GB404261A - Improvements in or relating to the extraction of solutes from solutions - Google Patents

Abstract

<PICT:0404261/IV/1> <PICT:0404261/IV/2> <PICT:0404261/IV/3> <PICT:0404261/IV/4> The extraction of solutes from solutions by means of solvents immiscible therewith and of different density is effected by causing the solution and solvent to flow in counter-current through a column, at least one of the liquids being introduced in finely divided form. The extraction may be effected in stages, with emulsification between the stages. The invention is described with reference to the extraction of lactic acid from its aqueous solution by means of ether. The aqueous acid is fed into a column 1, Fig. 1, from a pipe 43 having a distributor 2 and fills the column, ether being forced in through a spray nozzle 4. The ethereal solution collects in a layer 5 and is drawn off at 6 and, after the separation of the lactic acid, the ether is returned through the nozzle 4. Two columns 7, 8, may be arranged as shown in Fig. 2, with an emulsifier 9 between. The emulsifier comprises a perforated plate 12 between two similar rotary plates 13, 14. Ether is fed into the column 7 through a spray nozzle 10, and lactic acid solution is fed into the column 7 through a distributor 11, the whole apparatus being full of liquid. In the lower column drops of aqueous acid fall through ether, and in the upper column drops of ether rise through aqueous acid, an aqueous layer 17 forms below the ether inlet, and is drawn off at 15, and an ether extract layer 18 forms at the top of the upper column and is withdrawn at 16. Several emulsifiers may be arranged in a single column so as to divide it into several sections, as shown in Fig. 3, in which the emulsifiers comprise rotary perforated plates 22 between stationary perforated plates 23. Sleeves 26 may surround the shaft 24 to prevent agitation between the emulsifiers. The aqueous acid is led in at 20 and the ether at 21. In another modification, Fig. 4, a single column is used with an emulsifier, the aqueous acid entering at 29 and the ether at 31. The invention may be applied to the extraction of solid solutes, and also to the transfer of a solute from a light to a heavy solvent, for instance for the transfer of lactic acid from ethereal to water solution.