Process Mineralogical Characteristics of Niobium in Different Ore Types of the Bayan Obo Mine

To clarify the process mineralogical characteristics and distribution patterns of niobium in different types of ores from the Bayan Obo East Main Mine, and to provide a basis for the precise beneficiation and efficient utilization of this strategic niobium resource, this study systematically compared the process mineralogical properties of niobium in various ore types from this deposit using atomic absorption spectroscopy, ICP−AES, chemical analysis, and an automated mineral analysis system. The results show that the niobium content varies significantly among different ore types, with the aegirine−type niobium−rare earth−iron ore having the highest average Nb₂O₅ content (0.18%). The Nb₂O₅ content also fluctuates considerably among different samples of the same ore type; individual samples of aegirine−type, mica−type, dolomite−type, massive, and fluorite−type niobium−rare earth−iron ores can reach up to 1.16%, 1.03%, 0.57%, 0.39%, and 0.38% Nb₂O₅, respectively, demonstrating good industrial utilization potential and making them key targets for prospecting industrially viable niobium ores. There are also notable differences in the types of niobium minerals among different ore types: aeschynite predominates in massive, aegirine−type, and amphibole−type niobium−rare earth−iron ores, whereas columbite and niobian rutile are more abundant in dolomite−type, fluorite−type, and mica−type niobium−rare earth−iron ores. Furthermore, niobium minerals are generally fine−grained, primarily concentrated below 20 µm. When the grinding fineness reaches 90% passing 74 µm, the degree of monomer liberation remains below 20%, and it is almost nonexistent in low−grade samples. This is one of the main reasons why the niobium resources at Baiyun Ebo are currently difficult to utilize effectively.