活性炭动态富集-火焰原子吸收光谱法测定金矿石中金的影响因素探讨

Discussion on Influencing Factors of Determination of Gold inGold Ore by Flame Atomic Absorption Spectrometry withDynamic Enrichment of Activated Carbon

金在新一轮找矿突破战略行动矿产分析中占有重要的地位,采用活性炭动态富集-火焰原子吸收光谱法测定岩石矿物样品中金的分析方法已被广泛应用。然而其分析条件的影响因素较多,在测定过程中活性炭的用量、灰分的大小、吸附层的设计以及洗涤液溶液温度等因素对测定结果的准确性具有重要影响。分别以活性炭用量、不同灰分值、吸附层数以及洗涤溶液的温度为变量,对金分析标准物质GBW(E)070013b、GBW07297a、GBW07299a、GBW07810进行实验对比分析。结果表明,金的回收率随着活性炭用量的增加而不断提升,在0.5 g后趋于稳定;活性炭灰分值越大,金元素损失越多,当灰分值小于0.05%时,回收率趋于稳定,接近99%;活性炭吸附层设计为双层和三层时,测定值的平均值与认定值的相对偏差(RE)和相对标准偏差(RSD,n=6)分别为0.14%~3.2%和0.040%~3.7%,优于混合层和单层,满足岩石矿物质控标准规范中正确度和精密度的要求;抽滤洗涤热溶液(70~80℃)时,金矿石标准物质金元素的平行样的准确度和相对标准标准偏差最小,均小于2.1%,通过方法验证,测定金的正确度精密度(RSD,n=6)分别小于0.76%和3.8%,满足DZ/T 0130.3—2006《地质矿产实验室测试质量管理规范》中岩石矿物样品化学成分分析的质量要求。优化了活性炭吸附测金的实验条件,方法的正确度和精密度均满足要求,能满足金矿石中金的准确测定。

Gold plays an important role in mineral analysis in the new round of strategic breakthroughs in mineral exploration.The analytical method of using activated carbon dynamic adsorption flame atomic absorption spectrometry to determine gold in rock and mineral samples has been widely applied.However,there are many factors influencing the analysis conditions.During the measurement process,factors such as the amount of activated carbon,the size of ash,the design of the adsorption layer,and the washing solution temperature have important impacts on the accuracy of the measurement results.The experiment compared and analyzed the gold analysis standard materials GBW(E)070013b,GBW07297a,GBW07299a,and GBW07810 using the amount of activated carbon used,different ash content values,adsorption layers,and washing solution temperature as variables.The results show that the recovery rate of gold continuously increases with the increase of activated carbon dosage,and tends to stabilize after 0.5 g.The higher the ash content of activated carbon,the greater the loss of gold element.When the ash content is less than 0.05%,the recovery rate tends to be stable,approaching 99%;When the activated carbon adsorption layer is designed as double and triple layer,the relative deviation(RE)and relative standard deviation(RSD,n=6)between the average value of the measured value and the certified value are 0.14%-3.2%and 0.040%-3.7%respectively,superior to the mixed layer and single layer,meeting the requirements of accuracy and precision in the rock and mineral quality control standard specifications.When the gold ore standard substance gold element is washed into a hot solution(70-80℃)through suction filtration,the accuracy and relative standard deviation of the parallel sample are the smallest,lessing than 2.1%.Through method validation,the accuracy of determining gold is less than 0.76%,and the precision(RSD,n=6)is less than 3.8%,meeting the quality requirements for chemical composition analysis of rock and mineral samples in Quality Management Specification for Geological and Mineral Laboratory Testing(DZ/T 0130.3—2006).This method optimizes the experimental conditions for active carbon adsorption to determine gold,and the accuracy and precision of the experimental method meet the requirements,which can meet the accurate determination of gold in gold ore.