Sublimation Kinetics of Zirconium Tetrafluoride

Abstract:

An important step of a new process being developed for the beneficiation of the mineral zircon (Zr (Hf)SiO₄) to produce nuclear grade zirconium (Zr) metal, is the separation of the Zr from the hafnium (Hf). Zr ores typically contain between 1 and 3% Hf , whereas the use of Zr metal in the nuclear industry requires a Hf content <100 ppm, owing to its high neutron-capture cross section. The separation step is therefore key in the preparation of nuclear grade Zr, which is considered to be very difficult due to the various similarities in their chemical properties. The preparation of hafnium free zirconium relies on the traditional wet separation systems, for example solvent extraction systems. In contrast to the traditional aqueous chloride systems, Necsa focusses on dry fluoride-based processes. Dry processes have the advantage of producing much less hazardous chemical waste. In the work reported her, separation is achieved by sublimation/de-sublimation in the tetrafluoride form. The tetrafluoride is prepared by fluorination of plasma dissociated zircon (PDZ or Zr (Hf)O₂•SiO₂) with ammonium bifluoride (ABF). The separation involves the selective sublimation of the two tetrafluorides in an inert atmosphere under controlled conditions, and subsequent similarly selective desublimation. An accurate estimation of the sublimation rates the zirconium tetrafluoride (ZrF₄) and hafnium tetrafluoride (HfF₄) as a function of temperature is required since this forms the basis of the development of a sublimation model to determine whether the concept under consideration is theoretically possible. The sublimation kinetics of ZrF₄ is reported in this paper.

• Periodical: Advanced Materials Research (Volume 1019)
• Pages: 398-405
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1019.398
• Online since: October 2014
• Authors: C.J. Pretorius*, A.D. Pienaar, P.L. Crouse, H.F. Niemand
• Keywords: Hafnium, Sublimation Kinetics, Zirconium

References

[1] X. J. Yang, A. G. Fane, C. Pin, Separation of zirconium and hafnium using hollow fibres: Part I. Supported liquid membranes, Chem. Eng. J. 88 (2002) 37–44.

DOI: 10.1016/s1385-8947(01)00256-x

[2] M. Smolik, A. Jakóbik-Kolon, M. Porański, Separation of zirconium and hafnium using Diphonix® chelating ion-exchange resin, Hydrom. 9 (2009) 350–353.

DOI: 10.1016/j.hydromet.2008.05.010

[3] M. Benedict, T. H. Pigford, H. W. Levi, Nuclear Chemical Engineering. McGraw-Hill, New York, 1981, pp.333-341.

[4] D. J. Branken, G. Lachman, H.M. Krieg, O.S.L. Bruinsma, Influence of KF and HF on the selectivity of Zr and Hf Separation by Fractional Crystallization of K2Zr(Hf)F6, Ind. Amp Eng. Chem. Res. 49 (2010) 797–808.

DOI: 10.1021/ie900747k

[5] H. Ishizuka, Process for refining zirconium tetrachloride containing hafnium tetrachloride, US Patent number: 385, 647, 724 (1974).

[6] K. Reuter, G. Passing, S. Kirchmeyer, Process for separating zirconium and hafnium, US Patent number: 763, 539, 622 (2009).

[7] Z. Xu, L. Wang, Y. Wu, R. Chi, L. Zhang, M. Wu, Solvent extraction of hafnium from thiocyanic acid medium in DIBK-TBP mixed system, Trans. Nonferrous Met. Soc. China. 22 (2012) 1760–1765.

DOI: 10.1016/s1003-6326(11)61384-8

[8] R. Banda, H. Y. Lee, M. S. Lee, Separation of Zr from Hf in hydrochloric acid solution using amine-based extractants, Ind. Eng. Chem. Res. 51 (2012) 9652–9660.

DOI: 10.1021/ie3008264

[9] N. V. Deorkar, S. M. Khopkar, Liquid-liquid extraction of zirconium from hafnium and other elements with dicyclohexyl-18-crown-6, Anal. Chim. Acta. 245 (1991) 27–33.

DOI: 10.1016/s0003-2670(00)80197-x

[10] A. E. P. Brown, T. V. Healy, Separation of zirconium from hafnium in nitric acid solutions by solvent extraction using dibutyl butylphosphonate: Part 1. Chemistry of the separation, Hydrom. 3 (1978) 265–274.

DOI: 10.1016/0304-386x(78)90027-0

[11] M. Taghizadeh, R. Ghasemzadeh, S. N. Ashrafizadeh, K. Saberyan, M. G. Maragheh, Determination of optimum process conditions for the extraction and separation of zirconium and hafnium by solvent extraction, Hydrom. 90 (2008) 115–120.

DOI: 10.1016/j.hydromet.2007.10.002

[12] M. Taghizadeh, M. Ghanadi, E. Zolfonoun, Separation of zirconium and hafnium by solvent extraction using mixture of TBP and Cyanex 923, J. Nucl. Mater. 412 (2011) 334–337.

DOI: 10.1016/j.jnucmat.2011.03.033

[13] L. E. Sarbeck, D. R. Lee, L. J. Jacoby, J. C. Haygarth, C. T. Goodwin, W. A. Crocker, Zirconium-hafnium separation process, US Patent number 517, 687, 805 (1993).

[14] X. J. Yang, A. G. Fane, C. Pin, Separation of zirconium and hafnium using hollow fibres: Part I. Supported liquid membranes, Chem. Eng. J. 88 (2002) 37–44.

DOI: 10.1016/s1385-8947(01)00256-x

[15] C. H. Byers, W. G. Sisson, T. S. Snyder, R. J. Beleski, T. L. Francis, U. P. Nayak, Zirconium and hafnium separation in chloride solutions using continuous ion exchange chromatography, US Patent number: 576, 289, 009 (1998).

[16] J. M. Begovich, W. G. Sisson, Continuous ion exchange separation of zirconium and hafnium using an annular chromatograph, Hydrom. 10 (1983) 11–20.

DOI: 10.1016/0304-386x(83)90073-7

[17] F. J. Hurst, Separation of hafnium from zirconium in sulphuric acid solutions using pressurized ion exchange, Hydrom. 10 (1983) 1–10.

DOI: 10.1016/0304-386x(83)90072-5

[18] X. J. Yang, C. Pin, A. G. Fane, Separation of hafnium from zirconium by extraction chromatography with liquid anionic exchangers, J. Chromatogr. Sci. 37 (1999) 171–179.

DOI: 10.1093/chromsci/37.5.171

[19] K. T. Qiuquan Wang, Separation of zirconium(IV) and hafnium(IV) by extraction chromatography using di(1-methylheptyl) methylphosphonate as a stationary phase, Anal. Sci. 13 (1997) 27–31.

DOI: 10.2116/analsci.13.27

[20] L. Delons, S. Lagarde, A. Favre-reguillon, S. Pellet-Rostaing, M. Lemaire, L. Poriel, Process for the separation and purification of hafnium and zirconium, US Patent number: 770, 896, 204 (2010).

[21] D. F. McLaughlin, R. A. Stoltz, Molten salt extractive distillation process for zirconium-hafnium separation, US Patent number: 487447517 (1989).

[22] O. S. Monnahela, W. G. Augustyn, J. T. Nel, C. J. Pretorius, J. B. Wagener, The Vacuum Sublimation Separation of Zirconium and Hafnium Tetrafluoride, PMDN Conference, Cape Town, (2013).

[23] A. I. Solov'ev, V. M. Malyutina, Production of metallic zirconium tetrafluoride purified from hafnium to reactor purity, Russ. J. Non-Ferr. Met. 43 (2002) 14–18.

[24] A. I. Solov'ev, V. M. Malyutina, Metallurgy of less-common and precious metals. Production of metallurgical semiproduct from zircon concentrate for use in production of plastic metallic zirconium, Russ. J. Non-Ferr. Met. 43 (2002) 9–13.

[25] J. Withers, A. J. Woytek, J. T. Lileck, Process for the production of high purity zirconium tetrafluoride and other fluorides, " US Patent number: 4983373 (1991).

[26] M. L. Kotsar', V. B. Bateev, P. B. Baskov, V. V. Sakharov, V. D. Fedorov, V. V. Shatalov, Preparation of high-purity ZrF4 and HfF4 for optical fibres and radiation-resistant glasses, Inorg. Mater. 37 (2001) 1085–1091.

DOI: 10.1023/a:1012399615098

[27] G. Dai, J. Huang, J. Cheng, C. Zhang, G. Dong, K. Wang, A new preparation route for high purity ZrF4, J. Non-Cryst. Solids, 140 (1992) 229–232.

DOI: 10.1016/s0022-3093(05)80772-0

[28] K. Fujiura, Y. Ohishi, S. Sakaguchi, Synthesis of high-purity ZrF4 by chemical vapor-deposition, Yogyo-Kyokai-Shi. 95 (1987) 86–88.

[29] D. R. MacFarlane, P. J. Newman, A. Voelkel, Methods of purification of zirconium tetrafluoride for fluorozirconate glass, J. Am. Chem. Soc. 85 (2002) 1610–1612.

DOI: 10.1111/j.1151-2916.2002.tb00320.x

[30] R. C. Pastor, M. Robinson, Method for preparing ultra-pure zirconium and hafnium tetrafluorides, US Patent number: US 457, 8252 A25 (1986).

[31] R. C. Folweiler, Chemical vapor purification of fluorides, US Patent number: US 465, 2438 A24 (1987).

[32] L. J. Abate, H. A. Wilhelm, Sublimation of zirconium tetrafluoride, United States Atomic Energy Commission, Ames Laboratory, ISC-151 (1951).

[33] J.T. Nel, W.L. Retief, J.L. Havenga, W. du Plessis, J.P. le Roux, Treatment of chemical feedstocks. WO2013054282 A1 (2013).

[34] A. Khawam, D. R. Flanagan, Solid-state kinetic models: basics and mathematical fundamentals, J. Phys. Chem. B. (2006) 17315–17328.

DOI: 10.1021/jp062746a

[35] J. H. Shin, M. S. Choi, D. J. Min, J. H. Park, Isothermal and non-isothermal sublimation kinetics of zirconium tetrachloride (ZrCl4) for producing nuclear grade Zr, Mater. Chem. Phys. 143 (2014) 1075–1081.

DOI: 10.1016/j.matchemphys.2013.11.007

[36] S. Vyazovkin, A. K. Burnham, J. M. Criado, L. A. Pérez-Maqueda, C. Popescu, N. Sbirrazzuoli, ICTAC Kinetics Committee recommendations for performing kinetic computations on thermal analysis data, Thermochim. Acta,. 520 (2011) 1–19.

DOI: 10.1016/j.tca.2011.03.034

[37] J.T. Nel, W. du Plessis, P.L. Crouse, W.L. Retief, Treatment of zirconia-based material with ammonium bi-fluoride. WO2011013085 A1 (2011).

[38] J. S. Chickos, W. E. Acree, Jr., Enthalpies of Sublimation of Organic and Organometallic Compounds. 1910-2001, J. Phys. Chem. Ref. Data. 31 (2002).

DOI: 10.1063/1.1475333

[39] P. L. Brown, E. Curti, and B. Grambow, Chemical Thermodynamics of Zirconium, OECD Nuclear Energy Agency, Data Bank, Issy-les-Moulineaux (France).