Preparation and Certification of Niobium-Tantalum Concentrate Reference Materials

BACKGROUND Niobium-tantalum concentrate reference materials play an important role in monitoring mineral smelting and sample analysis. There is a great demand of niobium-tantalum concentrate reference materials in the dressing plant and metallurgical system, but no domestic and foreign literature has reported these materials. The nature of niobium-tantalum mineral determines the crushed grain size and homogeneity of the niobium-tantalum concentrate and puts forward higher requirements for the development of a niobium-tantalum concentrate standard substance. OBJECTIVES To develop the four standard materials of niobium-tantalum concentrate with different contents. METHODS The preparation process of niobium-tantalum concentrate reference materials is introduced. Niobium-tantalum concentrate samples collected from the Yichun and Nigeria selection plant were finely milled and mechanically mixed by air milling and high-alumina ball milling. The packaged samples were randomly selected for homogeneity and stability testing and determined values. The homogeneity and stability of the samples were tested by Inductively Coupled Plasma-Optical Emission Spectrometry/Mass Spectrometry (ICP-OES/MS). RESULTS Twelve elements of different samples are detected by the different analytical methods, with a calibration method for collaborative testing in multiple laboratories, the certified value and uncertainty of each element are given. The samples have good uniformity and stability. CONCLUSIONS The contents of Ta(Nb)2O5 in the four antimony concentrates are 9.89%, 20.55%, 40.79% and 53.69%, respectively, forming a complete system from crude concentrates to concentrates, which meets the sample requirements for reference materials in the stages of metallurgical tests.