FFC Cambridge process 1829571 221165702 2008-06-23T09:29:18Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. The '''FFC Cambridge Process''' is an [[electrochemical]] method in which ''solid'' metal compounds, particularly [[oxide]]s, are cathodically reduced to the respective metals or [[alloy]]s in molten salts. ==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". Metalysis Ltd own the worldwide exclusive rights to exploit the process for all metals and alloys. ==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). In the molten calcium chloride, molten calcium metal is free to wander about in the melt, including diffusing into and reducing crystalline [[titanium dioxide]] and other [[metal oxide]]s. 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 reoxidized 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 [[coulomb]]ic current efficiency losses in the FFC Cambridge process might be quite tolerable. Ion recycling between cathode and anode can be helped by using suitable electrolyte separating diaphragms. The FFC process 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 savings 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]]. 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 rock]]s ([[ilmenite]], FeTiO<sub>3</sub>) to support space travel and celestial habitation. == References == * {{cite journal | author = G. Z. Chen, D. J. Fray, T. W. Farthing | title = Direct Electrochemical Reduction of Titanium Dioxide to Titanium in Molten Calcium Chloride | journal = [[Nature (journal)|Nature]] | year = 2000 | volume = 407 | pages = 361–4 | doi = 10.1038/35030069}} * {{cite journal | title = Calciothermic reduction of TiO<sub>2</sub> and in situ electrolysis of CaO in the molten CaCl<sub>2</sub> | author = Ryosuke O. Suzuki | journal = [[Journal of Physics and Chemistry of Solids ]] | volume = 66 | year = 2005 | pages = 461–465 | doi = 10.1016/j.jpcs.2004.06.041}} * {{cite journal | title = Production of titanium powder directly from TiO<sub>2</sub> in CaCl<sub>2</sub> through an electronically mediated reaction (EMR) | author = Il Park, Takashi Abiko and Toru H. Okabe | journal = Journal of Physics and Chemistry of Solids | volume = 66 | year = 2005 | pages = 410–413 | doi = 10.1016/j.jpcs.2004.06.052}} *[http://63.1911encyclopedia.org/C/CA/CALCIUM.htm A molten calcium chloride electrolysis reference] *[http://www.epa.gov/epaoswer/other/mining/minedock/id/id4-cal.pdf An aluminothermic calcium production reference] == External links == * [http://www.metalysis.com/ Metalysis Ltd] * [http://www.nottingham.ac.uk/~enzgzc/FFC_Process.htm www.nottingham.ac.uk] * [http://www.msm.cam.ac.uk/djf/ Materials Chemistry Group at Cambridge University] [[Category:Chemical processes]] [[Category:Electrochemistry]] [[Category:Titanium]]