Now showing items 1-7 of 7

    • Comparison of extractants for the separation of TaF5 and NbF5 in different acidic media 

      Ungerer, M.J.; Van der Westhuizen, D.J.; Lachmann, G.; Krieg, H.M. (Elsevier, 2014)
      To optimise the solvent extraction (SX) of Ta and Nb, eight different extractants were investigated, including the cation exchangers di-iso-octyl-phosphinic acid (PA) and di-(2-ethylhexyl)-phosphoric acid (D2EHPA), the ...
    • Density functional theory study with and without COSMO of H2SO4 reactions in an aqueous environment for metal extraction 

      Ungerer, Maria Johanna; Van Sittert, Cornelia Gertina Catharina Elizabeth; Van der Westhuizen, Derik Jacobus; Krieg, Henning Manfred (Wiley, 2019)
      In a recent study investigating the suitability of solvent extraction (SX) for the separation of Ta and Nb, it was shown that speciation data would be required to help explain the data obtained. As traditional speciation ...
    • Molecular modelling of tantalum fluoride in sulphuric acid medium: a DFT study 

      Ungerer, M.J.; Van der Westhuizen, D.J.; Krieg, H.M.; Van Sittert, C.G.C.E. (Elsevier, 2019)
      During the solvent extraction (SX) experiments of tantalum (Ta) and niobium (Nb), the aqueous phase consisted of tantalum- and niobium penta-fluoride (Ta(Nb)F5), water (H2O) and sulphuric acid (H2SO4), which was contacted ...
    • Molecular modelling of tantalum in an aqueous phase 

      Ungerer, M.J.; Van Sittert, C.G.C.E.; Van der Westhuizen, D.J.; Krieg, H.M. (SAIMM, 2017)
      The transition metals tantalum (Ta) and niobium (Nb) are of significant importance, for example in the nuclear energy sector where they are used as cladding materials, as well as in capacitors and specialized materials. For ...
    • Molecular modelling of tantalum penta-halides during hydrolysis and oxidation reactions 

      Ungerer, M.J.; Van Sittert, C.G.C.E.; Van der Westhuizen, D.J.; Krieg, H.M. (Elsevier, 2016)
      The transition metals tantalum (Ta) and niobium (Nb), which are usually found together in nature, have similar chemical and physical properties, making their separation challenging. There are various methods available for ...
    • Molecular modelling of the hydrolysis of tantalum and niobium pentafluoride 

      Ungerer, Marietjie J.; Van der Westhuizen, Derik J.; Krieg, Henning M.; Van Sittert, Cornelia G.C.E. (Trans Tech Publications, 2014)
      Tantalum (Ta) and niobium (Nb) are two metals with similar chemical and physical properties and are found together in nature. One form of Ta is tantalum pentafluoride, which is stable in reducing environments, is corrosive ...
    • The time dependent solvent extraction of Ta and Nb 

      Van der Westhuizen, Derik J.; De Beer, Leon; Ungerer, Marietjie J.; Krieg, Henning M. (Trans Tech Publications, 2014)
      The suitability of Liquid-liquid extraction (LLE) for the selective extraction of chemically similar tantalum (Ta) and niobium (Nb) mixtures was investigated by determining the influence of the acid concentration, extractant ...