From: zenadsl6186@zen.co.uk   
      
   Ian Stirling wrote:   
      
   > Paul F. Dietz  wrote:   
   >> Henry Spencer wrote:   
   >>   
   >>> And indeed, the big snag is availability.  If you want a thousand tons of   
   >>> xenon, you simply can't get it in any reasonable amount of time.  Even a   
   >>> hundred tons would be problematic unless you order years ahead.  This is   
   >>> essentially independent of the price you're willing to pay; even if you   
   >>> outbid everyone else, there simply isn't that much production capacity.   
   >>   
   >> I'm sure if you wanted to spend enough money, you could get more, but   
   >> the cost would be frightening.  Xenon is obtained as a byproduct of   
   >> air liquefaction/separation, and is affordable only because almost all   
   >> the cost is borne by the customer who needs the oxygen, nitrogen, etc.   
   >> You'd have to build entire new air separation plants just for making   
   >> the xenon.   
   >   
   > I was about to ask this earlier.   
   > Does anyone happen to know what fraction of air seperation plants extract   
   > the Xenon - as upgrading ones that don't might be cheap.   
   > Also, what's the size of this sector?   
   > I'd guess at tens of billions a year, in which case you'd probably need   
   > to spend rather a lot to double or more capacity.   
      
      
      
   Air is 1 part in 20 million xenon. If the recovery rate is 50% then to get   
   1,000 tons of xenon you would need to liquify 40 billion tons of air.   
      
   If we generously estimate the present rate of worldwide air liquification at   
   about 500 million tons pa (I think it's actually about 100 million tons),   
   that's about 80 years production, if everyone recovers xenon.   
      
   Air liquification is likely to decrease though, as PSA technology becomes   
   more widely used for oxygen and nitrogen production.   
      
      
      
      
   Xenon is also available in small quantities from some geological sources,   
   wells and springs and suchlike, but that's a drop in the bucket.   
      
   I had a quick look at some other potential air extraction methods, for   
   instance chilling but not liquifying air (xenon boils at -108C), cold   
   extraction with ?argon liquid, differential absorbtion, and venturi/cyclone   
   methods; but there is just too little xenon in the air for the cheaper   
   methods to work, and even the cheaper methods would be - expensive.   
      
   Just fanning that much air into a gentle breeze would cost $100 million or   
   so ...   
      
      
   --   
   Peter Fairbrother   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)