The FFC Cambridge Process is an electrochemical method in which solid metal compounds, particularly oxides, are cathodically reduced to the respective metals or alloys in molten salts. Electrochemistry is the study of the electronic and electrical aspects of chemical reactions. ... An oxide is a chemical compound of oxygen with other chemical elements. ... An alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ...

History and invention

The method was invented by three scientists, George Z. Chen, Derek J. Fray and Tom W. Farthing, between 1996 and 1997 in the University of Cambridge, from the names of whom derive the three letters in the name of the process. Chen 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, Fray suggested an experiment to reduce small pellets of titanium dioxide powder, which Chen carried out successfully between late 1996 and early 1997. Farthing, who first suggested to electrochemically remove oxygen from titanium metal, later commented on the discovery as "completely out of expectation". The University of Cambridge, located in Cambridge, England, is the second-oldest university in the English-speaking world. ... Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. ...

Chemistry of the process

The basic underlying principle of the FFC Cambridge process is that metallic calcium - unlike sodium or magnesium - is quite soluble in its own molten chloride salt: molten calcium chloride dissolves up to a few mole percent calcium metal (3.9 mol% Ca at 900 °C). This molten salt dissolved, molten calcium metal is free to wander about in the melt, including diffusing into and reducing crystalline titanium and other metal oxides. The calcium mobility in the melt is both a blessing and a curse: it's a blessing for providing this calciothermic reduction of titanium dioxide, but a curse when it comes to current efficiency, because the cathode-reduced metallic calcium can also wander back to the anode, and get reoxidised with the evolved gases there. For this reason, the electrolytic production of pure calcium metal from its molten chloride involves an iron rod cathode that must be gradually raised, and a layer of calcium metal deposits as a continuation of the iron rod. Should the calcium rod be left to soak in the molten salt, it would simply wash away as it forms, and recycle to the anode. For this and other economic reasons, the commercial calcium metal production is done via the aluminothermic reduction/calcium vapor vacuum distillation route instead of an electrolytic one, similar to how magnesium is produced via the silicothermic Pidgeon process. Still, considering that the highly uneconomical batch-based Kroll process can take 2-5 days for a single batch to complete, the coulombic current efficiency losses in the FFC Cambridge process — due to ion recycling between cathode and anode, which can be helped by using suitable electrolyte separating diaphragms — might be quite tolerable. General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... Calciothermic reactions are thermic chemical reactions which use calcium metal as the reducing agent at high temperature. ... Aluminothermic reactions are exothermic chemical reactions using aluminium as the reducing agent at high temperature. ... Silicothermic reactions are thermic chemical reactions using silicon as the reducing agent at high temperature (800-1400°C). ... // Overview The Pidgeon process is one of the methods of magnesium metal production, via a silicothermic reduction, practical production requiring roughly 35-40 MWh/ton of metal produced, which is on par with the molten salt electrolytic methods of production, though above the 7 MWh/ton theoretical minimum. ... The Kroll process is a pyrometallurgical industrial process used produce metallic titanium and was invented in 1940 by William J. Kroll, at the Albany Research center in Oregon. ...

The new method is much simpler in operation and uses less energy than many current industrial technologies, such as the Kroll process, and promises a great potential for cheap production of useful reactive metals such as titanium, zirconium and tantalum. Its other advantage is to produce various metal alloys directly from mixed metal oxide powders, which will offer more saving in energy and operation cost. It is also scientifically interesting because the electrolysis can be carried out on an insulator oxide, such as zirconia and silica. Furthermore, the process can extract pure oxygen gas from oxide based minerals. This is useful, for example, for generating oxygen gas on the Moon from lunar rocks (ilmenite, FeTiO₃) to support space travelling and even living by humans. General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Atomic mass 91. ... General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Atomic mass 180. ... Zirconia (ZrO2) is a white crystalline oxide of zirconium. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Ilmenite (FeTiO3) is a weakly magnetic iron-black or steel-gray mineral found in metamorphic and plutonic igneous rocks. ...

External links

• britishtitanium.co.uk
• www.nottingham.ac.uk

References

• Direct electrochemical reduction of titanium dioxide to titanium in molten calcium chloride George Zheng Chen, Derek J. Fray, Tom W. Farthing Nature 407, 361-364 (21 Sep 2000) Abstract
• Calciothermic reduction of TiO₂ and in situ electrolysis of CaO in the molten CaCl₂ Il Parkb, Takashi Abikoc, Toru H. Okabea, Journal of Physics and Chemistry of Solids 66 (2005) 461-465
• A molten calcium chloride electrolysis reference
• An aluminothermic calcium production reference