CA2242573A1 - Means and method for screening suspensions - Google Patents
Means and method for screening suspensions Download PDFInfo
- Publication number
- CA2242573A1 CA2242573A1 CA002242573A CA2242573A CA2242573A1 CA 2242573 A1 CA2242573 A1 CA 2242573A1 CA 002242573 A CA002242573 A CA 002242573A CA 2242573 A CA2242573 A CA 2242573A CA 2242573 A1 CA2242573 A1 CA 2242573A1
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- CA
- Canada
- Prior art keywords
- sieve
- screening
- particles
- suspension
- fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
- B07B1/50—Cleaning
- B07B1/55—Cleaning with fluid jets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/06—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums
- B01D33/11—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums arranged for outward flow filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/35—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition
- B01D33/37—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition in parallel connection
- B01D33/39—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition in parallel connection concentrically or coaxially
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/44—Regenerating the filter material in the filter
- B01D33/48—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
- B01D33/50—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/44—Regenerating the filter material in the filter
- B01D33/48—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
- B01D33/50—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles
- B01D33/503—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps with backwash arms, shoes or nozzles the backwash arms, shoes acting on the cake side
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
- B01D33/72—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding
- B01D33/727—Filters with filtering elements which move during the filtering operation having feed or discharge devices for feeding provoking a tangential stream
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/80—Accessories
- B01D33/801—Driving means, shaft packing systems or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/18—Drum screens
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/18—Drum screens
- B07B1/22—Revolving drums
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/18—Drum screens
- B07B1/22—Revolving drums
- B07B1/24—Revolving drums with fixed or moving interior agitators
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Combined Means For Separation Of Solids (AREA)
- Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
Abstract
A screening means (10) for a suspension of at least two types of particles dispersed in a fluid comprising at least one substantially cylindrical screen (12), supported on a frame (11), adapted to rotate about a substantially vertical axis. Each screen (12) is adapted to allow particles of dimensions less than a certain dimension to pass through the screen (12) and so be separated from those particles that are greater than the certain dimensions which are retained within the screen (12). Those particles retained within the screen (12) can be dislodged and recovered through use of a jet of fluid from nozzle (26) directed against the outer surface of the screen (12) which washes the particles into a launder (27) where they are collected.
Description
CA 02242~73 1998-07-08 W O g7/25124 PCT/AU97/00003 ~EANS AND ~v~ETHOD FOR SCR~:ENING SUSPENSIONS
Field of the Invention The present invention relates to means and methods for the screening of suspensions of at least two types of particulate materials in a fluid to 5 achieve separation of the two types of particles one from the other.
Back~round Art It is known from Australian Patent Specification No AU-B-50521/85 to screen suspensions in a device comprising a screening drum that has a substantially horizontal shaft about which it is rotatable. In this device feed 10 means are provided inside the device that have an outlet gap for discharging a ~low of suspension substantially tangentially in the directioll of rotation ofthe screening drum. The feed means is adapted to impart to the flow of the suspensioll a speed substantially e~lual to the peripheral speed of tlle drum.
Undersi~e particles and the suspending fluid pass radially outwardly through 15 the screenillg drum while the oversize particles are retained within the screen and can be removed laterally by external jets or sprays of water, air, orany other suitable fluid and discharged through an open end of the screen.
Disclosure of the Invention The present inventor has now realised that substantial advantages 20 can be achieved if the screening drum is mounted substalltially vertically, or at an angle to the horizolltal, rather than horizontally as previously proposed.Thus, in a first aspect, the present invention consists in a method for screening a suspension of at least two types of particles dispersed in a fluid, comprising the steps of:
25 (a) rotating a substantially cylindrical sieve means, through which the fluid and only one of the said two types of particles may readily pass, about a substaIltially vertical axis of symmetry;
(b) inLroducing the suspension into the sieve means substal1tially tangelltially to, and in the direction of rotation of, the sieve means at a speed 30 substantially equal to the peripheral speed of the sieve means;
(c) collecting the one type of particle from radially outside the sieve means; and (d) collecting at least the other type of particle.
The other type of particles are preferably washed to below the sieve 35 means by lifting off the other type of particles collected on an inner surface CA 02242~73 1998-07-08 W O 97~5124 PCT/AU97/00003 _ 2 of the sieve means using, for example, a jet or spray of water, air or other suitable fluid.
In a further aspect, the present invention consists in a screening means for a suspension of at least two types of particles dispersed in a fluid, 5 comprising:
(a) a substantially cylindrical sieve means, througl1 which the fluid and ol1ly one of the said two types of particles may readily pass;
(b) means to cause the sieve means to rotate about a substantially vertical axis of symmetry; and 10 (c) means to collect at least the other type of particles.
In one embodiment of this aspect, the screening means further con1prises a meaIls of spraying an outer surface of the sieve means with a jet of fluid. The jet of fluid, in part, passes tllrough the sieve means and dislodges the other type of particles that have accumulated on an inner 15 surface of the sieve means. The dislodged particles will preferably be washed into a launder disposed below tlle sieve means for the collection of the other type of particles.
The screening means can comprise more than one sieve means. In one embodiment, the screening means can be operated wllere only one or 20 some of a number of sieve means are employed at one time.
The advantages of using a substantially cylindrical sieve means designed to rotate about a substantially vertical axis, as opposed to the horizontal axis as previously proposed, are substantial. They include:
~a) the bearings may be at the top of the sieve means well out of the ~5 range of falling or draining water;
(b3 heavier concel1trations of solids, including fibrous nlaterials, have a substantially vertical fall illtO a launder or other suitable collection device thereby avoiding "hangup" of sticky or fibrous materials;
(c) the sieve means are substantially self-cleaning an(l self-draining 30 when the flow of suspensioll stops;
(d3 the sieve meal1s may be easily accessed by lifting a lightweight moulded or fabricated cover;
(e3 the drive for the sieve means may be disposed above or below the sieve means and a single drive may run a plurality of sieve means;
CA 02242~73 1998-07-08 . 3 (fl the sieve means may be held in place with its OWIl weight and substantially without retention bolts thereby facilitating quick and easy screen replacerment;
(g) the arrangement is readily adapted to multiple unit installations with common headers, launders and the like;
~h) a substantially vertical arrangement allows unlimited length/diameter ratios as there is less tendency for the screen to accumulate a load of solids during shutdown, there is also a space advantage in having the screen longer and the cost of launders, pipes, and the like, is less; and (i) a substantially vertical sieve axis is better disposed for flexible mounting of the sieve means as changes in load do not deflect the axis direction. A single pOillt flexible mounting will allow an out-of-balance screen to rotate about its centre of gravity, placing less shess on the relatively fragile screen medium, and hansmitting less vibration to the support structure.
As used in this specification the term substantially vertical axis n1ealls an axis that is no more than about 45~ inclined to the vertical, preferably no more than 30~ and most preferably no more than 15~.
The sieve means may comprise a frame covered with any suitable sieve medium which will allow through one type of particle but inhibit the passage of the other type. Suitable sieve media illclude wedgewire screens rolled into cylinders; laser cut perforated metal screens; polyurethane wedgewire screen panels Oll a cylindrical frame; or conventional cloth screens of woven wires of metal or plastic.
The means to drive the screen may comprise a conventional mechanical or electrical motor coupled directly or indirectly to the sieve means. An alternative arrangement is to use a hydrodyllamic or hydrostatic drive to drive the sieve means. In its simplest form a hydrodynamic drive may comprise an impeller formed integrally with a hub on which a cvlindrical sieve screen is hung. A stream of drive water is directed to impinge against the impeller. This same stream may be used as a cleaning stream for the sieve screen or may be merely recycled to drive the sieve screen. In this way a simple valve may be used to control the rotation of ~ each of a group of devices driven from a commoll hydrodynamic fluid source.
In a still further embodiment, the means to rotate the sieve screen can comprise the iet of fluid which is directed at the outer surface of the sieve CA 02242~73 1998-07-08 _ 4 means to remove the particles collected on the inner surface. The rotational speed of the sieve means can be controlled by adjusting the pressure, flow rate and angle of impingement of the jet of fluid.
The present invention can be used to separate coarser material from finer material in slurries. For example, the present invention can be used to separate coal fines in slurry stream based on the size of the fines in the slurry. Other applications can be envisaged including useiIl chrysotile and asbestos fibre particle separation.
Brief Description of the Drawings Hereinafter by way of example only, preferred embodiments of the present inventioil are described with reference to the accompanying drawings, in which:
Fig. 1 is a partly cut-away side elevational view of one embodiment of a screening device according to the present inventioll;
Fig. 2 is a vertical sectional view through the screening device of Fig.
l;
Fig. 3 is a plan view of the screening device of Fig. l;
Fig. 4 is a partly cut away side elevational view of another embodinlent of a screening device according to the present invention;
Fig. 5 and Fig. 6 are respectively an underneath plan view and a cut-away side elevational view of a hydrodynamic drive for a screening device according to the present invention;
Fig. 7 is a partially cut-away side elevational view of a still further embodinlent of the screening device according to the present invention;
Fig. 8 is a cross-sectional view of one of the sieve means of the screening device depicted in Fig. 7 showing details of the header and cleaning apparatus;
Fig. 9 is a plan view of the header of Fig. 8, showillg the deflector plate, cleaning fingers and cleaning bar; and Fig. 10 is a further cross-sectional view of the sieve means of Fig. 7.
Best l~lode of Carrving out the Invention A screening device for a coal slurly suspension con~ining at least two types of particles dispersed in a fluid according to the present invention is generally depicted as 10 in Figs. 1 to 6. The screening device 10 could be readily adapted to screen coarser material from filler material in other slurries.
CA 02242~73 1998-07-08 _ 5 The screenillg device 10 comprises a frame 11 (see Fig. 3) and a pair of cylindrical laser cut stainless steel screens 12 having slots of 150 microns Width. II1 the arrangemellt shown in Figs. 1 to 3, the screens 12 are each ~lounted vertically with a closed top 13 and an open bottom 14. The top 13 is connected to a centrally located spindle 15 mo~mted in a bearing 16. The upper end of each spindle 15 carries a pulley wheel 17 comlected by a drive belt 18 to a common motor tllrough a common drive shaft 19. Each of the screens 12 is covered by a light weight cylindrical shield 21 that drops over the drive shaft 15 when the pulley 17 has been removed. Each shield 21 directs material that passes through the associated screen 12 into a launder 22 below the respective screen 12.
~Iaterial to be screened is introduced through a horizontal duct 23 froLn whence it rises upwardly and thell downwardly into a vertical discharge header 2~. Each SUCh header 24 has an elongate discharge nozzle 25 arranged to project the suspension to be screened OlltO the inside surface of the screen 12 and substantially tangentially thereto (as depicted by arrow B
in Fig. 3).
The suspension on the inside surface of the screen 12 is subject to strong centrifugal force that projects the fluid, usually a liquid and normally water, in which the particulate matter is suspended, and the undersize particles radially out through the screen and into launder 22. The oversize particles are held by centrifugal force against the inside surface of the screen12 until they are physically removed. This removal is via air, water, or another fluid being discharged forcefully substantially radially inwardly, against the outside of the screen 12 (as depicted by arrow A in Fig. 3). This fluid is projected through elongate, vertically oriented, nozzles 26 (see Fig.
3). The oversize particles dislodged by the fluid discharged through nozzles 26 are captured by vertical launder 27. The launders 27 are supported on either side by plates 28 connecting the launders to a respective one of the tubular support members 29. The tubular support member 29 supports, through a bearing 31, the spindle 15.
The arrallgemellt shown in Fig. 4 differs from that shown in Figs. 1 to 3 only in that valve 32 is provided to control the flow of suspension individually to each screen 12.
In the arrangement shown in Figs. 5 and ~, the screen 12 is driven by a pelton wheel integral with the screening device 10. Each support member CA 02242~73 l998-07-08 W O 97t25124 PCT/AU97/00003 2g is connected internally to a source of high pressure water. This water is directed, through arm 33, against a series of vanes 34 on the underside of the top 13 of the associated screen 12. The screen 12 is thus driven by the water pressure. The rate may be determined by controlli~g the flow of water 5 through tap 35. The water discharged against the vanes 34 may be collected and recycled as clear water or it may be used to flusll oversize product down the vertical launder 27.
A further embodiment of a screening device according to the present invention is gellerally depicted as 10a in Figs. 7 to 10. In this embodiment, 10 where like features have been numbered as described above, each of the screens 12 are mounted on the screening device 10a at 45~ to the horizontal.
In the embodiment 10a, a deflector plate 40 is disposed proximate the outlet of the llozzles 25 to deflect the cylindrical stream from the nozzles 25 into a wide, flat stream before it reaches the screen 12. The spacing and 15 dimensiolls of the nozzles 25 provides full coverage of the surface of the screen 12. II1 one embodiment, the nozzles 25 can constitute a single slot for discharge of the suspension.
Oversize material, sgglomerating matelial, or fibrous material can have lumps which are larger than the orifices of the nozzles 25, or a number 20 of lumps which are individually smaller than the orifice can combine to block a nozzle 25 in certain instances. In order to relllove sucll blockages, nozzle cleaning fingers ~1 are mounted on a cleaning bar 42, which can be rotated about its axis to push the fingers ~1 through the orifice, dislodging the lulnps back into the header 24. As the cleaning bar 42 is rotated about its 25 axisJ the end cover plate 43 is moved away from the header end nozzle 44 allowhlg the oversize material to be discharged illtO the launder 27. The downward flow in the header 24 also assists this action. For those applications where nozzle bloclcage is rare, oversize material can collect at the bottom of header 2~ and, if necessary~ be discharged infrequently by 30 mall~lal removal of a pl~lg.
The downward flow of the suspellsion into the header 24 also allows SiZillg of the header to compellsate for the change in head pressure along the length of the header 2~. Wllere the header pressure is high. the isolating valve 45 can be closed during the cleaning process. This arrangement of 35 cleaning equipment allows for automation of the cleaning process.
=
.
_ 7 The material which is retained on the inner surface of each sieve screen 12 is removed by a water jet directed towards the outer surface of the - screen 12 fron1 a spray header. The water passes through the slots in the screen 12 and so washes the retained material into the launder 27 where it is 5 collected.
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to 10 be considered in all respects as illustrative and not restrictive.
Field of the Invention The present invention relates to means and methods for the screening of suspensions of at least two types of particulate materials in a fluid to 5 achieve separation of the two types of particles one from the other.
Back~round Art It is known from Australian Patent Specification No AU-B-50521/85 to screen suspensions in a device comprising a screening drum that has a substantially horizontal shaft about which it is rotatable. In this device feed 10 means are provided inside the device that have an outlet gap for discharging a ~low of suspension substantially tangentially in the directioll of rotation ofthe screening drum. The feed means is adapted to impart to the flow of the suspensioll a speed substantially e~lual to the peripheral speed of tlle drum.
Undersi~e particles and the suspending fluid pass radially outwardly through 15 the screenillg drum while the oversize particles are retained within the screen and can be removed laterally by external jets or sprays of water, air, orany other suitable fluid and discharged through an open end of the screen.
Disclosure of the Invention The present inventor has now realised that substantial advantages 20 can be achieved if the screening drum is mounted substalltially vertically, or at an angle to the horizolltal, rather than horizontally as previously proposed.Thus, in a first aspect, the present invention consists in a method for screening a suspension of at least two types of particles dispersed in a fluid, comprising the steps of:
25 (a) rotating a substantially cylindrical sieve means, through which the fluid and only one of the said two types of particles may readily pass, about a substaIltially vertical axis of symmetry;
(b) inLroducing the suspension into the sieve means substal1tially tangelltially to, and in the direction of rotation of, the sieve means at a speed 30 substantially equal to the peripheral speed of the sieve means;
(c) collecting the one type of particle from radially outside the sieve means; and (d) collecting at least the other type of particle.
The other type of particles are preferably washed to below the sieve 35 means by lifting off the other type of particles collected on an inner surface CA 02242~73 1998-07-08 W O 97~5124 PCT/AU97/00003 _ 2 of the sieve means using, for example, a jet or spray of water, air or other suitable fluid.
In a further aspect, the present invention consists in a screening means for a suspension of at least two types of particles dispersed in a fluid, 5 comprising:
(a) a substantially cylindrical sieve means, througl1 which the fluid and ol1ly one of the said two types of particles may readily pass;
(b) means to cause the sieve means to rotate about a substantially vertical axis of symmetry; and 10 (c) means to collect at least the other type of particles.
In one embodiment of this aspect, the screening means further con1prises a meaIls of spraying an outer surface of the sieve means with a jet of fluid. The jet of fluid, in part, passes tllrough the sieve means and dislodges the other type of particles that have accumulated on an inner 15 surface of the sieve means. The dislodged particles will preferably be washed into a launder disposed below tlle sieve means for the collection of the other type of particles.
The screening means can comprise more than one sieve means. In one embodiment, the screening means can be operated wllere only one or 20 some of a number of sieve means are employed at one time.
The advantages of using a substantially cylindrical sieve means designed to rotate about a substantially vertical axis, as opposed to the horizontal axis as previously proposed, are substantial. They include:
~a) the bearings may be at the top of the sieve means well out of the ~5 range of falling or draining water;
(b3 heavier concel1trations of solids, including fibrous nlaterials, have a substantially vertical fall illtO a launder or other suitable collection device thereby avoiding "hangup" of sticky or fibrous materials;
(c) the sieve means are substantially self-cleaning an(l self-draining 30 when the flow of suspensioll stops;
(d3 the sieve meal1s may be easily accessed by lifting a lightweight moulded or fabricated cover;
(e3 the drive for the sieve means may be disposed above or below the sieve means and a single drive may run a plurality of sieve means;
CA 02242~73 1998-07-08 . 3 (fl the sieve means may be held in place with its OWIl weight and substantially without retention bolts thereby facilitating quick and easy screen replacerment;
(g) the arrangement is readily adapted to multiple unit installations with common headers, launders and the like;
~h) a substantially vertical arrangement allows unlimited length/diameter ratios as there is less tendency for the screen to accumulate a load of solids during shutdown, there is also a space advantage in having the screen longer and the cost of launders, pipes, and the like, is less; and (i) a substantially vertical sieve axis is better disposed for flexible mounting of the sieve means as changes in load do not deflect the axis direction. A single pOillt flexible mounting will allow an out-of-balance screen to rotate about its centre of gravity, placing less shess on the relatively fragile screen medium, and hansmitting less vibration to the support structure.
As used in this specification the term substantially vertical axis n1ealls an axis that is no more than about 45~ inclined to the vertical, preferably no more than 30~ and most preferably no more than 15~.
The sieve means may comprise a frame covered with any suitable sieve medium which will allow through one type of particle but inhibit the passage of the other type. Suitable sieve media illclude wedgewire screens rolled into cylinders; laser cut perforated metal screens; polyurethane wedgewire screen panels Oll a cylindrical frame; or conventional cloth screens of woven wires of metal or plastic.
The means to drive the screen may comprise a conventional mechanical or electrical motor coupled directly or indirectly to the sieve means. An alternative arrangement is to use a hydrodyllamic or hydrostatic drive to drive the sieve means. In its simplest form a hydrodynamic drive may comprise an impeller formed integrally with a hub on which a cvlindrical sieve screen is hung. A stream of drive water is directed to impinge against the impeller. This same stream may be used as a cleaning stream for the sieve screen or may be merely recycled to drive the sieve screen. In this way a simple valve may be used to control the rotation of ~ each of a group of devices driven from a commoll hydrodynamic fluid source.
In a still further embodiment, the means to rotate the sieve screen can comprise the iet of fluid which is directed at the outer surface of the sieve CA 02242~73 1998-07-08 _ 4 means to remove the particles collected on the inner surface. The rotational speed of the sieve means can be controlled by adjusting the pressure, flow rate and angle of impingement of the jet of fluid.
The present invention can be used to separate coarser material from finer material in slurries. For example, the present invention can be used to separate coal fines in slurry stream based on the size of the fines in the slurry. Other applications can be envisaged including useiIl chrysotile and asbestos fibre particle separation.
Brief Description of the Drawings Hereinafter by way of example only, preferred embodiments of the present inventioil are described with reference to the accompanying drawings, in which:
Fig. 1 is a partly cut-away side elevational view of one embodiment of a screening device according to the present inventioll;
Fig. 2 is a vertical sectional view through the screening device of Fig.
l;
Fig. 3 is a plan view of the screening device of Fig. l;
Fig. 4 is a partly cut away side elevational view of another embodinlent of a screening device according to the present invention;
Fig. 5 and Fig. 6 are respectively an underneath plan view and a cut-away side elevational view of a hydrodynamic drive for a screening device according to the present invention;
Fig. 7 is a partially cut-away side elevational view of a still further embodinlent of the screening device according to the present invention;
Fig. 8 is a cross-sectional view of one of the sieve means of the screening device depicted in Fig. 7 showing details of the header and cleaning apparatus;
Fig. 9 is a plan view of the header of Fig. 8, showillg the deflector plate, cleaning fingers and cleaning bar; and Fig. 10 is a further cross-sectional view of the sieve means of Fig. 7.
Best l~lode of Carrving out the Invention A screening device for a coal slurly suspension con~ining at least two types of particles dispersed in a fluid according to the present invention is generally depicted as 10 in Figs. 1 to 6. The screening device 10 could be readily adapted to screen coarser material from filler material in other slurries.
CA 02242~73 1998-07-08 _ 5 The screenillg device 10 comprises a frame 11 (see Fig. 3) and a pair of cylindrical laser cut stainless steel screens 12 having slots of 150 microns Width. II1 the arrangemellt shown in Figs. 1 to 3, the screens 12 are each ~lounted vertically with a closed top 13 and an open bottom 14. The top 13 is connected to a centrally located spindle 15 mo~mted in a bearing 16. The upper end of each spindle 15 carries a pulley wheel 17 comlected by a drive belt 18 to a common motor tllrough a common drive shaft 19. Each of the screens 12 is covered by a light weight cylindrical shield 21 that drops over the drive shaft 15 when the pulley 17 has been removed. Each shield 21 directs material that passes through the associated screen 12 into a launder 22 below the respective screen 12.
~Iaterial to be screened is introduced through a horizontal duct 23 froLn whence it rises upwardly and thell downwardly into a vertical discharge header 2~. Each SUCh header 24 has an elongate discharge nozzle 25 arranged to project the suspension to be screened OlltO the inside surface of the screen 12 and substantially tangentially thereto (as depicted by arrow B
in Fig. 3).
The suspension on the inside surface of the screen 12 is subject to strong centrifugal force that projects the fluid, usually a liquid and normally water, in which the particulate matter is suspended, and the undersize particles radially out through the screen and into launder 22. The oversize particles are held by centrifugal force against the inside surface of the screen12 until they are physically removed. This removal is via air, water, or another fluid being discharged forcefully substantially radially inwardly, against the outside of the screen 12 (as depicted by arrow A in Fig. 3). This fluid is projected through elongate, vertically oriented, nozzles 26 (see Fig.
3). The oversize particles dislodged by the fluid discharged through nozzles 26 are captured by vertical launder 27. The launders 27 are supported on either side by plates 28 connecting the launders to a respective one of the tubular support members 29. The tubular support member 29 supports, through a bearing 31, the spindle 15.
The arrallgemellt shown in Fig. 4 differs from that shown in Figs. 1 to 3 only in that valve 32 is provided to control the flow of suspension individually to each screen 12.
In the arrangement shown in Figs. 5 and ~, the screen 12 is driven by a pelton wheel integral with the screening device 10. Each support member CA 02242~73 l998-07-08 W O 97t25124 PCT/AU97/00003 2g is connected internally to a source of high pressure water. This water is directed, through arm 33, against a series of vanes 34 on the underside of the top 13 of the associated screen 12. The screen 12 is thus driven by the water pressure. The rate may be determined by controlli~g the flow of water 5 through tap 35. The water discharged against the vanes 34 may be collected and recycled as clear water or it may be used to flusll oversize product down the vertical launder 27.
A further embodiment of a screening device according to the present invention is gellerally depicted as 10a in Figs. 7 to 10. In this embodiment, 10 where like features have been numbered as described above, each of the screens 12 are mounted on the screening device 10a at 45~ to the horizontal.
In the embodiment 10a, a deflector plate 40 is disposed proximate the outlet of the llozzles 25 to deflect the cylindrical stream from the nozzles 25 into a wide, flat stream before it reaches the screen 12. The spacing and 15 dimensiolls of the nozzles 25 provides full coverage of the surface of the screen 12. II1 one embodiment, the nozzles 25 can constitute a single slot for discharge of the suspension.
Oversize material, sgglomerating matelial, or fibrous material can have lumps which are larger than the orifices of the nozzles 25, or a number 20 of lumps which are individually smaller than the orifice can combine to block a nozzle 25 in certain instances. In order to relllove sucll blockages, nozzle cleaning fingers ~1 are mounted on a cleaning bar 42, which can be rotated about its axis to push the fingers ~1 through the orifice, dislodging the lulnps back into the header 24. As the cleaning bar 42 is rotated about its 25 axisJ the end cover plate 43 is moved away from the header end nozzle 44 allowhlg the oversize material to be discharged illtO the launder 27. The downward flow in the header 24 also assists this action. For those applications where nozzle bloclcage is rare, oversize material can collect at the bottom of header 2~ and, if necessary~ be discharged infrequently by 30 mall~lal removal of a pl~lg.
The downward flow of the suspellsion into the header 24 also allows SiZillg of the header to compellsate for the change in head pressure along the length of the header 2~. Wllere the header pressure is high. the isolating valve 45 can be closed during the cleaning process. This arrangement of 35 cleaning equipment allows for automation of the cleaning process.
=
.
_ 7 The material which is retained on the inner surface of each sieve screen 12 is removed by a water jet directed towards the outer surface of the - screen 12 fron1 a spray header. The water passes through the slots in the screen 12 and so washes the retained material into the launder 27 where it is 5 collected.
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to 10 be considered in all respects as illustrative and not restrictive.
Claims
CLAIMS:
1. A screening means for a suspension of at least two types of particles dispersed in a fluid, comprising:
(a) a substantially cylindrical sieve means, through which the fluid and only one of the said two types of particles may readily pass;
(b) means to cause the sieve means to rotate about a substantially vertical axis of symmetry;
(c) means for introducing a suspension into the sieve means in a direction of rotation of the sieve means; and (d) means to collect at least the other type of particles.
2. The screening means of claim 1 wherein the axis of symmetry is inclined no more than 45° to the vertical, or no more than 30° to the vertical, or no more than 15° to the vertical.
3. The screening means of claim 1 comprising at least two substantially cylindrical sieve means each inclined at an angle of 45° to the vertical.4. The screening means of any one of the preceding claims wherein the sieve means comprises a frame covered with a sieve medium which will allow through the one type of particle but inhibit the passage of the other type.
5. The screening means of claim 4 wherein the sieve media include wedgewire screens rolled into cylinders, laser cut perforated metal screens, polyurethane wedgewire screen panels on a cylindrical frame, or cloth screens of woven wires of metal or plastic.
6. The screening means of any one of the preceding claims wherein the means to rotate the sieve means comprises a mechanical or electrical motor coupled directly or indirectly to the sieve means.
7. The screening means of any one of claims 1 to 5 wherein the means to rotate the sieve means comprises a hydrodynamic or hydrostatic drive.
8. The screening means of claim 7 wherein the hydrodynamic drive comprises an impeller having a plurality of vanes and formed integrally with the sieve means, the impeller being driven by a stream of water that is directed to impinge against the vanes.
9. The screening means of any one of the preceding claims further comprising a means of spraying an outer surface of the sieve means with a jet of fluid.
10. The screening means of any one of the preceding claims wherein the means for introducing a suspension comprises at least one discharge nozzle arranged to project the suspension to be screened onto an inner surface of the sieve means.
11. The screening means of claim 10 wherein a deflector plate is disposed proximate the discharge nozzle.
12. The screening means of claims 10 or 11 wherein the suspension is introduced into the sieve means substantially tangentially to the sieve means.
13. The screening means of any one of claims 10 - 12 further comprising a discharge nozzle cleaning means.
14. The screening means of claim 13 wherein the discharge nozzle cleaning means comprises a plurality of fingers adapted to enter the discharge nozzle and dislodge any particles caught therein.
15. A method for screening a suspension of at least two types of particles dispersed in a fluid, comprising the steps of:
(a) rotating a substantially cylindrical sieve means, through which the fluid and only one of the said two types of particles may readily pass, about a substantially vertical axis of symmetry;
(b) introducing the suspension into the sieve means substantially tangentially to, and in the direction of rotation of, the sieve means at a speedsubstantially equal to the peripheral speed of the sieve means;
(c) collecting the one type of particle from radially outside the sieve means; and (d) collecting at least the other type of particle.
1. A screening means for a suspension of at least two types of particles dispersed in a fluid, comprising:
(a) a substantially cylindrical sieve means, through which the fluid and only one of the said two types of particles may readily pass;
(b) means to cause the sieve means to rotate about a substantially vertical axis of symmetry;
(c) means for introducing a suspension into the sieve means in a direction of rotation of the sieve means; and (d) means to collect at least the other type of particles.
2. The screening means of claim 1 wherein the axis of symmetry is inclined no more than 45° to the vertical, or no more than 30° to the vertical, or no more than 15° to the vertical.
3. The screening means of claim 1 comprising at least two substantially cylindrical sieve means each inclined at an angle of 45° to the vertical.4. The screening means of any one of the preceding claims wherein the sieve means comprises a frame covered with a sieve medium which will allow through the one type of particle but inhibit the passage of the other type.
5. The screening means of claim 4 wherein the sieve media include wedgewire screens rolled into cylinders, laser cut perforated metal screens, polyurethane wedgewire screen panels on a cylindrical frame, or cloth screens of woven wires of metal or plastic.
6. The screening means of any one of the preceding claims wherein the means to rotate the sieve means comprises a mechanical or electrical motor coupled directly or indirectly to the sieve means.
7. The screening means of any one of claims 1 to 5 wherein the means to rotate the sieve means comprises a hydrodynamic or hydrostatic drive.
8. The screening means of claim 7 wherein the hydrodynamic drive comprises an impeller having a plurality of vanes and formed integrally with the sieve means, the impeller being driven by a stream of water that is directed to impinge against the vanes.
9. The screening means of any one of the preceding claims further comprising a means of spraying an outer surface of the sieve means with a jet of fluid.
10. The screening means of any one of the preceding claims wherein the means for introducing a suspension comprises at least one discharge nozzle arranged to project the suspension to be screened onto an inner surface of the sieve means.
11. The screening means of claim 10 wherein a deflector plate is disposed proximate the discharge nozzle.
12. The screening means of claims 10 or 11 wherein the suspension is introduced into the sieve means substantially tangentially to the sieve means.
13. The screening means of any one of claims 10 - 12 further comprising a discharge nozzle cleaning means.
14. The screening means of claim 13 wherein the discharge nozzle cleaning means comprises a plurality of fingers adapted to enter the discharge nozzle and dislodge any particles caught therein.
15. A method for screening a suspension of at least two types of particles dispersed in a fluid, comprising the steps of:
(a) rotating a substantially cylindrical sieve means, through which the fluid and only one of the said two types of particles may readily pass, about a substantially vertical axis of symmetry;
(b) introducing the suspension into the sieve means substantially tangentially to, and in the direction of rotation of, the sieve means at a speedsubstantially equal to the peripheral speed of the sieve means;
(c) collecting the one type of particle from radially outside the sieve means; and (d) collecting at least the other type of particle.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPN7469A AUPN746996A0 (en) | 1996-01-09 | 1996-01-09 | Means and method for screening suspensions |
| AUPN7469 | 1996-01-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2242573A1 true CA2242573A1 (en) | 1997-07-17 |
Family
ID=3791787
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002242573A Abandoned CA2242573A1 (en) | 1996-01-09 | 1997-01-07 | Means and method for screening suspensions |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AUPN746996A0 (en) |
| CA (1) | CA2242573A1 (en) |
| WO (1) | WO1997025124A1 (en) |
| ZA (1) | ZA97180B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106039818A (en) * | 2016-07-22 | 2016-10-26 | 安徽省味之源生物科技有限公司 | Roller screen for boiled soybean milk |
| CN113713476A (en) * | 2021-08-24 | 2021-11-30 | 中广核工程有限公司 | Driving device for drum-shaped filter screen |
| CN114367140A (en) * | 2021-12-31 | 2022-04-19 | 江苏电力装备有限公司 | Parallel shaft driving device for drum-shaped filter screen |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997038064A1 (en) * | 1996-04-10 | 1997-10-16 | Ilecard Pty. Ltd. | Process for treating coal tailings |
| CN1139420C (en) * | 2001-01-15 | 2004-02-25 | 牛子久 | Rotation-type filter method for well-drilling fluid and 4 special devices for implementing it |
| CN114733249B (en) * | 2022-06-14 | 2022-09-09 | 山西省科技情报与战略研究中心 | Solid-liquid separation treatment system |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3743094A (en) * | 1971-12-20 | 1973-07-03 | Sweco Inc | Rotating screen separator |
| US5143220A (en) * | 1990-11-08 | 1992-09-01 | Ingersoll-Rand Company | Apparatus for screening to remove knots from a fluid borne slurry of fibers and knots |
| US5183568A (en) * | 1991-08-22 | 1993-02-02 | G A Industries, Inc. | Self-cleaning strainer |
| US5312544A (en) * | 1992-10-23 | 1994-05-17 | S. P. Kinney Engineers, Inc. | Continuous strainer |
-
1996
- 1996-01-09 AU AUPN7469A patent/AUPN746996A0/en not_active Abandoned
-
1997
- 1997-01-07 WO PCT/AU1997/000003 patent/WO1997025124A1/en active Application Filing
- 1997-01-07 CA CA002242573A patent/CA2242573A1/en not_active Abandoned
- 1997-01-09 ZA ZA97180A patent/ZA97180B/en unknown
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106039818A (en) * | 2016-07-22 | 2016-10-26 | 安徽省味之源生物科技有限公司 | Roller screen for boiled soybean milk |
| CN113713476A (en) * | 2021-08-24 | 2021-11-30 | 中广核工程有限公司 | Driving device for drum-shaped filter screen |
| CN114367140A (en) * | 2021-12-31 | 2022-04-19 | 江苏电力装备有限公司 | Parallel shaft driving device for drum-shaped filter screen |
Also Published As
| Publication number | Publication date |
|---|---|
| ZA97180B (en) | 1997-07-09 |
| WO1997025124A1 (en) | 1997-07-17 |
| AUPN746996A0 (en) | 1996-02-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |