450 BOC Gases, Otis, Kan. 1,100 ExxonMobil, Shute Creek, Wyo. 1,200 Keyes Helium, Keyes, Okla. 140 Nitrotec Energy, Chillicothe, Tex. Crude helium is recovered from helium-bearing natural gas using cryogenic refrigeration and rectification. It is then purified, either over activated charcoal at cryogenic temperatures or by pressure swing adsorption.
Product is distributed either as compressed gas or cryogenic liquid.
Air Products, BOC, Liquid Air and Praxair market product from ExxonMobil. Air Products markets product from Keys Helium. BOC and Praxair market product from Union Pacific Resources. About 65 percent of the total is purchased as compressed gas, and 35 percent as cryogenic liquid. The strongest segment for helium is optical fiber production, which is growing at about 20 percent per year, albeit from a relatively small base.