WO2009029962A1 - Cribles - Google Patents

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Publication number
WO2009029962A1
WO2009029962A1 PCT/ZA2008/000078 ZA2008000078W WO2009029962A1 WO 2009029962 A1 WO2009029962 A1 WO 2009029962A1 ZA 2008000078 W ZA2008000078 W ZA 2008000078W WO 2009029962 A1 WO2009029962 A1 WO 2009029962A1
Authority
WO
WIPO (PCT)
Prior art keywords
screen
frame
vibratory
inner frame
cloth
Prior art date
Application number
PCT/ZA2008/000078
Other languages
English (en)
Inventor
Gavin Campbell Armstrong
Original Assignee
Gavin Campbell Armstrong
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Gavin Campbell Armstrong filed Critical Gavin Campbell Armstrong
Publication of WO2009029962A1 publication Critical patent/WO2009029962A1/fr

Links

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
    • 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
    • B07B1/42—Drive mechanisms, regulating or controlling devices, or balancing devices, specially adapted for 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
    • B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
    • B07B1/50—Cleaning
    • B07B1/54—Cleaning with beating devices
    • 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
    • B07B2201/00—Details applicable to machines for screening using sieves or gratings
    • B07B2201/04—Multiple deck screening devices comprising one or more superimposed screens

Definitions

  • This invention lies in the field of mineral recovery, with particular application to diamond recovery.
  • the application of the invention extends to the recovery of precious stones, minerals and any materials which have to be sized or classified for industrial or recovery purposes.
  • This invention relates particularly to vibratory screening as a preliminary process step in diamond recovery as its primary application but is applicable to the wider field of materials sizing and classification.
  • Diamond gravel or crushed primary kimberlite requires screening into specific size fractions for delivery to diamond concentrating plants, whether these are rotary pans, dense or heavy medium recovery plants, jig classification plants or other means of separation of materials of different specific gravity.
  • the material concentrated by the above or any other means may require further separation into specific size fractions for the separation and/or recovery of diamonds over grease tables and/or through diamond X-ray machines.
  • a vibratory screen in accordance with this invention includes a structural frame that is rectangular, fabricated from profiled structural members, defining a length and width of the frame, the frame having within its surround a woven wire mesh screen cloth that is supported between the structural members by suitable securing means, having transverse bracing struts extending across the width of the frame and located below the mesh, characterised by vibratory motors attached to the outside of the structural members that define the length of the frame, with the direction of the feed in use along the length of the frame.
  • the length is longer than the width.
  • the vibratory motors are provided with their vibration axes oriented at an acute angle to the length of the screen, which is the feed direction of the screen.
  • An acute angle means an angle that is not orthogonal to the length of the frame and not parallel to the length direction of the frame, i.e. an angle that lies between 90 degrees and 0/180 degrees.
  • the angle lies within 10 or 20 degrees of 45 degrees to the longitudinal direction of the frame, that is, between 25 and 65 degrees, preferably between 35 and 55 degrees.
  • the angle of the motors is important for the performance of the screen and may be adjusted for the type of material screened, the feed rate, moisture level, nature of the material and other criteria during use, it is found that adjustment is not required for most applications.
  • the advantage of the screen is its exceptional lightness and simplicity leading to relatively light, low power consumption vibratory motors being effective for vibratory screening of a relatively large mass of material.
  • an inner frame is located inside the structural frame and carries the screen cloth.
  • the inner frame is fixed to the structural frame by bolting.
  • This provides a reinforced structure with the screen cloth fixed to the inner frame plus the advantage that the inner frame may be easily detached from the structural frame by unbolting.
  • the vibratory motors are attached to the screen by bolting rather than welding, and preferably the bolting passes through both the structural frame and the inner frame of the screen.
  • the structural members of the structural frame and the inner frame are in accordance with the invention preferably made of hollow tubing. Hollow tubing has a higher strength to mass ratio especially in bending action than solid bar, this gives effect to the goal of the invention which is a lightweight vibratory screen, that has been referred to above. Bolting not only affords the advantage of ease of disassembly but also avoids risk of fatigue fracture that is a tendency with welded joints subjected to vibratory action.
  • a multiple deck screening assembly is created that has the abovementioned features applied to each deck, thus for example a four deck screening assembly is built, or any other number of decks within reason.
  • the screen decks screen into separate fractions and these are collected separately for delivery to bins or to separation equipment.
  • the decks are bolted together by means of fish plates on the sides.
  • each deck is provided with a guide bar that directs the fraction retained on the screen to a position in which the fraction falls into a bin or onto a further processing component or a position on a component separate to the other fractions.
  • a four deck screen for example into two two-deck screens so that vibratory motors that are suitable to the size ranges on each pair of screens can be used. Otherwise it can happen that the vibration is too much for the fine fraction on one screen but too little for a coarse fraction on another screen.
  • the screening device feeds directly in this way into a separation device and not into temporary holding bins, for example a grease or X-ray separating screen. This is particularly important with diamond separation, for example, as in some chemical conditions the diamonds develop surface conditions that militate against later separation technologies.
  • the vibratory motors are mounted on flat plates that are bolted to the outer frame of the screen deck or each deck in the case of a multiple deck screen assembly, the plates serving also to secure the decks of a multiple deck screen together and to secure an outer frame to an inner frame of the screen deck.
  • the screens can be adapted to allow them to be inclined in the feed direction either upwardly or downwardly.
  • a technique to prevent blinding of a screen may be adopted which is to locate an additional screen below the screen and provide between the two screens a multiplicity of rings or short tubes of plastic material that vibrate between the two screens during use.
  • the gap between the two screens is only slightly more than the dimension of the short tubes which are oriented with their axial direction orthogonal to the screen cloth. It is found that these tubes tend to knock out particles that are blinding the screen and the screen below is made with a larger aperture than the screen above so as to pass the material that passes the upper screen.
  • the vibratory motors may enter the screen at 600 degrees centigrade.
  • the motors may in such cases be mounted on extension plates so as to raise the motors or lower them to a position where they may be above or below respectively of a partition that closes off the very hot material on the screen.
  • Figure 1 is an oblique projection of a single deck screen
  • Figure 2 is an oblique projection of a single deck screen raised on legs
  • Figure 3 is an oblique projection of a two deck screen
  • Figure 4 is an oblique view of a four deck screen
  • Figure 5 is an oblique view of a five deck screen
  • Figure 6 is an oblique view of a single deck screen with raised motors
  • Figure 7 is an oblique view of a single deck screen with lowered motors
  • Figure 8 is an oblique view of short tubes between a double mesh to prevent blinding
  • Figure 9 is an enlarged scale transverse cross section of a single deck screen showing features of the screen
  • Figure 10 is another enlarged scale transverse cross section showing other features of the screen
  • Figure 11 is a transverse cross section of the single deck screen shown in figure 1.
  • the vibratory screen consists of a single deck shown in figure 1 , a two deck shown in figure 2, a three deck shown in figure 3, a four deck shown in figure 4 and a five deck assembly shown in figure 5.
  • Each deck consists of an outer frame that is rectangular, fabricated from profiled structural members, longitudinal members 1 and transverse members 2 of the frame, the frame having within its surround a woven wire mesh 3 that is supported between the structural members by suitable securing means, having transverse bracing struts 4 extending across the width of the frame and located below the mesh, characterised by vibratory motors 5 attached to the outside of the longitudinal structural members.
  • the outer frame is made of thick walled rectangular tubing, for example 25mm by 75mm with a wall thickness of 4mm. This is suitable for a screen up to about 2 meters in length, for longer lengths a stiffer frame is required to avoid a whip action towards the ends of the frame.
  • the frame may be a rectangular section tube of 150mm by 50mm by 4mm or 6mm wall thickness. The reason to avoid a whip action is that this results in the amplitude of vibration of the screen at the ends that is too large and reduces the throughput of undersize fractions through the screen.
  • An inner frame of square tubing has longitudinal members 6 and transverse members which constitute the transverse bracing struts 4 and in this example longitudinal bracing struts 7 which are optional. If longitudinal struts are used it is necessary to have blocking strips 8 on top of the screen positioned above these struts, so as to avoid material that is located above the longitudinal struts travelling the length of the screen without being screened (see also figure 10).
  • the inner frame is bolted to the outer frame using bolts that pass through bushes 9 welded into the outer frame and are screwed into threaded bushes 10 which are welded into the inner frame square tubing (see figure 9).
  • the screen frame is mounted on a base frame 11 by means of springs 12 on brackets 13.
  • Light screen cloths are also preferably stretched in a jig so that they are taught when fixed to the inner frame.
  • Light screen cloths may be considered to be those below 2 mm aperture size.
  • This jig may be a rectangular frame that is placed around the screen frame, the screen cloth connected to the jig around the edges of the cloth in a manner that allows the cloth to be tensioned in both longitudinal and transverse directions.
  • the goal is generally that the amplitude of vibration of the screen cloth in use in the direction orthogonal to the screen surface is around 3 mm, for example. An amplitude larger than this tends to cause too much bouncing of the material so that the undersize material does not pass through the screen as promptly as it could.
  • the longitudinal bracing struts 7 combined with the transverse struts are important as they define squares of support 14 for such cloths which increases the effective rigidity of the areas cloth inside each square. This avoids floppiness or flexibility of the screen cloth, which improves the screening efficiency. This is not essential in the case of screen cloths that have thick wire, which is used for large apertures as the cloth itself has sufficient rigidity.
  • Figure 2 shows adjustable leg mountings by which the angle of the screen may be adjusted so that flow of material is "uphill” or "downhill” if required.
  • a solution may be adopted which is to fix a second screen cloth 15 to the underside of the inner frame.
  • the second cloth has a larger apertures than the screen cloth 16 above the inner frame.
  • Between the two screen cloths are located loosely a large number of short tubes 17, their length slightly less than the space between the cloths and oriented so that the axes of the tubes are orthogonal to the screen cloths.
  • These tubes vibrate between the cloths in use and are effective in preventing the blinding by knocking the material that tends to blind from underneath the upper screen cloth.
  • the tubes cannot fall over and so remain in the orientation shown.
  • the tubes are made of a plastic like PVC or polyurethane for example. Several tubes are located concentrically inside each other and are packed fairly closely over the whole screen area.
  • the two vibrating motors which drive the screen are each attached at the centre of the long sides of the screen frame and are inclined to the direction of feed, which is longitudinally along the screen, at 45 degrees.
  • the inclination is forward in the direction of the feed.
  • the mounting is done by bolting a metal plate 18 of suitable size and thickness to each side of the screen using threaded bushes welded into the screen outer frame.
  • the vibratory motors are then attached to the metal plate by bolting using threaded holes in the metal plates at the required positions.
  • the bolts that hold the motors may be passed through the plate and both the outer and inner frame members, using bushes welded into the outer frame and threaded bushes welded into the inner frame.
  • the weight settings of the motors may be altered to change the vibration performance and also the motor power rating is selected according to the required size and performance of the vibratory screen.
  • the motor may be mounted on a circular disc to allow the angle of the motor to be adjusted. However, it is found that a 45 degrees angle is suitable for most applications.
  • the single deck screen can be duplicated to configure a double or multiple deck screen simply by extending the size of the side securing plates 19 which bolt all the decks together and altering the positions of the threaded motor securing holes to accommodate the various size motors required to drive the screens of different deck multiples and screen weights.
  • the side securing plates are held by the bolts on either side of each screen frame which secure the inner frame to the outer frame, thus being used to further secure the multi-deck assembly.
  • the bolts hold the inner screen to the outer screen and the various screen decks together.
  • the inner screen frames can be easily removed simply by removing the four securing bolts on each side of the securing frame and removing the frame from the top or the bottom of the multiple screen assembly, whichever is applicable.
  • a screen in between other screens can be removed by sliding it out like a drawer after releasing the necessary few bolts; this is of great practical advantage.
  • the delivery end 21 of the screen may be made to simply omit the transverse frame member 2, as shown in figures 1 and 2.
  • deflector bars 22 may be provided with a drop chute 23 for collection of material that does not pass the screen, as shown in figures 3 to 7. In multiple deck screens these deflectors will deflect in differing directions so as to provide for separate collection of the fractions.
  • This screen is then easily cleaned for replacement or immediately replaced by a spare screen.
  • each individual outer frame or inner screen frame can easily be disassembled by removing the relevant securing bolts. All components are manufactured to be interchangeable.
  • this screen system has distinct advantage over conventional screens. This is particularly the case in the diamond recovery industry in the following two recovery applications.
  • the screens made according to the invention are 10% to 20% of the weight of conventional screens, they use 10% to 20% of the power required by the heavy conventional screens and being low profile can fit into spaces not possible for conventional screens.
  • Prejudices of current practice are that heavy screen structures are necessary for durability, influenced by the development of polymeric screen panels which require heavy supporting structure. Most of the power goes into vibrating these heavy structures, whereas with the invention most of the power goes into the material being screened, because the screen is relatively so light.

Landscapes

  • Combined Means For Separation Of Solids (AREA)

Abstract

L'invention concerne un crible vibrant d'une légèreté et d'une simplicité exceptionnelles permettant à des moteurs vibrants relativement légers, à faible consommation électrique, d'être efficaces pour un criblage vibratoire d'une masse de matière relativement importante. Le crible possède un cadre rectangulaire avec un treillis métallique tissé, présentant des contrefiches transversales s'étendant d'un côté à l'autre de la largeur du cadre et placées sous le treillis, et il est caractérisé par des moteurs vibrants attachés à l'extérieur des éléments structurels qui définissent la longueur du cadre.
PCT/ZA2008/000078 2007-08-31 2008-08-29 Cribles WO2009029962A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA200707459 2007-08-31
ZA2007/07459 2007-08-31

Publications (1)

Publication Number Publication Date
WO2009029962A1 true WO2009029962A1 (fr) 2009-03-05

Family

ID=40225268

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/ZA2008/000078 WO2009029962A1 (fr) 2007-08-31 2008-08-29 Cribles

Country Status (2)

Country Link
WO (1) WO2009029962A1 (fr)
ZA (1) ZA201000768B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101869889A (zh) * 2010-06-22 2010-10-27 成都大宏立机器制造有限公司 一种编织筛网组合式振动筛
JP2014079706A (ja) * 2012-10-17 2014-05-08 Dalton Corp 振動篩
CN104550034A (zh) * 2014-12-30 2015-04-29 河南元上高温设备有限公司 金刚石砂、粉分选机双层三角振动盘
CN109201454A (zh) * 2018-08-21 2019-01-15 大同新成新材料股份有限公司 一种脱硫脱硝活性炭精选装置及工艺
WO2020156756A1 (fr) * 2019-01-31 2020-08-06 Spaleck GmbH & Co. Kommanditgesellschaft Tamiseuse dotée d'éléments de tamisage disposés en rangées

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1037102A (en) * 1963-02-20 1966-07-27 Wilkinson Rubber Linatex Ltd Improvements in or relating to screens
US4274953A (en) * 1980-05-27 1981-06-23 J & H Equipment, Inc. Vibrating screen separator
EP0197191A2 (fr) * 1985-04-03 1986-10-15 Carl Schenck Ag Tamis avec panneau de criblage souple
EP0238455A2 (fr) * 1986-03-17 1987-09-23 F.lli DE POLI S.r.l. Tamis vibrant simple ou multiple
US5051171A (en) * 1990-04-27 1991-09-24 Sweco Incorporated Self-cleaning system for vibratory screens
JPH0422441A (ja) * 1990-05-17 1992-01-27 Kunihiko Yoshino 製粉機
WO1995023655A1 (fr) * 1994-03-03 1995-09-08 United Wire Limited Tamis ameliore
US5456364A (en) * 1993-09-27 1995-10-10 Lambert; Gene F. Powered screening apparatus
JP2001129481A (ja) * 1999-11-08 2001-05-15 Sanshin Kogyo Kk 振動篩機及び振動篩設備
ES2156806A1 (es) * 1999-02-23 2001-07-16 Maquinaria De Canteras Triman Maquina para cribar aridos.
US20050205471A1 (en) * 1999-11-02 2005-09-22 M-I L.L.C. Screen

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1037102A (en) * 1963-02-20 1966-07-27 Wilkinson Rubber Linatex Ltd Improvements in or relating to screens
US4274953A (en) * 1980-05-27 1981-06-23 J & H Equipment, Inc. Vibrating screen separator
EP0197191A2 (fr) * 1985-04-03 1986-10-15 Carl Schenck Ag Tamis avec panneau de criblage souple
EP0238455A2 (fr) * 1986-03-17 1987-09-23 F.lli DE POLI S.r.l. Tamis vibrant simple ou multiple
US5051171A (en) * 1990-04-27 1991-09-24 Sweco Incorporated Self-cleaning system for vibratory screens
JPH0422441A (ja) * 1990-05-17 1992-01-27 Kunihiko Yoshino 製粉機
US5456364A (en) * 1993-09-27 1995-10-10 Lambert; Gene F. Powered screening apparatus
WO1995023655A1 (fr) * 1994-03-03 1995-09-08 United Wire Limited Tamis ameliore
ES2156806A1 (es) * 1999-02-23 2001-07-16 Maquinaria De Canteras Triman Maquina para cribar aridos.
US20050205471A1 (en) * 1999-11-02 2005-09-22 M-I L.L.C. Screen
JP2001129481A (ja) * 1999-11-08 2001-05-15 Sanshin Kogyo Kk 振動篩機及び振動篩設備

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101869889A (zh) * 2010-06-22 2010-10-27 成都大宏立机器制造有限公司 一种编织筛网组合式振动筛
JP2014079706A (ja) * 2012-10-17 2014-05-08 Dalton Corp 振動篩
CN104550034A (zh) * 2014-12-30 2015-04-29 河南元上高温设备有限公司 金刚石砂、粉分选机双层三角振动盘
CN109201454A (zh) * 2018-08-21 2019-01-15 大同新成新材料股份有限公司 一种脱硫脱硝活性炭精选装置及工艺
WO2020156756A1 (fr) * 2019-01-31 2020-08-06 Spaleck GmbH & Co. Kommanditgesellschaft Tamiseuse dotée d'éléments de tamisage disposés en rangées
US20220097100A1 (en) * 2019-01-31 2022-03-31 Spaleck GmbH & Co. Kommanditgesellschaft Screening machine having screening elements arranged in succession
US11766697B2 (en) 2019-01-31 2023-09-26 Spaleck GmbH & Co. Kommanditgesellschaft Screening machine having screening elements arranged in succession

Also Published As

Publication number Publication date
ZA201000768B (en) 2010-10-27

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