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Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride


Many reactive metals are difficult to prepare in pure form without complicated and expensive procedures1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18. Although titanium has many desirable properties (it is light, strong and corrosion-resistant1), its use has been restricted because of its high processing cost. In the current pyrometallurgical process—the Kroll process4,5—the titanium minerals rutile and ilmenite are carbo-chlorinated to remove oxygen, iron and other impurities, producing a TiCl4 vapour. This is then reduced to titanium metal by magnesium metal; the by-product MgCl2 is removed by vacuum distillation. The prediction that this process would be replaced by an electrochemical route6,7,8,9,10 has not been fulfilled; attempts involving the electro-deposition of titanium from ionic solutions have been hampered by difficulties in eliminating the redox cycling of multivalent titanium ions and in handling very reactive dendritic products6,7,8,9,10. Here we report an electrochemical method for the direct reduction of solid TiO2, in which the oxygen is ionized, dissolved in a molten salt and discharged at the anode, leaving pure titanium at the cathode. The simplicity and rapidity of this process compared to conventional routes should result in reduced production costs and the approach should be applicable to a wide range of metal oxides.

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Figure 1: Cyclic voltammograms of titanium foils in molten CaCl2.
Figure 2: Reduction of titanium oxide scale to titanium metal.
Figure 3: Electrolytic cells for the reduction of TiO2 pellets.
Figure 4: Reduction of the TiO2 powder to titanium metal.


  1. Habashi, F. (ed.) Handbook of Extractive Metallurgy 1129–1180 (Wiley-VCH, Weinham, 1997).

    Google Scholar 

  2. Sadoway, D. R. in Refractory Metals Extraction, Processing and Applications: Proc. TMS Annual Meeting, New Orleans 1991 (eds Liddel, K. C., Sadoway, D. R. & Bautista, R. G.) (TMS—The Minerals, Metals & Materials Society, Warrendale, 1991).

    Google Scholar 

  3. Massalski, T. B., Okamoto, H., Subramanian, P. R. & Kacprzak, L. (eds) Binary Alloy Phase Diagrams 2nd edn, Vol. 3, 2924–2927 (ASM International, Materials Park, 1990).

    Google Scholar 

  4. Kroll, W. J. The production of ductile titanium. Trans. Am. Electrochem. Soc. 78, 35–47 ( 1940).

    Article  Google Scholar 

  5. Ikeshima, T., in Titanium Science and Technology, Proc. 5th Int. Conf. Titanium, München 1984 (eds Lutjering, G., Zwicker, U. & Bunk, W.) 3– 14 (DGM-Deutsche Gesellschaft für Materialkunde e.V., Oberursal, 1985).

    Google Scholar 

  6. Cobel, G., Fisher, J. & Synder, L. E. in Titanium ’80, Science and Technology, Proc. 4th Int. Conf. Titanium, Kyoto 1980 (eds Kimura, H. & Izumi, O.) 1969–1976 (The Metallurgical Society of AIME, Warrendale, 1980).

    Google Scholar 

  7. Opie, W. R. & Moles, O. W. A basket cathode electrolytic cell for production of titanium. Trans. Met. Soc. AIME 218 , 646–649 (1960).

    CAS  Google Scholar 

  8. Ginatta, M. V. Method of producing metals by cathodic dissolution of their compounds. US Patent 4,400,247 (23 Aug. 1983).

  9. Froes, F. H. Titanium and other light metals: let's do something about cost. JOM 50, 15 (1998).

    Article  Google Scholar 

  10. Hartman, A. D., Gerdemann, S. J. & Hansen, J. S. Producing lower-cost titanium for automotive applications. JOM 50, 16–19 (1998).

    CAS  Article  Google Scholar 

  11. Suzuki, K. The high-quality precision casting of titanium alloys. JOM 50, 20–23 (1998).

    CAS  Article  Google Scholar 

  12. Okabe, T., Ohkubo, C., Watanabe, I., Okuno, O. & Takada, Y. The present status of dental titanium casting. JOM 50, 24–29 ( 1998).

    CAS  Article  Google Scholar 

  13. Froes, F. H. The production of low-cost titanium powders. JOM 50 , 41–43 (1998).

    CAS  Article  Google Scholar 

  14. Tapphorn, R. M. & Gabel, H. The solid-state spray forming of low-oxide titanium components. JOM 50, 45–46, 76 (1998).

    CAS  Article  Google Scholar 

  15. Elliott, G. R. B. The continuous production of titanium powder using circulating molten salt. JOM 50, 48–49 (1998).

    CAS  Article  Google Scholar 

  16. Sohn, H. Y. Ti and TiAl powders by the flash reduction of chloride vapors. JOM 50, 50–51 ( 1998).

    CAS  Article  Google Scholar 

  17. Segall, A. E., Papyrin, A. N., Conway, J. C. Jr & Shapiro, D. A cold-gas spray coating process for enhancing titanium. JOM 50, 52–54 (1998).

    CAS  Article  Google Scholar 

  18. Larson, H. R. & Eagar, T. W. The plasma-enhanced recovery of titanium by the electrolysis of titanate slags. JOM 50, 56–57 (1998).

    CAS  Article  Google Scholar 

  19. Okabe, T. H., Oishi, T. & Ono, K. Deoxidation of titanium aluminide by Ca-Al alloy under controlled aluminum activity. Metall. Trans. B 23, 583– 590 (1992).

    Article  Google Scholar 

  20. Okabe, T. H., Deura, T., Oishi, T., Ono, K. & Sadoway, D. R. Thermodynamic properties of oxygen in yttrium-oxygen solid solutions. J. Alloys Compounds 237, 841–847 (1996).

    Article  Google Scholar 

  21. Boghosian, S., Godo, Aa., Mediaas, H., Ravlo, W. & Ostvold, T. Oxide complexes in alkali alkaline-earth chloride melts. Acta Chem. Scand. 45, 145– 157 (1991).

    CAS  Article  Google Scholar 

  22. Gruber, H. & Krautz, E. Magnetoresistance and conductivity in the binary-system titanium oxygen. 2. Semiconductive titanium-oxides. Phys. Status Solidi A 69, 287–295 (1982).

    ADS  CAS  Article  Google Scholar 

  23. McQuillan, A. D. & McQuillan, M. K. Titanium 402–426 (Butterworths Scientific, London, 1956).

    Google Scholar 

  24. McKee, D. W. Gasification of graphite in carbon-dioxide and water-vapour—the catalytic effects of alkali-metal salts. Carbon 20, 59–66 (1982).

    CAS  Article  Google Scholar 

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This research was sponsored by the EPSRC. T.W.F. first suggested the electrochemical deoxidation of titanium metal. G.Z.C. was the first to observe that it was possible to reduce thick layers of oxide on titanium metal using molten salt electrochemistry. D.J.F. suggested the experiment, which was carried out by G.Z.C., on the reduction of the solid titanium dioxide pellets. M. S. P. Shaffer took the original SEM image of Fig. 4a.

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Correspondence to Derek J. Fray.

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Chen, G., Fray, D. & Farthing, T. Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride. Nature 407, 361–364 (2000).

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