金作保护剂铅试金分离富集-石墨炉原子吸收光谱法测定矿石中痕量铑

Determination of Trace Rhodium in Ore Sample by Graphite Furnace Atomic Absorption Spectrometry with Gold as Protective and Lead Fire Assay for Separation and Preconcentration

铑矿石是获取铑的重要来源,但矿石中的铑含量极低,且分布不均匀,准确测定其含量一直是分析测试中的难题。建立了一种可高效富集矿石中铑元素的铅试金-石墨炉原子吸收光谱法测定矿石中痕量铑的方法。采用金作保护剂,铅试金分离富集矿石中的铑,形成的金-铑合金用王水溶解,石墨炉原子吸收光谱法进行测定。实验结果表明,熔剂配比m(硼砂)∶m(纯碱)∶m(黄丹粉)∶m(淀粉)=5∶5∶10∶1,加入15 mg金作为保护剂,灰吹温度900℃,可完全富集50μg铑。用石墨炉原子吸收光谱仪进行检测,方法的相对标准偏差RSD(n=11)为7.0%~11.2%,线性范围为0.17~50μg/L,加标回收率为99.4%~101%,10倍于铑的其他共存贵金属对测定无干扰。方法准确、可靠、简便,可用于矿石样品中铑的日常分析,对铑资源勘探开采及铑矿物的综合利用研究具有重要意义。

Rhodium ore is an important source of rhodium,but the content of rhodium in the ore is very low and unevenly distributed.Accurate determination of its content has always been a difficult problem in analysis.In this study,a lead assay graphite furnace atomic absorption spectrometry method for highly enriching rhodium in ore was established.Using gold as protective agent,gold rhodium alloy was formed after lead fire assay separation and preconcentration.The gold rhodium alloy was dissolved in aqua regia and determined by graphite furnace atomic absorption spectrometry(GFS).Result indicated that when flux ratio m(Na_(2)B_(4)O_(7))∶m(Na_(2)CO_(3))∶m(PbO)∶m(C_(6)H_(12)O_(6))=5∶5∶10∶1,gold protective regent 15 mg,cupellation temperature 900℃,50μg of rhodium was enriched.Under the selected GFAAS instrument conditions,the RSD(n=11)of rhodium was 7.0%—11.2%,the recovery was between 99.4%—101%,other coexisting precious metals 10 times as much as rhodium had no interference with the determination.This method is reliable,simple and rapid.It can be used for daily determination of Rh in mineral sample.This study is of great significance to the exploration and exploitation of rhodium resources and the comprehensive utilization of rhodium minerals.