GB1211104A - Process and apparatus for the enrichment of isotopic mixtures - Google Patents

Abstract

1,211,104. Separating gaseous isotopic mixtures. SOC. NATIONALE DES PETROLES D'AQUITAINE. 8 Jan., 1968 [17 Jan., 1967; 20 Feb. 1967; 7 Aug., 1967], No. 1075/68. Heading B1L. Gaseous mixtures of isotopic constituents are separated into enriched fractions by differential sorption, e.g. on molecular sieves or on metal halides, by passing the mixture into a bed of the sorbent which has previously been saturated with a different inert 'buffer gas until the mixture has displaced the buffer gas and one enriched fraction has traversed the bed, discontinuing injection of the isotopic mixture and once more passing buffer gas through the bed to displace and separately collect at the outlet of the bed the various enriched isotopic fractions. In a preferred embodiment, a plurality of sorption units are used in cascade, the mixture to be separated being passed to the middle unit, the enriched head fraction therefrom being passed for further enrichment to the unit next downstream, the other enriched tail fraction being passed for further enrichment to the unit next upstream, and the intermediate fraction of similar composition to the original feed being recycled, with further similar enrichment being carried out in each unit. Particular separations described are <SP>12</SP>C from <SP>13</SP>Cby enrichment of carbon monoxide fractions using a 5A molecular sieve and helium as buffer gas; <SP>20</SP>Ne from <SP>23</SP>Ne at the temperature of liquid nitrogen using a molecular sieve and helium as buffer gas; <SP>10</SP>B from <SP>11</SP>B at 10‹C. by enrichment of boron trifluoride fractions using "Chromosorb WAW" impregnated with dioctyl sulphide and nitrogen as buffer gas; and <SP>235</SP>U from <SP>238</SP>U at 400‹C. by enrichment of uranium hexafluoride using sodium fluoride and a mixture of nitrogen and fluorine as buffer gas.