Spectroscopic study on rare earth deposits in Yen Phu mine

Aoyagi, Noboru   ; Nakada, Masami  ; Kumagai, Yuta   ; Watanabe, Masayuki   ; Nguyen, T. T.*; Nguyen, V. T.*; Nguyen, T. H.*; Le, B. T.*

We demonstrate mineral characterization of rare earth-containing ores from Yen Phu mine, using microscopic and spectroscopic techniques: SEM-EDX, Mssbauer spectroscopy, FT-IR microscopy, and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The results of Mssbauer spectroscopy indicate formation of magnetite-like, hematite-like, and iron(III) salt phases in common with three ores sampled at different points in the mine. Around the grain boundary in the magnetite-like mineral phase the presence of phosphate bands were confirmed by FT-IR microscopy. The chemical state of the rare earth species has not been entirely obtained through these methods. However, the results of TRLFS analysis on Eu imply that the Eu species are identical in the different phases observed by Mssbauer spectroscopy.