U S Pat 3 773 889 1973 Nov; :
A solution or slurry is passed up through an ion-exchange resin column which is subdivided into a series of vertical sections each separated by a zone of reduced diameter. The flowrate of the solution or slurry is sufficiently high to provide a velocity of the upflowing solution or slurry greater than the settling velocity of the resin in the zone of reduced diameter. The mixing of resins occurs within each section but not between sections. This improves sorption efficiency and thereby reduces resin and equipment requirements. Operation of the column is semicontinuous and the operation can be fully automated. Thus, a feed solution containing u3o8 8.9 Ppm was passed through an ion-exchange column containing dowex 21k (16-20 mesh). Resin withdrawals and additions were made at 8-hour intervals. The solution flow rate was 20 gal/(ft2-min) and the u3o8 recovery was 99 pct.
U.S. Pat. 3,773,889; Nov. 20, 1973; Chem. Abstr. 80:123,526K