硝酸-氢氟酸微波消解-电感耦合等离子体发射光谱法测定钨钼矿石中钨钼铜锌

Determination of W, Mo, Cu and Zn in Tungsten-Molybdenum Ores by Inductively Coupled Plasma-Optical Emission Spectrometry after Microwave Digestion with Nitric Acid-Hydrofluoric Acid

  • 摘要: 钨钼矿的共伴元素较为丰富,准确、快速地分析关键元素钨钼以及伴生元素铜锌的含量,对于钨钼矿矿床资源的开发利用和长远发展具有重要意义。钨钼元素在酸性环境中易发生水解,当前针对钨钼矿石的国家标准与行业标准分析方法普遍采用碱熔法进行样品前处理。然而,相较于酸溶法等方法,碱熔法虽能有效地抑制钨钼水解,但引入的碱金属基体对分析仪器的测试精度产生干扰,并可能降低检测灵敏度下限。本文通过硝酸-氢氟酸混合酸体系,于180℃对钨钼矿石样品进行微波消解45min,消解后样品直接溶解于含2%氢氟酸与1%硝酸的介质中,并采用配置耐氢氟酸进样系统的电感耦合等离子体发射光谱仪(ICP-OES)完成测定。方法精密度为1.38%~3.46%(RSD,n=11),检出限为 1.91~4.40μg/g。该方法应用于钨钼矿石国家标准物质和实际样品分析,标准物质的测定值与标准值一致,实际样品的测定结果与国标法和封闭酸溶消解法测定结果相吻合。该方法在抑制钨钼水解反应的同时,规避了碱熔法引入大量盐类而导致复杂基体干扰及高背景值的缺陷,显著缩减了试剂消耗与实验周期,无需赶酸、复溶等耗时步骤,操作流程简单,适用于批量钨钼矿石样品的测定。

     

    Abstract: Tungsten-molybdenum ore represents a crucial and valuable mineral resource in China, characterized by its abundant associated elements. Accurate and rapid analysis of key elements (W, Mo) and associated elements (Cu, Zn) holds significant importance for the exploitation and sustainable development of tungsten-molybdenum ore deposits. In acidic environments, W and Mo are prone to hydrolysis. Current national and industry standard analytical methods for tungsten-molybdenum ores predominantly employ alkali fusion for sample pretreatment. While alkali fusion effectively suppresses hydrolysis, it introduces alkali metal matrices that may interfere with the analytical instrument’s precision and potentially elevate the lower detection limit. In this paper, a microwave digestion method was developed using a mixed acid system of nitric acid and hydrofluoric acid. Samples were digested at 180℃ for 45 minutes, and were directly dissolved in a medium containing 2% HF and 1% HNO3, followed by determination using inductively coupled plasma-optical emission spectrometry (ICP-OES) equipped with an HF-resistant sample introduction system. The precision of the method (RSD) was 1.38%–3.46% (n=11) and the detection limits of this method were 1.91μg/g to 4.40μg/g. Validation using certified reference materials (CRMs) and real-world samples confirmed agreement between measured and certified values for CRMs, as well as consistency with results obtained by national standard methods and closed-vessel acid digestion. This method effectively suppresses the hydrolysis of W and Mo, while circumventing the drawbacks of alkali fusion methods, such as complex matrix interferences and elevated background values caused by the introduction of excessive salts. Moreover, it significantly reduces reagent consumption and experimental duration by eliminating the need for time-consuming steps such as acid evaporation and redissolution. The streamlined protocol is operationally simple and suitable for the determination of batch tungsten-molybdenum ore samples.

     

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