US3443748A - Dynamic mixer and centrifuge combination for solvent extraction - Google Patents

Description

May 13, 1969 R. w. HooPL-:R 3,443,748

DYNAMIC MIXER AND CENTRIFUGE COMBINATION FOR SOLVENT EXTRACTION May 13, i969 R. w. HooPER 3,443,748

DYNAMIC MIXER AND CENTRIFUGE COMBINATION FOR SOLVENT EXTRACTION Filed oct. 24, 1965 sheet 2 of 3 NOR/YE Y May 13, 1969 R. w. HOOPER DYNAMIC MIXER AND CENTRIFUGE COMBINATION FOR soLvENT EXTRACTION Filed Oct. 24. 1965 Sheet nited States Patent 3 443,748 DYNAMIC MIXER ND CENTRIFUGE COM. BINATION FOR SOLVENT EXTRACTION Robert W. Hooper, 11855 SE. 284th St., Kent, Wash. 98031 Filed Oct. 24, 1965, Ser. No. 504,754 Int. Cl. B04b 1/00, 3/00 U.S. Cl. 233-28 10 Claims ABSTRACT OF THE DISCLOSURE Through passages in opposite ends of a shaft an extracting solvent and a solution are supplied to the interior of a centrifuge barrel. Impeller disks spaced along the shaft are located between bafiie sections including a plurality of vanes projecting edgewise inwardly from the barrel. The freely rotatable barrel is rotated more slowly than the power driven shaft by the uid coupling action of fluid between the impeller disks and the -bafile section vanes. During such rotation the solvent and the solution iloW in opposite directions to discharge, at opposite ends of the barrel, solvate and raflinate which have been separated by centrifugal force generated by rotation of the barrel.

This invention is particularly -useful in solvent extraction operations.

It has been proposed previously to com-bine in a single device initial mixing and subsequent separating actions by use of centrifugal force employing devices such as shown in the United States patents of Webb No. 2,234,- 921, Zabriskie No. 2,819,014 and Vaughan No. 2,819,015. Such devices, however, have generally been more complicated and less effective than the device of the present invention.

The device disclosed in the Webb patent includes an outer tube or shell and an inner shaft arranged concentrically, both of which are rotated by individual drives, the shaft being rotated in the same sense as the shell, but at a somewhat slower speed. The shell is formed of an assembly of components providing a tortuous passage axially through the shell and providing chambers in which agitators keyed upon the central shaft are received.

The Zabriskie and Vaughan patents disclose generally similar devices including a rotor into which extends coaxially a stationary conduit on which are mounted stationary stirring blades relative to which lthe rotor turns. Each of these patents comments that while the stirring or mixing blades have been described as being held stationary, such blades could be rotated either in the same direction as the rotor, but at a different rate, or in a direction opposite to the direction of rotation of the rotor.

In any solvent extraction operation utilizing a centrifuge it is necessary for the extracting solvent to have a specific gravity sufficiently different from the specific gravity of the initial solution or its raiiinate to enable the solvate and the rainate to be separated by centrifugal force. For such operation it is immaterial Which of the solvate and raffinate is the heavier material. Also, it is necessary for the extracting solvent and the solvent of the initial solution to be immiscible, although they should be emulsifiable to a reasonable degree. Further, it is desirable for the extracting solvent to have a greater ainity than the solvent of the initial solution for the solute so that during the solvent extraction operation the solute will be partitioned to have a larger proportion of it dissolved in the extracting solvent than in the solvent of the initial solution.

Also, while the device of the present invention may be used in some instances for a liquid/gas extraction it is principally useful for liquid/liquid extraction processes.

3,443,748 Patented May 13, 1969 ice In each instance the technique employed is to mix the extracting solvent intimately with the initial solution so that an emulsion is formed in which the transfer of solute to the extracting solvent can occur, and then the emulsion is broken by centrifugal force to separate the solvate from the raiiinate.

It is an object of the present invention to provide an apparatus in which the initial solution and the extracting solvent can be emulsied quickly and effectively, followed Iby rapid breaking of the emulsion, while the entire solvent extraction process is accomplished in the same apparatus.

A further object is to provide apparatus for effecting mixing of the initial solution and the extracting solvent suiciently intimately to enable effective partitioning of the solute to occur Without the emulsion being so tight as to resist breaking excessively.

It is also Aan object to provide apparatus which is compact, while accomplishing an effective solute transferring operation.

Another object is to provide such an apparatus which can be varied in size depending upon the capacity desired, and the operation of which can be varied so as to be most effective for the particular type of materials being handled in the solvent extraction process.

An apparatus capable of accomplishing these objects includes a central mixing shaft arranged concentrically within a centrifuge barrel. Supply passages are provided in opposite ends of the mixing shaft through which initial solution and extracting solvent, respectively, flow into the interior of the barrel to be commingled. The mixing shaft is driven rotatively and the lluid coupling between such shaft mixer and the centrifuge barrel effects rotation of such barrel at a speed sufficient to 'break the emulsion and effect separation of the solvate and rainate. Such separated products are withdrawn from the centrifuge `at locations spaced axially of the centrifuge barrel and arranged relative to the supply duets in the lmixer shaft so that the initial solution progresses `axially through the centrifuge in the direction opposite the progress of the extracting solvent. Because of the slip between the mixer shaft and the centrifuge barrel the angular velocity of the centrifuge barrel is less than that of the mixer shaft and such speed differential accomplishes the mixing of the initial solution and the extracting solvent sufficient to form the emulsion in which solute is transferred from the initial solution to the extracting solvent.

FIGURE 1 is a longitudinal vertical central section through a mixer and centrifuge combination of the present linvention, FIGURE 2 is a transverse section through the combination on line 2 2 of FIGURE 1, and FIG- URE 3 is a similar section on line 3-3 of FIGURE 1, with a portion broken away. FIGURE 4 is a transverse section through the centrifuge of the combination on line 4 4 of FIGURE 1 and FIGURE 5 is a similar section on line 5-5 of FIGURE 1.

FIGURES 6, 7, 8, 9` and 10 are similar perspectives of different types of mixing elements, part of the element in FIGURE 9 being broken away.

FIGURE 11 is a central longitudinal section through a different formI of mixer and centrifuge combination.

The apparatus shown in FIGURES l to 5 includes a mixer and centrifuge combination rotatable about an upright axis. Such combination is housed within a casing including a cylindrical wall 1 having its ends closed Iby an upper end wall Z and a lower end wall 3. A centrifuge Disposed concentrically within the centrifuge barrel 6 is a mixer shaft 7, which preferably is hollow, having a central bore 8. Into one end of such bore, the lower end as shown in FIGURE l, is pressed a tube 9 which is held in place in the bore by an anchoring pin 10 extending diametrically of the shaft 7 and the tube. Such tube projects downward beyond the lower end of shaft 7 through the end plate 4 of the centrifuge barrel and into registry with the lower end wall 3 of the casing. Shaft 7 is mounted for rotation relative to the centrifuge barrel 6 by one or more lantifriction radial bearings 11, which also serve to take any end thrust between the shaft and centrifuge barrel.

Into the opposite or upper end of the bore 8 of mixer shaft 7 is pressed another tube 12, which is secured against rotation relative to shaft 7 by a pin 13 extending diametrally through the shaft and tube. The upper end of this tube projects beyond the upper end of the mixer shaft 7 up through the hollow neck of the upper end plate 4 of the centrifuge barrel and the upper end wall 2 of the casing. The mixer shaft 7 is steadied for rotation relative to the centrifuge barrel by a radial antifriction bearing 14, which encircles the portion of tube 12 projecting beyond the end of shaft 7 and fits in a bore in the centrifuge end plate 4. The tube is further steadied for rotation relative to the casing upper end Wall 2 by a radial antifriction bearing 15 received in a recess in the upper side of such end wall.

To the portion of the tube 12 projecting beyond the upper end wall 2 of the casing is keyed a ribbed pulley 16, with which a complementally ribbed belt 17 meshes to effect a positive drive between such belt and pulley. The belt can be driven by a motor mounted on a motor mount 18 which is secured to an accessory mounting plate 19 attached to the side of the casing structure. The power supply belt 17 can therefore rotate the tube 12 and, in turn, the mixer shaft 7 at any desired speed relative to the casing, such as several thousand r.p.m. The speed of the drive will depend upon the size of the machine, the m-aterial of which the machine is made and the material being processed.

One component of the material being processed can be supplied to the space between the mixer shaft 7 and the centrifuge barrel through the bore 20 of tube 12. The end of such tube bore is closed by a plug 21 fitted tightly into the bore S of the mixer shaft 7 at the end of tube 12. The upper end of this tube may project into a block 22 above the pulley 16 and secured to the upper end wall 2 of the casing by tie rods 22'. A sealing ring 23 encircling the upper end of tube 12 will seal such tube end with respect to the block, despite rotation of such tube relative to the block. A liquid supply pipe 24 is connected to the block 22 for supply of liquid to the bore 20 of tube 12 during its rotation.

From the bore 20 of tube 12 liquid supplied to such bore through the supply conduit 24 can pass into the space between the mixer shaft 7 and the centrifuge barrel through radial ports 2S in the wall of such tube and the mixer shaft at a location adjacent to the upper end of the centrifuge barrel. Such liquid enters a space within a core wall 26 of the centrifuge barrel disposed concentrically with the mixer shaft and spaced from it to form an annular chamber 27. The cylindrical core wall interconnects the inner edges of radial vanes 28 extending between such wall and the barrel 6 of the centrifuge. The opposite ends of the yannular chamber 27 are sealed relative to the upper end wall 4 of the centrifuge barrel by a sealing ring 29 and relative to the lower end wall of the centrifuge by a sealing ring 30.

At the end of the mixing shaft 7 opposite tube 12 the bore 34 of the tube 9 also serves as a supply duct for ow of material into the tortuous passage of the centrifuge barrel. The inner end of such bore is closed by a plug 3S fitting in the bore 8 of the hollow mixer shaft 7, and preferably abutting the end of tube 9. The opposite end of such tube is sealed relative to the lower end wall 3 of the casing by a sealing ring 36. A fluid supply connection 37 is fitted into an aperture in the lower end wall 3, which is in alignment with the bore 34 of tube 9. Consequently, a uid can be Supplied to such bore while the mixer shaft is being rotated and the seal 36 will prevent the fluid from bypassing such bore to ow into the interior of casing 1 outwardly of the centrifuge barrel. From the tube bore 34 uid can ow into the tortuous passage of the centrifuge barrel through radial ports 38 extending through the walls of tube 9 and shaft 7.

A number of baflie sections, each including a circumferential core wall 26 and radial vanes 28 projecting edgewise inwardly from the barrel 6, are spaced axially along the centrifuge barrel. Adjacent ends of adjacent sections are spaced apart far enough to receive mixing disks 31 disposed in planes perpendicular to shaft 7 between them. As will be seen in FIGURES l and 1l, the disks and vanes are in overlapping relationship axially of the mixer and centrifuge combination. Such disks are secured to the mixing shaft 7 in any secure manner, such as by wires 32 extending chordwise, and preferably diametrally, through such mixing shaft and through holes 32 in the inner periphery of the disk. The ends of the wires can then be brought around to one side of the shaft and twisted together, as shown in the center of FIGURE 1, and in FIGURE 4. Such disks 31 cooperate with the sections of core wall 26 and the vanes 28 to form a tortuous passage extending lengthwise of the centrifuge barrel 6. The radial ports 25 and 38 lead into such passage. Each vane and core wall section provides one mixing and separating stage.

While fluid is supplied to the interior of the centrifuge barrel 6 through the bores of the end tubes 9 and 12, as described, other provision must be made for enabling fiuid to escape from the centrifuge barrel. Since the centrifuge separates fluids of different specific gravity discharge passages are provided at different locations for such respective uids. In order to provide the most effective separation of such fluids it is preferred that lighter iiuid be discharged from one end of the centrifuge barrel and heavier uid be discharged from the opposite barrel end. In the device of FIGURE 1 the rotative axis of the centrifuge is upright and it is arranged for the lighter iiuid to be discharged at the upper barrel end and for the heavier fiuid to be discharged at the lower barrel end.

Adjacent to the upper end of the centrifuge barrel 6 is a wall 39 in the form of an annular plate having an inner aperture v40 suiiiciently larger than the circumference of the mixer shaft 7 as to leave an ample axial passage alongside the mixer shaft from the upper end of the centrifuge drum. Such aperture serves as an internal circular Weir over which any uid moving into the radial discharge ports 41 must flow in order to pass into the annular Huid-receiving chamber formed between the axially spaced walls 42 and y43l in the upper portion of the casing 1. Preferably these annular walls are curved concavely downward so that fluid will drain into the lower portion of this chamber and then flow circumferentially of the chamber out through t-he discharge port 44 into the spout 45.

In most instances radial vanes 28 are preferably of axial lengths corresponding to the axial lengths of the sections of core wall 26. Some heavy liquid supplied to the barrel through upper ports 25 may tend to migrate upward along the inside of the core wall 26 and be discharged with the lighter liquid if centrifugal force cannot move such heavy liquid to the outer part of the barrel. To minimize such adulteration of the light liquid, notches 33 in the end of the adjacent core wall 29 provide passages for such heavy liquid to move outward to the wall 6.

4Encircling the mixer shaft 7 in the lower end of the centrifuge barrel is a plate 46 arranged so that its external periphery forms an external circular weir. Such plate is mounted on the lower end plate 4 of the centrifuge barrel by spacer screws `47 so as to provide a radial passage between the plates 4 and 46. In contrast the plate 39 is secured to the opposite end plate 4 of the centrifuge barrel tightly to avoid formation of such a radial passage, and the joint between these two plates can be sealed by a suitable packing ring 48. Alternatively, the inner circular weir could be formed as an integral part of the upper end plate 4. The peripheries of such end plates are sealed relative to the inner surface of the centrifuge annular fwall by sealing rings 49 -iitting in circumferential grooves of the end walls.

The inner periphery of the external weir plate 46 should not make direct contact with the exterior surface of mixer shaft 7 because such plate is carried by the centrifuge barrel and, as explained above, the mixer shaft and centrifuge barrel are mounted for relative rotation. A seal can be effected between the inner periphery of plate 46 and the mixer shaft 7 conveniently by providing a cylindrical flange 50 on the inner periphery of such plates, which is located alongside the surface of the mixer shaft, and the end of which flange engages the sealing ring 30. Any iluid which escapes from the lower end of the centrifuge barrel must therefore pass through the chamber 51 and over the outer periphery of the plate 46 through the annular passage 52 into the passage 53 between the weir plate 46 and the lower end plate 4 of the centrifuge barrel.

In order to insure that the centrifuge barrel remains full of fluid the heavier liquid which, as a result of centrifugal action, passes the external circular weir formed by the outer periphery of plate 46 is not discharged drectly from the centrifuge barrel. Instead, additional heavy liquid, separated by centrifugal force, must flow through the annular passage 52 to force previously separated heavy liquid through the passage 53 toward the center of the centrifuge into the annular axial passage 54 spaced inwardly from the circumference of the barrel. This passage leads into radial discharge ports 55 corresponding to the upper radial discharge ports 41, and from these ports the liquid passes into the chamber between axially spaced upper and lower walls 56 and 57 in the lower portion of the casing 1. These walls are curved to provide convex lower sides and are sloped radially outward to enable liquid discharged between them to drain into the annular trough formed at the junction of the wall 57 and the cylindrical Wall 1 of the casing. In this trough the liquid flows circumferentially and through the discharge port 58 into the spout 59.

Because the walls 42 and 43 and the walls 56 and 57 are stationary, it is necessary for their inner edges to be spaced slightly from the rotating cylindrical wall 6 of the centrifuge barrel. Consequently, it is possible that a small amount of liquid may fail to cross the gap from the upper discharge ports 41 to the chamber between the walls 42 and 43. Such liquid can be removed through a drain port in the casing wall 1 above wall 55, which is not shown. When the barrel is being brought to a stop some liquid will not pass from the lower discharge ports 5S to the chamber between the plates 56 and 57. Such liquid will run down the, outer wall of the centrifuge barrel into a trough 60 in the 'bottom wall 3 of the casing. Liquid can be removed from such trough through a drain. opening which may be closed by plug 61.

In a typical liquid/ liquid solvent extraction operation it is desired to remove a solute from an initial solution. Such initial solution may, for example, be a penicillin culture in aqueous beer broth. To remove the penicillin, constituting the solute. an extracting solvent must be selected which is virtually immiscible with the initial solution, has a specific gravity sufficiently different from that of the initial solution to enable the initial solution and the extracting solvent to be separated by centrifugal force, and preferably has an ainity for the solute to be extracted which is greater than the affinity of the initial solution solvent for such solute. Methyl isobutyl ketone is an extracting solvent having all of these characteristics. It is lighter than the beer broth initial solution because such beer broth solution would have a specific gravity of approximately one, whereas the specific gravity of methyl isobutyl ketone is approximately 0.8.

In using the apparatus of the present invention in a penicillin solvent extraction operation the heavier beer broth initial solution of penicillin would be introduced into the apparatus through the upper connection 24 under a small pressure, and the solvent, methyl isobutyl ketone, would be introduced into the bottom of the device through the connection 37 under a small pressure. Thus, the initial solution and the extracting solvent would be fed to opposite ends of the device. The initial solution would flow through the bore 20 of tube 12 and the ports 25 in the mixer shaft wall into the centrifuge barrel. Simultaneously the extracting solvent would ow through the bore 34 of tube 9 and outward through the ports 38 into the centrifuge barrel. As a sufficient quantity of each of the two liquids is thus supplied the centrifuge barrel would become reasonably well filled with such liquid.

As the mixing shaft 7 is rotated rapidly, the viscosity of the beer broth and the methyl isobutyl ketone, while notV great, is great enough to provide a fluid-coupling force sufficiently great to turn the centrifuge barrel 4, 6 at an angular velocity close to that of the mixer shaft. The first effect of the differential rotation of the mixer shaft and the centrifuge barrel is to cause the disks 31 to create turbulence in the liquid contained in the centrifuge barrel so as to produce an emulsion of the initial solution and the extracting solvent. The second effect on the liquid is breaking of the emulsion and separation of the liquids of different specific gravity. Such second action is effected by centrifugal force produced by rotation of the centrifugal barrel.

When the initial beer broth solution of penicillin and the extracting methyl isobutyl ketone solvent are mixed intimately as an emulsion, the penicillin will be partitioned with the major proportion of the penicillin migrating from the beer broth into the extracting solvent. By the time the emulsion is broken the larger portion of the penicillin will have transferred to the extracting solvent to form a solvate, whereas a relatively small amount of pencillin will remain in the raffinate. Because of the relative specific gravities of water and methyl isobutyl ketone the heavier raffinate will be thrown by centrifugal force to form a layer of liquid adjacent to the inner wall of the cylindrical shell 6 of the barrel, lwhereas the lighter solvate will be located nearer to the center of the centrifuge.

As initial solution continues to be supplied through the upper connection 24 to the interior of the centrifuge barrel, and extracting solvent continues to be supplied through the lower connection 27, the centrifuge barrel will become sufliciently full of liquid so that liquid will begin to be discharged through the spouts 45 and 59. The heavier initial solution will have passed downward through the tortuous passage of the centrifuge barrel in intimate contact with the extracting solvent until the centrifugally separated raffinate moves from the chamber 51 over the edge of the external circular weir formed by the outer periphery of plate 46 and through the annular passage 52 into the passage 54 from which such raffinate 1s discharged through the radial ports 55, chamber between plates 56 and 57, port 58 and spout 59. The quantity of raffinate thus discharged will be approximately equal to the amount of initial solution supplied to the centrifuge barrel through the connection 24 and boie 20 of tube 12.

The extracting solvent being moved toward the center of the barrel, by breaking of the emulsion and movement of the raffinate toward the wall of the barrel, will move upward through the barrel in the form of the solvate to pass over the internal circular weir formed by the inner periphery of plate 39. Such liquid will then flow from the passage 40 into the radial discharge ports 41, the chamber between plates 42 and 43, the outlet port `44 and the spout 4S. The amount of such solvate thus discharged will correspond approximately to the amount of extracting solvent supplied to the connection 37. It is, of course, not necessary for equal quantities of initial solution and of extracting solvent to be supplied, but the relative proportions of such liquid supplied will depend upon what proportions will afford the most effective extraction.

Another example of a type of solvent extraction operation f or which the present apparatus is suitable is the extraction of such fractions of petroleum, or adulterants in the petroleum, to provide lubricating oil having the xmost desirable characteristics. In this instance, also, only a single operation is required for the solvent extraction in which the initial solution and the extracting solvent are fed into opposite ends of the centrifuge barrel and the nal solvate and raffinate are discharged respectively at different locations spaced lengthwise of the barrel. Because the mixer shaft 7 drives the centrifuge barrel 6, 4 through the fluid coupling of the liquid between the mixer shaft and the barrel, it is assured that all liquid in the centrifuge barrel will be rotating at an angular velocity at least as great as the centrifuge barrel very shortly after it is discharged into such barrel from the feed tubes. The mixing and emulsifying action must be effected sutliciently quickly and thoroughly to prevent either the initial solution or the extracting solvent from simply passing through the centrifuge barrel without adequate contact with each other. Adequacy of contact is, however, assured by causing the initial solution and the extracting solvent to move in countercurrent fashion through the centrifuge barrel, and by providing the disks 31 which effect the mixing action during transition of the liquid from one core and vane section to the next.

Actually, the disks 31 can be constructed to provide Whatever degree f mixing action is most effective. While in FIGURES 1 and 6 a plain smooth disk is shown, the disk 31a of FIGURE 7 has a plurality of radial grooves distributed around its periphery in circumferentially spaced positions. Each groove 62 of disk 31a is indicated as increasing in depth away from the center of the disk. The grooved side of such disk should open toward the end of the centrifuge barrel into which the lighter liquid is supplied. The grooves will tend to catch the lighter liquid owing toward such disk to impel it toward the circumference of the centrifuge barrel for increasing the mixing action.

The mixing disk 31b of FIGURE 8 has closely spaced V-shaped notches 63 in its circumference forming teeth which will increase the agitation of the liquid in the region adjacent to the Wall of the centrifuge barrel.

The disk 31C of FIGURE 9 will have an action somewhat similar to disk 31a of FIGURE 7 because movement of liquid from the central portion of the centrifuge lbarrel toward its outer portion will be expedited through the radial passages 64. The inner ends of such passages open into a circular groove 65 located just outward of the mixer shaft 7. When disks of this type are used in the device the circular groove 65 should open toward the end of the centrifuge barrel into which the lighter liquid is supplied. Liquid entering such groove is pumped by rotation of the disk 31e through the radial passages to a location adjacent to the Wall of the centrifuge barrel to be mixed with the heavier liquid.

In the disk 31d of FIGURE l0 holes 66 are provided as a means to increasee viscous shear and therefore increase the mixing action of the heavier and lighter liquids.

While the device has been shown in FIGURE 1 as being equipped only with mixing disks 31, it should be understood that all of such disks could be of any of the other types 31a, 31b, 31e` and 31d illustrated in FIG- URES 7 to l() inclusive. Alternatively, various numbers and types of such disks could be mounted on the mixer shaft 7 in any desired arrangement which would be most effective to produce the type of emulsion desired in conjunction with the speed of rotation of the mixer shaft for each particular type of solvent extraction operation to be performed by the device.

FIGURE 11 shows an alternate type of mixer and centrifuge combination which is generally comparable to that shown in FIGURE l, but in this instance the rotative axes of the mixer shaft 7 and the centrifuge barrel are arranged horizontally. Because the casing 1, centrifuge barrel and mixer shaft components of this device and the related parts are all substantially the same as the corresponding parts of the combination device shown in FIGURE 1, such parts have been designated with the same numbers and a description of their construction and characteristics need not be repeated. The principal difference of this device resides in the construction of the barrel ends.

ln the upper portion of FIGURE ll the left end member 4' of the centrifuge is in the form of a stepcone rather than a plate. The smaller step-cone end is received within the inner race of an annular antifriction 5bearing 5', the outer race of which is mounted in a collar 67 secured to the end wall 2 or 3 of the casing by bolts 68. Between the shoulder of the step-cone next to the bearing 5 and the collar 67 is a sealing ring 69. Between the next step of the barrel end and such collar is another sealing ring 70. Corresponding sealing rings are located between the step-cone 4' at the right end of the barrel and the collar 67 at that end.

Between the inner side of each step-cone barrel end 4 and the mixer shaft tube 9 at the right end and 12 at the left end, are the bearings 11 and 14', respectively. In addition, bearings 15 mount such tubes for rotation relative to the casing end walls 2 and 3. Passages 41 extend axially through the left step-cone of FIGURE 1l to connect the internal circular Weir passage 40 with the lighter liquid outlet passage 44', which is drained by the outlet connection 45. At the right end of the device the axial passages 5S' enable heavier liquid to flow from the passages 54 to the outlet passage S8 and the outlet drain 59' for the heavier liquid discharge.

In the apparatus shown in FIGURE 11 the heavier initial liquid will be supplied through the connection 24 at the left end of the device and the heavier nal liquid will be discharged through the connection 59' at the right end of the device. Conversely, the lighter initial liquid will be supplied to the connection 37 at the right end of the device and the lighter final liquid will tbe drained olf through the connection 45' at the left end of the device. Again, therefore, the heavier and lighter liquids will flow through the device in countercurrent fashion and during such flow through the centrifuge barrel the immiscible liquids will be emulsitied, the solute will be partitioned between such liquids, the emulsion will be broken and the two components of different specific gravity will be separated by centrifugal force to be withdrawn from the apparatus at the two different locations mentioned.

While the device as described has been designed particularly for liquid/liquid solvent extraction, the same principles could be utilized in apparatus applicable to distillation, gas absorption, evaporation and partial condensation operations. Alternatively, such an apparatus could be used for chemical reactions, particularly those in which a solvent extraction operation is involved. An example of such a use would be nitration of toluene or other hydrocarbon in which two immiscible liquids are supplied with the organic feed liquid being used as an extracting solvent for the organic product in the spent acid.

I claim:

1. A dynamic mixer and centrifuge combination, comprising a centrifuge barrel having a plurality of baffle sections spaced axially therealong, each of said sections including radial vanes projecting edgewise inwardly from said barrel for rotation therewith, means mounting Said centrifuge barrel for free rotation about an axis, a mixer shaft disposed concentrically within said centrifuge barrel, a mixing disk carried by said mixer shaft in a plane perpendicular to said shaft and projecting outward therefrom between adjacent baffle sections sufiiciently to be disposed in overlapping relationship with said inwardly projecting radial vanes on opposite sides thereof for forming a tortuous passage extending lengthwise of said centrifuge barrel, means mounting said mixer shaft and said mixing disk for rotation relative to said centrifuge barrel and said baffle sections about the rotative axis of said centrifuge barrel, means for supplying liquid to the space between said mixer shaft and said centrifuge barrel, and means operatively connected to said mixer shaft for effecting positive rotation thereof and consequent rotation of said freely rotatable centrifuge `barrel slower than said mixer shaft by the Huid-coupling of the liquid between said mixing disk and said radial vanes.

2. The combination defined in claim 1, including at least one additional mixing disk, the mixing disks being carried by the mixer shaft at spaced locations corresponding to the spacing of the baffle sections along the centrifuge barrel so that the mixing disks on the mixer shaft are located axially between adjacent baille sections, respectively, of the barrel.

3. The combination defined in claim 1 in which the mixing disk has radial passage means through which liquid may flow outward to the periphery of the disk.

4. The combination defined in claim 3, in which the disk passage means includes radial grooves in a side of the disk.

5. The combination defined in claim 4, in which the radial grooves increase in depth toward the periphery of the disk.

6. The combination defined in claim 3, in which the disk passage means includes radial ducts provided in the disk between opposite sides thereof.

7. The combination defined in claim 6, in which a disk has an annular groove in one side thereof at a location spaced from the periphery of the disk, which groove is in communication with the inner ends of the radial ducts.

8. The combination defined in claim 1, in which the mixing disk has a plurality of apertures extending axially therethrough.

9. The combination defined in claim 1, in which the mixing disk has a plurality of notches in its periphery.

10. The combination defined in claim 9, in which the notches in the disk periphery are located sufiiciently close together circumferentially to form substantially sharp projections between adjacent notches.

References Cited UNITED STATES PATENTS 1,595,644 8/1926 Coleman 233-18 2,234,921 3/1941 Webb.

2,646,921 7/1953 Adams et al 233-8 X 2,819,014 1/1958 Zabriskie 233-15 3,069,074 12/ 1962 Moyer et al 233-32 3,073,517 1/l963 Pickels et al. 233-32 2,254,455 9/1941 Sorenson 210-215 HENRY T. KLINKSIEK, Primary Examiner.

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