WO1999049127A1 - Procede pour eliminer les impuretes contenues dans les vieux papiers - Google Patents

Procede pour eliminer les impuretes contenues dans les vieux papiers Download PDF

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Publication number
WO1999049127A1
WO1999049127A1 PCT/NL1999/000163 NL9900163W WO9949127A1 WO 1999049127 A1 WO1999049127 A1 WO 1999049127A1 NL 9900163 W NL9900163 W NL 9900163W WO 9949127 A1 WO9949127 A1 WO 9949127A1
Authority
WO
WIPO (PCT)
Prior art keywords
compartment
pulp
foam
contaminants
waste paper
Prior art date
Application number
PCT/NL1999/000163
Other languages
English (en)
Inventor
Robert William Catsburg
Original Assignee
Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
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 Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno filed Critical Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
Priority to EP19990912153 priority Critical patent/EP1080262A1/fr
Priority to AU30579/99A priority patent/AU3057999A/en
Publication of WO1999049127A1 publication Critical patent/WO1999049127A1/fr

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Classifications

    • 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
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/08—Subsequent treatment of concentrated product
    • B03D1/082—Subsequent treatment of concentrated product of the froth product, e.g. washing
    • 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
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/14—Flotation machines
    • B03D1/1431—Dissolved air flotation machines
    • 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
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/14—Flotation machines
    • B03D1/1493—Flotation machines with means for establishing a specified flow pattern
    • 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
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/14—Flotation machines
    • B03D1/24—Pneumatic
    • B03D1/242—Nozzles for injecting gas into the flotation tank
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
    • D21C5/02—Working-up waste paper
    • 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
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/14—Flotation machines
    • B03D1/1412—Flotation machines with baffles, e.g. at the wall for redirecting settling solids
    • 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
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/14—Flotation machines
    • B03D1/1443—Feed or discharge mechanisms for flotation tanks
    • B03D1/1475—Flotation tanks having means for discharging the pulp, e.g. as a bleed stream
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/64—Paper recycling

Definitions

  • the invention relates to a process for removing contaminants from waste paper.
  • the collected waste paper comprises newspapers, magazines, cardboard boxes and so forth and is usually printed with various types of ink.
  • the waste paper will comprise several other contaminants, such as filler compounds. It is necessary that the various contaminants present in the waste paper are removed if it is desired to produce new (i.e. recycled) paper which is sufficiently white in color.
  • new (i.e. recycled) paper which is sufficiently white in color.
  • the extent in which the contaminants have to removed will vary. For applications such as stationery or paper for glossy magazines a very high degree of whiteness is required. For other applications, such as newsprint paper, paper having a more or less gray shade may be acceptable.
  • flotation deinking is based on the difference in hydrophobic nature of the paper fibers and the ink. With the exception of water-based (including flexographic) inks, ink particles are more hydrophobic than paper fibers. In some cases, chemicals are added to increase the difference in hydrophobic nature. Further, it has been found that the deinking of magazines and newspapers combined leads to better results than the deinking of newspapers alone. Due to the chemical complexity of the process, an explanation for this phenomenon has not yet been found.
  • the ink particles In order for the flotation process to be successful, a number of interactions must occur. First of all, the ink particles must be sufficiently free to have the opportunity to collide with an air bubble. The ink particles should thus not be attached or bound to fiber surfaces, or trapped in fibrillar areas. Further, the collision between an ink particle and an air bubble must provide sufficient energy for a complex to be formed, which complex must rise to the surface, along with the other air bubbles, and be removed.
  • the air bubbles used have a minimal diameter of approximately half a centimeter. Smaller bubbles, as are used in dissolved air flotation, would reduce the chance of collision with an ink particle too much and tend to increase the loss of paper fibers. Furthermore, a high turbulence because of for instance increased air injection should, according to McKinney, be avoided, as this could lead to the breaking up of the ink-bubble complexes and might prevent the complexes from rising to the surface.
  • EP-A-0 798 416 discloses a method wherein contaminants and paper fibers are separated from each other in a flotation method, while water is being sprayed on top of the waste paper suspension.
  • EP-A-0 537 416 a tertiary flotation treatment of waste paper is described. In this treatment, paper fibers are recovered, which were removed in the flotation from the waste paper suspension along with contaminants.
  • the invention relates to a process for removing contaminants from waste paper comprising a) leading an inert gas through an aqueous pulp in a vessel, which pulp comprises waste paper fibers and contaminants, to produce a foam comprising at least part of the contaminants, which foam forms a layer on top of the pulp, and b) removing foam from the vessel .
  • a reduction in fiber loss of up to 50% is achieved.
  • the amount of contaminants that is removed in a process according to the invention may be significantly improved.
  • the foam layer that is formed in a process according to the invention, two gradients have been observed. In the most upward regions of the foam layer, lower concentrations of paper fibers occur m the foam when compared to the downward regions of the foam layer. For the concentration of contaminants m the foam layer, a gradient m the opposite direction has been observed. Thus, the foam layer establishes selectivity m a process of removing contaminants from the waste paper.
  • the waste paper that is purified m a process according to the invention may be any form of paper that has been used for any sort of purpose. Suitable stocks include newspapers, magazines, cardboard boxes and so forth. These stocks may be processed separately or combined. Preferably, a mixture of different sorts of waste paper (for instance both newspapers and magazines) is purified, which is believed to lead to a more efficient removal of contaminants. Moreover, a labor and/or cost intensive sorting step may thus be avoided.
  • the waste paper is processed m the form of an aqueous pulp.
  • the waste paper is mixed with a suitable amount of water, and the obtained mixture is stirred, minced and/or chopped, so that the paper product mainly falls apart into paper fibers.
  • the amount of water added will usually be chosen such that a pulp is obtained which comprises of from 0.5 to 2.5 weight percent of paper fibers, based on the pulp. It is preferred that the pulp comprises more than 1 weight percent of paper fibers. In a highly preferred embodiment, the pulp comprises more than 1.5 weight percent of waste paper fibers.
  • the aqueous pulp will generally comprise (paper) fibers, filler compounds and ink.
  • the pulp When the pulp is formed from waste paper directly after having been collected after its use, the pulp will often also comprise other materials, which may have been part of a paper product, such as metals (from staples and the like) or adhesives (from labels, book bindings and the like) , but also materials which accidentally or erroneously have been discarded in the same effluent stream as the waste paper, such as glass or plastics. These materials may be removed from the pulp in a conventional manner, e.g. by use of a cyclone and/or a sieve, before a process according to the invention is carried out.
  • contaminants are removed from the aqueous pulp by using a foam fractionation technique.
  • an inert gas is lead through the pulp to produce a foam layer on top of the pulp.
  • air is bubbled through an aqueous pulp of waste paper.
  • the ratio of the height of the foam layer to the height of the pulp layer is at least three, preferably at least five, more preferably at least 10.
  • a highly selective removal of contaminants is achieved by performing the process such that a foam layer of at least 30 cm high is produced. Even better results are achieved when a foam layer of even greater height is produced.
  • a foam layer of at least 50 cm, more preferred at least 100 cm is produced.
  • the size of the air bubbles is much less relevant .
  • the residence time of the paper pulp in a process according to the invention may be shorter than that in a flotation process.
  • Typical residence times in a process according to the invention are between 1 and 4 minutes, which is in the order of a factor 2-3 less than in conventional flotation processes .
  • the inert gas may be any gas which does not chemically react with the materials present in the pulp and which is capable of physically interacting with the contaminants to be removed. Suitable gases include air, and nitrogen gas. For economic reasons, air will generally be used as the inert gas. The amount of gas used will be adjusted to generate the desired amount of foam in a manner which is within the normal skill of the skilled person.
  • the amount of added gas will be at least 1 liter per liter of the added pulp.
  • the ratio of the gas flow with respect to the pulp flow will preferably be at least 100 vol.%, preferably at least 200 vol . % .
  • said ratio will usually not exceed 500 vol . % .
  • a process according to the invention can suitably be carried out at a temperature of from 25 to 45°C.
  • the temperature is chosen around 35°C. It has been found that temperatures within the specified ranges have a beneficial on the formation of a foam.
  • water is sprayed on top of the foam layer.
  • the result of the spraying of the water is that an even smaller amount of paper fibers will be removed together with the foam. In other words, the selectivity of the process is enhanced by the spraying of the water.
  • the spraying is performed in such a manner that the amount of water sprayed is evenly distributed over the upper surface of the foam layer.
  • the amount of water sprayed is adjusted so that the foam does not collapse under the force of the falling water, but that the production of foam is optimally enhanced.
  • the ratio of the flow of the spraying water with respect to the pulp flow in the process is below 5 vol . % .
  • the aqueous pulp is kept in turbulent conditions. In contrast to what is described by Mckinney, it has now been found that it is 7
  • a pulp having a higher fiber consistency (concentration) can be processed.
  • the desired turbulence may be created in any known manner. It is for instance possible to stir or shake the pulp, or to increase the flow (velocity) of the inlet gas stream. It is also possible to perform the present process in a vessel comprising protuberances in one or more side-walls, which have the effect that the inert gas that is lead through the pulp creates a turbulence. This latter embodiment will be further elucidated hereinbelow. It has further been found that a high turbulence is beneficial to the formation of foam. Also, homogenization of the pulp will prevent the flocculation of the paper fibers in the pulp. Flocculation may result in encapsulation of contaminants in fiber aggregates, because of which a certain amount of contaminants will not be removed in the process.
  • a process according to the invention can suitably be carried out in a vessel comprising an upward tapering, for example frustoconical first compartment, a second compartment extending from the open top side upwardly, like a neck.
  • the second compartment has an open top side and a vertical length which is relatively large compared to the height of the first compartment; whereas the width of the second compartment is small relative to the maximal width of the first compartment .
  • the first compartment is provided with an inlet and outlet for the aqueous pulp.
  • air inlet openings for example air jets are provided in the first compartment, preferably at least in or near the bottom thereof, for providing streams of air bubbles through the first compartment.
  • Means are provided for creating a high turbulence in the aqueous pulp in the first compartment, for example stirring means, whereas the high turbulence can also be created by means of the air jets. Due to the layout and inter alia the high turbulence in the aqueous pulp and the air inlet foam is being created in at least the second compartment and, preferably, near the tapering top side of the first compartment. Due to the relatively large height of the second compartment and the narrow cross section thereof a foam layer having a large height is being created, providing for sufficient fractionation within the foam. Over the open top end of the second compartment spraying means are provided for spraying water on top of the foam layer, for even further enhancing fractionation within the foam.
  • means are provided for skimming at least the top fraction of the foam layer, which means can be of any suitable form, for example blowing means, scraping means or an overflow and suction means or the like.
  • blowing means scraping means or an overflow and suction means or the like.
  • a device for mineral separation by using foam fractionation.
  • the device comprises two frustoconical compartments, extending upwardly like a neck.
  • the vertical lengths on top of these frustoconical compartments are relatively short m comparison with the vessel compartment beneath the two frustoconical compartments.
  • a preferred embodiment at least the foam fraction skimmed from the second compartment is introduced into a further foam fractionating device according to the present invention, for removing at least part and preferably almost all of the fibers left m the foam.
  • the pumping of gas through the pulp may be terminated.
  • the process is carried out continuously, which means that there is a constant stream of pulp into the first compartment of the vessel, and a constant stream of pulp from which contaminants have been removed out of the vessel . The latter pulp will subsequently be further processed in process steps conventional in the field of paper recycling into new paper products.
  • aqueous effluent streams are obtained.
  • these effluent streams are wash water and thickener water. It is normal procedure to isolate the ash, comprising among others filler compounds, and other solid materials (usually referred to as Total Suspended Solids, TSS) present in these effluent streams.
  • TSS Total Suspended Solids
  • DAF Dissolved Air Flotation
  • the obtained ash may be dispensed with in the usual manner.
  • This application of the present invention to effluent streams of a paper recycling process significantly increases the efficiency of said recycling process.
  • the pulp from which the filler compounds and so forth have been removed, obtained in this recovery process is preferably re-used in the recycling paper process.
  • the foam comprising the contaminants may be discarded.
  • the invention also relates to the waste paper fibers that are purified, and to articles of recycled paper manufactured therefrom, in a process as outlined hereinabove .
  • Figure 1 shows schematically a device according to the present invention
  • Figure 2 shows schematically a paper recycling unit according to the present invention.
  • Figure 1 shows schematically, in cross section a fractionating device 1, comprising a first compartment 2 and a second compartment 3.
  • the first compartment 2 has a 11
  • the first compartment 2 can for example be frustoconical but is preferably elongated in the direction perpendicular to the plane of the drawing, having flat or also tapering endwalls (not shown) .
  • first pumping means 7 On the opposite side near the bottom 4 an outlet 8 is provided for the aqueous pulp, after treatment within the first compartment 2.
  • Second pumping means 9 can be provided near the outlet 8. At top 10, the first compartment 2 is connected to the second compartment 3.
  • the second compartment 3 has a width W considerably smaller than the maximum width D of the bottom 4 of the first compartment.
  • the height H of the second compartment 3 is considerably larger than the height T of the first compartment.
  • the volume of the first compartment can be comparable to or smaller than the volume of the second compartment 3.
  • the top end 11 of the second compartment 3 is open.
  • Spraying means 12 are positioned above the open top end 11.
  • a casing 13 is provided over the top end 11 and the spraying means 12, from which casing 13 foam, developed in the second compartment 3 , can be extracted by means of third pumping means 14 , connected to the casing 13 at outlet 15.
  • first air inlet means 16 are provided, preferably in the form of air nozzles, for providing streams of air bubbles through the aqueous pulp within the first compartment 2.
  • Second air inlet means 16A can be provided in for example the sidewalls 5.
  • the air inlet means 16, 16A With the air inlet means 16, 16A a relatively large amount of air is introduced into the aqueous pulp.
  • the volume air introduced into the first compartment per hour can for example be equal to or even larger than the volume of aqueous pulp being treated within the device during the same time. 12
  • the layout of the fractionating device, especially of the first compartment 2 is such that a high turbulence is created within the aqueous pulp m the first compartment.
  • protuberances 17 can be positioned on the inside of for example the sidewalls 5.
  • stirring means or the like can be provided within the first compartment 2. Due to this layout a turbulent stream of aqueous pulp is created within the first compartment 2 between the inlet 6 and the outlet 8.
  • Fourth pumping means 18 are provided for directing air or any other suitable inert gas to the various air inlet means 16, 16A, wherein the layout of the air inlet 16, 16A can be such as to increase the turbulence within the aqueous pulp.
  • Figure 1A shows a preferred layout of an inlet, which may be used as the inlet 6 for the pulp or the air inlet 16.
  • the inlet 6 or 16 is provided m the bottom 4 or a side wall 5, having an outlet 19 for pulp or air within the first compartment 2 and a first inlet 20 for pulp or air, connected to pumping means 7 or the fourth pumping means 18, respectively.
  • a second inlet 21 is connected to the inlet means 6, 16 between the first inlet 20 and the outlet 19.
  • FIG. 2 shows schematically a paper pulp treatment plant 22 comprising a number of fractionating devices 1 according to the present invention, and for example shown m Figure 1.
  • the plant 22 comprises m line, leading to the inlet 6 of a first fractionating device 1A subsequently a 13
  • the foam of the second fractionating device 1A is discarded, for example burned, whereas the aqueous pulp, extracted from the outlet 8 is fed into the inlet 6 of the first fractionating device 1.
  • any fibers left m the foam layer of the first fractionating device 1 will be recycled intp the first compartment of the first fractionating device 1 through the second fractionating device 1A.
  • the aqueous pulp distracted from the first compartment 2 of the first fractionating device 1 through the outlet 8 is fed into a second cyclone 26, distracting unwanted particles from the aqueous pulp, such as sand, after which the aqueous pulp is fed into a washer or thickener device 27, m which a large amount of water is pressed from the fibers.
  • the distracted water is fed into a third fractionating device IB for a further fractionating of the aqueous pulp.
  • the foam is discarded from the third fractionating device IB, whereas the effluent thereof is recycled into the stream of aqueous pulp to be fed into the first fractionating device 1.
  • the paper fibers resulting from the washer or thickener device 27 are fed into a paper making device 28, 14
  • the casing 13 can be replaced by other means for skimming the foam layer, such as means for blowing away part of the foam layer to distracting means.
  • the foam distracting means can advantageously be provided as scraping means, movable along the top side 11 of the second compartment 3. With these scraping means the top layer of the foam layer can be scraped or lifted from the second compartment 3 and be pushed or carried or the like to the third pumping means 14.
  • the first to end second compartment 3 can have different shapes and dimensions, depending inter alia on the desired turbulence m the aqueous pulp, the concentration of said pulp and the type and amount of pulp to be processed.
  • the height T of the first compartment can be for example up to 75 centimeters, the height H of the second compartment being more than 30 centimeters, preferably between 1 and 2 meters .
  • the width W of the second compartment is for example, 25 centimeters, the width B of the bottom 4 of the first compartment 75 centimeters.
  • these dimensions can suitably be adapted to the desired capacity of the device.
  • the above dimensions provide some guidance as to a suitable relation between the various dimensions of the device. 15
  • a conventional flotation process comprising a primary and a secondary flotation, of a pulp from wood free waste paper (heavily bleached sulfate board) comprising 1.18% of paper fibers and having an ash content of 17.4% was carried out.
  • the inlet stream of air was 15 1/min.
  • the residence time was 10 min., and the air to pulp ratio was 30%.
  • the ash content of the reject was 55%, which corresponds to a loss of ash from the pulp of 59%.
  • the loss of fiber amounted to 15%.
  • a procedure in accordance with the invention was carried out in a frustoconically shaped vessel, of which the layout correspondeded to the vessel as shown in Figure 1.
  • the height of the first compartment was 50 centimeters.
  • the second compartment was 100 cm high and 25 cm wide.
  • the used pulp was from wood free waste paper (heavily bleached sulfate board) which comprised 1.18% of paper fibers and an ash content of 17.4%.
  • the inlet air stream was 18 1/min., the air to pulp ratio was 30%, and the residence time was 1.30 min.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Biotechnology (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Paper (AREA)

Abstract

L'invention concerne un procédé permettant d'éliminer les impuretés contenues dans les vieux papiers. Ce procédé consiste: a) à diriger un gaz inerte à travers une pâte aqueuse, laquelle renferme des fibres de vieux papiers et des impuretés, de manière à produire une mousse comprenant au moins une partie de ces impuretés, cette mousse formant une couche sur le sommet de ladite pâte, et b) à éliminer cette mousse. L'invention concerne également un dispositif permettant de mettre en oeuvre ce procédé.
PCT/NL1999/000163 1998-03-25 1999-03-24 Procede pour eliminer les impuretes contenues dans les vieux papiers WO1999049127A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19990912153 EP1080262A1 (fr) 1998-03-25 1999-03-24 Procede pour eliminer les impuretes contenues dans les vieux papiers
AU30579/99A AU3057999A (en) 1998-03-25 1999-03-24 A process for removing contaminants from waste paper

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP98200944.1 1998-03-25
EP98200944 1998-03-25

Publications (1)

Publication Number Publication Date
WO1999049127A1 true WO1999049127A1 (fr) 1999-09-30

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ID=8233516

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NL1999/000163 WO1999049127A1 (fr) 1998-03-25 1999-03-24 Procede pour eliminer les impuretes contenues dans les vieux papiers

Country Status (3)

Country Link
EP (1) EP1080262A1 (fr)
AU (1) AU3057999A (fr)
WO (1) WO1999049127A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0146235A2 (fr) * 1983-10-21 1985-06-26 The University Of Newcastle Research Associates Limited Procédé de flottation
EP0537416A1 (fr) * 1991-09-13 1993-04-21 Voith Sulzer Stoffaufbereitung GmbH Procédé pour le traitement de pâte à papier
EP0618012A1 (fr) * 1993-04-02 1994-10-05 J.M. Voith GmbH Dispositif de flottation
EP0798416A1 (fr) * 1996-03-26 1997-10-01 Voith Sulzer Stoffaufbereitung GmbH Procédé de flotation et dispositif pour la séparation de particules solides d'une suspension à fibres

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0146235A2 (fr) * 1983-10-21 1985-06-26 The University Of Newcastle Research Associates Limited Procédé de flottation
EP0537416A1 (fr) * 1991-09-13 1993-04-21 Voith Sulzer Stoffaufbereitung GmbH Procédé pour le traitement de pâte à papier
EP0618012A1 (fr) * 1993-04-02 1994-10-05 J.M. Voith GmbH Dispositif de flottation
EP0798416A1 (fr) * 1996-03-26 1997-10-01 Voith Sulzer Stoffaufbereitung GmbH Procédé de flotation et dispositif pour la séparation de particules solides d'une suspension à fibres

Also Published As

Publication number Publication date
EP1080262A1 (fr) 2001-03-07
AU3057999A (en) 1999-10-18

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