Possible methodology for niobium, tantalum and scandium separation in ferrocolumbite

Ferrocolumbite was successfully dissolved with NH4F⋅HF (1:10 sample to flux ratio at 200 °C for 60 min), which yielded solutions containing 91% Ta, 96% Nb and 99% Sc recoveries while satisfactory LODs (0.07768, 0.01045 and 0.001085 mg/L respectively) were also obtained. Inclusion of a magnetic separation step (only 31% Fe in magnetic portion) to simplify the down-stream beneficiation processes did not contribute to the successful removal of Fe/Ti. Methyl isobutyl ketone (MIBK) successfully extracted the Ta in the ore (94%) into the organic layer and left Nb (88%) and Sc (99%) in the aqueous layer at [H2SO4] < 8 M. At higher acid levels ([H2SO4] > 10 M) the Sc present in the non-magnetic portion of the ore migrated in significant amounts and quantities (95%) to the organic layer. Thus a possible process for the separation of the three elements from one another was created. Octan-1-ol yielded similar results to MIBK while methyl isoamyl ketone (MIAK) successfully removed Ta from the aqueous layer (87%), but left the two other elements in the aqueous layer, even at 16 M [H2SO4]. A much simplified process flow sheet compared to current operational practices for the possible separation of Nb, Ta and Sc from ferrocolumbite and mine tailings is proposed.