Characterisation and Pre-concentration of a Pegmatite Columbite Ore for Niobium Extraction

Abstract

A columbite ore of pegmatite origin was characterised by subjecting it to energy dispersive X-ray fluorescence (XRF) and diffraction (XRD) analyses as well as scanning electron microscope-energy dispersive spectrometer (SEM–EDS) and Fourier Transform Infra-Red (FTIR) analysis. The sample was pre-concentrated with shaking table to upgrade its niobium content. The XRF analysis shows that the ore contains niobium and zirconium at 2.29 and 2.52 wt%, concentrations, respectively. The XRD chart gave prominent peaks at 2θ angles of 27.31, 30.38, 35.79, 38.07, 53.60, 55.92, and 63.70°, which indicate orthorhombic crystal structure of the columbite-iron (FeNbO₄) mineral phase. The SEM–EDS spot analyses showed points with Nb, Pt, Si, and Ta having 59.55, 34.03, 33.83, and 16.37 wt% concentrations, respectively. FTIR analysis reveals strong absorption band for Ta and Nb oxides in the regions 1100–1000 cm⁻¹ and 900–800 cm⁻¹, respectively. Shaking tabling pre-concentration increased the Nb assay from 2.29 in the ore to 3.65 wt% in the concentrate.