Can anyone provide details on the Castner's process for sodium production? I am specifically looking for rate of reaction and energy consumption for the castner's process. Also which companies use this type of process for sodium production?
Dear Bryan Gathuka.
The Costner process is a process for manufacturing sodium metal by electrolysis of molten sodium hydroxide at approximately 330 °C. Below that temperature, the melt would solidify; above that temperature, the metal would start to dissolve in the melt.
The diagram shows a ceramic crucible with a steel cylinder suspended within. Both cathode (C) and anode (A) are made of iron or nickel. The temperature is cooler at the bottom and hotter at the top so that the sodium hydroxide is solid in the neck (B) and liquid in the body of the vessel. Sodium metal forms at the cathode but is less dense than the fused sodium hydroxide electrolyte. Wire gauze (G) confines the sodium metal to accumulating at the top of the collection device (P) The cathode reaction is
2Na+ + 2e− → 2Na
The anode reaction is
2OH− → ½O2 + H2O + 2e−
Despite the elevated temperature, some of the water produced remains dissolved in the electrolyte. This water diffuses throughout the electrolyte and results in the reverse reaction taking place on the electrolyzed sodium metal:
Na + H2O → ½H2 + Na+ + OH−
Regards,
Prem Baboo
http://www.sciencemadness.org/talk/viewthread.php?tid=9797
Sodium Metal-Illustrated Practical Guide
More informations on this link
Dear Brian, I have decommissioned a lot of such plants in the past (more than 10, world wide). - But it is considered as a technology from yesterday. Therefore the guys who knew about design parameters are either dead or in retirement. Otherwise in the UK there are still some plants in operation.
For the sake of completeness: Correctly it is the Caster - Kellner Process, because it was called after Castner Kellner Alkali Co, chemical manufacturers, of Weston Point, Runcorn and Carville (Wallsend-on-Tyne).
Karl Kellner was the intellectual father of the process and he was also the holder of the patent. - It is also interesting to see, that some the founders of the British Chemical Industry were either Germans or Austrians such as Kellner, Caster, Brunner and Mond.
kind regards
Ruediger
Dear Prem and Bryan,
The process also works with Potassium Chloride Brine. In the original "Castner-Kellner-Process" beaded mercury was used a running kathode. Commonly they used high direct current in a range of more than 10 kilo Ampere for this Electrolysis Process. The main objective of these plants was to produce chlorine gas. In Germany in the Thirties they used the Sodium generated by the "Amalgam process" as a catalyst for the production of synthetic rubber from the gas butadiene "Bu-Na-Process".
Companies used the CASTNER - KELLNER process were: Solvay, Orica, BuNa Schkopau (now DOW), EKA, SolVin, Spolchemie, AkzoNobel, Perstorp, Arkema, MSSA, PPChemicals, Prod. Chim. d'Harbonnières, BASF, Bayer, CABB, Evonik Degussa, INEOS ChlorVinyls, VESTOLIT, Wacker Chemie, Hellenic Petroleum, BorsodChem, Altair Chimica, Borregaard, Elkem and many more.
Regards Ruediger
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