US2937078A

US2937078A - Mixer-settler apparatus

Info

Publication number: US2937078A
Application number: US636406A
Authority: US
Inventors: Dukes John Alexander; Parish Fred
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1956-02-03
Filing date: 1957-01-25
Publication date: 1960-05-17
Anticipated expiration: 1977-05-17

Description

y 1960 J. A. DUKES ET AL 2,937,078

MIXER-SETTLER APPARATUS Filed Jan. 25, 1957 m UE United States Patent MIXER-SETTLER APPARATUS John Alexander Dukes, Clifton, Preston, and Fred Parish,

Lea Preston, England, assignors to The United Kingdom Atomic Energy Authority, London, England Application January 25,1957, Serial No. 636,406

Claims priority, application Great Britain February 3, 1956 1 Claim. (Cl. 23270.5)

This invention relates to mixer-settler apparatus for contacting two substantially immiscible liquids of differing densities.

The flow of fluids through a mixer-settler apparatus may be achieved by providing for an overall gravityfall (i.e. vertical or inclined apparatus) or by lifting during the course of mixing (e.g. air lift, centrifugal pump, a screw).

The mixer-settler apparatus of the present invention is horizontally arrayed and possesses no positive lifting arrangements.

According to the present invention a mixer-settler apparatus comprises, in each mixer compartment, double impeller arrangement adapted to rotate about a vertical axis, the impellers being arranged above and below a port between the mixer compartment and its associated settler compartment and the double impeller arrangement being such that the upper impeller. drives downwards and the lower impeller drives upwards.

One form of mixer-settler apparatus embodying the invention will now be described with reference to the accompanying drawing wherein Fig. l is a front elevation, with a cut away part, Fig. 2 is a front elevation of an impeller, and Fig. 3 is a side elevation of an impeller.

Fig. 1 shows the mixer-settler apparatus having a conrows indicate flow in the front row compartments, and

ventional layout, that is two adjacent rows of alternate I mixer compartments 10 and settler compartments 11. The compartments 10, 11 alternate both along and across the rows, so that behind each front row mixer compartment 10 there is an associated back row settler compartment 11, and similarly in front of each back row mixer compartment 10 there is an associated front row settler compartment 11.

In each mixer compartment 10 there is a simple double impeller arrangement comprising a vertical shaft 12 carrying an upper impeller 13 and a lower impeller 14. At a level between the

impellers

13, 14, a transfer port 15, interconnecting the mixer compartment 10, and associated settler compartment 11, is shown. Referring to Figs. 2 and 3, the impellerhas a rectangular-section boss 16 drilled to provide a hole 17 to fit on the shaft 12. (A grub screw 18 is available for locating the impeller on the shaft.) The boss 16 has two

rectangular vanes

19, 20 welded to it and inclined as shown in Fig. 3. The impeller 13 has vanes arranged in the opposite sense to those on impeller 14 so that, on rotation of the shaft 12 in the correct direction, impeller 13 forces the liquids in the mixer compartment downwards and the impeller 14 forces the liquids upwards to produce mixing. I

The other features of construction are now described.

The mixer-settler is built in a container 21 and pro- The

ports

23, 25, have outlet boxes 26, 27,

- 2,937,078 Patented May 17, 1960 respectively. Between mixer compartments 10 and ad jacent settler compartments 11 there are adjustable light phaseweirs 28' and heavy phase ports 29 with hoods 30. The shafts 12 are powered from an electric motor 31 driving througha chain 32a central shaft 33 running in

journals

34, 35 supported onst'ifieners 38. Four chain drives 36 are taken from the shaft 33 to bevel gears 37 which are coupled with the shafts 12 and supported on brackets 39.

In alternative arrangements the

impellers

13 and 14 are mounted on separate shafts and: suitably driven.

In operation, the mixer-settler apparatus is used to extract metal values from an aqueous solution (the heavy phase) using an organic solvent (the light phase) by repeatedly mixing and separating the two liquids. The flow of the two liquids is as follows (dotted arrows indicate flow in the back row compartments, full-line archain-dotted lines indicate levels).

The light phase flows in continuously from the port 22 (as shown by arrow 40) into the mixer compartment 10 at the right-hand end of the front row. After mixing it flows through the port 15 to the associated back row settler compartment 11, as shown by the tail symbol 41. After settling, the light phase flows over a weir (like weir 28 in the second front row settler compartment 11) into the adjacent back row mixer compartment 10 and then, after mixing, through the port 15 into the associated front row settler compartment 11, as shown by the point symbol 42. After settling, the light phase flows overv the weir 28, as shown by arrow 43, into the front row mixer compartment 10. This flow pattern is continued until the light phase enters .the settler compartment '11 at the left-hand end of the front row, from which,

setller compartment 11, as shown by the point smbol 46. After settling, the heavy phase flows through the port 29 into the adjacent front row mixer compartment 10, as shown by arrow 47. After mixing, the heavy phase flows through the port 15 into the associated back row settler compartment 11, as shown by the tail symbol 48.

This flow pattern is continued until the heavy phase enters the settler compartment 11 at the right-hand end of the back row, from which, after settling, it flows into the outlet box 27 and thence out through the port 25, as shown by arrow 49.

The general effect of the impellers in the mixer compartments can be regarded as driving the heavy phase entering the mixer compartments upwards (as shown by arrow 50) into the light phase and the light phase entering the mixer compartmentsdownwards (as shown by arrow 51) into the heavy. phase thereby achieving intimate mixing. The head of mixed phase above the ports 15 coupled with the forces set up by the action of the impellers is adequate to cause 'flow through the ports 15 against the head of light phase above the ports 15 determined by the level of the weirs' 28, thus achieving flow in a horizontally arranged apparatus without using any positive lifting arrangements.

The speed of the shaft 12 is 300 rpm. and the throughput of the mixer settler is of the order of 3 cubic metres/hour with overall dimensions of 70" long, 2'-3" high and 5'-3f' wide.

We claim:

A mixer-settler apparatus for. contacting two substantially immiscible liquids of differing densities comprising e 3 a first row of alternate similar mixer compartments and similar settler compartments, a second row of alternate similar settler compartments and similar mixer compartments, each mixer compartment in one row being associated with a settler compartment in the other row by means defining a transfer port for flow from mixer to settler compartment, the mixer compartments at the ends of the apparatus each having means defining an inlet port, the settler compartments at the ends of the apparatus each having means defining an outlet port, each settler compartment having an overflow weir connecting with the mixer compartment on one side of said settler compartment and means defining an underfiow port con meeting with the mixer compartment on the other side of said settler compartment, and in each mixer compartment two impellers adapted to rotate about a common vertical shaft, the upper impeller being disposed above said transfer port and adapted to drive downwards and the lower impeller beingdisposed below said transfer port and adapted to drive upwards.

References Cited in the file of this patent UNITED STATES PATENTS 1,297,170 Holley et a1 Mar. 11, 1919 1,297,171 Holley et a1. Mar. 11, 1919 2,139,871 Wilson et a1. Dec. 13, 1938 2,614,821 Tatman Oct. 21, 1952 2,709,680 Watson May 31, 1955