GB998646A - Improvements in or relating to liquid-liquid extraction - Google Patents

Abstract

998,646. Centrifugal liquid-liquid extraction. VITAMINS Ltd. July 2, 1964 [April 3, 1963], No. 13243/63. Heading B1F. In centrifugal liquid-liquid extraction, the liquids to be contacted are centrifugally distributed in the form of separate layers of annular form, agitated by insertion of an agitator into said layers and allowed to re-form into said layers by removal of the agitator, one of said layers being then separately collected. As shown in the Figures, a plurality of cells separated by annular plates 11 attached to a rotatable drum 10 each comprise one such extraction zone, the drum being rotated by means of a drive connected to one of supporting rollers 12. A tube 14, parallel but not coaxial with drum 10, supports an agitator 17 withdrawal tube 19 and drain tube 18 for each of said cells and is rotated by means of a drive to supporting shaft 35 in the reverse direction to the drum. As the tube 19 rotates, the agitators 17 first enter the layers of liquid formed by rotation of the drum whereby strong ,agitation takes place: further rotation of the tube lifts the agitators clear of the liquids which thus re-form into layers, after which the withdrawal tubes 19 reach the position shown in Fig. 7 and begin to remove the inner layers into separate cells formed in tube 14 by means of discs corresponding in position to the annular plates 11. Continued rotation of the inner tube brings the outlet pipes 18 into a position to discharge the removed liquid, and said pipes are so shaped as to convey said liquid into the next adjacent zone of the outer drum. The lower phase is filled into the apparatus before commencing to run the machine: the upper phase is introduced by means of a scoop 24 which enters a reservoir shown in broken outline at 38. Liquid is removed through line 25. Further modifications show (a) the provision of a second series of withdrawal pipes to remove the outer layers after removal of the inner layers, the arrangement being such that an inner layer from one cell and an outer layer from an adjacent cell are collected into a single cell in the central tube, (b) a withdrawal pipe having chamfered end surfaces to obviate disruption of the layers, and (c) a different arrangement of agitator and tubes on tube 14 whereby the latter may be rotated in the reverse direction. In a further embodiment each cell in tube 14 has a median partition forming two halves into which the inner and outer layers from adjacent cells in the drum are withdrawn, for subsequent discharge into a common cell in said drum. It is also stated that by the use of two withdrawal tubes both layers may be transferred in opposite directions, the liquid to be treated being introduced at the centre of the apparatus whilst effluents of constant composition are withdrawn at the ends.