GB775415A - Improved method and means for extracting an adsorbable solute from a suspension of finely divided solids in a solution - Google Patents

Abstract

In extracting a soluble component from a suspension of finely divided solids in a solution, the solution is passed through a static bed of granular adsorbent and the flow thereof pulsated to subject the bed to momentary expansion, the soluble component bein adsorbed on successive zones of the bed and finally being recovered from the adsorbent. The pulsating action momentarily retards, interrupts or reverses the flow of the solution. The adsorbent bed may rest on a perforated screen and <PICT:0775415/III/1> <PICT:0775415/III/2> <PICT:0775415/III/3> <PICT:0775415/III/4> the minimum size of the particles making up the bed be at least twice that of the perforations in the screen. While inoperative, a bed of granular adsorbent material 1 almost fills the space in a casing 2 between an upper screen 3 and a bed of granular sand 5 resting on a coarse screen 4 which separates the casing 2 from a lower chamber 6 containing a bed 12 of coarse sand adapted to distribute evenly an upward flow of suspension 11 fed from a valved stand pipe 8 into a bottom chamber 7 havin gits lower surface formed as a diaphragm 10 adapted to be oscillated by a crank device 14. Treated suspension flows away through a pipe 15. The screen 4 and sand beds 5, 12 may be replaced by a single bed of graded sand into the mid-portion of which the suspension is fed by a pump, the stand pipe 8 being omitted: a bed of filter particles of less specific gravity than the adsorbent material 1 contacts the underside of the upper screen 3. In the construction shown in Fig. 3, supension entering the casing at the top through a pipe 28 spreads over a baffle 29 and flows downwards through adsorbent 24 and a distribution bed 27 of Raschig rings to a stand pipe 32 leading to an overflow pipe 34. By placing a valve in the pipe 34 and fitting a pipe such as the pipe 15, Fig. 1, in the top of the casing, the apparatus can be adapted for either downward or upward flow. If an adsorbent of low density is used, and the flow is upwards, only the upper screen is required. The suspension itself may be pulsated by a device 51, Fig. 6, before entering the casing holding the adsorbent 47 which rests on a bed 48 of graded sand in which is a spreader 53 for the suspension: the flow is controlled to avoid undue turbulence which would cause loss of adsorbent through the discharge pipe. The pulsator may be an oscillating diaphragm or a piston and cylinder device or the suspension may enter a chamber 68, Fig. 9, and lift a diaphragm 72 against the pressure of an adjustable spring 71: the movement of the diaphragm opens a valve 70 blocking the outlet pipe 67 until loss of pressure due to the escaping liquid closes it again. In an example, leach pulp containing about 15 per cent by weight of suspended solids that would pass a 200 mesh, and 2.5 gms/lit. of uranium oxide were passed through a tower containing adsorbent sold under the Registered Trade Marks "Amberlite" and "De-Acidite" with pulsations of \sB 1/8 inch at 110 strokes/min. Break through of uranium occurred at 45 per cent saturation of adsorbent.