Rare earth elements (REEs), consisting of 17 elements including the lanthanides, yttrium, and scandium, are strategically significant due to their unique physical and chemical properties. These elements are widely applied in various industries such as new energy, new materials, aerospace, electronic information, and energy conservation and environmental protection. Accurate determination of the grades of key elements in rare earth ores is crucial for their extraction, processing, and utilization. This paper discusses the importance of rare earth elements, the basic principles of inductively coupled plasma mass spectrometry (ICP-MS), its application in rare earth element analysis, and the research progress in precise determination techniques for key element grades in rare earth ores.
1. Introduction
Rare earth elements are a group of strategically important and scarce resources. Their unique properties make them indispensable in numerous high-tech applications. The distribution of rare earth elements in nature varies, and their occurrence forms significantly affect accurate analysis and determination. Therefore, developing precise determination techniques for key element grades in rare earth ores is essential for efficient extraction and utilization of these valuable resources.
2. Importance of Rare Earth Elements
Rare earth elements play a vital role in promoting technological advancements and contributing to societal development. They are widely used in industries such as electronic information, petrochemicals, metallurgy, machinery, and energy. Furthermore, their applications in missile technology, smart weapons, navigation systems, and jet engines have garnered significant attention.
3. Basic Principles of ICP-MS
ICP-MS is a highly sensitive and accurate elemental analysis technique. It utilizes a high-frequency induction current to generate a plasma as an excitation light source, atomizing, exciting, and ionizing the elements in the sample, producing specific spectral lines. By detecting and analyzing these spectral lines, the elemental content in the sample can be accurately determined. ICP-MS offers advantages such as rapid analysis speed, high sensitivity, high accuracy, and the ability to simultaneously analyze multiple elements, making it widely used in rare earth element detection.
4. Application of ICP-MS in Rare Earth Element Analysis
ICP-MS has found extensive application in the analysis of rare earth element minerals, quality control of rare earth materials, and environmental monitoring of rare earth elements. By accurately determining the elemental content in different minerals, it provides a scientific basis for the mining, processing, and utilization of rare earth elements. In addition, ICP-MS can quickly and accurately determine the elemental content in rare earth materials, ensuring stable and reliable material performance. It also supports environmental monitoring by accurately determining rare earth element pollutants.
5. Research Progress in Precise Determination Techniques
In recent years, Chinese geological researchers have discovered a new type of sedimentary rare earth ore in Yunnan and Guizhou provinces. This ore is unique, occurring in clay rocks and differing from fluorocarbonate, monazite, and southern ionic rare earth ores. A study by Liu Shujun et al. compared different ore digestion methods for two rare earth samples from different mining sites and grades in the adjacent areas of Yunnan and Guizhou. The results showed that a closed-vessel digestion system using four acids (HCl, HNO3, HF, HClO4) was the optimal method for dissolving this new type of sedimentary rare earth ore. ICP-MS was found to be an accurate and efficient determination method with good precision and accuracy.
Another study by Zhang Shitao et al. investigated a method for simultaneously determining 15 rare earth elements in strontium ore using ICP-MS. The method involved extracting semi-molten HCl from a mixed solvent of Na2CO3 + H2C2O4 + KNO3. The detection limit of the method was 0.006–0.015 µg/g, with a relative standard deviation (RSD) of 1.95%–7.48% and a recovery rate of 91.4%–105.4%. The results were in good agreement with certified values, demonstrating the method’s simplicity, low detection limit, broad linear range, and good accuracy and precision for detecting and analyzing rare earth elements in rock minerals.
Accurate determination of key element grades in rare earth ores is crucial for their efficient extraction and utilization. ICP-MS, with its high sensitivity, accuracy, and ability to simultaneously analyze multiple elements, has become a widely used technique in rare earth element analysis. Research on precise determination techniques continues to advance, contributing to the sustainable development and utilization of rare earth resources.