Recovery of Rare Earths, Niobium, and Thorium from the Tailings of Giant Bayan Obo Ore in China

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2012-06, Vol.43 (3), p.485-493
• Main Authors: Yu, Xiu-Lan, Bai, Li, Wang, Qing-Chun, Liu, Jia, Chi, Ming-Yu, Wang, Zhi-Chang
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Exact sciences and technology; Iron; Materials Science; Metallic Materials; Metallurgy; Metals; Metals. Metallurgy; Minerals; Nanotechnology; Niobium; Production of metals; Rare earth metals; Recovery; Separation; Structural Materials; Surfaces and Interfaces; Tailings; Thermodynamics; Thin Films; Thorium; Trace elements
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-012-9638-2

The recovery of rare earths, niobium, and thorium from Bayan Obo’s tailings has been investigated because the Bayan Obo ore is rich in rare earths and rich in niobium and thorium, but it is mined mainly as an iron ore and will be used up soon. By carbochlorination between 823 K (550 °C) and 873 K (600 °C) for 2 hours, 76 to 93 pct of rare earths were recovered from the tailings, which were much higher than those from Bayan Obo’s rare earth concentrate, together with 65 to 78 pct of niobium, 72 to 92 pct of thorium, 84 to 91 pct of iron, and 81 to 94 pct of fluorine. This suggests a cooperative reaction mechanism that carbochlorination of iron minerals (and carbonates) in the tailings enhances that of rare earth minerals, which is supported by a thermodynamic analysis. Subsequently, niobium separation from the low-volatile, ultrahigh iron chloride mixture was achieved efficiently by selective oxidation with Fe 2 O 3 . This process, combined with the best available technologies for separation of rare earths and thorium from the involatile chloride mixture and for comprehensively using other valuable elements, allows the ore to minimize radioactive waste and to use rare metal resources sustainably in the future.