The FFC Cambridge Process

The content of this webpage was first provided in January 2001, and updated on 24 September 2003.
Use of the information in this and associated pages for education and research are welcome, although appropriate acknowledgement is appreciated.

by George Zheng Chen, (MSc, PhD, DIC, CChem)

The Fray-Farthing-Chen (FFC) Cambridge Process is a new process for the extraction of metals and alloys from their solid oxides by molten salt electrolysis. The FFC Cambridge Process can be summarised as follow, using titanium dioxide (rutile or anatase) and titanium as an example.

TiO₂ (solid, cathode) => molten salt electrolysis => Ti (cathode) + O₂ (anode)

To see a schematic presentation, click here.

Titanium produced by the FFC Process may be in the form of a powder or sponge. In both cases, the microstructure is composed of nodular particles whose sizes range between 10⁰ and 10² micrometers.

Click here to view an SEM image showing the typical microstructure of the FFC titanium sponge.

The FFC titanium sponge is also structurally very similar to the Kroll titanium sponge produced by a pyrometallurgical method invented by William J. Kroll in 1940.

Like aluminium (~£1,200/tonne) and other reactive metals, titanium (~£8,000/tonne) can in principle be extracted much more economically by an electrolytic method than a pyrometallurgical one, such as the Kroll process. Acknowledging the high cost of the pyrometallurgical method, William J. Kroll predicted in early 1950's that his invention would be replaced by an electrolytic route within 15 years. In the past 50 years, many attempts, supported by millions and millions of dollars, have been made to firstly dissolve titanium compounds (e.g. oxides and halides) into a molten electrolyte and then cathodically deposit titanium from the electrolyte solution. These attempts may be summarised as follow.

TiO or TiCl₄ (dissolved in molten electrolyte) => electrolysis => Ti (cathode) + O₂ or Cl₂ (anode)

Major problems encountered in the solution phase include i. redox recycling of the multivalent titanium ions between cathode and anode; ii. diaphragm failure; iii. dendritic deposition. These problems are avoided in the FFC process in which titanium always remains in the solid phase at the cathode.

The invention of the FFC Cambridge Process, patent filed in 1998, involved three people: Dr George Zheng Chen, Prof. Derek Fray and Dr. Tom W. Farthing. It resulted, "completely out of expectation" (TWF), from an EPSRC programme (a joint application of DJF and TWF) on removing oxygen from Group IV metals, particularly the alpha case on titanium and alloys by molten salt electrolysis.

GZC was the first to discover in late 1996 that oxide scales on titanium foils can be reduced to the metal by molten salt electrochemistry. After seeing the evidence with thick oxide scales, DJF suggested an experiment to reduce small pellets of TiO₂ powder, which GZC carried out successfully between late 1996 and early 1997. The work was soon introduced to DERA (part of it is now called QinetiQ), represented by Prof. Malcolm Ward-Close, who then decided to finance further research at Cambridge. At almost the same time, MWC acquired financial support for pilot testing the FFC invention at Farnborough from Mr. James Hamilton who later formed a new company, British Titanium plc, to explore the FFC invention for titanium based metals. At the end of 2001, with the support of the University Challenge Fund, a second new company, formerly called FFC Limited but now changed to Metalysis, was formed to develop the FFC Cambridge Process for extracting non-titanium metals.

Up to the end of 1999, results obtained from laboratories in both Cambridge and Farnborough, carried out mainly by GZC and Dr. Alastair Godfrey respectively, suggested a potential breakthrough on the production technology for titanium metal. The work was highlighted in the departmental magazine "Materials Eye" and published as a Letter to Nature in September 2000. The relevant international patent was published on 16 December 1999, and is now available on the internet (visit the webpage of esp@cenet and find WO9964638). In January 2002, the European Patent Office issued a Notice of Intention to grant this patent. It has also been or is being granted by a number of other countries.

More recent work carried out in the Materials Chemistry Group at Cambridge has proven that the FFC Process can also be applied to many other refractory and rare earths metal oxides, e.g. Cr₂O₃, Nb₂O₅, ZrO₂, Ta₂O₅, SiO₂, WO₃, CeO₂. The additional benefit of using the FFC Process is that the mixture of metal oxides can also be reduced to produce various alloys and intermetallics e.g. TiNi, TiAl₃, Ni₃Al_, TiNb, Ti6Al4V, Ni₂MnGa. These laboratory observations together with the pilot tests (kg scales) carried out at Cambridge and a few other independent institutions indicate that the FFC Cambridge Process may really open a great future for not only lowering the production cost of known metallic and semi-metallic materials but also for new materials that cannot be produced by existing technologies.

Selected patents and publications

Superconductor materials fabrication method using electrolytic reduction and infiltration
Chen GZ, Fray DJ, Yan XY, and Glowacki B, (UK filing date: October, 2001, GB 0124303.9, Inter. Pub. No.WO03031665)

Metal and alloy powders
Fray DJ, Chen GZ (UK filing date: November 2000, GB27929.9, Inter. Pub. No. WO0240725 )

Intermetallic Compounds
Fray DJ, Copcutt R and Chen GZ, (UK filing date: Nov. 2000, GB 0027930.7)

Removal of oxygen from metal oxides and solid solutions by electrolysis in a fused salt
Fray DJ, Farthing TW and Chen Z (UK filing date: 5 June 1998, PCT/GB99/01781, Inter. Pub. No. WO9964638)

Direct electrolytic preparation of chromium powder
Chen GZ, Gordo E, Fray DJ
Metall. Mater. Trans. B, (submitted in Apr., recommended for publication in July 2003)

Electrochemical fabrication of nickel manganese gallium alloy powder
Wood JM, Copcutt R, Chen GZ, Fray DJ,
Adv. Eng. Mater., (accepted in May 2003)

Voltammetric Studies of the Oxygen-Titanium Binary System in Molten Calcium Chloride
Chen GZ and Fray DJ
J. Electrochem. Soc., 149 (2002) E455 - E467

Cathodic deoxygenation of the alpha-case on titanium and alloys in molten calcium chloride
Chen GZ, Fray DJ and Farthing TW
Metall. Mater. Trans. B, 32B (2001) 1041-1052

Novel cathodic processes in molten salts
Chen GZ and Fray DJ
MS6, Proceedings of 6th International Symposium on Molten Salt Chemistry and Technology, eds. Chen Nianyi, Qiao Zhiyu, Shanghai University Press, Shanghai, China, Oct. 2001, (2001) 79-85. ISNB 7-81058-391-3.

Electro-deoxidation of Metal Oxide
Chen GZ and Fray DJ
Light Metals, TMS 2001, 1147

Cathodic refining in molten salts: removal of oxygen, sulfur and selenium from static and flowing molten copper
Chen GZ and Fray DJ
J. App. Electrochem., 31 (2001) 155

Novel Direct Electrochemical Reduction of Solid Metal Oxides to Metals Using Molten Calcium Chloride as the Electrolyte
Chen GZ and Fray D J
Progress in Molten Salt Chem., vol. 1, eds. Berg, R.W. and Hjuler, H.A. , Elsevier, Paris, (2000)157.

Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride
Chen GZ, Fray DJ and Farthing TW
Nature, 407 (2000) 361.

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For more information, please contact

Dr. George Z. Chen

Email: george.chen@nottingham.ac.uk

Tel: +44 (0)115 9514171
Fax: +44 (0)115 9514115 (FAO Dr. George Z. Chen)