Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N1/00—Pretreatment of moulding material
• • 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
  • B07B4/00—Separating solids from solids by subjecting their mixture to gas currents
  • B07B4/02—Separating solids from solids by subjecting their mixture to gas currents while the mixtures fall

Definitions

• the present invention relates to a method for sepa ⁇ rating heavy particles, such as lumps of glue, from a particulate material, such as glue-coated wood fibres, which is pneumatically conveyed from a first station, such as a container, to a second station, such as a plant for making fibreboards, said particulate material being introduced in a settling chamber to which a carrier air flow is supplied for entraining the particulate material while heavy particles contained therein fall to the bottom of the settling chamber, said particulate material being introduced in the settling chamber as a downwardly- directed flow of material through a downwardly-directed chamber inlet and leaving the settling chamber in an upwardly-directed flow of material and air through a cham ⁇ ber outlet located beside said inlet.
• the invention also concerns a device for separating heavy particles from a particulate material.
• glue-coated wood fibres are pneumatically conveyed, first from a drying plant to a collecting container, and from there to a forming station, where the fibres are spread as a mat on a wire through which the carrier air is drawn off. Then, the fibre mat is compressed into fibreboards under set pressure and tem ⁇ perature conditions.
• One object of the present invention is, therefore, to provide a method which makes it possible to utilise a relatively small carrier air flow in the separation and, consequently, to perform the separation during the trans ⁇ port of the wood fibres from the container to the forming station.
• this object is achieved by a method which is of the type stated by way of intro- duction and which is characterised in that compressed-air jets, which are directed obliquely towards the downwardly- directed flow of material, are blown into the settling chamber to decelerate the flow of material and to spread it in its transverse direction towards the outlet, and that the carrier air flow is blown into the settling cham ⁇ ber to encounter from below the decelerated, transversely spread flow of material so as to form therewith said flow of material and air.
• Another object of the invention is to provide a suit ⁇ able device for implementing the method.
• this object is achieved by a device which has a settling chamber with a down- wardly-directed inlet for said material and an upwardly- directed outlet located beside said inlet, and which is characterised by a first means for blowing compressed-air jets obliquely towards the downwardly-directed inlet, and a second means for blowing an upwardly-directed carrier air flow into the settling chamber on a level below said first means.
• the illustrated device is arranged between a con ⁇ tainer (not shown) holding glue-coated wood fibres, and a forming station (not shown) where thin fibreboards are shaped. Further, the device has a settling chamber 1 with a downwardly-directed inlet 2 for supplying the material and an upwardly-directed outlet 3 for discharging the material, the outlet 3 being located beside the inlet 2. Moreover, the inlet 2 communicates with the container from which glue-coated wood fibres are introduced in the settling chamber 1 in the form of a downwardly-directed flow of material Fl.
• the container preferably is a meter ⁇ ing container which is placed directly on the settling chamber 1 and distributes the flow of material Fl over the entire cross-section of the inlet 2.
• the outlet 3 communicates with the forming station by means of an upwardly-directed trnsport pipe 4 of upwardly decreasing cross-sectional area.
• the pipe 4 In its upper portion, the pipe 4 has a 180° bend 4a and, after the bend, branches into two separate conduits 4b and 4c.
• the conduit 4b leads to the forming station.
• the device further has an inlet 5 through which a carrier air flow F2 is blown into the lower portion of the settling chamber 1.
• Adjustable guide rails 6 are provided in the inlet 5 to distribute the carrier air flow over the entire settling chamber 1.
• a discharge trough 8 is provided at the bottom of the settling chamber 1, and a conveyor screw 9 is arranged in the trough 8 to discharge heavy particles collected therein.
• the inlet 2 has a perforated metal sheet 10 which is inclined about 50° to the hori ⁇ zontal plane.
• the sheet 10 is formed with a plurality of perforations which are distributed across the sheet surface and through which the settling chamber 1 communi- cates with a blow box 11.
• Compressed-air jets S which owing to the inclination of the sheet 10 are directed obliquely upwards, i.e. obliquely towards to the down ⁇ wardly-directed flow of material Fl, are blown into the settling chamber 1 to decelerate the flow of material and to spread it horizon ⁇ tally towards the outlet 3.
• Glue-coated wood fibres containing impurities in the form of comparatively heavy particles, such as lumps of glue and chips, are, as mentioned earlier, introduced in the settling chamber 1 in the form of a downwardly-direct ⁇ ed flow of material Fl which preferably is spread over the entire cross-section of the inlet 2.
• the flow of material encounters the compressed-air jets S, and is thus dece ⁇ lerated and spread over the entire cross-section of the settling chamber 1.
• the carrier air flow F2 supplied through the inlet 5 entrains the particulate material in a flow of material and air F3 through the outlet 3 and the transport pipe 4, while heavy particles fall down into the trough 8 to be discharged by the conveyor screw 9.
• the carrier air flow can be considerably reduced compared with that required in the prior-art separation method described by way of introduction. This effect is further enhanced when the flow of material Fl is spread, as described above, over the entire cross-section of the inlet 2.
• the flow of material and air F3 is accele- rated in the transport pipe 4 owing to the decreasing cross-sectional area thereof.
• the flow then has a high speed in the bend 4a, and the wood fibres therein are thus flung outwards, following the outer wall of the bend 4a and finally being conducted, together with some of the carrier air, into the conduit 4b which leads to the form ⁇ ing station.
• perforated metal sheets and blow boxes supplementing the metal sheet 10 and the blow box 11 may, for instance, be arranged adjacent to the walls of the discharge trough 8 to enable the injection of oblique ⁇ ly and upwardly directed compressed-air jets. This may be necessary if the discharge of material from the container takes place intermittently, so that the compressed-air jets are unable to decelerate and spread all the material. It may then be necessary to further decelerate and spread the material.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Preliminary Treatment Of Fibers (AREA)
• Combined Means For Separation Of Solids (AREA)
• Dry Formation Of Fiberboard And The Like (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20380484

Family Applications (1)

Country Status (4)

Families Citing this family (9)

Family Cites Families (6)

• 1990
  • 1990-09-28 SE SE9003092A patent/SE467044B/sv not_active IP Right Cessation
• 1991
  • 1991-09-24 AU AU86376/91A patent/AU8637691A/en not_active Abandoned
  • 1991-09-24 EP EP19910917644 patent/EP0553140A1/de not_active Withdrawn
  • 1991-09-24 WO PCT/SE1991/000603 patent/WO1992005882A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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