Preparation of Phosphate Ore Reference Materials for Chemical Composition Analysis

For the development and comprehensive utilization of phosphate ore it is not only necessary to analyze the main elements such as phosphorus, but it is also necessary to determine accurately the rare earth, trace and other elements. Phosphate Ore Reference Materials (PORMs) with numbers of components and suitable contents can be used for quality control during analysis. However, available PORMs in China and abroad do no meet the requirements in terms of the element contents and the content range. Four different types of PORMs have been developed and are described in this study. The samples of phosphate ores were collected from the Zhangjiakou Fanshan phosphate mine in Hebei province, Xinhua phosphate mine in Zhijin of Guizhou Province, Kunyang phosphate mine in Yunnan Province, and Huolian phosphate mine in Shennongjia of Hubei Province. Zhangjiakou Fanshan phosphate mine and Xinhua phosphate mine are rich in rare earth elements (REEs). Four samples were homogeneous and stable. The results from 11 laboratories were combined to confirm certified values and uncertainty of 37 components, which include major elements, REEs, and trace elements. Three components were taken as reference values and the rest were characterized as certified values. The four PORMs cover a complete content series from cut-off grade, production-grade, to phosphate concentrate with P₂O₅ contents of 10.57%, 18.91%, 27.78% and 39.40%, respectively, and the total REEs contents of 0.16%, 0.11%, 0.032% and 0.0083%, respectively. The developed PORMs meet the requirements for exploration, evaluation, and comprehensive utilization of phosphate ores.