US2718353A - Continuous centrifuge - Google Patents

Description

Sept. 20, 1955 w. H. KELSEY CONTINUOUS CENTRIFUGE 8 Sheets-Sheet 1 Filed June 9, 1952 ZNVENTOE: 14/41 /M A! KZZX Sept. 20, 1955 w. H. KELSEY commuous CENTRIFUGE 6 Sheets-Sheet 2 Filed June 9, 1952 .ZNVENTOZ' W/LLMM H KHSFX I rrokme-xs P 20, 1955 w. H. KELSEY 2,718,353

CONTINUOUS CENTRIFUGE Filed June 9, 1952 6 Sheets-Sheet 3 INVENTOR. WILLIAM H. KELSEY,

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Sept. 20, 1955 w. H. KELSEY 2,718,353

CONTINUOUS CENTRIFUGE Filed June 9, 1952 e Sheets-Sheet 4 firroxe/wsfxs.

Sept. 20, 1955 w. H. KELSEY CONTINUOUS CENTRIFUGE 6 Sheets-Sheet Filed June 9, 1952 INVENTOR WILLIAM H. KELSEY,

W l a i Sept. 20, 1955 w. H. KELSEY 2,718,353

CONTINUOUS CENTRIFUGE Filed June 9, 1952 6 Sheets-Sheet 6 IN V EN TOR.

WLLlA-M H. KELSEY, BY fl Hiram/5K5.

United States Patent 2,713,353 CO IN U CENTR FUGE William H. Kelsey, Stockton, Utah Application June 9, 1952, Serial No. 292,450

32 Claims. (Cl, 233-3) This invention relates to machines for operating upon metallurgical and other industrial pulps and slurries to accomplish certain desired results in the processing thereof, It has particular reference to what are known as centrifugal machines or centrifuges, and is especially concerned with such machines as constructed for continuous feed and discharge of materials during any given period of Operation.

The present application constitutes a continuation-inpart of my allowed copending application Serial No. 191,396, filed October 21, 1950, entitled Continuous Centrifugal Jig, which application has been abandoned.

Industrial pulps and slurries are generally understood to be liquid suspensions of solid particles, whether coarse or fine, and, for the purposes of this disclosure, are intended to comprehend ore pulps, many semi-liquids (including colloids and gelatinous media) encountered in chemical operations, slimes of various kinds, such as sewage, and practically any other separable mixture of solid articles and liquid. They are customarily treated by centrifuging, jigging, filtering, thickening, raking, and similar mechanical operations for separating and concentrating the solid particles relative to the liquid suspending media. In addition to these operations, which eliminate surplus liquid from the slurry, it is often required that the solid particles be classified or separated relative to one another on the basis of specific gravities and physical characteristics.

In practice, the aforementioned operations are ordinarily carried out with equipment which has become standard for the respective purposes concerned. There are various types of centrifuges, jigs, filters, thickeners, mechanical rakes, classifiers, concentrators, etc., which are regarded as standard equipment for handling materials if this kind, and which are routinely specified by engineers.

Centrifugal machines or centrifuges have had their place principally in batch operations, since the solids tend tocollect and pack tightly about the inner periphery of the centrifuge bowl, where they must be removed following the centrifuging operation. Continuous centrifuges equipped with complicated mechanical plow mechanisms and the like are presently available and are frequently used industrially, but their use is ordinarily limited to non-abrasive, non-corrosive, and non-packing pulps. Original and maintenance costs are excessive, and can only be justified in large and highly profitable operations. On the other hand, continuous feed and discharge classifiers of so-called cyclone type, wherein the material is given high velocity centrifugal motion within a stationary bowl, are limited in application and are subject to excessive wear.

The machine of this invention, however, utilizes a rotating centrifuge bowl which subjects a stream of materials passing through it to centrifugal force, thereby effecting segregation of components of the stream due to differences in specific gravity and other significant characteristics of such components, and, at the same Patented Sept. 20, 1955 time, exerts, in a very simple manner, positive transportative action on the heavier components to insure con.- tinuity of travel thereof through the machine. The internally disposed, mechanical plows customarily used in this type of machine are completely eliminated, and there is very little wear on the machine as a whole.

Controls which are built into the machine may be used to regulate the degree of centrifugal force, the rate of feed, the proportions and degree of segregation, and the extent of agitation, so that the machine can be employed efiiciently as a thickener, clarifier, separator, or classifier, and as various combinations of these. i

Accordingly, the principal object of the invention is to provide a relatively inexpensive, easily maintained, and easily acid-proofed machine for subjecting a con.- tinuous flow of industrial pulp or slurry to centrifugal action, whereby components of such pulp or slurry have their respective, normal, specific gravities multiplied by many times to facilitate separation of such components, and in which machine the segregated heavier components will be subjected to positive and continuous expelling action by externally applied forces operative during the normal course of operation of the machine.

Other important objects are:

To provide such a machine that will be capable of carrying out a variety of different processing operations on an industrial pulp or slurry by simple changes in adjustment of the operating mechanism.

To effect a continuous, expulsive flow of solids from centrifuge in accordance with results desired in the Processing of an industrial pulp or slurry, so that the rnachine will be self-cleaning without the use of the internally disposed and mechanically driven plows customarily employed in continuous centrifugal machines of known construction.

To provide a superior way of de-watering partially precipitated solids in many chemical processes.

To provide a low cost, space saving apparatus for thickening metallurgical and other industrial pulps or slurries prior to filtering.

To provide a more eflicient way of classifying mineral particles.

To provide a better way of beneficiating ores than presently employed in customary jigging procedures and heavym di p cesses- These and other objects and purposes of the invention are attained by a novel structural combination, which, among other essential elements, includes what may be appropriately termed a circumferentially corrugated centrifuge bowl, wherein externally protruding corrugations thereof are flexible, hollow, and open to the centrifuge chamber within the bowl, for the reception during operation of the machine, of heavier components of any material fed into the bowl.

Corrugated and flexible centrifuge bowls are not new as such, but have been proposed and may have been utilized practically to a limited extent for the recovery of gold and other metallic values from the gangues with which they are ordinarily associated. Bowls of this type are shown in U. S. Patent No. 2,161,476 granted June 6, 1939, to Alfred H. Leia, for Ore Concentrator, and in U. S. Patent No. 2,179,807 granted November 14, 1939, to Jes Asmussen, for Centrifugal Vibrator.

In those bowls, however, the flexible corrugations are of the nature of independent and discontinuous, circumferential riffles, into which particles of gold or other heavy precious metals are thrown, and within which they are collected, by reason of centrifugal action on an ore pulp containing same. They are strictly batch machines.

The centrifuge bowl of this invention differs from those bowls, in that its corrugations are provided by at least one hollow flexible rib, which extends continuously in convo- The upper assembly is arranged. for the feed of an industrial Pulp or slurry o th hollow interior of th centrifuge bowl, and for the discharge therefrom of the lighter or liquid components separated by the centrifuge. The lower assembly is arranged for the discharge of the heavier or solid components of the pulp or slurry, as separated within the centrifuge and conveyed to discharge by the helical rib or thread 12a.

The mechanism thus far described is rotatably mounted in a supporting structure made up of a horizontal framework 13, in which the aforesaid lower assembly is journaled, and a plurality of supporting standards 14, serving, in effect, as legs for the framework 13, and rising above the centrifuge bowl to support parts of the aforesaid upper assembly.

In the illustrated instance, there are three standards 14, which pass through and are immovably fixed within respective sleeves 15 serving as spacers for upper and lower plates 16 and 17, respectively, of the horizontal framework 13.

The lower assembly, which provides discharge for separated heavier components of the pulp or slurry being treated by the apparatus, comprises a circular closure plate '18 arranged to mate with the lower flange b of the rigid cylinder 10. Such closure plate 13 and flange 10b receive and securely clamp, therebetween, the lower flanged end 12b of the flexible liner 12, thereby anchoring such liner in place and enabling the flanged end thereof to serve as a gasket preventing leakage from the interior of the centrifuge. For this purpose, the plate 18 is provided with a relatively wide and shallow, flat, circumferential groove 19 adjacent its outer peripheral edge, see Fig. 1. Bolts 20, or other suitable fastening means, serve to clamp the plate 18 and flange 10b tightly together about the gasket-providing, flexible flange 12b.

Depending from fixed circumferential securement, as by welding, to the bottom surface of closure plate 18 is a funnel structure 21, whose stem 21a extends downwardly as a discharge conduit. Such stem is journaled at spaced locations along its length by ball bearings 22 suitably mounted on the upper and lower plates 16 and 17, respectively, of the framework 13, and provides the rotatable support for the entire centrifuge.

The upper assembly, which provides slurry feed to the apparatus and discharge of the lighter and more liquid components as separated within the centrifuge bowl, comprises a circular closure plate 23, similar in formation to the closure plate 13 so as to receive and clamp the flanged upper end 120 of the flexible liner 12 between it and the upper flange 10a of centrifuge cylinder 10, as an upper gasket preventing leakage from the interior of the centrifuge drum.

As part of such upper assembly, a cylindrically-formed launder 24, defining an internal, annular discharge cup 24a for material flowing from the interior of the centrifuge drum, is fixedly mounted on brackets 25, which extend from fixed securement to the upper ends of respective standards 14. A discharge pipe 26 leads from cup 24a to any suitable place of disposal or use of the lighter or liquid components of the pulp or slurry.

Extending downwardly of the launder 24 through the central opening of annular discharge cup 24a and through openings provided centrally of the respective centrifuge closure plates 23 and 18, is a slurry feed pipe 27. A spider 28, secured to closure plate 23 and keyed to feed pipe 27, as at 281, centers the upper end of the feed pipe relative to the launder and centrifuge bowl, while a sleeve bushing 29, secured to closure plate 18, centers the lower end thereof. Gusset plates 30 reinforce securement of bushing 29 to closure plate 18, while a sleeve 31 is held in position by shaft nuts 32, which are threaded on the upper end of feed pipe 27 of helical cylinder 10 against any tendency toward elongation during operation.

The open upper end of feed pipe 27 communicates, in closely spaced relationship, with a feed nipple 33a dep nding fr a f up 3. hro gh hi h p p or slu ry supp ie tro y s table source isc ntin u ly fed to the centrifuge. The lower end of feed pipe 27 is closed by a plate or plug 34, and outlet ports 35 are provided through the side wall of such feed pipe in direct flow communication with the lower portion of the hollow interior of the centrifuge bowl.

Rising from securement, as by welding, to the spider 28 and centrifuge closure plate 23, is a tubular structure 36 having an outwardly depending circumferential flange 36a formed at its upper end as a lip overhanging the inner wall of annular discharge cup 244;. Such tubular structure 36 is concentric with feed pipe 27, and .is of greater diameter than the sleeve 31, thereby defining an annular discharge passage 37 leading upwardly from the discharge openings 38 in spider 28 to an overflow across lip 36a into discharge cup 24.

The helical rib or thread 12a of the flexible centrifuge bowl liner 12 terminates at the lower end of the cylinder 10 over a discharge opening 39 formed through centrifuge closure plate 18 adjacent the outer periphery thereof. It should be noted that such opening 39 comrnunicates directly with the interior of the flared body portion of funnel structure 21, and thus leads into the discharge stern 21a thereof. An annular wall 18-1 rises from fixed securement to the upper surface of closure plate 18 as a mounting collar for the lower end of flexible liner 12 and as a closure for the lowest convolution of the helical rib or thread 12a thereof.

In the illustrated instance, the lower end of discharge stem 21a is open, and a discharge cup 40, supported by legs 41 and having a discharge spout 42, is positioned directly underneath to receive and pass on to any suitable storage receptacle or flow channel (not Shown) the discharge issuing from stem 21a. For controlling such discharge, a conical valve head 43 is mounted at the upper end of an adjustable valve stem 44, which is threaded through the bottom of cup 40. I

Keyed or otherwise suitably fixed to the lower end of the discharge stem 21a of the funnel structure 21 is a drive member, here shown as a V-belt pulley 45 arranged to be driven from any suitable source of power, for example, an electric motor (not shown).

For imparting a positive transportative and jigging wave action to the centrifuge bowl during operation of the apparatus, a plurality of elongate rollers 46there being three in the illustrated instance-are individually rotatably mounted on respective supporting standards '14, between respective sets of upper and lower brackets 47 and 48 and on axes which are'parallel orapproximately parallel to the rotative axis of the centrifuge bowl.

The individual brackets 47 and 48 of each set are fixed to respective adjusting stems 49, which are threaded through a corresponding standard 14 in suitably spaced relationship and on axes radially disposed with respect to the axis of rotation of the centrifuge bowl. Thus, the rollers 46 may be moved toward or away from the outer circumferential surface of the centrifuge bowl, .and into any desired degree of indenting relationship with the flexible rib or thread 12a, thereby imparting a series of localized, circumferentially spaced deformations to such rib.

In the operation of the apparatus, the centrifuge bowl, inclusive of both .the rigid cylinder 10 and the flexible liner 12, together with the entire lower assembly and the feed pipe 27 .and tubular discharge structure 36 of the upper assembly, are rapidly rotated through the drive connection at 45.

An industrial pulp or slurry to be treated is introduced into the machine through feed cup 33, the same passing downwardly through feed nipple 33a into the feed pipe 27, from where it flows outwardly through ports 35 into the lower interior of the centrifuge bowl. Within the bowl, the pulp or slurry flows upwardly and, at. the same time, rotates with the bowl. As it travels upwardlyin discharge ports 68b, Fig. 8, opening into the lower in! terior of the flexible tube 60, i. e. into centrifuge chamber 83, Fig. 6.

In order to make more positive the imparting, within the centrifuge chamber 83, of proper rotative motion to the pulp or slurry feed entering through the ports 68b of rotating feed pipe 68, and for the further purpose of structurally reinforcing the connection of such feed pipe 68 to the centrifuge bowl, a plurality of upwardly tapering and radially disposed gusset plates 84 are attached to the lower end portion of feed pipe 68 and to the upper surface of lower end plate 63, as by welding. Such gusset plates 84 form, in eflect, an impeller operative upon the pulp or slurry feed.

For protecting the lower portion of the conduit or channel 85 defined by the hollow and open interior of the helical rib or corrugation 60a, from the force and washing action of the inflowing pulp or slurry, and for the other purposes hereinbefore attributed to the annular wall 18-1, an annular wall or baffle 86 rises from the upper surface of the lower end plate 63 in encircling relationship with the gusset plate impeller 84.

An elongate and arcuate discharge port 87, Fig. 8, preferably conforming in configuration to a sector of the lower periphery of the interior of the flexible tube 60, and disposed in registry with the lower termination of the interior 85 of the convoluted rib or corrugation 60a, is provided in the lower end plate 63 for the discharge of heavier components transported thereto by such rib or corrugation. The discharge port 87 opens directly into the discharge cone 69, and corresponds to the discharge opening 39 of the previously described embodiment.

As in the previously described form of the invention, a plurality of elongate rollers, mutuallly spaced around the outer periphery of the centrifuge bowl or drum, and extending along the length thereof on respective rotative axes which are parallel with the rotative axis of the centrifuge proper, provide the pressure elements for producing and advancing localized deformations in and along the flexible rib or corrugation. Similarly, such rollers are adjustable radially toward and away from the centrifuge bowl, so as to be capable of effecting greater or less localized indentation of the flexible rib or corrugation in providing the transportative wave action on the heavier components of the pulp or slurry deposited by centrifugal action in the hollow interior of such rib or corrugation. In this instance, however, a somewhat different adjustable mounting is provided for the respective rollers.

As illustrated, see especially Fig. 7, there are three elongate and cylindrical rollers 88 positioned 120 apart about the outer periphery of the flexible centrifuge tube 60. Each roller is rotatably mounted on a vertically disposed mounting post 90, as by means of sets of upper and lower ball bearings 89, Fig. 6, which are fixed to the post. The upper and lower ends of each mounting post are fixed within respective eccentric sleeves 91, as by means of keying, and such sleeves are journaled in respective bushings 92 which are fixed within suitable receiving openings of bracket supports 93 extending from respective frame members 71-1.

For enabling manual adjustment of the respective rollers 88 relative to the flexible rib or corrugation a of the flexible centrifuge tube 60, and retention of any given adjustment, each of the mounting posts 90 is equipped with a handle 94 projecting radially outwardly from fixed securement thereto immediately above stationary locking plate 95. The latter itself extends outwardly from fixed securement to the structural framework 71. A locking screw 96, depending from handle 94, travels within a semi-circular slot 97 in locking plate 95 as the handle is moved to the left or the right in the positioning of its roller either closer to or farther away from the center of the machine, and provides for anchoring such roller in any given adjusted position within the path of rotation of the flexible rib or corrugation 60a.

The flexible centrifuge tube 60 is, like the flexible liner 12 of the previously described embodiment, preferably molded to final form from rubber, so as to be both flexible and resilient. It has been found desirable to reinforce the internally projecting rib or corrugation 60b thereof, which extends between the convolutions of the externally projecting rib or corrugation 60a, as by means of fabric, cord, or the like (not shown), in order to establish a differential in yieldability between such externally projecting and such internally projecting ribs, the latter being made stiffer and less flexible than the former.

The operation of this embodiment of the invention is largely the same as that of the previously described embodiment. An industrial pulp or slurry to be treated is fed into the machine in a continuous stream through the feed pipe 68, passing into the lower part of the centrifuge chamber 83 through the feed ports 68b. In this embodiment, such material is acted upon by the impeller structure 84, to rapidly bring the feed up to the revolving speed of the bowl.

The lighter and more liquid components of the pulp or slurry pass upwardly through discharge passages 66 and the discharge riser 67 into the launder 74, being directed into the latter by deflector 75. The heaviest solids deposited along the length of the hollow interior 85 of the convoluted rib or corrugation 60:: are subjected to the transportative wave action induced by the rollers 88, and are forcibly propelled thereby toward and through the discharge port 87 into cone 69, through which they descend to the lower orifice 81 and to a final discharge from the machine by way of conduit 80.

As stated hereinbefore, the strength of the transportative wave action, and, therefore, rapidity of discharge in any given instance, is determined by the setting of the rollers 88 with respect to the convoluted rib or corrugation 60a. Other aspects of operation are controlled by the material feed input through feed pipe 68, the speed of rotation of the machine, the size of the discharge orifice 8 1, and the setting of the retarder fins 79. V

In operation, the centrifuge bowl acts as a sorting col.- umn, and the machine can therefore be used as a classifier. Since centrifugal force impels the solids to travel outwardly through the upward flow of pulp, and since the action of the centrifugal force is proportional to the specific gravity of the solids, the rate of upward flow of the pulp through the machine will, in great measure, determine the type and the quantity of solid particles to get through the rising column of pulp and reach the walls of the bowl. It will also largely determine the type and quantity of solid particles that are carried upwardly by the flow and out with the efiiuent.

Accordingly, if the rate of feed to the machine is increased, the rate of flow of the pulp through the machine is similarly increased, and proportionately fewer solid particles of the lower specific gravities reach the walls of the bowl. A proportionately greater number are carried out with the effluent. If, on the other hand, the rate of feed is reduced, the rate of flow of pulp through the bowl is similarly decreased, and proportionately more solid particles of the lower specific gravities reach the Walls of the bowl and are deposited in the corrugation. A proportionately less number are carried out in the effluent.

Similarly, since the centrifugal force acting on the solids is proportional to the square of the speed, if the bowl is speeded up, proportionately more of the solid particles of lower specific gravities, and more of the fines, will be impelled to travel through the rising column of pulp and into the corrugation. A proportionately less number will be carried out by the effluent.

Thus, by changing the rate of feed, or by changing the speed of rotation of the bowl, the end products of the rib, and discharge structure in flow communication with said opening; and an annular wall rises upwardly from the bottom of the centrifuge chamber a distance exceed ing the height of the discharge of the feed pipe, and surrounding the latter.

lO. The combination recited in claim 9, wherein an impeller structure is secured to the lower end of the feed pipe at and surrounding the discharge thereof and within the said annular wall.

11. The combination recited in claim 1, wherein the pressure element for locally indenting the flexible rib of the centrifuge bowl structure is a rotatable roller.

12. The combination recited in claim 11, wherein the mounting means for the pressure roller includes Structure adjustable in position radially of the centrifuge bowl.

13. The combination recited in claim 12, wherein there is a plurality of pressure rollers disposed about the circumferential wall of the centrifuge bowl, in mutually spaced relationship.

14. The combination recited in claim 13, wherein the pressure rollers are mounted for individual adjustment radially of the centrifuge bowl.

15. The combination recited in claim 1,=wherein the circumferential wall of the centrifuge bowl structure is of composite formation, the hollow flexible rib being made up of an elastic material, and the wall portions therebetween comprising a structurally rigid material.

16. The combination recited in claim 15, wherein the composite circumferential wall comprises a helically slotted cylinder of rigid material, and a liner of elastic material provided with an externally projecting hollow rib of helical formation which registers with and projects outwardly through the helical slot of said rigid cylinder.

17. The combination recited in claim 1, wherein the circumferential wall of the centrifuge bowl structure consists, as a whole, of a cylinder of elastic material, and includes the externally projecting, convoluted, flexible rib as an integral part thereof.

18. A machine of the character described, comprising rotatable centrifuge bowl structure defining a closed centrifuge chamber, said structure including a helically corrugated, cylindrical tube of flexible resilient material extending longitudinally of the rotative axis of said bowl and having at least one hollow, flexible rib protruding exteriorly therefrom and extending therearound longitudinally thereof, the hollow interior of said rib forming a continuous, helical conduit for the progressive travel of material therealong, and being open along its length to the centrifuge chamber for the reception of heavier components of material being processed within said chamber; means for introducing, within said chamber, material to be processed; an outlet leading from said chamber, adjacent said rotative axis of the bowl structure, for the discharge of lighter components of said material; outlet means leading from said chamber adjacent the periphery of the bowl structure and from communication with the hollow interior of said flexible rib, for the discharge of said heavier components; means mounting the bowl structure for rotation; drive means for imparting rotative movement to the bowl structure; a plurality of mutually spaced, elongate pressure rollers extending longitudinally of said circumferential wall of the bowl structure, exteriorly thereof; and means mounting said pressure rollers for movement within and across the path of rotation of said flexible rib, whereby said flexible rib is indented locally as the bowl structure rotates, and the said heavier components contained thereby are propelled toward and through the said outlet means.

19. The combination recited in claim 18, wherein the centrifuge bowl structure is substantially vertically disposed; the material introducing means comprises a feed pipe extending down through said centrifuge chamber from the upper end thereof to a discharge within said chamber adjacent the lower end thereof; the lighter components discharge outlet is disposed adjacent the upper end of said chamber; the heavier components outlet means comprises an outlet disposed adjacent the lower end of said chamber; and a circumferential wall surrounds the lower discharge end of said feed pipe, in close adjacency to the inner circumferential walls of said centrifuge chamber.

20. Material treatment apparatus, comprising a con trifuge bowl having an externally protruding and internally hollow and open, convoluted flexible rib; material feed means leading into said bowl; discharge means for liquid components of material fed into said bowl; discharge means communicating with one end of said rib, for the elimination from said bowl of solid components of said fed material; means for rotating said bowl; and pressure means disposed exteriorly of said bowl in localized pressing contiguity to said rib, for locally indenting said rib as the said bowl rotates, to produce an advancing wave action within said rib effective to propel the solid contents of said rib toward the said solid components discharge means.

21. A combined centrif ging, j ging, and classifying apparatus, comprising a centrifuge chamber defined by a rigid wall of circular configuration which has a hollow, flexible, convoluted rib protruding exteriorly therefrom and being open to said centrifuge chamber along i s length; means for introducing an industrial slurry into said centrifuge chamber; an outlet leading from adjacent the rotative axis of said centrifuge chamber, for con tinuously discharging separated lighter components of the said slurry; an outlet leading from adjacent the periphery of said centrifuge chamber and from communication with the hollow interior of said rib, for continuously discharging separated heavier components of said slurry collected by and within the said rib; means for rotating the centrifuge so formed; and means disposed exteriorly of but in operative adjacency to said centrifuge chamber and to said flexible, hollow rib, for squeeing said rib during rotation of said centrifuge.

22. A combined centrifuging, jigging, and classifying apparatus, comprising a rigid centrifuge cylinder having a hollow, flexible, convoluted rib protruding exteriorly thereof and communicating with the interior of said centrifuge cylinder along its length; means for introducing an industrial slurry into said centrifuge cylinder; an outlet leading from adjacent the rotative axis of said centrifuge chamber, for continuously discharging separated lighter components of the said slurry; an outlet leading from adjacent the periphery of said centrifuge cylinder and from communication with the hollow interior of said rib, for continuously discharging separated heavier components of said slurry collected by and within the said rib; means for rotating said centrifuge cylinder; and means disposed exteriorly of but in operative adjacency to said centrifuge cylinder and to said flexible, hollow rib, for squeezing said rib during rotation of said cylinder.

23. Apparatus of the character described, comprising a centrifuge bowl encircled by a hollow, flexible, convoluted rib which projects exteriorly therefrom and has its hollow interior open to the bowls interior; ribsqueezing means positioned exteriorly and radially of said centrifuge and within the path of travel of the outer periphery of said convoluted rib, for reducing the extent of radial protrusion of said rib as the centrifuge rotates; an inlet for supplying material to said bowl; an outlet for continuously discharging lighter components of said material from the bowl; and an outlet communicating with said rib, for discharging heavier components of said material from the bowl.

24. In a centrifuge, having a rotatable centrifuge bowl provided with an inlet for material to be treated and with outlets for relatively light components and for relatively heavy components, respectively, of the said material as separated within said bowl during rotation thereof, the new structural combination, which comprises a continuous, convoluted, hollow rib portion of flexible material

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