Occurrence of Niobium and Rare Earth Elements in Related Ores by Electron Microprobe

Abstract

BACKGROUND Niobium is a strategic metal with wide applications and plays a very important role in modern steel technology. The average content of Nb2O5 in a niobium-rare earth ore is 0.0855%, and the content of total rare earth (REO) is 1.03%, which is close to the minimum industrial grade requirement of niobium ore. Niobium minerals and rare earth minerals have the characteristics of small particles and complex intergrowths, which makes them difficult to find under a polarized microscope. OBJECTIVES To investigate the forms of niobium and rare earth elements. METHODS Electron probe backscatter image, energy spectrum analysis and electron probe spectrum quantitative analysis were used to analyze niobium and rare-earth ore. RESULTS Niobium mainly existed in the form of niobite and niobium-bearing rutile. The average content of Nb2O5 in niobite was 78.26% and that in niobium-bearing rutile was 5.26%. Rare earth elements mainly existed in the form of monazite, bastnaite and bastnaesite. The average content of rare earth elements (REO) in monazite, bastnaite and bastnaesite was 64.84%, 57.52% and 70.61%, respectively. Niobium and rare-earth minerals were distributed and dispersed. They were mostly trapped in the gangue minerals such as potassium feldspar, calcite and biotite. CONCLUSIONS The types and characteristics of the main niobium and rare earth minerals in the ore deposit were identified. This study has important guiding significance for the comprehensive utilization of niobium and rare earth deposits in the future.

Keywords

• niobium and rare earth ore
• mineral composition
• occurrence
• chemical composition
• electron microprobe