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酸溶-电感耦合等离子发射光谱法测定密西西比型铅锌矿床矿石中的铅

Determination of Lead in Mississippi Valley-type Ore by Inductively Coupled Plasma-Optical Emission Spectrometry after Acid Digestion

  • 摘要: 密西西比型(MVT)铅锌矿床的主要矿物有方铅石、闪锌矿, 常伴生有重晶石、萤石等矿物, 使得MVT型矿石在酸处理过程中易生成不溶于水和酸的硫酸铅钡复盐, 故而检测矿样中铅的含量偏低。本文建立了采用盐酸-硝酸-氢氟酸体系酸溶分解MVT型矿石, 电感耦合等离子体发射光谱法(ICP-OES)测定铅含量的分析方法。实验比较了盐酸-硝酸-氢氟酸、盐酸-硝酸-氢氟酸-高氯酸、盐酸-硝酸-硫酸三种酸溶体系的溶样效果, 并通过X射线衍射论证了方法的可行性。结果表明, 盐酸-硝酸-氢氟酸体系克服了复盐硫酸铅钡和硫酸铅沉淀的生成, 适量的氢氟酸促进了PbSO4的溶解, X射线衍射表征也表明此种酸溶体系的沉淀中不含有PbSO4, 可更彻底地分解MVT型矿石。本方法精密度(RSD)为0.3%~0.6%, 实际样品的加标回收率为96.0%~99.2%, 铅的最佳检测范围在0.01%~20.0%。

     

    Abstract: The main metal minerals in the Mississippi Valley-type (MVT) Pb-Zn deposit are galena and sphalerite. The associated barite and fluorite in the MVT ores can result in the formation of barium sulfate during acid digestion, leading to the determined Pb contents being lower than the real values. In this study, MVT ores are digested by hydrochloric acid-nitric acid-hydrofluoric acid (HCl-HNO3-HF) and then the Pb contents are determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Digestion effects of HCl-HNO3-HF, HCl-HNO3-HF-HClO4 and HCl-HNO3-H2SO4, are investigated by X-ray Diffraction (XRD). Experimental results show that HCl-HNO3-HF can prevent the formation of the mixed sulfate (Ba, Pb)SO4, and the appropriate amount of HF can promote the dissolution of PbSO4. XRD analyses also show that no PbSO4 remained in precipitation. The precision (RSD) ranges from 0.3% to 0.7%. Recoveries by the standard addition method range from 96.0% to 99.2%. The best detection range of lead in MVT ore samples was 0.01%-20.0% (m/m).

     

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