US3437202A - Flow channel for zigzag classifiers - Google Patents

Flow channel for zigzag classifiers Download PDF

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Publication number
US3437202A
US3437202A US628497A US3437202DA US3437202A US 3437202 A US3437202 A US 3437202A US 628497 A US628497 A US 628497A US 3437202D A US3437202D A US 3437202DA US 3437202 A US3437202 A US 3437202A
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flow
channel
flow channel
bed
air
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US628497A
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Fritz W Kaiser
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Alpine AG
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Alpine AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
    • B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
    • B03B5/62—Washing granular, powdered or lumpy materials; Wet separating by hydraulic classifiers, e.g. of launder, tank, spiral or helical chute concentrator type
    • B03B5/623—Upward current classifiers

Definitions

  • This material referes to a flow channel which conveys the material to be classified into a rising-tube classifier, particularly into a zigzag classifier, forwarding it in transverse direction to the rising classifying fluid stream, that ascends substantially from the bottom of said channel. As the fines are continuously carried out upwards, only a more or less clean coarse grain portion remains at the end of the flow channel.
  • flow channel indicates, as generally known, mostly slightly inclined channels, wherein dust fluidized by air blown in, is conveyed by gravity, this condition of dusts being named flow-bed. If operated in connection with a rising-tube classifier said flow-bed has to perform the following functions at a time:
  • the channel bottom consists of a screen with a hole width of -1-2 mm., blown through by air from below. To assist the conveying movement the screen is vibrated, but the flexible suspension Patented Apr. 8, 1969 as well as the sealing required involve considerable extra cost.
  • Vibration of the screen can be substituted, as already done in the so-called pulsating classifiers (ibid., page by pulsation of the air current. However, these classifiers did not give any better results.
  • the bottom of the channel must be provided with individual nozzles through which air is introduced and which are so designed that the emanating jets carry the grains of the flow-bed.
  • two conditions must be fulfilled as follows.
  • the jet diameter must at least be of the same dimensional order as the grain, rather be larger so as to ensure that the single grains are suspended by the jets without requiring the pressure-consuming initiation of a jet velocity higher than the speed needed according to condition (b).
  • the flow-bed condition is easy to check either visually or by putting the hand in and to adjust by a pressure drop large enough in relation to the level of material, such adjustment possibly requiring adaptation of the open sieve area in the channel bottom.
  • the invention equally provides several means.
  • the goal aimed at is attained according to the inven tion by operation of the flow-bed in flying bed condition. As described before, adjustments to obtain said conditions can easily be made during operation.
  • the flow channel bottom comprises a plate wherein several nozzles are fitted, this plate being most simply designed as a perforated sheet provided with round or otherwise shaped holes.
  • Precondition of the flow-bed condition is that the individual jets are strong enough to carry the single grains. This is mostly achieved by providing a perforated bottom with holes the diameter of which is equal to or larger than the diameter of the largest grains conveyed. A few oversize grains in the material are negligible.
  • the necessary impetus of the jets is obtained by calculating the number of holes and the open sieve area, respectively, in such a way that the pressure drop at the perforated bottom corresponds at least to the equation:
  • M ost essential is a certain inclination of the channel; a minimum inclination of 9 has proven eflicient.
  • Another feature is to make the individual air jets inclined in flow direction. Even to avoid any braking effect on the flow of material, they must have a forward component of a value at least equal to the flow speed of the material. A larger forward component exerts a propelling action.
  • These oblique jets are produced by nozzles inclined in direction of conveyance. Regarding the large number of nozzles, a low-cost manufacture is mandatory. This can easily be achieved by deforming the holes of the perforated sheet, subsequently, for instance, by pushing through a mandrel or when punching the holes.
  • this velocity In order to obtain a high velocity of the material in the channel, this velocity must already exist at the entry of material. This speed is most simply imparted to the material by a gravity chute with deflection in direction of conveyance prior to feeding the material into the channel. Dependent on flow speed, the height of fall provided by this chute may vary from a few decimeters up to a few meters.
  • perturbing bodies fitted on the bottom of the gravity channel immediately in front on the intake. They can be arranged so as to either break-up the film of material into several strands or throw-up the material for mechanical initiation of the flow-bed.
  • a rising-tube classifier which is not free of internal structures above the flow channel, but sub-divided into several small tubes, especially zigzag tubes, it is es sential to provide above said flow channel a defined headroom. Too small a headroom makes it diflicult for the non-entrapped material to fall again out of the classifying tube so that material would accumulate inside the tubes. With too large a headroom, on the other hand, the flow-bed would not extend to the tubes so that the latter would be fed with an amount of material not large enough to allow them to be utilized completely. From experience, a headroom of 70-200 mm., reaching to any existing subdivisions of the rising tube or tubes of the classifier should be provided.
  • aprons In order to increase the flow speed in the channel, it is of assistance to make the lower end portions of the rising-tube subdivisions, also called aprons, to face the direction of flow. For better adaptation to the service conditions that, under certain circumstances, require a headroom variable along the flow-bed length, it is advantageous to make the length of the aprons adjustable.
  • Cleanness of the coarse product is increased by extending the flow channel beyond the classifying chamber towards the coarse product side. This effect is particularly obtained by a flow path of the fines-laden air in counterdirection to the stream of coarse product so that fines that may be precipitated again are settling down in front of the spot where they have been whirled up, thus, they are given the chance of being whirled up once again.
  • the invention covers improvements in rising-tube classifiers and more particularly to a flow channel therefor, comprising the features described above, for conveying material to be classified at an incline downwardly across the classifier, the flow channel comprising a perforated plate provided with air flow nozzles pointing in the direction of flow and the other features associated therewith arranged to provide for a clean separation of fines from clean coarse material.
  • FIG. 1 is a sectional diagrammatic view showing in elevation the flow channel arranged beneath the tubes of a rising-tube zigzag classifier according to the invention
  • FIG. 2 is a plan view of the flow channel taken on the line IIII of FIG 1;
  • FIG. 3 is a broken sectional view on a large scale of the perforated plate and its nozzle structure
  • FIG. 4 is a detail view showing the arrangement of a compressed-air rapper.
  • FIG. 5 is a detail view of a flexible suspension means for a perforated bottom plate.
  • the essential parts of the classifier as shown in FIG. 1, are the zigzag shaped rising tubes 1, of which only the lower portion is shown, the flow channel 2 conveying the material to be classified in transverse direction to the possibly upwardly ascending air current.
  • the material to be classified is fed at point A into gravity chute 3, wherein it attains a certain velocity.
  • Deflection part 4 of the channel bottom 5 directs it subsequently onto the perforated bottom of the flow channel on which it is carried forward at rather high speed until the coarse product G leaves the classifier at the end of the flow channel through coarse product duct 6.
  • the classifying air produced by a suitable pneumatic installation, enters through a flanged pipe socket 7 into a distributing box 8, passes through bottom plate 5, ascends into the zigzag tubes 1 and, laden with the classified fines, it is discharged at the top of the tube unit 1 to be freed from dust in another pneumatic installation such as a cyclone separator.
  • the number and size of holes in the bottom 5, which, in correlation with the volume of air, determine the pressure differential at the perforated plate 5, as well as the level where classification takes place and which is dependent upon the quantity and velocity of the material being separated are matched so as to obtain the flow-bed condition of the material in the channel.
  • the material is constantly flung upwards and lifted to the classifying tubes 1, which, according to their separation boundary, carry all of the fines they can entrap upwards so that, atthe end of the flow-bed, only a more or less clean coarse product G remains.
  • the drawing indicates different means to impart to the material a high flow velocity: Bottom 5 is inclined by the angle 12, a high rate of fall is imparted to the material by gravity chute 3; the lower portions of zigzag tubes 1 have the aprons 13 inclined in flow direction so as to give the non-entrapped material falling down a certain forward component of velocity; the individual nozzles in the perforated bottom 5 are inclined in forward direction so as to give the issuing jets a forward component of impetus.
  • the headroom 14 above the flow channel is so largely dimensioned that only a very small portion of the forward impetus is destroyed by the impact action of aprons 13 against which the whirled-up ma terial is flung.
  • the inclination of the nozzles in the perforated bottom 5 is, as shown on FIG. 3, achieved in a simple manner by deforming the holes 15 in a normal perforated plate 5 with the aid of a mandrel 16 pushed through holes 15 to bend the forward edge down. If high wear is expected, a shape like that of hole 17 may prove advantageous.
  • the flow channel 5 is extended by measure or amount 18 beyond the end 19 of the rising tube or tubes.
  • the air escaping from 5 in the space 18 travels a certain distance in counter-direction to the stream of material which it frees, in a very eflicient manner, from the fines entrapped, without requiring any additional channel surface or extra air.
  • the same may be achieved to a certain extent by an air flow opening 22, so that air flows upwardly through the coarse material in duct 6.
  • FIG. 4 shows the arrangement of a known type of compressed-air rapper or vibrator 26, the interior design of which corresponds to that of a pneumatic hammer.
  • This rapper taps bedplate 27.
  • the upper end of bottom 5 passes through the rear side of the air distributing box 8, stiffened by means of welded-on straps 23 and connected to flange 24 carrying plate 27 of rapper 26.
  • the passage zone is sealed with soft rubber sections 25.
  • FIG. 5 illustrates a structure for arranging the lengthwise, flexible suspension of the perforated bottom 5. Since, due to the high impact frequency of the rapper, the vibration paths are short, said suspension may be rather rigid.
  • the perforated sheet 5 is interposed between three soft rubber sections 28.
  • the measures as contemplated by the invention present, singly and in combination, the advantage that the rising-tube classifiers, particularly zigzag classifiers of the special design incorporating a flow channel allowing large feed rates to be handled and to be separated cleanly.
  • the equipment needed to achieve this is inexpensive and very simple.
  • the example below shows the results obtained.
  • Example Minette was separated, with 30% residue on a 315 micron sieve in a rising-tube classifier similar to that of FIG. 1, having a cross section of 0.8 m. and being subdivided into ten classifying zigzag tubes.
  • the flow channel 500 mm. wide, had an inclination of 9 and was filtted with a perforated bottom with alternately ar ranged holes of 8 and 10 mm. diameter, 13% of the total sieve area being open. The pressure drop at these holes was about 70 mm. water gauge. Feeding 10 tons per hour, the fines yield was 6.2 tons per hour with 5% residue on a 315 micron sieve; 81% of the product smaller than 315 microns entered the fines fraction. A classification could still be achieved at a feed rate of 40 tons per hour, with the fines yield being corresponding smaller.
  • any other gas or steam may be used; also warm air for drying as operating fluid may be used.
  • a rising-tube classifier of the type including a zigzag rising-tube unit, a flow channel extending laterally across the unit for conveying material to be classified, means for supplying material onto one end of the flow channel, a discharge duct evacuating coarse material at the other end of the flow channel, and means for delivering classifying medium to the classifier to flow up through the flow channel and the material thereon, wherein the improvement comprises a flow-channel including a perforated bottom plate provided with individual air-flow nozzles, the diameter of the nozzles and the pressure drop therein being so rated that the individual jets from said nozzles are strong enough to carry the single grains of said material along and upwardly.
  • a classifier as claimed in claim 2 wherein means additional to said air-flow nozzles is provided for increasing the initial rate of flow of material on the inlet end of the flow channel 4.

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US628497A 1966-04-06 1967-04-04 Flow channel for zigzag classifiers Expired - Lifetime US3437202A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4181591A (en) * 1976-08-10 1980-01-01 King Arthur S Electrostatic and electrolytic clarifier apparatus
US4741443A (en) * 1985-01-08 1988-05-03 Aluminium Pechiney Fluidized bed for continuous separation of two mixed solid phases
US4755284A (en) * 1984-04-14 1988-07-05 Hambra Machinery Limited Elutriator
EP0332031A2 (de) * 1988-03-11 1989-09-13 Bayer Ag Zick-Zack-Sichter
WO2000076680A1 (en) * 1999-06-15 2000-12-21 Grana Inc. Improvements in wind tunnel for cleaning and classifying solid particle material

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016101739A1 (de) * 2016-02-01 2017-08-03 Ventilatorenfabrik Oelde Gmbh Verfahren zum Schreddern von Feststoff sowie Vorrichtung zur Durchführung des Verfahrens

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US187193A (en) * 1877-02-06 Improvement in riffle-boxes for concentrating ores
US1720861A (en) * 1926-10-14 1929-07-16 Albert H Stebbins Classifier
GB380196A (en) * 1931-07-11 1932-09-15 Carves Simon Ltd Improved process and apparatus for removing dust from coal
US2106027A (en) * 1936-08-07 1938-01-18 Joseph L Rosenberg Riffle
US2258789A (en) * 1938-01-13 1941-10-14 S S Bruce Method of and apparatus for separation of materials
US2279590A (en) * 1939-02-06 1942-04-14 Roberts & Schaefer Co Apparatus for separating particulate materials
US2743817A (en) * 1956-05-01 Pneumatic separator
US2815858A (en) * 1956-04-16 1957-12-10 Day Company Of Canada Particle classifier for refuse screenings and the like
DE969075C (de) * 1951-04-27 1958-04-30 Arno Andreas Vorrichtung zum Sichten von Massenguetern
GB1014723A (en) * 1961-06-15 1965-12-31 Alpine Ag A method of and apparatus when used for the separation of grain

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE626782C (de) * 1934-06-03 1936-03-02 Heinrich Junkmann Dipl Ing Verfahren und Vorrichtung zum Entstauben von koernigem oder stueckigem Gut
DE683938C (de) * 1936-07-31 1939-11-18 Fritz Brandes Verfahren und Vorrichtung zum Abtrennen des Feinststaubes aus feinem Gut von im wesentlichen 0 bis 2 mm Korngroesse
US2203821A (en) * 1938-03-02 1940-06-11 Zonolite Company Vermiculite processing machine
US2200472A (en) * 1938-06-29 1940-05-14 Schering Corp Granular material separating machine
DE926763C (de) * 1952-10-17 1955-04-25 Guenther Voelsen Sieb aus Blech fuer Windreinigung mit nach oben und unten herausgepresster Durchdrueckung
DE970099C (de) * 1954-07-09 1958-08-21 Franz Moser Dipl Ing Verfahren und Einrichtung zum Bewegen, Aufbereiten oder Behandeln von koernigen Stoffen
DE1183451B (de) * 1960-05-10 1964-12-17 Grenobloise Etude Appl Vorrichtung zur Trennung von Korngemischen durch Fluidisierung
DE1889687U (de) * 1962-09-29 1964-03-19 Miag Muehlenbau U Ind G M B H Sichter mit einer luftdurchlaessigen schwingrinne.
FR1398143A (fr) * 1964-03-27 1965-05-07 Birtley Soc Fond perméable pour appareils de traitement pneumatique de matières solides divisées

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US187193A (en) * 1877-02-06 Improvement in riffle-boxes for concentrating ores
US2743817A (en) * 1956-05-01 Pneumatic separator
US1720861A (en) * 1926-10-14 1929-07-16 Albert H Stebbins Classifier
GB380196A (en) * 1931-07-11 1932-09-15 Carves Simon Ltd Improved process and apparatus for removing dust from coal
US2106027A (en) * 1936-08-07 1938-01-18 Joseph L Rosenberg Riffle
US2258789A (en) * 1938-01-13 1941-10-14 S S Bruce Method of and apparatus for separation of materials
US2279590A (en) * 1939-02-06 1942-04-14 Roberts & Schaefer Co Apparatus for separating particulate materials
DE969075C (de) * 1951-04-27 1958-04-30 Arno Andreas Vorrichtung zum Sichten von Massenguetern
US2815858A (en) * 1956-04-16 1957-12-10 Day Company Of Canada Particle classifier for refuse screenings and the like
GB1014723A (en) * 1961-06-15 1965-12-31 Alpine Ag A method of and apparatus when used for the separation of grain

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4181591A (en) * 1976-08-10 1980-01-01 King Arthur S Electrostatic and electrolytic clarifier apparatus
US4755284A (en) * 1984-04-14 1988-07-05 Hambra Machinery Limited Elutriator
US4741443A (en) * 1985-01-08 1988-05-03 Aluminium Pechiney Fluidized bed for continuous separation of two mixed solid phases
EP0332031A2 (de) * 1988-03-11 1989-09-13 Bayer Ag Zick-Zack-Sichter
EP0332031A3 (de) * 1988-03-11 1991-07-31 Bayer Ag Zick-Zack-Sichter
US6213307B1 (en) * 1995-11-15 2001-04-10 Grana Inc. Fluid-bed cleaner and grades sorter for particle form materials
WO2000076680A1 (en) * 1999-06-15 2000-12-21 Grana Inc. Improvements in wind tunnel for cleaning and classifying solid particle material

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DE1507686B1 (de) 1972-05-25

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