素消除了可能存在的质谱干扰,选用¹⁸⁵Re作为¹⁰³Rh的内标,²⁰³Tl作为¹⁹³Ir的内标消除了信号漂移的影响。在优化的实验条件下测定铑和铱混合标准溶液系列,结果表明,铑、铱在10~50 μg/L质量浓度范围内分别和铑、铱质谱强度与内标质谱强度之比呈线性关系,相关系数大于0.999,方法检出限分别为0.58 μg/L和0.035 μg/L,定量限分别为1.74 μg/L和0.11 μg/L。按照实验方法测定6个分金渣试样中铑和铱,测定结果的相对标准偏差(RSD)在1.7%~4.9%之间,加标回收率在90%~103%之间。根据分金渣实际物相组成以及铑和铱的含量,使用金粉(wAu>99.99%)、银粉(wAg>99.99%)、铂粉(海绵铂,wPt>99.97%)、钯粉(海绵钯,wPd>99.97%)、纯铑粉(海绵铑,wRh>99.97%)和纯铱粉(海绵铱,wIr>99.97%)研磨均匀混合后制备分金渣模拟试样,按照实验方法进行测定,测定值与理论值相一致。

Determination of rhodium and iridium in gold residue by inductively coupled plasma mass spectrometry with nickel sulfide fire assay

The establishment of determination method for the contents of rhodium and iridium in gold residue was of great significance for the effective extraction of rhodium and iridium from gold residue, the development of new smelting process for rhodium and iridium, and the improvement of comprehensive recovery and utilization of copper anode slime. The gold residue was pretreated by nickel sulfide fire assay, and the nickel matte buckle was dissolved with 6 mol/L hydrochloric acid to separate the precipitates of rhodium and iridium from other impurity elements. The solution was filtered while it was hot, and the precipitates were digested by aqua regia (1+1) in closed system. The determination of rhodium and iridium in gold residue by inductively coupled plasma mass spectrometry (ICP-MS) was realized with ¹⁰³Rh and ¹⁹³Ir as the determination isotopes. The experimental conditions were investigated, including the ingredient of nickel sulfide fire assay, the concentration of hydrochloric acid for dissolution of nickel matte buckle, the closed digestion temperature and time. The possible mass spectral interference was eliminated by selecting the suitable determination isotopes. ¹⁸⁵Re and ²⁰³Tl were selected as the internal standard of ¹⁰³Rh and ¹⁹³Ir, respectively, which eliminated the influence of signal drift. A series of mixed standard solution of rhodium and iridium were determined under the optimized experimental conditions. The results showed that the mass concentration of rhodium and iridium in range of 10-50 μg/L were linear to the ratio of corresponding intensity of rhodium and iridium to the internal standard. The linear correlation coefficients of calibration curves were higher than 0.999. The limit of detection of this method was 0.58 μg/L and 0.035 μg/L, respectively. The limit of quantification was 1.74 μg/L and 0.11 μg/L, respectively. The contents of rhodium and iridium in six gold residue samples were determined according to the experimental method. The relative standard deviation (RSDs, n=7) of determination results were between 1.7% and 4.9%, and the recoveries were in range of 90%-103%. According to the actual phase composition and the contents of rhodium and iridium in gold residue, the simulation samples were prepared with gold powder (w_Au>99.99%), silver powder (w_Ag>99.99%), platinum powder (sponge platinum, w_Pt>99.97%),palladium powder(sponge palladium, w_Pd>99.97%), rhodium powder (sponge rhodium, w_Rh>99.97%) and iridium powder (sponge iridium, w_Ir>99.97%) after grinding and uniform mixing. The contents of rhodium and iridium in gold residue simulation samples were determined according the experimental method, and the results were consistent with the theoretical values.