电感耦合等离子体发射光谱法测定磷矿石中磷镁铝铁

Determination of P,Mg,Al and Fe in Phosphate Ores by Inductively Coupled Plasma-Atomic Emission Spectrometry

运用电感耦合等离子体发射光谱法(ICP-AES)分析磷矿石样品中的多元素,通常采用氢氟酸+盐酸+硝酸混合酸分解石样品,其中的氢氟酸是为了彻底分解地质样品中以硅酸盐形式存在的待测元素,但赶除氢氟酸的程序繁琐。本文在实际工作中发现,仅需测定磷矿石中的磷、镁、铝、铁元素时,可不加氢氟酸,四种元素的分析结果已能满足要求,这可能是与样品处理过程中生成的少量氢氟酸有关。为了验证不加氢氟酸的样品分解能力,采用浓硝酸-浓盐酸混合酸(体积比1∶1)加热分解试样,稀酸浸取,溶液冷却定容后直接用ICP-AES测定。分析结果显示溶样酸中是否含有氢氟酸,对磷、镁、铝、铁的测定结果不存在显著影响。方法检出限为磷100μg/g、镁0.3μg/g、铝20μg/g和铁6μg/g。经国家一级标准物质分析验证,方法精密度(RSD)小于5.0%,相对误差小于1.5%。本方法针对性强,分析快速准确,适用于实际工作中不包括钙和硅元素在内的磷矿石简项测定。

The traditional method for determining multiple elements in phosphate ores is to decompose the phosphate ore samples with a mixture of HNO3,HCl and HF,and take measurements using Inductively Coupled Plasma-Atomic Emission Spectrometry（ ICP-AES）.The addition of HF thoroughly decomposes silicates in which the target elements are found.However,the process of HF removal is very complicated.A rapid sample processing method has been determined to simplify the method.If only four elements of P,Mg,Al and Fe need to be determined,the addition of HF is unnecessary,which may be related to a small amount of HF introduced during the samples processing by HNO3 and HCl.In order to verify the decomposition capacity of the mixed acids,phosphate ores samples were decomposed in a conical flask with mixed acids of HNO3 and HCl（HNO3∶ HCl = 1 ∶1） without HF,and dissolved with dilute acid solution,then the sample solution was determined directly by inductively coupled plasma-atomic emission spectrometry.Analysis results show that there is no significant impact on the results of P,Mg,Al and Fe,and the detection limits of the method were 100 μg /g（P）,0.3 μg /g（Mg）,20 μg /g（Al） and 6 μg /g（Fe）,respectively.The presented method has been applied to the determination of P,Mg,Al and Fe in the national standard reference materials.The results show that the determination precision（RSD） is better than 5.0%（n =12） and the relative error is less than 1.5%.The method has advantages of high accuracy,simplicity and rapidity,and can meet the demands of practical analysis for phosphate ores without Ca and Si elements.