A comprehensive review on recent progress in beneficiation of Nb-bearing minerals /Nb ores

Mainly produced by Brazil and Canada, the global production of niobium (Nb) surpassed 79,000 tons in 2022. Among the 150 kinds of Nb-bearing minerals, pyrochlore, columbite and tantalite are the predominant primary sources. There are several challenges in Nb ores’ beneficiation, such as low abundance in earth crust (20 ppm), fine dissemination in primary ores, and the poor performance of amines collectors. Generally, the separation efficiency of Nb-bearing minerals is low, referring to the Nb recovery of 60–70 % with the Nb2O5 grade below 60 %. For Nb ores at Bayan Obo mine, a typical low-grade Nb deposit in China that has not been produced on an industrial scale, the grade of Nb2O5 could only be upgraded from 0.1–0.2 % to 1–5 % via physical beneficiation. The related research focused on simplifying the flowsheet of minerals processing and seeking potential alternatives to amine collectors. Hydroxamic acids, fatty acids, phosphonic acids and arsenic acids are promising alternatives, while their efficiency in tacking primary Nb ores at the industrial scale is unclear. Besides, there are certain knowledge gaps regarding the interaction mechanisms between Nb-bearing minerals and flotation reagents. Recommending the development of floc-flotation and carrier flotation is essential due to the fine dissemination and high degree of sliming exhibited by Nb-bearing minerals during grinding. The combination of physical and chemical methods, such as roasting, fusion and leaching, holds great promise for the beneficiation of low-grade Nb ores (containing 0.1–0.2 % Nb2O5).