US1881875A - Bowl classifier - Google Patents

Description

H. w. NEWTON BOWL CLASSIFIER Oct. 11, 1932.

Filed May 29. 1931 2 Sheets-Sheet 1 awueuboz HARRY N NEWTON 1'1, 1932- H. w. NEWTON BOWL CLASSIFIER.

Filed May 29, 1931 2 Sheets-Sheet 2 aywwnfoz HARRY N. NEWTON Patented Oct. 11, 1932 UNITED STATES PATENT. OFFICE DELAWARE BY masnn ASSIGN- Bowl. cnas'srrma Application filed Kay 29, 1931. Serial No. 540,898.

This inv'ention relates to classifiers, and more particularly to that ty of classifiers intended to perform a classi ying or sorting operation of particles of mixed sizes or different specific gravities or both, by hydromechanical means. Such classifiers operate on the principle of hindered settling of the heaviest and intermediate particles and overthe settled matefiow of the finer particles,

the settling tank 19 rials being removed from by mechanical means. I 4

In classifiers of this type, two cooperating tanks are generally employed, the upper one, known as a primary chamber or bowl, feeding 1 through its bottom to asecondary compartment. The feed from the bowl to the under compartment is by gravity, the settled material dropping from the bowl through a restricted opening. The material is then re- 20 classified in the under or secondary compart-- ment, the lighter particles being thrown into suspension and returned by a fluid current to the bowl. Outflow of the fluid and the discharge of fine particles in suspension is over 2.) a weir from the bowl, while the heavier material settles in the under compartment and is mechanically removed, as by a rake.

I In the use of classifiers, it is common knowledge and almost an everyday occurrence to an experience difficulty of operation by a congested condition developing in one or both tanks. Without confining the invention to any particular theory of causes and effects,

it would appear that this congestion is theo-' retically the result of the classifier being out of balance. Agitation in the upper or primary tank is such that intermediate sizes of particles are allowed to settle and therefore pass to the secondary compartment. In the I secondary compartment agitation may .be such that those intermediate. sizes of particles or-part of them are not allowed to settle, and will accumulate between the two tanks hindering fiow either way andcausing such congestion as to often bend or break operating arts of the mechanical devices for removing the settled material. The present invention seeks toovercome, or at least relieve that congestion so that theclassifier will continue to function properly and without a breakdown.

It would appear that much of the material A CORPORATION 01' of critical or intermediate size allowed to settle in the primary chamber but not allowed to settle in the secondary compartment, might be reclassified if returned to the bowl so that the smaller particles thereof would escape over the outflow weir and the larger returned to the secondary compartment for discharge by the mechanical means. Heretofore, there has been such interference through the opening between the two tanks that the critical sizes are impeded to such extent in attempting to return to the bowl that they are often kept in suspension just below the opening. As the congestion increases, the impediment adversely afiects sizes other than just critical sizes so that it may be said as a very general proposition that the trouble encountered with classifiers of thistype lies in the physical interference between the downflow of material from the bowl to the under compartment and the upfiowof fluid from the lower compare,

ment to the chamber. An inventive concept in the present case is disclosed in means for overcoming such physical impediment of necessary but conflicting flows of material from one tank to the other.

Attempts have been made heretofore to solve the problem of congestion by overflowing much of the critical sizes of particles which should, by rights, be allowed to settle andbe saved with the heavier particles. The present invention seeks to materially lessen suchloss, both for any given product or maing considerably a classifier able to adjust itself to constantly terial being treated and for materials difiertherefrom, thus providing changing conditions under which it may be aforced to operate.

, tions.

In classifiers as heretofore employed, the same have exhibited great sensitivity to variations in feed conditions of the material, necessitating care in the introduction of the material. Also the speed of the bowl raking mechanism has required very careful regulation and constant adjustment for varying material supply and conditions of material. The present invention seeks to overcome the need for constant and minute adjustments and to dispense with skilled attendants or continuous supervision.

A further propensity of classifiers as heretofore constructed and operated has been to produce an abnormal superelevation of the fluid content of the secondary compartment over the fluid level in the primary compartment. An object of the invention is to overcome abnormal superelevation, not only for maintaining an equalized differential in the two tanks to obtain constant pressure and even flow from the secondary to the primary, but also to limit dilution in the backflow. n this connection, it may be observed that proper utilization of additional fluid for this backflow is important as. it maybe necessary to keep the dilution low with certain products.

So the nature of this invention may be said to reside in separating the inflow to and the outflow from the bowl.- with respect to the classifier or secondary compartment into oppositely directed independent streams which are preferably concentrically arranged.

Further objects are to provide means for automatically regulating the backwash; to

"provide air supply for relieving congestion;

to secure simplicity of construction and operation; and to obtain other advantages and results as may be brought out in the followin description.

Referring to the accompanying drawings in which like numerals of reference indicate similar parts throughout the several views;

Figure 1 is a plan of a classifier embodying the present invention;

Figure 2 is a longitudinal sectional view of the bowl classifier shown in Fig. 1;

Figure 3 is a sectional view on line 3-4) of Fig. 2; and

Figure 4 is a partial vertical sectional view of the separate inflow and'outflow' arrangement to the bowl compartment.

' In the specific embodiment of the invention illustrated in said drawings, the basic construction shown provides two settling tanks identifiedas primary settling chamber.

or bowl 1, and secondary settling compartment or classifier 2, respectively. The 'secondary compartment extends beneath the primary chamber and is inter-connected therewith for down-passage of sediment from the upper 'to the lower and upflow of fluid and fine particles from the secondary to the pri- 'mary. This interconnection between the two settling tanks is one of the features of the present invention and will be described more in detail hereinafter. The bottom of the primary chamber forming a substantial horizonal partition in the second or classifier chamber preferably provides said inter-connection at its middle, the said bottom sloping downwardly toward the middle. Bladed rake arms 3 are mounted in the chamber to be revolved therein, as by motor 4, both for actuating the settled material toward the discharge opening to the secondary compart-- ment and to slightly agitate the material so Much of the construction of the secondary compartment is old in the art for it is preferably of the well-known Dorr type, and a brief description of these old portions will there-.

fore suflice for those skilled in the art. As shown, the secondary compartment 2 is in the form of an inclined trough the lower end of which etxends under the middle part of the primary chamber and the upper end of which extends considerably beyond the bowl and above the same. Longitudinally within the secondary compartment are positioned mechanically operated partially submerged reciprocating classifier rakes 7 which actuate the material upwardly with a step by step motion while at the same time setting up a zone of liquid agitation therearound due to their reciprocation.

The bladed raking classifierelement 7 of the secondary compartment is' carried by "two hangers 8, 9, one, as 8, near the upper or discharge end and the other 9, toward the lower end, both hangers being supported by inter-connected bell cranks 10, 11 respectively, the upper one 10, of which has a rocker lever '12 depending therefrom for actuation by a cam v13 driven through suitable reduction gears by a motor 14. This structure obtains in offsetting movement of the entire rake toward and away from the bottom of thetrough. Reciprocation of the rake is obtained by a cran k operated pitman 15, this reciprocal movement, resulting in an orbital movement by which the materials settling on the bottom of the trough will be intermittently dragged up the incline with a step by step motion.

' Heretofore upflow of fluid with particles in suspension hasbeen through a restricted opening at the bottom of 'the bowl and lower end of the secondary compartment, the downfiow of material also passing through the same opening. This passage of material in opposite directions has caused considerable I interference and has been one of the factors in causing congestion and improper classification. It is one of the features of the present invention to obtain a passage of material from one tank to the other with minimum interference. As shown more particularly in Figures 2, 3 and 4, the bot-tom of thebowl is apertured, and within the aperture, is an upflow sleeve or pipe 16 providing an interior passage 17, said sleeve being spaced from the periphery of the aperture so as to leave an outside passage 18 between itself and said periphery ofthe aperture. If this embodiment be used, the upflowing column of liquid in the passage 17 naturally is annular.

Sleeve or conduit 16 is preferably adjustable in length by any suitable means, and for purposes of illustration the same is shown as providing upper and lower sections 19, 20 respectively, screw threaded at their adjacent ends and receiving a correspondingly screw threaded coupling nut 21. In use, the nut will be applied to the lower section 20, and then can be screwed onto the upper section more or less to obtain the desired longitudinal adjustment of the two sections. It -will be understoodthat the upper section is carried in longitudinal fixed relationship, and for purposes of the present showing is passed through and welded to a plate or disc 22 forming the central or hub portion ofthe bowl rake 3. vThe upper edge of the sleeve is at a fixed height preferably substantially the same height asthe liquid level in the bowl which is controlled by the height of the overfiow weir 5 around the edge of the bowl A feedwell 23 is rotated with the rake structure, and associated with this feedwell 23 positioned in spaced relationship above the sleeve 16 is a distributing plate 24 shown parallel to the hub plate 22; The distributing plate 24 v also acts in the nature of a baflle in that it cured together by any suitable means, such as bolts 25, so the rake will be rotated from disoverlies the upper end. of. sleve 16 to prevent material introduced above the sleeve from entering thereinto. This distributing or baffle plate 24 and hub plate 22 of the rake are setributing plate 24, which in turn is actuated through a vertical shaft 26 the upper endof which is splined in a suitable driving gear actuated from motor 4.heretofore described. Any suitable. lifting means, such as hand wheel 27, may be provided with the hub plate to a point pre erably The material to be classified is introduced at the top of the bowl within the feedwe1l23, and that material preferably passes through openings 28 in the lower part of the feedwell of appropriate size and disposition. The efiluent, with fine particles in suspension, passes over the overflow weir 5 of the bowl while the heavier particles drop to the bot: tom' of the bowl and are raked to an annular opening 18 between the sleeve and the edge of the opening in the bottom of the bowl. These particles fall through to the under or classification compartment wherein the rake 7 rakes the solid particles up the inclined bottom thereof and agitates them sufficiently to throw back into suspension any fine part1 cles which have been carried-through to this lower compartment. A backflow of fluid is provided in this secondary compartment, and this backflow with the fine particles in suspension returns to the bowl through the sleeve16, again passing into the feedwell 23, and again passes into the bowl from the openings 28 in this feedwell. It .is to be noted that the distributing plate 24 overlies the upper end of the sleeve so that the freshly openings to and from the primary chamber,

means are provided for introducing fluid under pressure in such manner as to obtain a violent agitation, when required, at this particular point. In the specific construction illustrated, an air supply pipe 29 is shown within the sleeve'16 substanding upward stantially co-axial therewith, 'this ipe being introduced through the side wall 0? the lower compartment to a point beneath the sleeve, and there turnj}, upwardlyw-ithin the sleeve above the normal fluid level. in the bowl., This construction prevents fluid from the bowl getting into this air under pipe when no air pressure is being r introduced therethrough. The air pipe 29 is shown within a large pipe 30 depending from and held with respect to the distributing plate 24, this pipe 30 being open at its bottom and having. its bottom substantially at the bottom of the sleeve. Space is provided between the upstanding air pipe 29 and this overlying pipe 30 and also between the said pipe 30 and the sleeve 16." The space pro vided between the air pipe and the enclosing pipe 30 will therefore form an air-reservoir and permit airto pass downwardly .therebetween 'to the normal congested area where it creates a violent ebullition action or agitation which breaks or overcomes. the usual congestion at that point. The annularspacel? between the air enclosing pipe and the sleeve 16 is made of proper pro ortion to permit free passage of" the back ow or upflow from thesecondary or classifier compartment up through the sleeve to the primary chamber or bowl. The agitation produced has as its object to assure an upward impulse or surge to the liquid column in the space 17 so it may be produced in other ways provided the upward surge is the result thereof.

It will be noted .from the drawings that the lower end of the sleeve or pipe 16 preferably flares outwardly as at 31 so that this construction acts as a funnel to protect the upward flowing fluid in the sleeve from the downward dropping material passing from the bowl to the classifying compartment, thus insuring a full supply of fluid of proper character to vpass upwardly to the bowl without molestation or interference.

The bottom of the bowl is preferably leveled off at its central portion, as by means of a bottom plate 32 the outer edge of which merges part way down' with the sloping bottom and the inner apertured edge thereof is provided with a downwardly flared or funnel shaped depending portion 33 forming a connection between the bottom plate 32 and the lower end of the sloping bottom of the bowl. The downwardly flaring shape of the connecting portion 33 and the flaring lower end 31 of the sleeve cooperate to direct the down-- wardly passing material in an outward direction to thus avoid, as far as possible, interference between the upflowing material from the classifier and the, downflowing material from the bowl.

It is a general practice in connection with classifiers of the present type, to provide a supply-of fluid, known as backwash, in the secondary compartment above the fluid level.

The amount of this backwash has heretofore been regulated by workmen, who usually turn it on when the apparatus is set in motion after which it is left on until the classifier is shut down. When there is congestion interfering with upflowof material from the secondary compartment to the primary compartment which begins to mount from the normal superelevation to abnormal superelevation and unless the congestion is relieved the fluid is apt to overflow the secondary compartment. the backflow is illustrated as introduced by a pipe 34 into the leg 35 of a vTv-shaped trough 36, the leg 35 of this trough extending longitudinally of the secondary compartment and the-cross portion 37 of the trough extending from side to side of the compartment with a plurality of openings in the bottom obtaining a distribution of the flow of water introduced'into the trough.- The supply pipe 34 is. provided with a valve 38 operated automatically through a leverzconnection 39 to a float '40.. The float is mounted In the present showing.

shown mounted on the side wall of the bowl.

As the fluid level in the compartment rises the float will be buoyed and thereby operate through suitable levers and links or other connection, to shut ofl the valve 38 and decrease or stop the supply of water or other fluid; and as the float is allowed to move downward by ebbing of the fluid level in the secondary compartment, the suppl valve 38 will again be opened and water a mitted to the trough and compartment, thus maintaining a substantially constant level of fluid in the compartment.

It is also a feature of the present inven tion to automatically operate the air supply for air pipe 29 to break up congestion in the bottom of the secondary compartment. This automatic operation can be conveniently obtained from the same lever 39 and float 40 which operates the water supply. For illustrative purposes a valve 42 is provided in the air lineand this valve is connected by an appropriate link 43 to said lever 39 in such manner that, as the float is raised by an abnormal superelevation the valve will be operated and air admitted to break up the congestion, thus enabling the abnormal elevation to be overcome by. normal passage of the fluid through the sleeve 16 to the bowl. Since both the air supply and the backwash are controlled by the superelevation in the secondary compartment, they will cooperate to prevent congestion and maintain a steady passage of material both ways betweenthe tanks. v

Obviousl detail changes and modifications may be made in the construction and use of theimproved classifier described without departing from the spirit or scope of the invention,'and it is not to be understood that limitations are imposed by the foregoing specification except as specifically set forth in the following claims when construed in the light of the prior art.

Having thus described the invention, 1 claim 1. A classifier comprising a primary chamber adapted to receive fluid supply at its top and middle part and contain the fluid to a substantially predetermined level, a secondary compartment, said primary chamber and secondary compartment being interconnectedfor passage of settled material in' the chamber to'the compartment, means for independently passing fluid from the secondary compartment to and discharging the same substantially at the fluid level in the primary chamber, and means for protecting the fluid thus discharging into said chamber from the fluid supply to said chamfluid in said sleeve.

upflow sleeve for passing fluid from the secondary compartment to an upper part of the primary chamber, a baflieassociated with the upper end of said sleeve and means for giving an upward impetus to the upflowing 3. A' classifier comprising a primary chamber and a secondarycompartment', a

4. A classifier comprising a primary chamber and a secondary compartment, a

chamber proj ecting substantially mary chamber spaced from the bottom thereof, a sleeve from the bottom of said introducing an up ow of fluid to a part of the chamber above said plate, and means for supplying agitated fluid to said upflowing fluid to give the flowing fluid an upward impetus through said sleeve.

5. A. classifier comprising a primary chamher and a secondary compartment, an-upfiow sleeve for passing fluid from the .secondary compartment to an upper part of the pri-' mary chamber, an air supply pipe for in- .troducing air under'pressure to the compartpp y P p .ceiving they and distributing the backwash in the cornment at the lower end of said sleeve for breakion, a valve for ing up congestion in that re said air supply pipe, and a oat connected to said valve for automatically controlling operation of said valve.

6. A classifier comprising a primary chamber and a secondary compartment, an upflow sleeve for passing fluid from the secondary compartment to an uplper part of the primary chamber, an air supp y pipe for introducing air under pressure to lower end of said sleeve for breaking up congestion in-that region, .a valve for said air and a float compartment connected to said valve for automatically controlling operation of said valve by the fluidlevel in the said compartment.

7. A classifier comprising a primary chamber and a secondary compartment, said compartmerit and chamber being interconnected for passa e of material and fluid therebetween, a backwash supply pipe, ,atrough rebackwash from the supply pipe partment, a valve for controlling the supply of backwash, and a float connected to said valve for automatically controlling operation of said valve.

8. A classifier comprising a primary chamber and a secondary compartment, said compartment and chamber'being interconnected substantially at through which an horizontal plate in said pri-v through said plate for acting agitation in the compartment at the.

in the secondarycally controlling operation of said valve by the fluid level in the said compartment.

9. A classifier havingua; sloping bottom, a partially submerged ra g element therein, means for positively creating a zone of upwardly acting agitation inthe liquid in the classifier, a bowl above said zone, a pipe depending from said bowl extending upwardly from adjacent said raking element to a pointindependent column of liquid is caused to surge upwardly by said agitation, and an independent discharge from saidjbowl to said zone of agitation.

10. A classifier having a sloping bottom,

a partially submerged raking element theremeans for setting up a zone of upwardly I the liquid in said classifier, a bowl like chamber superposed on said classifier having its bottom located below the liquid level in said classifier, a pipe depending from said chamber bottom and extending from said zone adjacent said raking element the liquid level of said bowl into said chamber substantially at the liquid level therein in which a column of uid is caused to surge upwardl therethrough and overflow into said cham er and a discharge from said classifier independent of saidupwardly surging columnof liquid.

.f'1-1. A classifier having a sloping bottom,

a partially submerged raln'ng element, means for producing a zone of upwardly acting agitation in the liquid in said classifier and an annular conduit extending upwardly from adjacent said raking element to a point substantially above the liquid level in said classifier through which an. independent annular column of liquid sur es upwardly.

compartment and a superposed bowl, providedwith a feed for said bowl, a discharge from said bowl to said classifier compartment, an independent upflow conduit from u said classifier com artment to said bowl, and

having I a classifier 14. A bowl classifier having a classifier I 12. A bowl -classi er havmg a classifier superposed bowl, procompartment and a superposed bowl, provided with a discharge from said bowl to said classifier compartment, and means'for causing an upflow from said compartment intov with respect to said classifier compartmentsaid bowl independent of said discharge comprising a pipe andvan air-reservoir associated with said pipe adapted to emit air upwardly through said pipe.

15. A bowl classifier having a classifier compartment and a superposed bowl, provided with independent passages between said classifier compartment and said bowl in the bottom of the bowl, said bowl having an 1 inverted cone-shaped bottom, and a. levelled off portion in the bottom of said bowl encircling said passages.

s In testimonywhereof I aflix my signatlire.

HARRY W. NEWTON.

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