Patent GB-860428-A (GB)
Title: Liquid-liquid contact extractor
IPC: C22B60/02
Filed: 1959-01-28
Abstract: 860,428. Contacting liquids. ATOMIC ENERGY OF CANADA Ltd. Jan. 28, 1959 [Jan. 29, 1958], No. 3098/59. Class 46. A heavy liquid phase to be purified or otherwise treated enters chamber 14b of mixing section 14 of the first of the series of mixersettler units 3. A gas, preferably air, enters chamber 14b through conduit 27 and draws the heavy liquid phase up through lift tube 6 into the upper portion 14a of the mixing section. The heavy liquid phase then passes into settling section 15 where it drops to the lower zone thereof because of its higher density. From the lower zone of settling section 15 the heavy liquid phase is drawn through conduit 18 into the upper portion 14a of mixing section 14 of the next succeeding unit 3 where it flows through opening 16 of plate 11 back into chamber 14b and is again drawn up through lift tube 6 of that mixing section and passes into the settling section 15 of that unit. The drawing action in chamber 14b creates suction at opening 16 which draws the heavy liquid phase through conduit 18. The heavy liquid phase is drawn into upper portion 14a rather than directly into mixing chamber 14b in order that plate 11 may act as a weir and prevent excess pump action by the suction created in chamber 14b which would lower the interface in the preceding settling section from which the heavy liquid phase is drawn. The light liquid phase or solvent enters the chamber 14b of mixing section 14 of the final mixer-settler unit 3 of the series. From chamber 14b the light liquid phase is drawn up through tube 6 and enters settling section 15 of each unit 3 where it remains in the upper zone of that section due to its lighter density. Conduit 19, acting as a weir, to prevent excess draw-off conducts the light liquid phase from settling section 15 down into chamber 14b of mixing section 14 of the next preceding unit 3 in the series. The light liquid phase is drawn through conduit 19 by the suction created in chamber 14b. In chamber 14b of this next proceeding unit the light liquid phase is again drawn up through lift tube 6 by the action of the fluid entering through inlet opening 16 and, by this action, is intimately mixed with the heavy liquid phase being simultaneously drawn up through tube 6. Emerging from tube 6 the light liquid phase enters settling section 15 and is again drawn off through conduit 19 to the mixing section of the next preceding unit in the series. Finally, the depleted heavy phase is drawn off from settling section 15 of the final unit 3 in the series through the opening 23 while the solvent, containing the transferable components, is drawn off from the settling section 15 of the first unit 3 of the series through opening 22. A substantial portion of both the heavy and light liquid phases will recirculate through opening 16 in horizontal plate 11 back into the lower chamber 14b, where they will again pass up through lift tube 6, if the feed rate of the gas entering chamber 14b through conduit 27 is appreciable. If greater recirculation is desired, horizontal plate 11 could be replaced by radial bars holding lift tube 6 in its central position. In a modification (not shown) of the device, to allow more recirculation partition 12 may extend to a point adjacent the top 20 of housing 1, dividing unit 3 into a mixing chamber and a settling chamber. A horizontal slot would then be provided in partition 12 to allow some of the mixed light and heavy phase liquids emerging from tube 6 to enter the settling chamber. If desired, a conduit 30 may be provided which leads into each conduit 18 to allow for the addition of fresh heavy or light liquid phases to mixing section 15 of any unit 3 of the series. Samples can be taken from settling sections 15 through probe openings 26 for chemical analysis of the separation process and the addition of fresh liquids governed thereby. Conduit 30 would also allow for the addition of a third liquid to the process, if desired. A process requiring two or more steps could be carried out by means of the present invention. By placing a plurality of extractors in series, liquids flowing from the outlets of a one extractor could be introduced into the next extractor either at the ends of intermediate thereof, thus enabling a complex flow pattern to be obtained. Of course, the apparatus described could be modified by interconnecting a series of individual units rather than by providing a housing subdivided into such units. Also, the flow of gas through the mixing sections 14 of the apparatus could be effected either by supplying the gas under pressure or by providing a vacuum in association with vent 29.