超声波辅助-活性炭富集-火焰原子吸收光谱法测定岩石矿物中的金

Determination of Gold in Rocks and Minerals by Flame Atomic Absorption Spectrometry with Ultrasonic Assisted Activated Carbon Enrichment

在战略性矿产资源中,金一直都是极其紧缺且重要的元素。目前测定岩石矿物中金使用较广泛的方法主要为火试金重量法、活性炭动态富集-原子吸收光谱法。然而这两种方法分析步骤都比较繁琐,受环境条件影响大,测定周期长,不适合大批量分析测试任务。通过超声波辅助,活性炭在超声空化所产生的局部高温、高压、冲击波、微射流等加强传质作用下,能快速高效地对样品中的金离子进行富集,采用一种独特的活性炭富集方法,通过改进过滤方式,运用火焰原子吸收光谱仪测定金。通过对9个金矿石成分标准物质进行实验对比,优化活性炭用量,超声波频次与功率、时间、溶液温度等实验条件。研究表明,活性炭用量为0.5 g后金的回收率趋于稳定,超声波频次和时间设定为100 kHz、20 min不仅测定数据准确且能较大幅度缩短工作时间,溶液温度控制在20℃为宜。在优化条件下,方法验证测定得出金的质量浓度在0~20 mg/L校准曲线方程为Abs=0.01958 c+0.000642,相关系数(R^(2))为1.0000,以金矿石标准物质GBW(E)070012a平行测定12次计算得出方法检出限(MDL)为0.022μg/g;以GBW07807a等8个金矿石标准物质进行精密度和正确度方法实验,相对误差(RE)为0.23%~1.5%,相对标准偏差(RSD)为0.43%~3.6%。与国家标准方法进行比对,实验证明新方法满足岩石矿物中金的分析要求。

Gold has always been an extremely scarce and important element in strategic mineral resources.At present,the widely used methods for determining gold in rocks and minerals include fire assay gravimetric method and activated carbon enrichment atomic absorption spectroscopy.However,both methods have cumbersome analysis steps,are greatly affected by environmental conditions,have long sample testing cycles,and are not suitable for large-scale analysis and testing tasks.Activated carbon quickly and efficiently enriched gold ions in samples under the local high temperature,high pressure,shock wave,micro jet and other enhanced mass transfer effects generated by ultrasonic cavitation,with the assistance of ultrasound.A unique active carbon enrichment method was established,and the filtration method was improved.A new method for determining gold using flame atomic absorption spectroscopy was used.Through experimental comparison and analysis of nine gold ore composition standard substances,the experimental conditions such as activated carbon dosage,ultrasonic frequency and power,time,and solution temperature were optimized.Research results showed that the recovery of gold tended to stabilize after the amount of activated carbon was determined to be 0.5 g.The ultrasonic frequency and time were set to be 100 kHz,and 20 minutes,this not only accurately measured the data but also significantly shortened the working time.The solution temperature should be controlled at 20℃.Under the optimized conditions,the calibration curve equation of gold mass concentration in the range of 0-20 mg/L was Abs=0.01958 c+0.000642,and the correlation coefficient(R^(2))was 1.0000.The method detection limit(MDL)was calculated as 0.022μg/g using the gold ore standard substance GBW(E)070012a for 12 parallel measurements.Precision and accuracy method experiments were conducted using 8 gold ore reference materials such as GBW07807a.The relative error(RE)was 0.23%-1.5%,and the relative standard deviation(RSD)was 0.43%—3.6%.Comparative experiments with national standard methods have shown that the new method met the analysis requirements for gold in rocks and minerals.