US2715460A - Hydraulic classification apparatus - Google Patents

Description

Aug. 16, 1955 G. M. DARBY HYDRAULIC CLASSIFICATION APPARATUS 4 Sheets-Sheet 1 Filed Aug. 7, 1953 INVENTOR George M. Darby ATTORNEY Aug. 16, 1955 e. M. DARBY 2,715,460

HYDRAULIC CLASSIFICATION APPARATUS Filed Aug. '7, 1953 4 Sheets-Sheet 2 INVENTOR George M. Darby o mkmgk ATTORN EY Aug. 16, 1955 Filed Aug. 7, 1953 G. M. DARBY HYDRAULIC CLASSIFICATION APPARATUS 4 Sheets-Sheet 3 INVENTOR George M. Darby ATTO RN EY Aug. 16, 1955 e. M. DARBY 2,715,460

HYDRAULIC CLASSIFICATION APPARATUS Filed Aug. 7, 1953 4 Sheets-Sheet 4 Fig. 4.

INVENTOR George M. Darby ATTORNEY United States Patent fiice 2,715,450 iatented Aug. 16, 1955 HYDRAULIC ctAssrFrcATroN APPARATUS George M. Darby, Westport, Conn, assignor to The Dorr Company, Stamford, Conn., a corporation of Delaware Application August 7, 1953, Serial No. 372,919

6 Claims. (Cl. 2G-18) This invention relates to the wet or hydraulic classification treatment of pulp containing a range of particle sizes from fine to coarse, as exemplified by metallurgical pulp or pulps of wet-ground ore, to effect the separation of the mixture of particles into a coarse and a fine fraction of sizes, these fractions herein to be simply termed the coarse fraction and the fines fractions, or else the oversize and the undersize. The coarse fraction then contains substantially all sizes above an intermediate size while the fines fraction contains substantially all those that are smaller than the intermediate size.

Hydraulic separation such as herein contemplated takes place in a classification pool into which the pulp is fed, while the coarse fraction is Withdrawn from the bottom of the pool and the fines fraction overflows from the pool across a weir. In order to aid and control the separation, the mixture of particle sizes While in transit through this pool may be kept mobilized by being subjected to the effect of controlled mechanical agitation, or subjected to the efiect of a stream of auxiliary so-called hydraulic operating water upfiowing through the pool at a controlled velocity, however, as contemplated by this invention, the mixture in the pool is subjected to the joint effects of both mechanical and hydraulic action, with the result that a desired coarse fraction above a certain mesh size will collect at the bottom of the pool to be withdrawn therefrom, while a corresponding fraction of fine sizes with its carrier water overflows from the pool, thus to afiord superior means of separation control presently to be set forth.

It is among the basic problems in such wet classification or separation treatment that there be effected as sharp a separation as possible between the oversize and the undersize or elsebetween the underflow sizes and the overflow sizes; thus the aim is. to. conduct the classification treatment in such a manner or with such type of apparatus that each of the two fractions be obtained as free as possible from stray sizes of the other fraction.

Another basic problem in such Wet classification treatment or apparatus is that of providing control means whereby the point of separation or fractionat on or cut between the two groups of sizes, the oversize and the undersize, can be readily established and accurately adjusted. For example, if the feed be of a run containing particle sizes ranging, say, from 28 to 200 mesh, then it should be possible, for example, to make a clean split at say, 100 mesh, yet it should be possible to readily shift the cut to say, 48 mesh. This calls for providing simple and efiectrvemeans for so adjusting or shifting. the cut while deriv ng the respective size fractions clean, that is, with a minimum of stray sizes admixed thereto. For example, the 1mportance of producing a clean coarse fraction s apparent where the classification apparatus operates in closed circuit with a wet grinding mill, the mill to receive coarse fraction particles, for regrinding, and where the admixture of an appreciable amount of undersize or stray sizes would burden the circulating load through the mill and would accordingly reduce its eificiency as well as that of the circuit as a whole.

Moreover, there is the general problem that such an apparatus should be capable of handling efiectively a feed slurry containing a relatively wide range of particles of extreme sizes, that is, from relatively very fine to relatively very coarse.

Also, there is to be considered in the operation of such classification treatment and apparatus the degree of dilution of the feed pulp, since it is desirable to produce a separation which remains substantially stable in spite of possible variations in the degree of feed dilution; another aspect lies in the fact that it may be desirable to derive the overflow of fines at the highest possible density, there being the difficulty that a high rate of hydraulic water required might run counter to the goal of attaining a desired degree of overflow density.

The invention provides improvements over the wet classification machine which employs the jointor compound etfect of mechanical and hydraulic classifying action shown in the patent to W. C. Weber, 2,302,588; that machine produces a sharp cut easily and accurately controllable, and is operable with a minimum of hydraulic operating water, and is capable of absorbing appreciable changes in the dilution of the feed pulp substantially without efiecting the cut itself, even though capable of producing the overflowing undersized fraction at relatively great density, and can handle a feed pulp containing a wide range of particle sizes from fine to coarse.

It is among the objects of the present invention to produce a machine possessing at least the operational characteristics and capabilities of the machine in the aforementioned patent, yet to be simpler of construction, lighter in weight, cheaper to build, as well as simpler to maintain, simpler to overhaul and simpler to service. The significance of these objects will appear more precisely from the following outline of the machine shown in that patent. in that machine, the pulp is fed to a significantly shallow pool the bottom of which is formed by a horizontal circular false bottom in the form of a perforated plate usually termed a constriction plate. A hydraulic supply chamber is associated with the underside of the constriction plate unitary therewith and has hydraulic operating water fed thereto continuously in order that such auxiliary water may continuously rise in the pool through and upwardly from the constriction plate at a controllable rate thus helping to maintain the particles in the pool in a mobilized state. Moreover, this hydraulic chamber with its constriction plate is mounted for oscillatory movement about a vertical axis by means of a hollow vertical column rising from the center of the constriction plate and suspended from an overhead bearing structure which carries drive mechanism for imparting the oscillatory movement through the column to the constriction plate and its associated hydraulic supply chamber. The slurry or pulp is fed to a central annular feed well surrounding the column and under normal operating conditions the pulp in the pool is subjected to the joint effect of the oscillatory motion of the constriction plate and of the hydraulic water rising therethrough. A uniform distribution of hydraulic water over the entire bottom of the pool is thus obtained not only by reason of the fact that the water is being introduced by the great many holes in the constriction plate, but also because these holes are constantly being oscillated incident to the oscillatory motion of the constriction plate.

The classifier pool is furthermore defined by a cylindrical stationary boundary wall the top edge of which constitutes an overflow weir for discharging the under- 3 7 size fraction of the pulp. This cylindrical boundary wall of the pool is concentric with the constriction plate although of a somewhat smaller diameter so that it is spaced slightly inwardly from the periphery of the constriction plate, yet also spaced upwardly from the marginal portion of the constriction plate. constriction plate may oscillate beneath the stationary boundary wall, with the vertical distance between this wall and the constriction plate constituting an annular sands passage or solids transfer passageway leading outwardly from the pool bottom to allow for the outward migration'and removal of the oversize fraction of the pulp from the pool. Importantly, along the periphery itself of the constriction plate there is provided what is herein termed a submerged sands discharge weir over which spill the sands or coarse fraction particles down into a receiving chamber which in turn surround the constriction plate. The sands discharge weir rises to a level at least somewhat higher than the sands passage, so that thereby there is maintained an annular sealing column of sands in transit between the passageway and the weir.

The annular space between the constriction plate and the surrounding receiving chamber is covered and closed by a top portion of the receiving chamber, which top portion in fact supports the cylindrical boundary wall of the pool by being rigidly connected therewith.

A body or column of clear water maintained in the sands receiving chamber defined by a clear water overflow weir of adjustable height, balances the column of pulp or mobilized particles in the pool, and this balance represents a hydraulic equilibrium condition in the machine, whereby the separation or cut is readily controllable, namely, as by adjustment of the height of the clear water overflow weir.

That is to say, when a pulp of a certain dilution is fed to the center of the classifying pool, and hydraulic operating water is supplied through the central hollow column to the supply chamber underneath the constriction plate, while motion of the oscillatory structure is being continuously maintained, there results in the pool a classifying Stratification of the particle sizes in a mobilized'condition with the greatest or largest size particles sinking to the bottom and the successively smaller sizes in rnobilized suspension finding their place in respective strata upward from the bottom of this pool. Once in operating equilibrium this pool will produce a continuous overflow of desired undersize fraction particles,

. while the desired oversize fraction particles collect in a bottom zone where they are nevertheless mobilized partly because of the motion of the constriction plate, and partly because of the hydraulic elfect of the operating water sutliciently so they will rnove or migrate outwardly radially in all directions towards and through the sands discharge passage and over the submerged sands discharge weir which surrounds the passage, and into the surrounding sands receiving chamber whence they can be removed into. emergence from a body of Thus, the i Morever, there is an additional control factoravailable of the undersize fraction accordingly, which means that some of the oversize fractions at the lower limit of its size range will be thrown over into the undersize fraction as a result of an increase of the height of the clear water overflow weir. Similarly, when the height of the clear water overflow weir is lowered, the effect with V respect to the split will be in the opposite sense.

for varying the point of separation, which lies in varying the rate of flow or pressure of the hydraulic water supplied to the underside of the constriction plate, hence results and features of controllability as have been set forth above. Moreover because of the coactionof horizontal mechanical motion and hydraulic action the prior machine is capable of handling effectively and efficiently a feed slurry containing a wide range of particle sizes, namely a range from relatively very fine to relatively very coarse; but the inertia of the oscillatory masses clear water as by any suitable conventional elevating 7 means. The sands discharge weir creates what is in effect an operational seal formed by the annular accumulation of migrating sands between the pulp column in the pool and the surrounding body of clear Water. in the sands receiving tank.

The exact mesh size at which the separation or cut is to be effected depends upon the adjusted equilibrium condition in terms of the adjusted height of the clear water overflow weir of the sands receiving chamber; that is to say, the greater the height of the clear water overflow weir, the greater will have to. be the average specific gravity of the pulp column in the pool to satisfy such equilibrium, and the greater will be the mesh size at the cut. In other words, raising the clear water overflow height will shift the cut towards reducing the oversize fraction while increasing the volume to be accelerated and retarded is considerable and therefore tends to impose a practical limit upon the diameter of the oscillatory structure, also the constriction plate is a relatively expensive item to produce and to replace, and in order to be replaced requires dismantling of the machine. Yet, a change of the constriction plate may at times be called for or desirable, either due to'wear and tear, or else because a different arrangement of the holes or perforations in the plate may be desired The body of hydraulic operating water within the oscillatory structure underneath the constriction plate represents a portion of the oscillatory mass and aggrevates the problem of inertia.

Thus, it is among the more specific objects of this invention to provide a machine which, while possessing at least the operating characteristics, features and advantages of a machine such as above outlined, is simpler and cheaper of construction, with a substantial reduction of the oscillatory or moving masses and thus of the inertia problem, and which provides such hydraulic water distribution means as will avoid the drawbacks of the constriction plate above set forth, but are nevertheless conducive to producing the desired state of classifying mobilization in the classifying pool.

This invention is based upon the concept and discovery that the jet-wise introduction of the hydraulic operating water instead of by oscillatory upward jets rising from the bottom, can be effected by the provision of stationary jets directed angularly towards the bottom, with substantially equivalent results as to uniformity of water distribution. structurally, this provides for an arrangement of stationary distributing elements so disposed at the bottom or in the bottom zone of the pool and having jet emitting means so arranged and distributed asto produce within the bottom zone of the pool jets-inclined at a suitable angle relative to a back-and-forth moving solid bottom; jets are provided in such numbers and sizes and in such arrangement that the desired mobilized classifying condition of the particles in the pool are properly maina tainable even though at a comparative minimum consumption of hydraulic operating water, and with a separation control comparable in effectiveness and sharpness to that above outlined.

This concept or discovery then, may be said to lie in employing the solids mobilizing effect of horizontal backand-forth motion of the bottom itself in conjunction with downward angularly directed stationary jets for establishing a solids mobilizing distribution of hydraulic operating water. whereby the water in effect rises uniformly from the entire effective bottom area. This provides for a jet emitting distributing system supported and supplied from above to readily lend itself to being inspected, replaced or 5 serviced without requiring any dismantling of the machine itself.

In summary then, the invention comprises feeding the pulp or slurry to be classified to a relatively shallow pool the bottom of which performs a movement such as to produce relative motions between it and a strata of oversize particles supported therein, providing stationary jets of hydraulic operating water in the bottom zone of the pool so they will be directed towards the pool bottom at a downward angle with respect thereto, with the result that the combined effect of the motion of the bottom and of the hydraulic jet action will produce in the pool those classifying conditions whereby the solids are maintainable in a state of uniform classifying mobilization at a minimum expenditure of hydraulic water, while readily and sharply controllable with respect to desired mesh sizes of separation, and whereby the machine is rendered capable of handling eflectively a feed slurry even though containing a wide range of particle sizes from fine to coarse. the pool, while the oversize fraction or sands pass from the pool as they migrate through the sands discharge passage against the controllable back pressure of a hydraulic column maintained outside the pool, which controllable back pressure column comprises a quantity of the discharging solids fraction or sands having communication through the submerged passage with the slurry column represented by the pool itself.

According to one embodiment, although in no limiting sense, the invention avails itself of structure similar to that of the aforementioned patent to the extent that I employ a circular relatively shallow classification pool defined by an oscillatory circular bottom, a stationary cylindrical boundary wall with peripheral overflow for the undersize fraction, an annular sands passage, an annular sealing column along and outside said passage and defined by a sands discharge weir surrounding the passage in concentrically spaced relationship therewith, a sands receiving chamber surrounding the sands overflow weir, a clear water column with adjustable overflow weir for controlling the pulp density in the pool and thus for maintaining a desired size separation or cut, and centrally disposed means for feeding the pulp or slurry to the pool.

The objects of the invention are attained in this embodiment by having the bottom solid or imperforate, while stationary jet-emitting elements for distributively introducing the hydraulic water are disposed in suitable relationship to each other and to the bottom. More in particular, such elements are in the form of a set of annular jet-emitting pipe structures disposed concentric with one another as well as concentric with the vertical axis about which the bottom oscillates. These jet-emitting pipe structures are suitably spaced from one another in a horizontal plane which in turn is suitably spaced from the bottom, so that the jets emitted at a suitable angle towards the bottom from each side of each such pipe will produce what is in effect an adequate and uniform distribution of hydraulic water to rise from the bottom for maintaining the desired mobilized condition of the solids in the pool.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the metes and bounds of the claims, or of forms that are their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

Figure l is a diagrammatic longitudinal sectional view I of the classification apparatus according to one embodiment of the invention, in which the tank structure or chamber holding the classifying pool of pulp has an oscillatory bottom with a stationary water jet emitting system The undersize fraction overflows from the top of aration.

superimposed thereon, where the tank structure of the classifying pool itself is in turn superimposed upon and has hydraulic balance communication with a sands receiving tank containing a body of clear water and having a sloping deck along which the sands or coarse fraction of the separation are raised from submergence and for discharge in a dewatered state.

Figure 1 is a cross-sectional detail view on line 1--1 taken on Figure l, to show the means for adjusting the superelevation.

Figure l is a side view taken on line 1 ---1 of Figure 1*.

Figure 2 is a plan view of the apparatus shown in Figure 1 showing a plan view of the jet emitting water supply system as well as of drive means for effecting oscillatory movement of the bottom plate of the classifier pool.

Figure 3 is a longitudinal section on line 3-3 of Figure 2.

Figure 4 is an enlarged detail view taken from Figure 3 of the supportingand maintaining means in section for the oscillatory bottom structure.

Figure 5 is an enlarged detail view from Figure 2 of the jet-emitting pipes relative to their immediate structural environment.

Figure 6 is a perspective view of the annular jet emitting pipes concentrically disposed in the horizontal plane although spaced from the oscillatory bottom plate.

According to the diagrammatic view in Figure l the classifying apparatus comprises a relatively shallow classifier pool or bath 10 containing and having fed thereto continuously the pulp mixture to be classified, and a sands receiving chamber or tank 11 disposed underneath and surrounding the classifier pool and having hydraulically effective communication therewith.

In this embodiment the classifier pool itself is round comprising a horizontal circular bottom plate 12 which in turn is part of a movable structure 0 mounted to oscillate about a vertical axis x-x, such oscillatory mounting being indicated by way of an annular vertical thrust bearing structure 13. The movable or oscillatory structure 0 then comprises the aforementioned circular bottom plate 12, and furthermore a central hollow tubular portion 14 rising from and having rigid connection with the bottom plate 12, which tubular portion 14 terminates upwardly in a flange portion 15 indicated to constitute the upper part of the annular thrust bearing structure 13. That is to say, the flange portion 15 is supported for oscillatory movement upon a stationary annular bearing portion 16 as by way of anti-friction ele ments or balls 17. The bottom plate 12 of the oscillatory structure 0 is shown to be reinforced underneath as by a plate structure 18 of shallow inverted conicity, and the central tubular portion 14 is shown to be rigidly connected to both the horizontal bottom plate 12 and to the conical reinforcing structure 18.

The classifier pool 16 is further defined by a cylindrical stationary wall 19 concentric with the vertical axis :cx of oscillation and rigidly connected with and supported by the sands receiving chamber or tank 11 by means of a substantially horizontal and substantially annular cover structure 20. In this way, the wall 19 is rigidly supported a suitable distance d from the bottom plate 12 to provide an outward annular passage 21 for the coarse fraction of solids resulting from the sep- The diameter of the cylindrical Wall 19 is smaller than that of the bottom plate 12 so that the bottom plate in eifect provides a peripheral portion in the form of an annular shelf 22 projecting outwardly beyond and extending around the cylindrical wall 19. Along the periphery of this annular shelf 22 or of the plate 12 there rises a sands discharge weir 23 extending somewhat higher than the height of the sands discharge passage 21. In this way, there is formed at the passage 21 and between the wall 19 on the one hand and the sands discharge weir 23 on the other hand, a functional se al effective between the classifier pool and a body of clearwater in the'sands receiving tank 11, even with the sands migrating continuously through the passage 21 V and discharging across the submerged weir 23 whence they at once drop to the bottom of receiving tank 11.

-' The cylindrical wall 19 provides a circular overflow edge 24 across which the 'fines fraction or undersize' fraction passes into an open receiving launder 25 for discharge through outlet 25.

A cylindrical feedwell is indicated at 26 with feed pulp indicated by arrow F to enter this well.

A supply system for effecting the jetwise introduction of hydraulic operating water into the pulp bath of the classifier pool is shown to comprise a pair of annular 1 jet emitting pipes 27 and 28 disposed concentrically with respect to one another as well as with respect to the vertical axis x.x.

Each of these annular jet-emitting pipes has apair of vertical supply pipes, such as the vertical supply pipes 27 and 27 for supplying the annular pipe 27, and vertical pipes 28 and 28 for supplying the annular pipe 28. All these vertical branch supply pipes are in turn shown to be served by a common supply header 29.

- Control valves manually operable are shown tobe provided at 30 for the header'29 aswell as for each of the numerals 30 30 30, and 30 Functionally important in Figure 1 is the fact that there is'to' be maintained in the practical operation of a this machine a superelevation S between the high level L1 of a body of clear water in the sands receiving tank and the low level hot the pulp in the classifier pool.

The extent or height of this superelevation S is to be adjustable so that by such adjustment there may be established a hydraulic back pressure of a desired'magnb tude to act upon the sands that are in a state of outward transit through and from the annular shelf space between the sands passage 21 and the submerged sands discharge weir 23'. Such hydraulic back pressure of a desired magnitude is established by way of the clear a water overflow C provided laterally of the sands receiving tank 11 and indicated more clearly in the detail views Figure -1 and l thereof. This overflow is disposed in a laterally disposed box 30 communicating with theinterior of tank 11 through an opening 30 provided in the respective side wall of that tank. Outlets3tl and 30 from box 36) allow for the discharge of clear water and'of any solids respectively that might have reached overflow C.

.Sincethe extent or height of the superelevation S balancesthrough the passage 21 of pulp column in the classifier pool, it follows that by a change of superelevation S there is attainable a corresponding change of the'density conditions in the pulp bath or classifier pool, and hence there is attainable by such a change of superelevation a corresponding shifting of the point of separation or cut between the overflowing fines fraction and the coarse fraction of sands passing across the submerged sands discharge weir 23.

. Figures 2, 3 and 5 present the essential parts of the apparatus more fully implemented as to structure. The base of the apparatus in fact is represented by a tank structure '31 which receives the sands or coarse fraction.

resulting from the classifying operation, and which is herein'termed the sand receiving tank. The coarse solids or sands are delivered into this tank 31 from a superposed pulp bath or classifying zone along with a necessary amount of water, so that with these coarse solids at once gravitating to the bottom of tank 31 there is to be present at all times in that tank a body of clear water from which the sands are to be recovered in dewatered portion 54, such bolt connection being indicated at 65 condition as by means of elevating mechanism of any suitable kind. The clear water level in this tankis to be maintained at a suitable elevation L3 adjustable, for j example, as by means of 'an adjustable weir plate indicated at 32 or its equivalent,here.shown to be provided upon one of thelateral walls of this tank.

wall portion 35 and an inwardly inclined end wall portion 36. The upper portion of this basic tank structure 31 'is substantially in the form of a shallow bowl 37 indicated as by the inverted conical wall portion 38 merging with the upper end of the boot 34 as well as with the side walls 39 and 40 of this tank structure and further by a cylindrical wall portion 41 constituting the top end portion of the bowl 37. The cylindrical wall 41 forms the inner Wall of an annularioverflow receiving launder 42 which is further defined by an annular bottom 43 and an outer cylindrical Wall 44, this overflow launder .42 being provided to receive the under size'or fines fraction overflowing from the classifying pool orbath and passing from the launder through an outlet 45.

'From the top end of the cylindrical wall 41 constituting 1 thetop edge portion of bowl 37, there extends inwardly and rigidly an annular cover portion or shelf 46 having waterproof connection with the top end of the cylindrical Rigidly connected with and welded to the.

Wall 41. inner edge of the inwardly overhanging annular shelf 46 is a vertical cylindrical wall 47 in, such a manner that the horizontal line of connection or welding line 48 runs horizontally intermediate the upper and lower ends of the cylindrical wall 47. In this way there is in effect formed aroundthe lower portion of the cylindrical wall 47 an annular space 49 which is downwardly open and I into which extends upwardly a sands, discharge weir 50 which is part of an oscillatory structure 02 hereinafter to bedescribed. The cylindrical boundary wall 41 has a lower end terminating short of the horizontal plate 52 a distance ah thereby constituting a peripheral sands dis charge passage P.

rigidly interconnected by a pair of shorter parallel beams 'j 59 and 60 which in turn are interconnected by a pair of still shorter beams 61 and 62. The beams 59 and 60 thus constitute With the beams 6i and 62 a substantially square horizontal opening having sides of the length I through which opening extends the tubular portion 54 of oscillating structure 02. The beams 59, 60 and 61, 62 support the.

annular thrust bearing structure 55 (see also Figure 4) by way of a cover plate 55 The thrust bearing structure 55 comprises a stationary lower annular member or bearing race member 63. bolted to the respective beams of the frame structure 56 as at 63 and a rotary or oscillatory upper annular member or bearing race member 64 bolted to a flange 65 formed at the top end of the tubular with anti-friction elements or bearingballs 66 transmitting the vertical thrust of the oscillatory structure 02 from the 7 upper race member 64 to the lower race memberv 63.

The oscillatory structure 02 comprises the sands discharge weir 50 extending along and rising from the peripheral edge'of the oscillatory'plate 52 andthu s extending upwardly into the aforementioned annular space 49 within the bowl 37, the height of this submerged weir 50 being slightly greater than the height of the associated clearance or sand passage P. The horizontal overhead frame structure 56 is here also employed for mounting and supporting a pipe system 66 for supplying hydraulic operating water to the classifying bath of pulp upon the oscillatory bottom plate 52. This water supplyand distributing pipe system is here shown to comprise a pair of circular jet emitting pipes 67 and 63 concentric with respect to each other as well as with respect to the vertical axis of the oscillatory structure 02. Each of these annular pipes 67 and 68 is formed by or subdivided into a pair of semi-circular sections or halves so that pipe 67 comprises the sections or halves 67 and 67 having between them a pair of flange connections 67 and 67 while pipe 68 is similarly formed by a pair of sections or halves 68 and 68 having between them flange connections 68 and 68 The various sections of the horizontal annular pipes 67 and 68 are supplied by respective vertical branch pipes 70, 71, 72 and 73 which branch pipes in turn are supplied from a horizontal header 74 having a central supply pipe 75. A control valve 76 is shown to be provided in the central supply pipe 75 while control valves 77 and 78 are shown to be provided for the branch pipes 71 and 72 respectively, and control valves 77 and 78 for branch pipes 70 and 73.

Each of the circular pipes 67 and 68 has at each side and along the length thereof a row of jet emitting openings 79 so disposed as to have the hydraulic jets omitted therefrom downwardly although at an angle w towards the oscillatory bottom plate 52. A suitable such angle w has been found to be on the order of about 20 below the horizontal, with a clearance of about 1" between the pipe 67 and 63 and the bottom 52.

Provisions are made upon the supporting super structure for the jet-emitting pipes 67 and 68 or else the pipe system to be adjustable with respect to the bottom of the classifier pool, whereby the clearance between the pipes 67 and 68 and the bottom is rendered adjustable.

Pulp to be classified is fed to the pulp bath upon the oscillatory bottom 52 through a feed pipe 88 leading to a stationary cylindrical vertical bathe 81 concentric with the oscillatory structure and supported from the underside of the overhead frame structure 56 as by brackets 81. This bafile 31 is surrounded by an annular feedwell 82 connected with and rising from the oscillatory bottom 52. That is to say, the oscillatory feedwell 82 comprises a vertical cylindrical wall 83 and an annular horizontal bottom 84 which is spaced a distance q from the horizontal bottom plate 52 and constitutes with the cylindrical wall 83 and with the column 54 the annular receiving trough or feedwell 82 there being provided openings or feed passages 85 in the wall 83 through which openings the feed pulp enters the classifier bath radially in all directions from the feedwell S2.

The concentric jet emitting pipes 67 and 68 are here shown to be spaced a distance s from each other (see Figure while the distance of pipe 67 from the inner boundary wall 83 of the classifier bath is one-half s and the distance of the pipe 68 from the outer boundary wall 47 of the classifier bath is equally one-half s. The distance s being in a practical instance, for example, 6 inches.

Apparatus for actuating or oscillating the oscillatory structure 0 has been shown in the initially mentioned Patent 2,302,588 and need here only be indicated diagrammatically. Such actuating means are here shown to be mounted upon the overhead frame structure 56, and to comprise a horizontal arm 86 rigidly extending from the upper bearing race member 64, an eccentric member 87, a connecting rod 88 between the outer end of arm 86 and the eccentric member 87, and motorized drive means indicated at 89 for rotating the eccentric member 87. The overhead construction 56 is shown to comprise a horizontal auxiliary frame extension 90 for supporting and mounting part of the actuating mechanism comprising the eccentric 87.

A practical example presenting a combination of struc rural and operational data is as follows:

The classifier pool is in the form of an annular space 42 outer diameter, 12" wide, and 9" deep, with an effective area of 7.8 square feet. The jet-emitting pipes of seamless tubing have diameter, that is, .666 inch inside diameter and .042 inch wall thickness, there being two concentric pipes spaced 6" from one another and spaced 3" from the respective outer and inner boundary walls of the pool. Each of these jet-emitting pipes has a pair of supply lines or risers, at diametrically opposed points, of 1" diameter pipe.

There are 288 jet holes in all in the bottom of the classifier pool with a total area of 1.79 square inches each hole having an area of .00622 square inch, at a spacing of the holes center-to-center of 5 degrees. At a rate of 25 gallons per minute the head loss through these holes was 1 foot of water column. The jet holes are provided along each side of each pipe and are directed towards the bottom at a downward angle of about 20 degrees below the horizontal. The clearance between the jet-emitting pipes and the bottom in a practical instance was 1" but was made adjustable by the provision of means for raising or lowering the jet-emitting pipe system.

There were 225 oscillations per minute imparted to the bottom so that the travel peripherally at the sands discharge passage was about 3 /2". The sands discharge passage was /2" high while the submerged sands discharge weir was high.

The feed to the classifier pool was a deslimed sands mixture having a range of sizes of -20 to 200 Tyler mesh. With a feed of 105.9 tons per day (dry weight) there was obtained an underflow or coarse fraction of 92.6 tons per day (dry weight) and an overflow fines fraction of 13.3 tons per day (dry weight). With superelevation being maintained at 5 /2" and a rate of 38 gallons per minute of hydraulic operating water, the separation in terms of the size of the cut" was 174 microns.

Screen analysis of the feed, of the underflow, and of the overflow were as follows:

Feed- E33 1 Overflow- Percent 01' Percent of Total 5955 5 Total Tyler Mesh Solids 8 ,3 Solids 53325? held by a Lilli? feed screen overflow I claim:

1'. Apparatus for the hydraulic classification treatment of a pulp containing a mixture of particle sizes ranging from fine to coarse, to efiect the separation of the mixture into a fraction of fines and a fraction of sands, defined as undersize and oversize particles respectively, which apparatus comprises a receptacle for holding a classifying pool with said mixture being continuously supplied thereto, and with undersize particles discharging from the top and oversize particles discharging from the bottom of the pool, said receptacle comprising a horizontally movable bottom structure, actuating means for imparting horizontal motion to said bottom. structure with repetitive reversal of the direction of said motion such as will produce relative motion between said bottom and oversize particles supported therein; controllable water supply couduit and distributing means extending from above into said pool and having water emitting lower terminal portions in the bottom zone of said pool and in spaced relationship with said bottom, for distributively emitting hydraulic auxiliary water at a controlled rate towards said bottom, said lower terminal portions being providedwi'th orifices for emitting water jets in a downwardly' sloping direction towards said bottom and in a manner whereby the water-in effect rises in'substantially uniform distribution from the bottom, and whereby in turn'there'ar'e in a teeter condition, there being provided an overflow weir for overflow discharge of undersize 'pa'rticles'from said top zone of the pool, and adjustable means for controlling the rate of underflow discharge of sands from said bottom zone .and for controlling the out between the undersize and. the oversize, so that by the concurrent action of the horizontal motion of the bottom surface and of the rising flow of the hydraulic water there are producible overflow and underflow size fractions each substantially free from stray particle sizes of the other.

2. Apparatus for the hydraulic classification treatment ofa pulp containing a mixture of particle sizes ranging from fine to coarse, to eflect the separation of the mix- "ture :into a fraction of fines and a fraction of sands, defined as undersize and oversize particles respectively, which apparatus comprises a receptacle for holding a classifying pool in which to effect such separation with said mixture being continuously supplied thereto while undersize particles discharge from the top and oversize particles discharge from the bottom of the pool, said receptacle comprising a boundary wall structure and a bottom structure horizontally movable with respect to the boundary wall structure and in sealing relationship therewith, said. bottom structure having a horizontal surface for supporting a strata of oversize particles thereon, actuating means for imparting horizontal motion to said bottomistructure with repetitive reversal of the direction of said motion such as will produce relative motion'between said supporting surface and the oversize particles of said bottom strata while maintaining said sealing relationship; controllable water supply conduit and distributing means top, and an intermediate zone containing ,a mixture of undersize and oversize particles in a teeter condition, there being provided an overflow weir for overflow discharge of undersize particles from 'said top zone of the pool,

and adjustable means for controlling the rate of underflow discharge of sands from said bottom zone, which latter means comprise asands discharge passage at the margin of said pool between said bottom andtheboundary'wall thereof, confining means providing a sands column outside said passage, and adjustable means for controlling the rate of sands discharge from said sands column and thus controlling the cut between the undersize and the oversize, so that by the concurrent action of the horizontal motion of the bottom surface and of the rising flow of the hydraulic water there are producible overflow and underflow size fractions each substantially free from stray particle sizes of the other,

3. 'Apparatus according to claim 1, inwhich said water emitting lower terminal portions comprise pipe means spaced from the bottom and extending horizontally substantially' in the direction of said horizontal motion, said pipe means having orifices disposed for emitting water jets in a lateral downwardly sloping'direction towards the bottom. i

4. Apparatus accordingto claim 1, in which the direc-,

tion of said horizontal motion is substantially transversely of the direction of general horizontal progress of the particles in the pool towards discharge.

5. Apparatus according to claim '2, in which said ad jus'table sands discharge control means comprise a sands 7 receiving chamber surrounding and enclosing said outside confining means and sands column therein, saidreceiving chamber providing aclear water column having extending from above into said pool and having water emittinglower terminal portions in the bottom zone of adjustable overflow, said overflow being adjustable for correspondingly controlling the point of separation.

' 6. Apparatus for the hydraulic classification of a pulp u containing a mixture of particle sizes ranging from fine to coarse, to eflect the separation of the mixture into a fraction of overflow fines and a fraction of underflow sands, defined as undersize and oversize particles respectively, which apparatus comprises a classifying pool in which to efiect such separation with sand mixture being.

continuously supplied thereto, said pool being defined by a stationary cylindrical boundary wall, a circular bottom substantially concentric with said boundary wall and having downwardly spaced relationship therewith to form an annular discharge passage for the sands, overhead structures and bearing means for centrally supporting-said bottom for horizontal oscillatory motion thereof with actuating means for imparting such oscillating motion, a peripheral sands discharge weir rising from the peripheral portion of the bottom and spaced 2. distance from said passage and to a height surmounting the upper edge of said passage and thereby adapted to contain a column ofsands in outward transit towards said sands discharge weir and constituting an operational seal, a stationary sands receiving chamber surrounding and'closing upon said stationary boundary wall while enclosingsaid sands discharge weir, and providing a clear water column having an adjustable overflow, controllable means for removing sands from said receiving chamber, and controllable water supply conduit and distributing means extending from above into said pool and having water emitting lower terminal portions in the bottom zone of said pool and in spaced relationship with said bottom, for distributively emitting hydraulic auxiliary water at a controlled rate towards said bottom and so disposed relative to the bottom that such Water in efiect rises in substantially uniform distribution from the bottom, and wherebyin turn there References Cited in the file of this patent UNITED STATES PATENTS Weber Nov. Harrington Nov.

Claims (1)

1. APPARATUS FOR THE HYDRAULIC CLASSIFICATION TREATMENT OF A PULP CONTAINING A MIXTURE OF PARTICLE SIZES RANGING FROM FINE TO COARSE, TO EFFECT THE SEPARATION OF THE MIXTURE INTO A FRACTION OF FINES AND A FRACTION OF SANDS, DEFINED AS UNDERSIZE AND OVERSIZE PARTICLES RESPECTIVELY, WHICH APPARATUS COMPRISES A RECEPTACLE FOR HOLDING A CLASSIFYING POOL WITH SAID MIXTURE BEING CONTINUOUSLY SUPPLIED THERETO, AND WITH UNDERSIZE PARTICLES DISCHARGING FROM THE TOP AND OVERSIZE PARTICLES DISCHARGING FROM THE BOTTOM OF THE POOL, SAID RECEPTACLE COMPRISING A HORIZONTALLY MOVABLE BOTTOM STRUCTURE, ACTUATING MEANS FOR IMPARTING HORIZONTAL MOTION TO SAID BOTTOM STRUCTURE WITH REPETITIVE REVERSAL OF THE DIRECTION OF SAID MOTION SUCH AS WILL PRODUCE RELATIVE MOTION BETWEEN SAID BOTTOM AND OVERSIZE PARTICLES SUPPORTED THEREIN; CONTROLLABLE WATER SUPPLY CONDUIT AND DISTRIBUTING MEANS EXTENDING FROM ABOVE INTO SAID POOL AND HAVING WATER EMITTING LOWER TERMINAL PORTIONS IN THE BOTTOM ZONE OF SAID POOL AND IN SPACED RELATIONSHIP WITH SAID BOTTOM, FOR DISTRIBUTIVELY EMITTING HYDRAULIC AUXILIARY WATER AT A CONTROLLED RATE TOWARDS SAID BOTTOM, SAID LOWER TERMINAL PORTIONS BEING PROVIDED WITH ORIFICES FOR EMITTING WATER JETS IN A DOWNWARDLY SLOPING DIRECTION TOWARDS SAID BOTTOM AND IN A MANNER WHEREBY THE WATER IN EFFECT RISES IN SUBSTANTIALLY UNIFORM DISTIBUTION FROM THE BOTTOM, AND WHEREBY IN TURN THERE ARE FORMED AND MAINTAINED IN SAID POOL SUBSTANTIALLY A SANDS ZONE OF OVERSIZE PARTICLES AT THE BOTTOM, A FINES ZONE OF UNDERSIZE PARTICLES AT THE TOP, AND AN INTERMEDIATE ZONE CONTAINING A MIXTURE OF UNDERSIZE AND OVERSIZE PARTICLES IN A TEETER CONDITION, THERE BEING PROVIDED AN OVERFLOW WEIR FOR OVERFLOW DISCHARGE OF UNDERSIZE PARTICLES FROM SAID TOP ZONE OF THE POOL, AND ADJUSTABLE MEANS FOR CONTROLLING THE RATE OF UNDERFLOW DISCHARGE OF SANDS FROM SAID BOTTOM ZONE AND FOR CONTROLLING THE CUT BETWEEN THE UNDERSIZE AND THE OVERSIZE, SO THAT BY THE CONCURRENT ACTION OF THE HORIZONTAL MOTION OF THE BOTTOM SURFACE AND OF THE RISING FLOW OF THE HYDRAULIC WATER THERE ARE PRODUCIBLE OVERFLOW AND UNDERFLOW SIZE FRACTIONS EACH SUBSTANTIALLY FREE FROM STAY PARTICLE SIZES OF THE OTHER.

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