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Thermodynamic Stabilities of U(VI) Minerals: Estimated and Observed Relationships

Published online by Cambridge University Press:  03 September 2012

Robert J. Finch
Robert J. Finch*
Affiliation:
University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada
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Abstract

Gibbs free energies of formation (ΔG°ƒ) for several structurally related U(VI) minerals are estimated by summing the Gibbs energy contributions from component oxides. The estimated ΔG°f values are used to construct activity-activity (stability) diagrams, and the predicted stability fields are compared with observed mineral occurrences and reaction pathways. With some exceptions, natural occurrences agree well with the mineral stability fields estimated for the systems Sio2-Cao-Uo3-UOH2O and Co2-caO-UO3-H2O providing confidence in the estimated thermodynamic values. Activity-activity diagrams are sensitive to small differences in ΔG°f values, and mineral compositions must be known accurately, including structurally bound H2O. The estimated ΔG°f values are not considered reliable for a few minerals for two major reasons: (1) the structures of the minerals in question are not closely similar to those used to estimate the ΔG°f* values of the component oxides, and/or (2) the minerals in question are exceptionally fine grained, leading to large surface energies that increase the effective mineral solubilities.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 1185
Copyright
Copyright © Materials Research Society 1997

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References

REFERENCES

1. Tardy, Y. and Garrets, R.M., Geochim. Cosmochim. Acta 41, 1051 (1976).Google Scholar
2. Finch, R.J. and Ewing, R.C., SKB Technical Report 91–15 (SKB, Stockholm) 1991.Google Scholar
3. Wronkiewicz, D.J., Bates, J.K., Gerding, T.J., Veleckis, E. and Tani, B.S., J. Nucl. Mater. 190, 107 (1992).Google Scholar
4. Grenthe, I. et al. Thermodynamics of Uranium. North-Holland (NY, Amsterdam) (1992) 656 p.Google Scholar
5. Alwan, A.K. and Williams, P.A., Mineral. Mag. 43, 665 (1980).Google Scholar
6. Stumm, W. and Morgan, J.J., Aqueous Chemistry, 2nd Edition, Wiley-Interscience (NY, 1981) 780 p.Google Scholar
7. Finch, R.J. and Ewing, R.C., J. Nucl. Mater. 190, 133 (1992).Google Scholar
8. Sandino, A. and Bruno, J., Geochim. Cosmochim. Acta 56, 4135 (1992).Google Scholar
9. Murakami, T., Ohnuki, T., Isobe, H. and Sato, T., Amer. Mineral, (submitted).Google Scholar
10. Tardy, Y. and Garreis, R.M., Geochim. Cosmochim. Acta 42, 87 (1977).Google Scholar
11. Tardy, Y. and Duplay, J., Geochim. Cosmochim. Acta 56, 3007 (1992).Google Scholar
12. O'Hare, P.A.G., Lewis, B.M. and Nguyen, S.N., J. Chem. Thermodynamics 20, 1287 (1988).Google Scholar
13. Finch, R.J., Hawthorne, F.C. and Ewing, R.C. in Scientific Basis for Nuclear Waste Management XIX, edited by Murphy, W.M. and Knecht, D.A. (Mater. Res. Soc. Proc. 412, Pittsburgh, PA, 1996) pp. 361–368.Google Scholar
14. Nguyen, S.N., Silva, R.J., Weed, H.C. and Andrews, J.E., J. Chem. Thermodyn. 24, 359 (1992).Google Scholar
15. Sergeyeva, E.I., Nikitin, A.A., Khodakovkiy, I.L. and Naumov, G.B., Geokhimiya 11, 1340 (1972) [English translation in: Geochem. Internat. 9, 900 (1972)].Google Scholar
16. Finch, R.J., Cooper, M.A., Hawthorne, F.C. and Ewing, R.C., Can. Mineral. 34, 1071 (1996).Google Scholar
17. Nickel, E.H. and Nichols, M.C., Mineral Reference Manual. Van Norstrand Reinhold (NY) 1992, 250 p.Google Scholar
18. Cejka, J., and Urbanec, Z., Secondary Uranium Minerals. Academia, Czechoslovak Academy of Sciences (Prague, 1990) 93 p.Google Scholar
19. Deliens, M. and Piret, P., Eur. J. Mineral. 4, 1271 (1992).Google Scholar
20. Burns, P.C., Miller, M.L., Ewing, R.C., Can. Mineral. 34, 845 (1996).Google Scholar
21. Frondel, C., Systematic mineralogy of uranium and thorium. Geol. Soc. Amer. Bull. 1064 (1958) 399 p.Google Scholar
22. Deliens, M., Piret, P. and Comblain, G., Les Minéraux Secondaires d'Uranium du Zaire. Musée Royal de l'Afrique Centrale (Tervuren, 1981) 113 p.Google Scholar
23. Finch, R.J., Miller, M.L. and Ewing, R.C., Radiochimica Acta 58/59, 433 (1992).Google Scholar
24. Finch, R.J., Ph.D. Thesis, University of New Mexico, 1994.Google Scholar
25. Pearcy, E.C., Prikryl, J.D., Murphy, W.M. and Leslie, B.W., Appl. Geochem. 9, 713 (1994).Google Scholar
26. Sandino, A. and Grambow, B., Radiochim. Acta 66/67, 37 (1994).Google Scholar
27. Vochten, R. and Van Havebeke, L., Mineral. Petrol. 43, 65 (1990).Google Scholar
28. Sowder, A.G., Clark, S.B. and Fjeld, R.A., Radiochim. Acta 74, 45 (1996).Google Scholar
29. Christ, C.L. and Clark, J.R., Amer. Mineral. 45, 1026 (1960).Google Scholar
30. Smith, D.K., in: Uranium Geochemistry, Mineralogy, Geology, Exploration and Resources, edited by De Vivo, B., Ippolito, F., Capaldi, G. & Simpson, P.R.. Instit. Min. Metall., London (1984). pp. 43–88.Google Scholar
31. Langmuir, D., Geochim. Cosmochim. Acta 42, 547 (1978).Google Scholar
32. Evans, H.T., Science 141, 154 (1963).Google Scholar
33. Miller, M.L., Finch, R.J., Burns, P.C., and Ewing, R.C., J. Mater. Res. 11, 3048 (1996).Google Scholar