GB960369A - Improved continuous counter current extractor - Google Patents

Abstract

<PICT:0960369/C4-C5/1> <PICT:0960369/C4-C5/2> A continuous counter-current extractor in which animal and fish protein, bones and cellulosic material are extracted or washed with a liquid, e.g. acetone, to obtain a fat or oil comprises a plurality of stages each stage embodying a screw-press conveyer and a container in which the solid and liquid are contacted and agitated by means of a rotary agitator 16 which incorporates scoops 17 by means of which the solid is removed from the container and deposited in the screw-press conveyer of that stage wherein the solid and liquid are largely separated, the liquid passing through the perforated or porous wall of the screw casing and to the next container down stream and the solid being conveyed in the opposite direction to the next container up stream. Preferably, the screw-press conveyers and agitators are all mounted on a common shaft 15 which passes from end to end of the casing of the extractor which is provided with a hinged cover 12 whereby the extractor may be sealed from the atmosphere and operated at an elevated pressure and temperature. Other optional features are the provision of a springloaded sealing member 66 on the exit ends of the screw-press conveyers depicted in Fig. 6 which holds back the solid material until it has been drained and pressed into a cake and an apportioning device whereby for example, only a part of the liquid extracted by a screw-press is passed in counter-current, the remainder being returned to the stage from whence it came, means, e.g. valves being provided to control the relative amounts of liquid following the alternative routes (see Fig. 6).