A Review of Niobium-Tantalum Separation in Hydrometallurgy
Niobium and tantalum are chemically similar and are associated with each other in nature which makes it very difficult to separate. For many years, the separation of tantalum from niobium involved the fractional crystallization of potassium heptafluorotantalate away from potassium oxypentafluoroniobate monohydrate, this method has been supplanted by solvent extraction from fluoride-containing solutions by the use of solvent extractants such as Octanol, bis(2-ethylhexyl)phosphoric acid (DEHPA), Alamine 336, methyl isobutyl ketone (MIBK), tri-nbutyl phosphate (TBP) or cyclohexanone. A detailed review of the various processes involved in the breakdown treatment of niobium and tantalum primary sources, extraction and separation and newer processes of extraction as well as the various technique involved were discussed. Keyword: Niobium, Tantalum, Columbite, Tantalite, Solvent extractant and Solvent extraction.
THE PRODUCTION OF FERRONIOBIUM AT THE NIOBEC MINE
This paper describes the process used at Niobec in the production of ferroniobium once the ore is brought from the underground mine. It also briefly presents the Niobec operation, which is celebrating its 25 anniversary as a niobium producer. The metallurgical process is not a straightforward operation and requires many steps before delivering ferroniobium to our customer. The concentration of pyrochlore ores is known to be a very complex process. In the case of Niobec, the process requires some 15 different types of reagents, a sophisticated control system, and the process is very sensitive to pH control. Finally, the article is written to enable most readers to understand the various steps in the production of ferroniobium.
Inorganic Extraction Studies on the System between Bis(2-ethyl hexyl)-orthophosphoric Acid and Hydrochloric Acid. II
The influence of solvent concentration in extractions from hydrochloric acid solutions of about flfty elements is shown. The distribution ratio, K/sub d,/ of a given nuclide was radiometrically determined. The details of and some remarks on the method used are given. The bis(2-ethyl hexyl)-orthophosphoric acid concentration in the organic layer was varied in the range 0.5 to 50 volume% for most extractions. Extraction with barren toluene containing no HDEHP was also checked. The acidity in the aqueous layer was kept constant in a series of extractions of a given element. (N.W.R.)