Abstract
Molten salts have been used in metal extraction for more than a century, and chemists and metallurgists have extensively studied the properties of these high-temperature phases. Because fundamental properties of salts, such as conductivity, viscosity, and density, have been determined to a high degree of accuracy, the processes have been optimized. Unfortunately, very few new, innovative processes have been developed in the past 50 years and many metals are still extracted by essentially the same routes as those used in the last century. This paper discusses possible new processes involving electrodeoxidation, mediated reactions, and novel cell designs.
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S. Boghosian et al., “Oxide Complexes in Alkali Alkaline-Earth Chlorides,” Acta Chem. Scand., 45 (1991), pp. 145–147.
R.G. Ward and T.P. Hoar, “The Electrolytic Removal of Oxygen, Sulfur, Selenium and Tellurium from Molten Copper, (1961–2), pp. 6–12.
G.Z. Chen and D.J. Fray, “Cathodic Refining in Molten Salts: Removal of Oxygen, Sulfur and Selenium from Static and Flowing Molten Copper,” J. Appl. Electrochemistry, 31 (2001), pp. 155–164.
F. Tailoka and D.J. Fray, “Fused Salt Electrorefining of Bismuth-Lead Alloys in a Recessed Electrode Cell,” Trans. IMM, 104 (1995), p. C51-C58.
A. Cox et al., “The Removal of Magnesium and Manganese from Secondary Aluminium During Recycling of Beverage, Can Scrap Using an Electrorefining Recessed Electrode Cell,” Global Symposium on Recycling, Waste Treatment and Clean Technology, eds. I. Gaballah, J. Hager, and R. Solozabel (Warrendale, PA: TMS, 1999), pp. 1045–1053.
T.H. Okabe, et al., “Electrochemical Deoxidation of Titanium,” Met. Trans., 24B (1993), pp. 449–455.
T.H. Okabe et al., “Electrochemical Deoxidation of Yttrium-Oxygen Solid Solution,” J. Alloys and Compounds, 237 (1996), pp. 150–154.
T.H. Okabe et al., “Thermodynamic Properties of Oxygen in Ln-O (Ln=La,Pr,Nd) Solid Solutions and Their Deoxidation by Molten Salt Electrolysis,” J. Mining and Materials Processing Institute of Japan, 114 (1998), pp. 813–818.
K. Hirota et al., “Electrochemical Deoxidation of RE-O (RE=Gd,Tb,Dy,Er) Solid Solution,” J. Alloys and Compounds, 282 (1999), pp. 101–108.
G.Z. Chen et al., “Cathodic Deoxygenation of the Alpha-Case on Titanium and Alloys in Molten Calcium Chloride,” Trans. Met. Soc. B, in press.
G.Z. Chen et al., “Direct Electrochemical Reduction of Titanium Dioxide to Titanium in Molten Calcium Chloride,” Nature, 407 (2000), pp. 361–364.
H. Gruber and E. Krautz, “Magnetoresistance and Conductivity in the Binary-System Titanium Oxygen— 2. Semiconductive Titanium-Oxides,” Phys. Status Solidi A, 69 (1982), pp. 287–295.
M. Ward-Colse and A. Godfrey, private communication.
G. Cobel et al., Titanium ′80, Science and Technology, Vol. 3, ed. H. Kimura and O. Izumi (Warrendale, PA: TMS, 1980), pp. 1969–1976.
W.R. Opie and O.W. Moles, “A Basket Cathode Electrolytic Cell for Production of Titanium,” Trans. Met. Soc. AIME, 218 (1960), pp. 646–649.
M.V. Ginetta, “Method of Producing Metals by Cathodic Dissolution of their Compounds,” U.S. patent 4,400,247 (23 August 1983).
F.H. Froes, “Titanium and Other Light Metals: Let’s Do Something About Cost,” JOM, 50 (9) (1998), p. 15.
A.D. Hartmann et al., “Producing Lower-Cost Titanium for Automotive Applications,” JOM, 50 (9) (1998), pp. 16–19.
G.Z. Chen and D.J. Fray, “Novel Direct Electrochemical Reduction of Solid Metal Oxides to Metals Using Molten Calcium Chloride as the Electrolyte,” Progress in Molten Salt Chemistry 1, ed. R.W. Berg and H.A. Hjuler (Paris: Elsevier, 2000).
G.Z. Chen and D.J. Fray, Electro-Deoxidation of Metal Oxides,” Light Metals 2001, ed J.L. Anjier (Warrendale, PA: TMS, 2001), pp. 1147–1151.
T.H. Okabe and D.R. Sadoway, “Metallothermic Reduction as an Electronically Mediated Reaction,” J. Materials Research, 12 (1998), pp. 3372–3377.
T. Uda et al., “Contactless Electrochemical Reduction of Titanium (II) Chloride by Aluminium,” Metall Mater. Trans. B, 31 (2000), pp. 713–721.
I. Park et al., “Tantalum Powder Production by Magnesiothermic Reduction of TaCl5 Through an Electronically Mediated Reaction (EMR),” J. Alloys and Compounds, 280 (1998), pp. 265–272.
T.H. Okabe et al., “Production of Niobium Powder by Electronically Mediated Reaction (EMR) Using Calcium as Reductant,” J. Alloys and Compounds, 288 (1999), pp. 200–210.
I. Park et al., “Semi-Continuous Production of Niobium Powder by Magnesiothermic Reduction of Nb2O5,” Mater Trans., 42 (2001), pp. 850–855.
A. Cox and D.J. Fray, “Application of Centrifugal Fields to the Electrowinning of Lithium,” Trans. IMM, 106 (1997), pp. C123-C128.
A. Cox, J.W.A. Morris, and D.J. Fray, “Improving the Energy Efficiency of Electrowinning of Lithium,” Light Metals 1998, ed. B. Welch (Warrendale, PA: TMS, 1998), pp. 295–298.
B. Chalmers, Principles of Solidification (New York: John Wiley, 1964).
P.R. Beeley, Foundry Technology (London: Butterworth Scientific, 1982).
D.J. Fray et al., “Electrochemical Titration of Sodium into Aluminium Alloys,” Light Metals 1995, ed. J.W. Evans (Warrendale, PA: TMS, 1995), pp. 1379–1383.
D.J. Fray, “The Electrochemical Addition of Alkali Metals to Molten Metals from Salt Mixtures,” Pyrometallurgy ′95 (London: IMM, 1995), pp. 193–206.
G.R. Doughty and D.J. Fray, “Use of Sodium Beta Alumina in Novel Processes for the Production of Metals,” Ionics, 5 & 6 (1998), pp. 315–318.
G.R. Doughty and D.J. Fray, “Electrochemical Removal of Sodium from Metals,” Trans. IMM, 108C (1999), pp. C167-C168.
K.E. Oberg et al., “Electrochemical Deoxidation of Induction Stirred Copper Melts,” Met. Trans., 4 (1973), pp. 75–82.
P. Soral et al., “A Pilot-Scale Trial of an Improved Galvanic Deoxidation Process for Refining Molten Copper,” Met. and Mater. Trans. B, 30 (1999), pp. 307–321.
U. Pal, private communication.
H. Kvande and W. Haupin, “Intert Anodes for AlSmelters: Energy Balances and Environmental Impact,” JOM, 53 (5) (2001), pp. 29–33.
D.R. Sadoway, “Inert Anodes for the Hall-Heroult Cell: The Ultimate Materials Challenge,” JOM, 53 (5) (2001), pp. 34–35.
J. Thonstad and E. Olsen, “Cell Operation and Metal Purity: Challenges for the Use of Inert Anodes,” JOM, 53 (5) (2001), pp. 36–38.
C. Brown, “Next Generation Vertical Electrode Cells,” JOM, 53 (5) (2001), pp. 39–42.
J. Keniry, The Economics of Inert Anodes and Wettable Cathodes for Aluminium Reduction Cells,” JOM, 53 (5) (2001), pp. 43–47.
L. Edwards and H. Kvande, “Inert Anodes and Other Technology Changes in the Aluminium Industry—The Benefits, Challenges, and Impact on Present Technology,” JOM, 53 (5) (2001), pp. 48–50.
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For more information, contact D.J. Fray, University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge, CB2 3QZ, U.K.; +44-1-223-334-306; fax +44-1-223-334-567; e-mail djf25@cam.ac.uk.
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Fray, D.J. Emerging molten salt technologies for metals production. JOM 53, 27–31 (2001). https://doi.org/10.1007/s11837-001-0052-5
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DOI: https://doi.org/10.1007/s11837-001-0052-5