Raman spectroscopic analysis of real samples: Brazilian bauxite mineralogy

In this investigation, Raman spectroscopy with 1064 and 632.8 nm excitation was used to investigate real mineral samples of bauxite ore from mines of Northern Brazil, together with Raman mapping and X-rays diffraction. The obtained results show clearly that the use of microRaman spectroscopy is a powerful tool for the identification of all the minerals usually found in bauxites: gibbsite, kaolinite, goethite, hematite, anatase and quartz. Bulk samples can also be analysed, and FT-Raman is more adequate due to better signal-to-noise ratio and representativity, although not efficient for kaolinite. The identification of fingerprinting vibrations for all the minerals allows the acquisition of Raman-based chemical maps, potentially powerful tools for process mineralogy applied to bauxite ores.

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► Application of Raman spectroscopy to assess bauxite mineralogy on real ore samples.
► Diagnostic Raman vibrations can be obtained using 1064 or 632.8 nm wavelenghts.
► Use of microRaman spectroscopy for mineralidentification in bulk samples.
► Simultaneous phase identification in bulk samples is better using FT-Raman (1064 nm).
► Raman-based chemical maps are potentially a powerful tool for process mineralogy.