Niobium, also known as columbium, is one of the new industrial metals likely to play an important role in industrial processing in the near future. Its high melting point (4376°F.) and low cross section for neutron absorption (1.1 barns) make it of special interest to the Atomic Energy Commission. Since tantalum, which invariably accompanies niobium in its ores, has a somewhat higher cross section for neutron absorption (21 barns) there is considerable interest in developing an industrial process for producing tantalum-free niobium. Tantalum itself is a valuable metal because of its high melting point (5160°F.) and its resistance to most corrosive chemicals.
Koerner, Ernest L. Jr.; Smutz, Morton; and Wilhelm, H. A., "Separation of niobium and tantalum by liquid extraction" (1956). Ames Laboratory ISC Technical Reports. 151.