Abstract
The dissolution reactions of Nb and Ta from columbite and tantalite in the aqueous solutions of HF, HF-HC1, NH4F-HCI, HF-H2SO4, and NH4F-H2SO4 were kinetically studied in the temperature range of 333 to 353 K. The presence of both H+ and F- in the leachant is necessary for the fast dissolution of columbite and tantalite. The increase in these ion concentrations and the elevation of temperature are effective in increasing the dissolution rate. The initial dissolution rate of Nb from columbite under the conditions employed in this work can be expressed as follows:R i =k o a(H+)1.2 C(F2212;)1.1 exp(−E a /RT) where an apparent activation energy,E a , ranges from 53.9 kJ mol−1 to 65.5 kJ mol−1.
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Formerly Graduate Student, Department of Metallurgy, Kyoto University, Japan
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majima, H., Awakura, Y., Mashima, M. et al. Dissolution of columbite and tantalite in acidic fluoride media. Metall Trans B 19, 355–363 (1988). https://doi.org/10.1007/BF02657733
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DOI: https://doi.org/10.1007/BF02657733