Extraction of niobium and tantalum from ferrocolumbite by hydrofluoric acid pressure leaching

•A HF leaching process was used to extract Nb and Ta from ferrocolumbite.•Temperature, reaction time and HF concentration affect Nb and Ta extraction.•The extraction efficiency of Nb and Ta reached 90% under the optimal conditions.

Pressure acid leaching was used to extract niobium and tantalum from a ferrocolumbite ore. The leaching was carried out in a pressure reactor using hydrofluoric acid as leachant. Various parameters, such as temperature, reaction time, HF concentration, stirring speed, particle size and solid-to-liquid ratio in the leaching process, were optimized. The reactants and products were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and specific surface area (BET). Experimental results showed that the maximum extraction of Nb and Ta, 90 and 80% respectively, it was achieved at an HF concentration of 9% v/v, reaction temperature of 220 °C, particle size of − 45 μm, solid-to-liquid ratio of 1.82% w/v and reaction time of 80 min. Crystalline structures, different from those originally present in the ore, were not detected by XRD analysis of the leaching residues.

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