SciELO - Scientific Electronic Library Online

 
vol.64Synthesis and antiplasmodial activity of EG-artemisinin ethers and artemisinin-quinoline hybridsCoordination of tridentate Schiff base derivatives of 4-aminoantipyrine to rhenium (V) índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados

Articulo

Indicadores

Links relacionados

  • En proceso de indezaciónCitado por Google
  • En proceso de indezaciónSimilares en Google

Compartir


South African Journal of Chemistry

versión On-line ISSN 1996-840X
versión impresa ISSN 0379-4350

S.Afr.j.chem. (Online) vol.64  Durban  2011

 

RESEARCH ARTICLE

 

Dissolution and quantification of tantalum-containing compounds: Comparison with niobium

 

 

Thomas A. TheronI; Motlalepula NeteI; Johan A. VenterI; Walter PurcellI, *; Johan T. NelII

IDepartment of Chemistry, University of the Free State, Bloemfontein, 9300, South Africa
IIThe South African Nuclear Energy Corporation Ltd. (Necsa), P.O. Box 582, Pretoria 0001, South Africa

 

 


ABSTRACT

Dissolution and quantification of different tantalum compounds was undertaken as part of the development of local processes for the beneficiation and separation of tantalum and niobium from different mineral ores. Dissolution of Ta metal powder, TAN-1 CRM, TaF5, TaCl5 and Ta2O5 was undertaken with different acid, alkaline fluxes as well as with microwave digestion while quantification was performed using ICP-OES analysis. The success of the different dissolution methods was evaluated on percentage recovery basis, the results discussed and finally compared with those obtained from the corresponding niobium compounds. Quantification results obtained from this study clearly indicated that the percentage recovery of tantalum depended on i) the type of tantalum source and ii) the dissolution process of the different tantalum compounds. Excellent recoveries were obtained with water soluble TaF5 and TaCl5 with 101(1) and 100(2) % respectively. Low tantalum recovery was obtained for Ta metal and Ta2O5 with microwave digestion in the presence of strong acids (4.1(8) and 9.7(8) %, respectively in the presence of H2SO4) and acidic fluxes (1.5(5) % with K2S2O7). Improved recoveries were obtained using basic fluxes for both the metal and the oxide. Fluxing the metal with KOH resulted in a 85(3) % Ta recovery while a maximum of 68(4) % Ta recovery was obtained for Ta2O5. Tantalum recoveries of between 75(10) and 90(6) % were obtained for TAN-1 CRM (Ta present as Ta2O5) and 95(6) % for Ta2O5 with Li2B4O7 as fluxing agent on the removal of the excess of boric acid prior to analysis. A stability study indicated constant recovery in abasic medium while a decrease of up to 10 % in tantalum recovery was obtained in an acidic environment. A comparison with the niobium results obtained in a previous study highlighted the different acid/base properties of the two oxides as well as a possible alternative dissolution/separation step for the two elements from the mineral ore.

Keywords: Dissolution, microwave, fluxes, tantalum, recovery


 

 

Full text available only in pdf format.

 

Acknowledgements

The authors thank the Research Fund of this University, NECSA and the New Metals Development Network of the Advanced Metals Initiative of the Department of Science and Technology of South Africa for financial support.

 

References

1 J. E. Schlewitz, Kirk-Othmer Encyclopaedia, of Chemical Technology, Published Online, 2009, http://onlinelibrary.wiley.com/doi/10.1002/0471238961 .1409150219030812.a01.pub2/full        [ Links ]

2 I.M. Gibalo, Analytical Chemistry of Niobium and Tantalum, Ann Arbor-Humphrey Science, Ann Arbor, London, 1970.         [ Links ]

3 Kirk-Othmer Encyclopedia of Chemical Technology, 4th edn., V.23, John Wiley & Sons, 1997, p. 658.         [ Links ]

4 Roskill, The Economics of Niobium, 10th edn., Roskill Information Services, London, 2005.         [ Links ]

5 Roskill, The Economics of Tantalum, 9th edn., Roskill Information Services, London, 2005.         [ Links ]

6 M.C. Marignac, Ann. Chim., 1866, 43, 276.         [ Links ]

7 O.S. Ayanda and F. A. Adekola, J. Miner. Mater. Charact. Eng., 2011, 10 (3), 245-256.         [ Links ]

8 M. Nete, W. Purcell, E. Snyders and J.T. Nel, S. Afr. J. Chem., 2010, 63, 130-134.         [ Links ]

9 E. Prichard and V. Barwick, Quality Assurance in Analytical Chemistry, Wiley, London, 2008, 20, 50- 92.         [ Links ]

10 C.C. Chan, Y.C. Lee, H. Lam and X-M Zhang, Ed., Analytical Method Validation and Instrument Performance Verification, Wiley-Interscience, Hoboken, New Jersey, 2004, pp. 16-22, 51-66.         [ Links ]

11 David R. Lide, Editor-in-Chief, CRC Handbook of Chemistry and Physics, 89th edn., CRC Press, Baco Raton, 2008, pp. 4-92.         [ Links ]

12 R.K. Winge, V.A. Fassel, VJ. Peterson and M.A. Floyd, Inductively Coupled Plasma-Atomic Emission Spectroscopy. An Atlas of Spectral Information, Appendix B, Elsevier, Amsterdam, 1993.         [ Links ]

13 D.A. Skoog, D.M. West, F.J. Holler and S.R. Crouch, Fundamentals of Analytical Chemistry, 8th edn., Thomson Brooks/Cole, Southbank, Australia, 2004, pp. 1049-1051.         [ Links ]

14 J. Bassette, R.C. Denney, G.H. Jefrery and G.H. Mendham, Vogel's Textbook of Quantitative Inorganic Analysis, 4th edn., Longman, London, 1978, pp. 105-106.         [ Links ]

15 H.M. Yau, S.J. Chan, S.R.D. George, J.M. Hook, A.K. Croft and J.B. Harper, Molecules, 2009, 14, 2521-2534.         [ Links ]

 

 

Received 30 May 2011
Revised 19 October 2011
Accepted 24 October 2011

 

 

Submitted by invitation to celebrate 2011 the 'International Year of Chemistry'.
* To whom correspondence should be addressed. E-mail: purcellw@ufs.ac.za

Creative Commons License Todo el contenido de esta revista, excepto dónde está identificado, está bajo una Licencia Creative Commons