US2452982A - Submerged reciprocating screen - Google Patents

Description

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SUBMERGED RECIPROCATING S GREEN Filed June 25, 1945 v 2 Sheets-Sheet 1 INVENTOR, BYEQN M. BIRD,

Nov. 2, 1948. B. M. BIRD 2,452,932

SUBMERGED RECIPROCATING SCREEN Filled June 25; 1945 2 Sheets-Sheet 2 INVENTOR, BYRON M. BIED,

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ATT'Y Patented Nov. 2, 1948 UNITED STATE SUBMERGED RECIPROCATING SCREEN Byron M. Bird, Columbus, Ohio, assignor to The Jeffrey Company, a corporation of Ohio Application June 25, 1945, Serial No. 601,397

This invention relates to an improved method of and apparatus for submerged screening by which granular material is screened or separated according to size below a water or liquid level.

An object of the invention therefore is to provide anrimproved method of and apparatus for sizing material by a continuousoperation which eliminates all dust hazard and which effects a very eflicient separation of material into two size ranges.

'Another object of the invention is to provide improved apparatus for the submerged screening of fine material from a mixture of various sized particles thereof wherein the fine particles to be screened are of such character as to permit them to become at leastpartially suspended in a liquid medium, the apparatus suspending said particles in a liquid and injecting or spraying liquid into that in which the particles are suspended to precipitate or settle the suspended particles thereform,.the apparatus causing the precipitated or settled particles to pass through a screen into a collecting chamber.

Another object of the invention is to provide an improved method and apparatus of the above mentioned type in which a .counter-flowpreferably of pulsating water or other liquid is employed to increase the. efiiciencyof the screening operation.

A further object of the invention is to provide a dustless method of separating material and particularly granular material by a screened action. I I

Other objects of the invention will appear hereinafter, the novelfeatures and combinations being set forth in the appended claim.

In the accompanying drawings, Fig. 1 is a combination elevational'and sectional view showing apparatus involving my invention; v

Fig. '2 is a sectional view taken on. the line 2-2 of Fig. 1, looking in the direction of the arrows; o

Fig. 3.is an enlarged sectional view taken on the line 3--3 of Fig. 1; and p Fig. 4 is a plan view of a portion of the apparatus showing a particular detail.

In the drawings there is illustrated a preferred embodiment of the apparatus involving my invention which is one form of apparatus capable of carrying out the invention of I my improved method.

Said apparatus includes a container or tank in provided with a plurality of cells, sections or compartments H and i2, respectively. As here 1 Claim. (Cl. 209-269) inafter described more completely, section or com-- partment I l is the oversize or large particle section or compartment and it receives the large or oversize material which settles to its conical bottom where it may be flushed out by opening a control valve l3. A similar control valve M is provided for the generally conical bottom of section; or compartment l2 to flush out the undersizeor small sizeparticles which accumulate therein):

The cell 1 section orcompartment [2 receives the downwardly. extending screening deck 15 of a vibratory electro-magnetic screen it havingj a vibratory electro-magnet'ic motor H. The electromagnetic vibratory screen It may be generally. of the structure disclosed in the patent to J ames' ArFlillt, No. 2,153,243, except that the deck. I5. is of different construction and thereis not neces-'* sarily any adjustment between the deck and the motor armature. This type of vibratory screen; per se, is we'llknown in the art and it operates at a frequency of 3600 vibrations or cyclesFper minutewhen energized from a mixed current source, thealternating current of which "has a" GO cycle frequency. In known push-pull ltypes ofvibratory screens ofthis same general character the frequencyfor 6 0 cycle alternatingcurrentwill be 1800 vibrations per minute. The screen i6 is suspended from any desired superstructure by means of non-shock transmit ting hangers l8; there being 'at least three and preferably four of said hangers, two attached to the motor Hand two to the; deck I5, as clearly illustrated in the drawings.

WhileI prefer to employ an electro-magnetic screen of the above mentioned type, it is evident that within the scope of myinvention, particularly in some of its broader aspects; a mechanical or other type of screen may beemployed. The screen illustrated, however, is particularly adapted for my invention because of the fact that the motor I! is above the deck l5 and thus there is no problem of suspending the screen with the screen'cloth below the water, as hereinafter 'describe. M

j The screening deck I5 extends in part below the liquid level IQ of the water or liquid in the section or compartment I2, which liquid level is determined by 'an outlet means inthe form of an overflow weir 20 leading to an overflow chute 2l' adjacent the rear or right-hand end of the tank ill. l 1 The screening deck i5 is, of course, rigi ly attached to the armature of the motor l 'l-tb receive "vibratory motion developed thereby and; it includes a pair of spaced water tightside walls 3 22 which are adequately reinforced by cross members 23 clearly illustrated in Fig, 1 of the drawings. Across its rear and extending between the side walls 22, the deck l includes an end plate or wall 24 which makes the end of the deck iii also water tight.

At its front the upstanding front edges of the side walls 22 of deck l5 are connected to the adjacent side walls of the tank 1 [l and to a trans versely extending partition member 25, which is a portion of a partition designated generally 26 which separates the sections or compartments II and i2, by virtue of a U-shaped-flexible water proof partition or Wall member 21. The flexible partition member 21 has its outer edges connected The bottom edge of the flexible par tition member 2'! is similarly attachedto the partition member 25. In addition, the inner edges of the flexible partition member 2;! are con nected'by water tight connections, with the'front of the side walls 22 of the deck and with a transverse plate 28 (see particularly Fig. 1) forming the bottom front portion of said deck The complete partition :26 also includes a 0811-, ter upright partition plate 29, the side edges of which are connected by spaced flexible water proof partition members 30 to the adjacent side walls '22 .of the deck 15, as best illustrated' n F s. 2.--and 3 .of the drawings. The plate 29 does .not vibrate with the deck 15 since it is not rigidly attachedqthereto, but it is supported. by adjustn levers 31 which re pivoted to a cr ss/piec forming a part of the tank I, the levers 3i being adjustable through a limited degree by an adjust.- inghook 133 which ,co-opera-tes therewith and which is adjustably mounted on an angle memberformed at the front .end of the-tank l0, as

clearly illustrated in Fig, 1 of the drawings.

The flexible partition members 30 provide for limited up and down adjustment of the plate 29. This provides for adjustment of the size of an opening or orifice 34 which is formed between the bottom edge of the plate 29 and a screen cloth holding roll 35 at the discharge or lower'end of the deck I5. I I

Near the bottom of the deck l5 there is the usual screen cloth 36 which extends the full length of the deck l5 and is supported on spaced transverse supporting and arching members 31 extending to a tension adjusting head roll 38 at the @upper ri ht-hand end of the screen cloth 36 which has a close fit with the bottom of the deck end plate 24. A screen cloth adjusting member 39 is provided for adjusting the tension ofthe screen cloth 36.

The granular material which is to be separated is prejerably relatively fine particle orat least contains a r ively fin on i u nt and thi submerged screening is particularly efiective in separating very fine particles of material from a mixture which includes them. To provide proper feeding of the material-to be separated or classifled, I provide a feed chute 40 which may be of any desired form; for example, it may be a chute of a vibratory feeder. This ,feed chute is preferably closed at its discharge end and extends below the water level I9, discharging the material adjacent the upper or feed end of the screen cloth.

I have also found that with many materialsit is desirable to spray them with water and to this end I have provided a pair of sprays M which 4 spray the material while in the chute 40, thus delivering the material with an appreciable water content tothe screen cloth 36. In some instances this spraying is not necessary.

The principal amount or all of the water delivered to the tank In is preferably fed by way of water pipe or fluid inlet means 42 under the control of valve 43 which delivers the water to the large particle-compartment"l5! in-whichthe Water level,-indicatedat '44, will be slightly above the water level in the fine compartment [2.

As a consequence of this fact, which is quite important inmany instances, the water reaching the fine compartment l2 must flow through the vopening:.cu'-..orifice ,34 from compartment H to compartment 12." It is, of course, obvious that in operation the large size material must also flow through this'orifice or opening 34 and con- ;sequentlyithere will be a counter-flow of water against this oversize material. This counter-flow of water will, wash the material free of any small particles and thus assure an efiicient separation of the material intosized constituents.

As best illustrated in Figs..1 and 4 of the drawings, I also preferably provide oneor more stationary partitions which extend downwardly between the side walls of the .deck l5, and divide the fluid compartment thereof into .a plurality of successive screening sections, compartments or cells. As best seen in Fig. 1 of the drawings, thereare two such partitions 45 and 45. These partitions are of similar construction, but partition v45 is necessarily higher than partition 46. Said part1: tion 45.,is. supported on a transversely extending combination support and spray or jet pipe '41 which in turn issupportedat each'end by a pair of upstanding angle members 48 which are rigidly attached to the twosidewalls of compartment.

[2,, as clearly illustrated in Figs. 1 and 4 of the drawings.

The partition plate 4.5 hangs downwardly from the pipe 4'! to whichit is rigidly attached 7 flexiblemember 30, as illustrated in Figs. .2 and 3 of the drawings. Conversely, plate 29 mayhave a sliding connection with the side wall 22 of the type illustrated at 49 for plate 45.

Adjacent its bottomthe plate 45 preferably carries a flexible rubber or canvas strip 50 which providesa flexible seal with the screen cloth "36. This strip 5!) has sufiicie'nt flexibility thatoversize material can travel under it and reversely flowing fluid can likewise travelunder it. The con-structionoithe partitionplate 4B andits associated mechanism is similar to that described in connection with plate 45. Water is supplied to the pipe 41 and a similar pipe associated with partition-4t, preferably under the control of valve means, that for pipe 4'! being seen at ,5! in Fig. 4. 4 7

As a consequence of thesepartitions 45 and 46 and their associated structure the compartmer t provided by the deck 15 is divided into a plurality of successive screening compartment-5,,

sections or cells and this helpsin the settling .of

particles, particularly if they are of very small size, Furthermore, the individual water supplying pipes, such as pipe 41, provide'for an adjustment of the amount of water to :be supplied to each screening compartment and consequently an adjustment of the quantity of water flowing downwardly therethrough because this water is delivered to the top of the liquid or pulp in each compartment and it will tend to flowdownwardly through the screen cloth 36 or under the strip 56 by reason of the super-elevation of the water level in the compartment. Because of-this flow and because the water is introduced into the compartment in the formof spray or jets the water will aid materially in settling or precipitating the fine particles of material which may tend to form a colloidal solution, suspension or pulp in said cell. Furthermore, the cell-like construction of the screening deck. prevents suspended fine particles from floating in the liquid from the feed side which is the right-hand side, as viewed in Fig. 1, to the discharge or left-hand side of the deck l5 and there settling and being. discharged with oversize. material into the section or compartment l I. Obviously, the partitions 45 and 46 will prevent such a flow of fine particles and cause them to settle on the screen cloth 36 which they will ultimately pass through.

It is, of course, to be understood, however, that in some of its broader aspects these partitions- 45 and 46 may be omitted, though in a more completeaspect of the invention they are highly desirable and important. i y i As illustrated in the drawings, the screen cloth 36,has a slope from-the feed end to the discharge end and, this slope is preferably from degrees to 30. degrees, depending upon the material being treated and the size ranges of the material.

The operation of the apparatus, with the consequent carrying out of the invention of my method, is as follows. The vibratory screen I6 is energized-and the deck 15 will be placedin material upon it a distinct Vertical or upward.

motion component which is essentially a screen; ing component and a distinct horizontalmotion component which is essentially a conveying component. The screen cloth 36 is preferably entirely below the liquid level I9 for it has been found that under certain circumstances if a portion of it projects above the liquid level the screen cloth will be broken in a very short time by the Vibration.

The material to be separated into two size ranges is. delivered by the feed chute 40, either with or without being. wetted by the addition of Water from sprays 4!, to the upper end of the screen cloth 36 and preferably substantially over its entire width. The granular material being separated Will, of course, flow downwardly over the screen cloth 36 and be separated, with the fine particles passing through the screen and into the bottom of section or compartment l2, including those particles which are fine enough to pass through the mesh of the screen cloth 36 which preferably is 10 mesh or less. The larger particles will ultimately flow over the lower edge of the screen cloth 36 and through the openingor orifice 34, falling through the water to the bottom.

of the section or compartment H. The ac cumu screen acts in oppositionto the. mass of the fine particles of material which areadjacent its upper surface and in opposition to the inertia of those fine particlesof materialwhich are falling against its upper surface, therefore the, upward stroke of. the deck co-operates to force the-fine particles.

of material through the screen 36. The particles of fine material, after having. passed through thescreen 36, settle in the section or compartmentl2.

y .The principal part or all of the water-involved Will be delivered by pipe or fluid inlet 42 under; the controljofvalve 43, first to compartment! i from which it will flow through the opening or,

orifice 34 counter to the-flow: of oversize material therethrough. This is the only opening by which.

the water can fiow from cell section orcomparh mentl linto cell section, or compartment l2. ,,Thewater in section, or'compartment lfi whioh comes through the orifice 34 can. only flowrout of sec-tion or compartment l2 over weir or outlet 20 by 01; chute-2i by flowing through the; screen cloth 36 becauseth egside walls of; the Ydeck l5;-

are attached to the partition 26 and extendabove; the level of the Water in-section 12. Thus the walls of the deckand thepartition 26 co-operate to form a means; which provides-a -fluid tight container structure or compartment, except for. opening or orifice 34 and the sloping screening bottom 36. This means or structure insures that all of .the water and fine particles of material entering section or compartment I 2 must pass downwardly through the sloping screen bottom 36 will, of course, aidin carrying or. forcing the fine particles therethroughinto section or compartment [2, which particles will settle outin the bottom thereof While the water, free of the granular particles, will flow or be decanted from section or compartment l2 over the weir or fluid outlet 26 .a'sabove mentioned; It has been found in practice that this is a very desirable method of continuously separating granular material into constituents of two size ranges and is particularly desirable where dust is a hazard or otherwise undesirable and in Which fine particles are to be separated to maintain the level of the water in section or compartment 12 above the bottom of the screen deck and below the top of its sides.

It is again particularly pointed out that the axis of vibration of the deck l5 makes an acute angle with the plane of the screen cloth 36 whereby the vibratory motion of the screen cloth imparts vertical and horizonal motion components to material upon it and that these components are such as to give a positive conveying and elevating action to the material. As a conse quence, it is not entirely necessary that the screen cloth 36 be sloping downwardly as illustrated. This is important because in some instances a over thei. The water flowing through the screen cloth ai-sasesz partition members, due to their fiiiibie 66hiii' ivide id? imjiitd aajas tmei tof the r timing thus dew-ma am shew mitten 6f aesiie to same Hy Patent 6f the'UI'ii td states-is;

a pa etus or the submerged mama to 's'iee'ri fine parfiaitmefits said partitions having flexible bottom 3: edges positioned adja'erit' to said s fi fliiid iiilet means fox sii'iiolyin'g fluid to said fiversfz ai'tielse'ctionyove 6w fluid outlet means asseth said fine particle section; said ovefl new fluid outlet means; being positicmed td determine the level ofthe' fluid above the'scfeenm the fiiie particle section of said container, means for de' dsitmg material to be scieened ifi the ugiiieimost compartment of "said screen, means for wettm'g'the material rior to its beirig defiosite'd therein, jet means adapted to inject fluid into the fluid above said scream and adjacent the pat'titions therein to eause precipitatidii' of fiafticles' of mat'eiial in said fluid and to'caus e a flow of fluid through said 'sci e'en into said fine particle seetiofi of said coritaix'ier thereby cariy= ing preeipitated fi'iie particles of material thereinto, and motor means for imparting Vibratory motion to" said screen at an acute angle with respect thereto, said scr'en therby'iinpar'ting ofivey'in'g motion components to material thefe= on and c'o'nve yiii'g material from one particle setion to th next iiartile section beyond said flexible means on the dividing fiait'itiofis, the fidid entering said oversize particle container setio'ii flowing through said oper'lin'g'ifi the (ion tamer dividirig partition into said fine partiele se'oti-or'i counter-current to the flow of oversize fiafticie's i assing through said opening thereby Washifig the fii'ie from said oversize particles, and

said fluid then flowing from said-fine particle s tier; thi'diigh Said screen thereby tending to particles or material pmseriemm the fiiie fiartil semen t6 'ai'iid through the i''ti and ther'iee "into said fiii fi'aiticl feceiii'ifig' section of the fih baitiol tifiii. v I

BYRON M. BIRD.

REFERENCES CIT-ED The following fe fereflces are of record if) the file of this patent:

UNITED STATES PATENTS I Numbei Name Date p 143392 Bi'adford h i Oct. 7,1373 {245,340 ehr Aiig. 9, i331 533,821 Montgomery Feb. 5, 1895' 697,353 McDermott Apr.- 8,- 1902 788,246 Callow d Apr. 25,1995 803,550 Qallow Nov. 7, 1905 1954,7933 Skinner in; Mai. 4, 1913 1,070,552 stefiy A'u -19, 1913 2,137,753 Flint Nov. 22, 1938 z ze'z ez' Ellen i Dec. 1941

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