Patent GB-813269-A (GB)
Title: Improvements in and relating to the extraction of uranium
IPC: C22B60/02
Filed: 1956-01-03
Abstract: <PICT:0813269/III/1> <PICT:0813269/III/2> Uranium is continuously extracted from a solution such as a leach liquor or desanded leach pulp by flowing the liquid upwardly through a bed of ion exchange resin retained between perforated plates in a column, the flow being pulsated so as to maintain the particles in a non-turbulent state of "teeter" (semi-fluidization), removing a slurry of loaded resin from the base of the bed, separating the retin from the liquid, countercurrently eluting the uranium from the resin which is then returned to the bed and recovering uranium from the eluate.  In the exemplified embodiment (see Fig. 1) a desanded leach pulp is passed by means of a pump 10 into a head tank 8 (above the level of the liquid in the exchange column) to which asymmetrical pulsations are applied by the operation of a rotary or slide valve 11 alternately connected to a source of vacuum and a vacuum release valve 13.  A float valve 14 prevents the inrush of liquor to the vacuum system. The liquor then passes via a lower chamber 7 where higher-frequency symmetrical impulses of smaller amplitude are applied by means of eccentric 42 and diaphragm 41, to the bed of exchange resin lying between perforated plates 3 and 4, the former of which includes an opening through which the resin is drawn due to the pulsations of the liquor.  Free air bubbles must be removed from the liquor prior to entry into the bed.  The liquor passes out through perforated plate 3 and outlet pipe 6. The loaded resin is passed to surge tank 16, and after dewatering on a device 17 having a pump 18 for return of liquid to the compartment 7 (or an earlier stage such as the leach pulp preparation stage of the process), is conducted to an elution unit 20 (as described and claimed in Specification 770,110, [Group II], consisting of a number of open compartments 28 (see Fig. 2) separated by baffles 26, 27 between which the resin passes due to its hydrostatic head and having a perforated base 21 through which the eluate enters from chambers 23 lying below said compartments 28. Each of chambers 23 is provided with a diaphragm and an eccentric to impart pulsations to the flow of eluting liquid, which enters at 34 and is passed from the upper part of one compartment 28 to the next compartment 23 in the series, via pipes 31 having non-return valves 33 (or positive transfer means such as a bucket wheel or pump) finally emerging at 35.  Uranium is recovered from this eluate. After reaching the right-hand end compartment the resin overflows into a sump 37 from which it is elevated and passed via a dewatering screen 39 (Fig. 1) back into the hopper 5 for reuse.  If desired one or two cells of the elution unit may be used as a rinse section and eluant initially fed to the preceding cell.  In an example, a leach pulp comprising 1.5 g/l. of uranyl sulphate and 15 per cent of slimy ore solids is used with an "Amberlite" (Registered Trade Mark) resin. The eluant was a solution of N sodium chloride + N/10 sulphuric acid and the uranium was precipitated as oxide from the uranyl sulphate solution thus produced.  Reference has been directed by the Comptroller to Specification 775,415, [Group II].