THE RECOVERY OF RADIO KRYPTON FROM DISSOLVER WASTE GASES BY FRACTIONAL EXTRACTION IN SOLVENTS
The use of solvents for scrubbing out soluble gases from mixtures is well known, but the separation of mixtures of relatively insoluble gases has not been studied very closely. A special case occurs, however, when small quantities of valuable gases occur in a mixture of less soluble gases. The mixture nitrogen, oxygen, argon, krypton, xenon, and nitrous oxide which constitutes dissolver waste gas is a pertinent example. The last three have an abundance of 1% or less. and the required products are krypton (stable and radioactive) and xenon (stable). The solubilities of nitrogen, oxygen, and argnn in carbon tetrachloride are <0.35 v/v and those of krypton, xenon, and nitrous oxide are>1 v/v. A plant designed to separate the first three from the last three components is described. In principle the system is similar to any two phase extraction system, but differs from the normal gas/liquid column in having a low gas flow and continuous liquid phase, and from a normal solvent extraction column in having bottom reflux. With low gas flows, back diffusion in a continuous gas phase would be very, disadvantageous, consequently a continuous liquid phase was used. In this case steady operation with low gas flows requires considerable care and control. The feed concentration of the required product gases is low, and the effective separation factors are comparatively low. This requires an efficient reflux system at the foot, and the reflux ratio must be high. Equations were derived for the behavior of each component on the assumption that each gas has the same plate height. The calculation is complicated by the fact that the flow rate (of gas in both phases) is not constant along the length of the column but increases towards the foot due to the accumulation there of the more soluble components. This also leads to maxima in the concentration gradients of all gases in the mixture except those of greatest and least solubility, an effect which can only occur to any large extent in mixtures of more than two components having widely different solubities. (auth)
- Research Organization:
- Atomic Energy Research Establishment, Harwell, Berks, Eng.
- NSA Number:
- NSA-13-007062
- OSTI ID:
- 4280052
- Report Number(s):
- A/CONF.15/P/309
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-59
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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