铅试金-石墨炉原子吸收光谱法测定铂钯矿浸出液中铂和钯

铂钯矿浸出液中铂和钯的准确测定,对铂和钯的综合利用具有十分重要的意义。铂钯矿浸取液中铂和钯含量较低,且还含有大量的共存离子,若直接对铂和钯进行测定,干扰较为严重。采用铅试金法对样品中铂和钯进行分离富集,在优化仪器参数的基础上,建立了石墨炉原子吸收光谱法(GF-AAS)测定铂钯矿浸出液中铂和钯的新方法。将10 mL铂钯矿浸出液滴在试金配方凹槽内,滴入硝酸银溶液作为灰吹保护剂,再覆盖试金配方,经高温熔融和灰吹,样品中的铂和钯被富集于银合粒中。采用先加入硝酸、再加入盐酸的方式溶解银合粒,用石墨炉原子吸收光谱法进行测定,实现了对样品中铂和钯的测定。优化了铂和钯的石墨炉灰化温度和原子化温度以及原子化读数时间。在选定的优化实验条件下,铂和钯的吸光度与其对应的质量浓度运用二次方程最小二乘法拟合校准曲线,曲线拟合良好,铂和钯校准曲线的决定系数分别为0.999 8、0.999 7,特征浓度分别为2.14、0.34 ng/mL。将实验方法应用于铂钯矿浸出液中铂和钯的测定,测得结果的相对标准偏差(n=6)为2.7%～5.7%,加标回收率为84%～118%,加标回收率满足国家地质矿产行业标准DZ/T 0130—2006的要求。

Determination of platinum and palladium in leaching solution of platinum-palladium ore by graphite furnace atomic absorption spectrometry after the preconcentration with lead fire assay

The accurate determination of platinum and palladium in leaching solution of platinum-palladium ore had very important significance for the comprehensive utilization of platinum and palladium. The content of platinum and palladium in leaching solution of platinum-palladium ore was relatively low. Moreover, it contained many coexisting ions. The interference would be serious if the contents of platinum and palladium in solution were directly determined. After the separation and enrichment of platinum and palladium in sample were realized by lead fire assay, a new method for determination of platinum and palladium in leaching solution of platinum-palladium ore by graphite furnace atomic absorption spectrometry (GF-AAS) was established based on the optimization of instrumental parameters. 10 mL of leaching solution of platinum-palladium ore was dropwise added into the groove of lead fire assay recipe. The silver nitrate solution was added as the cupellation protector. Then the groove was covered by assay recipe. After high-temperature melting and cupellation, platinum and palladium in sample was enriched into silver alloy granule. After the silver alloy granule was dissolved by adding nitric acid and then hydrochloric acid, the contents of platinum and palladium in sample were determined by GF-AAS. The graphite furnace ash temperature and atomization temperature of platinum and palladium as well as their reading times of atomization were optimized. Under the selected optimal experimental conditions, the calibration curve was fitted by the least square method of quadratic equation with the absorbance of platinum and palladium and the corresponding mass concentrations. The curve fit was good, and the determination coefficients were 0.999 8 and 0.999 7 for platinum and palladium, respectively. The characteristic concentrations were 2.14 ng/mL and 0.34 ng/mL, respectively. The proposed method was applied for determination of leaching solution sample of platinum-palladium ore. The relative standard deviations (RSD, n=6) of determination results were between 2.7% and 5.7%. The recoveries were between 84% and 118%, which could meet the requirements in National Geological and Mineral Industry Standard DZ/T 0130-2006.