EP1050342A1 - Method for removing impurities from an aqueous paper fiber suspension - Google Patents

Method for removing impurities from an aqueous paper fiber suspension Download PDF

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Publication number
EP1050342A1
EP1050342A1 EP00107633A EP00107633A EP1050342A1 EP 1050342 A1 EP1050342 A1 EP 1050342A1 EP 00107633 A EP00107633 A EP 00107633A EP 00107633 A EP00107633 A EP 00107633A EP 1050342 A1 EP1050342 A1 EP 1050342A1
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EP
European Patent Office
Prior art keywords
flotation
downstream
stage
flotation step
suspension
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Granted
Application number
EP00107633A
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German (de)
French (fr)
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EP1050342B1 (en
Inventor
Herbert Holik
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Voith Patent GmbH
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Voith Paper Patent GmbH
Voith Sulzer Papiertechnik Patent GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00—Flotation
    • B03D1/14—Flotation machines
    • B03D1/1418—Flotation machines using centrifugal forces
    • 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
    • B03D1/02—Froth-flotation processes
    • 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
    • B03D1/1406—Flotation machines with special arrangement of a plurality of flotation cells, e.g. positioning a flotation cell inside another
    • 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
    • B03D1/1462—Discharge mechanisms for the froth
    • 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
    • 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
    • B03D1/247—Mixing gas and slurry in a device separate from the flotation tank, i.e. reactor-separator type
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
    • D21F1/70—Pulp catching, de-watering, or recovering; Re-use of pulp-water by flotation

Definitions

  • the invention relates to a method for removing contaminants from a aqueous paper fiber suspension according to the preamble of claim 1.
  • JP 60134090 A shows a combination of a flotation cyclone with one downstream separation tank (secondary process tank). Doing so the flotation foam of the flotation cyclone for after-treatment in the second container guided.
  • the invention is therefore based on the object of creating a flotation process with which the spectrum of contaminated contaminant particles is large, without a too high equipment and operational expenditure is required.
  • the suspension should also be vented.
  • the inventive method has the advantage that a wide range of sizes the flotation can be recorded by - as is known per se - at least two on one each particular size range optimized sub-steps connected in series become.
  • the second step is without further aeration of the suspension executed what the expenditure of equipment, energy and process control essential reduced.
  • the air content in the accepted material of the upstream flotation section is used for further flotation. It is particularly advantageous that the downstream flotation step in a stronger force field, e.g. that one Flotation cyclones.
  • Such devices can be particularly effective with Separate relatively fine contaminants with the help of small air bubbles.
  • Another advantage of the process is that only the residual air in the accept of the upstream flotation step is still present and is often undesirable, must be removed by the downstream flotation step so that a Suspension with low air content is formed. This affects e.g. during operation subsequent disc filter for thickening the suspension favorably.
  • FIG. 1 shows a very simple diagram with an upstream flotation step 1 and a downstream flotation step 2.
  • the pulp suspension S is before it is fed to the upstream flotation step 1 in a mixing element 3 mixed with air L so that air bubbles of the desired size and number are created.
  • the processes of flotation step 1 are known; it becomes a flotation foam R1 formed, which contains a large part of the contaminants, as well as an acceptor A1, which from the cleaned pulp suspension is formed. This will be without further ventilation fed to the downstream flotation step 2 via the pump 5. While at that example shown here the upstream flotation section 1 alone in the Earth's gravity field is operated in the downstream flotation step 2 by Rotation of the suspension creates a centrifugal field.
  • the method shown schematically in FIG. 2 differs in some points of that in Fig. 1 and shows another way to implement the invention.
  • the upstream flotation step 1 consists of several one after the other switched flotation devices. Such a circuit is common in many cases and includes e.g. five to eight flotation processes connected in series. The Gutstoff, before it comes from the previous to the next flotation, via a pump promoted and mixed again with air.
  • the one from this upstream Acceptable substance A1 originating from flotation step 1 arrives in a flotation cyclone, which performs the downstream flotation step 2.
  • the flotation foam R2 is taken from the same side, seen axially, at which the accepting substance A1 is also introduced into the flotation cyclone. According to the invention there is no renewed ventilation.
  • the one from this flotation step Acceptable material A2 is drawn off at the axially opposite end, either tangentially or axial (dashed arrow).
  • the under gravity standing flotation cell (flotation step 1) has an oval shape and forms an im essentially closed housing. This allows the flotation foam R1 escaping air L can be sucked in again within the flotation vessel.
  • the Mixer 3 'for air L and fiber suspension S is part of a mixing tube which in the suspension is immersed. Of course, other ventilation can also be used be provided.
  • the downstream flotation step 2 takes place in a cylinder 6 carried out, in which the inflowing suspension, ie the accept A1, of the first Pumped in flotation step without further aeration and e.g. through a Tangential inlet is set in rotation.
  • Fig. 4 shows in supervision that it is for the downstream Flotation step 2 used apparatus is a cylinder 6. You can see that tangential feed for the accept substance A1 of the upstream flotation step (1) and the tangential exit for the good substance A2.

Abstract

Selective flotation stages (1,2) are used to separate foreign matter from a fiber suspension (S). The downstream flotation s (2) uses the residual air contained in the cleaned suspension flow (A1) from the first stage (1), without additional air to give bubbles for flotation. The second and downstream stage (2) acts as a flotation cyclone, with a centrifugal acceleration of the hydrocyclone of a v which is 5-200 times the rate of the spin of the earth, or 10-100 times. At the second and downstream flotation stage (2), the suspension from the first stage (1) is fed at a tangent into a cylinder. The flotation foam (R2) formed at the second stage (2) the cleaned suspension (A2) move out of the stage (2) at the axially opposite end to the inlet. The flotation foam (R2) is taken axially from the side of the second flotation stage (2) which also has the inflow, and the cleaned suspension (A2) is taken axia from the opposite side. The weaker force field used is the gravity of the earth. The cleaned suspension (A1) from the first flotation stage (1) is passed directly to the downstream flotation stage (2), without dwelling in a vat.

Description

Die Erfindung betrifft ein Verfahren zur Entfernung von Störstoffen aus einer wässrigen Papierfasersuspension gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a method for removing contaminants from a aqueous paper fiber suspension according to the preamble of claim 1.

Verfahren der genannten Art werden verwendet, um aus einer Papierfasersuspension zumindest einen Teil der darin suspendierten unerwünschten Feststoffteilchen, sog. Störstoffe, auszuscheiden. Bekanntlich wird bei einer Flotation ein die auszuscheidenden Stoffe enthaltender Schaum oder Schwimmschlamm gebildet. Ein typischer Anwendungsfall eines derartigen Verfahrens ist die Aufbereitung von einer aus bedrucktem Altpapier gewonnenen wässrigen Fasersuspension, in der die Druckfarbenpartikel bereits von Fasern abgelöst sind, so dass sie sich ausfiotieren lassen. Der hier beschriebene Flotationsvorgang nutzt die Unterschiede zwischen Papierfaserstoff und unerwünschten Feststoffteilchen in der Art, dass der Faserstoff aufgrund seines eher hydrophilen Charakters in der Fasersuspension verbleibt, während die angesprochenen Feststoffteilchen hydrophob sind und deshalb zusammen mit den Luftblasen in den Schaum gelangen. Neben den Druckfarbenpartikeln gibt es auch eine Vielzahl weiterer Stoffe, die hydrophob sind und sich daher durch Flotation von dem Faserstoff trennen lassen. Solche Stoffe sind insbesondere Kleber, feine Kunststoffpartikel und eventuell auch Harze. Da durch das hier angesprochene Flotationsverfahren Fasern von Verunreinigungen getrennt werden, spricht man von selektiver Flotation. Der ebenfalls benutzte Begriff "Flotationsdeinking" wird in der Regel nicht nur für die Entfernung von Drucktarbenpartikeln (ink = Druckfarbe), sondern auch allgemeiner für die selektive Flotation von Verunreinigungen aus Faserstoffsuspensionen verwendet.Methods of the type mentioned are used to get out of a paper fiber suspension at least part of the undesired solid particles suspended therein, so-called. Impurities to excrete. As is well known, flotation is one that has to be eliminated Foam or sludge containing substances is formed. A typical one The application of such a method is the preparation from one printed fiber paper obtained aqueous fiber suspension in which the Ink particles are already detached from fibers, so that they fiotate to let. The flotation process described here uses the differences between Pulp and unwanted particulates in the way that the pulp remains in the fiber suspension due to its rather hydrophilic character, while the mentioned solid particles are hydrophobic and therefore together with the air bubbles get into the foam. In addition to the ink particles, there are also a variety of other substances that are hydrophobic and are therefore flotated from the Have the fiber separated. Such substances are especially glue, fine Plastic particles and possibly also resins. Because by the one mentioned here Flotation process Fibers are separated from contaminants selective flotation. The term "flotation thinking" is also used in the Usually not only for the removal of ink particles (ink = ink), but also more generally for the selective flotation of contaminants Fibrous suspensions used.

Die JP 60134090 A zeigt eine Kombination eines Flotationszyklons mit einem nachfolgend geschalteten Abscheidebehälter (sekundärer Prozessbehälter). Dabei wird der Flotationsschaum des Flotationszyklons zur Nachbehandlung in den zweiten Behälter geführt.JP 60134090 A shows a combination of a flotation cyclone with one downstream separation tank (secondary process tank). Doing so the flotation foam of the flotation cyclone for after-treatment in the second container guided.

Besonders guten Effekt haben Verfahren mit zwei aufeinanderfolgenden Flotationsschritten, deren Wirkung jeweils unterschiedlich auf bestimmte Arten von Störstoffen speziell abgestimmt sind. So ist es aus der EP 0 888 819 A1 (DE 197 28 393) bekannt, zuerst eine Flotation im normalen Erdschwerefeld und danach eine weitere mit Hilfe eines Flotationszyklons auszuführen. Durch diese Kombination lassen sich Störstoffe ausscheiden, deren Partikelgröße in einem breiten Spektrum vorliegt. Dabei werden im zweiten Teilschritt besonders die in der Faserstoffsuspension vorliegenden kleineren Partikel durch ein darauf optimal abgestimmtes Starkfeld-Flotationsgerät ausflotiert, dessen Kraftfeld stärker ist als die Erdgravitation. Es lassen sich dann z.B. auch solche Druckfarbenpartikel erfassen, die durch Binder auf Ölbasis mit den Fasern verbunden waren.Processes with two successive ones have a particularly good effect Flotation steps, the effects of which differ on certain types of Contaminants are specially matched. So it is from EP 0 888 819 A1 (DE 197 28 393) known, first a flotation in the normal gravity field and then perform another using a flotation cyclone. Through this Combination can remove impurities, their particle size in a wide range Spectrum is available. In the second step, those in the Fibrous suspension smaller particles present by an optimal on it coordinated strong-field flotation device, whose force field is stronger than that Earth's gravity. Then e.g. also detect those ink particles that were connected to the fibers by oil-based binders.

In der DE 44 26 159 A1 wird ein Verfahren beschrieben, bei dem die zu reinigende Faserstoffsuspension zunächst in einen mit Fliehkräften arbeitenden Flotationszyklon gelangt und dann in Flotationszellen herkömmlicher Bauart, die im wesentlichen allein aufgrund der Schwerkraft arbeiten. Der Flotationsschaum der letztgenannten Flotationszellen - eventuell auch des Flotationszyklons - wird in einem weiteren Flotationszyklon, der die Sekundärstufe bildet, gereinigt.DE 44 26 159 A1 describes a method in which the one to be cleaned Fibrous suspension initially in a centrifugal flotation cyclone arrives and then in flotation cells of conventional design, which are essentially alone work due to gravity. The flotation foam of the latter Flotation cells - possibly also the flotation cyclone - are in another Flotation cyclone, which forms the secondary stage, cleaned.

Diese beiden Verfahren arbeiten zwar mit Vorteil in Kombination unterschiedlicher Flotationsschritte, sind aber relativ aufwendig, da jeder Teilschritt eine vollständige Flotation mit jeweils erneuter Belüftung enthält.These two methods work advantageously in a combination of different ones Flotation steps, however, are relatively complex since each sub-step is a complete one Contains flotation with renewed ventilation.

Der Erfindung liegt daher die Aufgabe zu Grunde, ein Flotationsverfahren zu schaffen, mit dem das Spektrum der ausfiotierten Störstoffpartikel groß ist, ohne dass ein zu hoher apparativer und betriebsmäßiger Aufwand benötigt wird. In speziellen Ausführungen soll außerdem eine Entlüftung der Suspension erfolgen. The invention is therefore based on the object of creating a flotation process with which the spectrum of contaminated contaminant particles is large, without a too high equipment and operational expenditure is required. In special The suspension should also be vented.

Diese Aufgabe wird durch die kennzeichnenden Merkmale des Anspruchs 1 in vollem Umfang gelöst.This object is fully characterized by the characterizing features of claim 1 Scope solved.

Das erfindungsgemäße Verfahren hat den Vorteil, dass ein breites Größenspektrum bei der Flotation erfassbar ist, indem - wie an sich bekannt - mindestens zwei auf einen jeweiligen speziellen Größenbereich optimierte Teilschritte hintereinandergeschaltet werden. Dabei wird der zweite Teilschritt ohne weitere Belüftung der Suspension ausgeführt, was den Aufwand an Apparaturen, Energie und Prozeßregelung wesentlich reduziert. Der Luftgehalt im Gutstoff des stromaufwärtigen Flotationsschnttes wird zur weiteren Flotation ausgenutzt. Dabei ist es von besonderem Vorteil, dass der stromabwärtige Flotationsschritt in stärkerem Kraftfeld, z.B. dem eines Flotationszyklons, durchgeführt wird. Solche Apparate können besonders wirksam mit Hilfe kleiner Luftblasen relativ feine Störstoffe abscheiden.The inventive method has the advantage that a wide range of sizes the flotation can be recorded by - as is known per se - at least two on one each particular size range optimized sub-steps connected in series become. The second step is without further aeration of the suspension executed what the expenditure of equipment, energy and process control essential reduced. The air content in the accepted material of the upstream flotation section is used for further flotation. It is particularly advantageous that the downstream flotation step in a stronger force field, e.g. that one Flotation cyclones. Such devices can be particularly effective with Separate relatively fine contaminants with the help of small air bubbles.

Ein weiterer Vorteil des Verfahrens liegt darin, dass nur die Restluft, die im Gutstoff des stromaufwärtigen Flotationsschrittes noch vorhanden und oft unerwünscht ist, durch den stromabwärtigen Flotationsschritt entfernt werden muß, so dass eine Suspension mit geringem Luftgehalt gebildet wird. Das wirkt sich z.B. beim Betrieb nachfolgender Scheibenfilter zur Eindickung der Suspension günstig aus.Another advantage of the process is that only the residual air in the accept of the upstream flotation step is still present and is often undesirable, must be removed by the downstream flotation step so that a Suspension with low air content is formed. This affects e.g. during operation subsequent disc filter for thickening the suspension favorably.

In den Abbildungen von manchen Publikationen wird die Belüftung bei den einzelnen Flotationsschritten nicht eingezeichnet, siehe z.B. in Figuren der DE 197 28 393 A1. Der Fachmann ist sich aber ohne Zweifel sicher, dass lediglich aus Gründen der einfacheren Darstellung solche hier selbstverständlichen Details weggelassen wurden. Ähnliches gilt z.B. für Pumpen, Regeleinrichtungen und Befestigungsmittel.The ventilation of the individual is shown in the illustrations of some publications Flotation steps not shown, see e.g. in figures of DE 197 28 393 A1. However, the person skilled in the art is no doubt certain that it is only for reasons of simpler representation such details that are taken for granted here have been omitted. The same applies e.g. for pumps, control devices and fasteners.

Die Erfindung wird erläutert an Hand von Zeichnungen. Dabei zeigen:

Fig. 1
ein Schema des erfindungsgemäßen Verfahrens;
Fig. 2
eine Variante des Verfahrens;
Fig. 3
schematisch: Eine erfindungsgemäße Anlage;
Fig. 4
schematisch: Flotationszylinder der Fig. 3 in Ansicht von oben.
The invention is explained with reference to drawings. Show:
Fig. 1
a scheme of the method according to the invention;
Fig. 2
a variant of the procedure;
Fig. 3
schematically: a system according to the invention;
Fig. 4
schematic: flotation cylinder of FIG. 3 in top view.

Fig. 1 zeigt ein sehr einfaches Schema mit einem stromaufwärtigen Flotationsschritt 1 und einem stromabwärtigen Flotationsschritt 2. Die Faserstoffsuspension S wird, bevor sie dem stromaufwärtigen Flotationsschritt 1 zugeleitet wird, in einem Mischorgan 3 mit Luft L so vermischt, dass Luftblasen der gewünschten Größe und Anzahl entstehen. Die Abläufe des Flotationsschrittes 1 sind bekannt; es wird ein Flotationsschaum R1 gebildet, der einen großen Teil der Störstoffe enthält, sowie ein Gutstoff A1, der von der gereinigten Faserstoffsuspension gebildet wird. Dieser wird ohne eine weitere Belüftung über die Pumpe 5 dem stromabwärtigen Flotationsschritt 2 zugeleitet. Während bei dem hier gezeigten Beispiel der stromaufwärtige Flotationsschntt 1 allein im Erdschwerefeld betrieben wird, wird beim stromabwärtigen Flotationsschritt 2 durch Rotation der Suspension ein Zentrifugalfeld erzeugt. Dadurch können, wie bereits beschrieben, feinere Störstoffe mit Hilfe von kleineren Luftblasen abgeschieden werden, so dass sie in den Flotationsschaum R2 gelangen. Dieses Zentritugalfeld ist mit Vorteil nicht so stark, dass die Gefahr des Trennens von Luftblasen und Störstoffpartikeln besteht. Günstige Werte liegen zwischen 10- und 100-facher Erdbeschleunigung. Die auf diese Weise nochmals gereinigte Faserstoffsuspension wird als Gutstoff A2 der weiteren Verwendung zugeführt. Die beiden Flotationsschäume R1 und R2 werden hier gemeinsam als Rejekt R abgeführt und verworfen. Bekanntlich können aber auch solche Rejekte in einer oder mehreren Sekundärstufen getrennt oder gemeinsam nachbehandelt werden, um Faserverluste zu vermeiden.1 shows a very simple diagram with an upstream flotation step 1 and a downstream flotation step 2. The pulp suspension S is before it is fed to the upstream flotation step 1 in a mixing element 3 mixed with air L so that air bubbles of the desired size and number are created. The processes of flotation step 1 are known; it becomes a flotation foam R1 formed, which contains a large part of the contaminants, as well as an acceptor A1, which from the cleaned pulp suspension is formed. This will be without further ventilation fed to the downstream flotation step 2 via the pump 5. While at that example shown here the upstream flotation section 1 alone in the Earth's gravity field is operated in the downstream flotation step 2 by Rotation of the suspension creates a centrifugal field. This, like already described, finer impurities are separated with the help of smaller air bubbles, so that they get into the flotation foam R2. This centrifugal field is an advantage not so strong that there is a risk of separation of air bubbles and contaminant particles consists. Favorable values are between 10 and 100 times gravitational acceleration. The in this way cleaned fiber pulp suspension is the accepted A2 fed further use. The two flotation foams R1 and R2 are here dissipated together as reject R and discarded. As is well known, such can also be the case Rejects treated separately or together in one or more secondary levels to avoid fiber loss.

Das in Fig. 2 schematisch dargestellte Verfahren unterscheidet sich in einigen Punkten von dem in Fig. 1 und zeigt eine weitere Möglichkeit, die Erfindung zu realisieren. Dabei besteht der stromaufwärtige Flotationsschritt 1 aus mehreren hintereinander geschalteten Flotationsvorrichtungen. Eine solche Schaltung ist in vielen Fällen üblich und umfasst z.B. fünf bis acht in Reihe geschaltete Flotationsvorgänge. Dabei kann der Gutstoff, bevor er aus der vorigen in die nächste Flotation kommt, über eine Pumpe gefördert und erneut mit Luft vermischt werden. Der aus diesem stromaufwärtigen Flotationsschritt 1 stammende Gutstoff A1 gelangt in einen Flotationszyklon, welcher den stromabwärtigen Flotationsschritt 2 vornimmt. Anders als im Beispiel gemäß Fig. 1 wird hier der Flotationsschaum R2 auf der - axial gesehen - selben Seite entnommen, an der auch der Gutstoff A1 in den Flotationszyklon eingeführt wird. Erfindungsgemäß erfolgt dabei keine erneute Belüftung. Der aus diesem Flotationsschritt stammende Gutstoff A2 wird an dem axial entgegengesetzten Ende abgezogen, entweder tangential oder axial (gestrichelter Pfeil).The method shown schematically in FIG. 2 differs in some points of that in Fig. 1 and shows another way to implement the invention. Here the upstream flotation step 1 consists of several one after the other switched flotation devices. Such a circuit is common in many cases and includes e.g. five to eight flotation processes connected in series. The Gutstoff, before it comes from the previous to the next flotation, via a pump promoted and mixed again with air. The one from this upstream Acceptable substance A1 originating from flotation step 1 arrives in a flotation cyclone, which performs the downstream flotation step 2. Unlike in the example according to FIG. 1 the flotation foam R2 is taken from the same side, seen axially, at which the accepting substance A1 is also introduced into the flotation cyclone. According to the invention there is no renewed ventilation. The one from this flotation step Acceptable material A2 is drawn off at the axially opposite end, either tangentially or axial (dashed arrow).

In der Fig. 3 werden die für die Flotationsschritte verwendbaren Flotationsvorrichtungen etwas detaillierter dargestellt. Die unter Schwerkraftswirkung stehende Flotationszelle (Flotationsschritt 1) hat eine ovale Form und bildet ein im wesentlichen geschlossenes Gehäuse. Dadurch kann die dem Flotationsschaum R1 entweichende Luft L innerhalb des Flotationsgefäßes wieder angesaugt werden. Der Mischer 3' für Luft L und Faserstoffsuspension S ist Teil eines Mischrohres, welches in die Suspension eintaucht. Selbstverständlich kann auch eine andere Belüftung vorgesehen sein. Der stromabwärtige Flotationsschritt 2 wird in einem Zylinder 6 durchgeführt, in dem die einströmende Suspension, also der Gutstoff A1, des ersten Flotationsschrittes ohne weitere Belüftung eingepumpt und z.B. durch einen Tangentialeinlauf in Rotation versetzt wird. Sowohl der Flotationsschaum R2 als auch der Gutstoff A2 werden hier an dem in Achsrichtung dem Einlauf gegenüberliegenden Ende des Zylinders 6 abgezogen. Eine andere diesbezügliche Lösung zeigt die Fig. 2. Zur Regelung der Schaummenge kann, wie hier dargestellt, eine Drosselung des Gutstoffes A2 mit Hilfe eines einstellbaren Drosselventils 7 vorgenommen werden. Auch hier werden wieder beide Flotationsschäume R1 und R2 zusammengeführt, was schon deshalb vorteilhaft ist, weil dann auch die aus dem Flotationsschaum R2 austretende Luft in den Mischer 3' gelangen kann. Anstelle von Luft L kann auch ein spezielles Gas verwendet werden.3 that can be used for the flotation steps Flotation devices are shown in somewhat more detail. The under gravity standing flotation cell (flotation step 1) has an oval shape and forms an im essentially closed housing. This allows the flotation foam R1 escaping air L can be sucked in again within the flotation vessel. The Mixer 3 'for air L and fiber suspension S is part of a mixing tube which in the suspension is immersed. Of course, other ventilation can also be used be provided. The downstream flotation step 2 takes place in a cylinder 6 carried out, in which the inflowing suspension, ie the accept A1, of the first Pumped in flotation step without further aeration and e.g. through a Tangential inlet is set in rotation. Both the flotation foam R2 and the accepted A2 material here on the opposite side of the inlet in the axial direction Pulled off the end of the cylinder 6. Another solution in this regard is shown in FIG Regulation of the amount of foam can, as shown here, throttling the accept A2 with the help of an adjustable throttle valve 7. Also be here again both flotation foams R1 and R2 merged, which is why is advantageous because then the air emerging from the flotation foam R2 into the Mixer 3 'can get. A special gas can also be used instead of air L. become.

Die Fig. 4 zeigt in der Aufsicht, dass es sich bei dem für den stromabwärtigen Flotationsschritt 2 verwendeten Apparat um einen Zylinder 6 handelt. Man erkennt den tangentialen Zulauf für den Gutstoff A1 des stromaufwärtigen Flotationsschrittes (1) und den tangentialen Austritt für den Gutstoff A2.Fig. 4 shows in supervision that it is for the downstream Flotation step 2 used apparatus is a cylinder 6. You can see that tangential feed for the accept substance A1 of the upstream flotation step (1) and the tangential exit for the good substance A2.

Claims (9)

Verfahren zur Entfernung von Störstoffen aus einer wässrigen Faserstoffsuspension (S) mit Hilfe mehrerer selektiver Flotationsschritte (1, 2), von denen ein stromaufwärtiger Flotationsschritt (1) mit einem schwächeren Kraftfeld betrieben wird als der unmittelbar stromabwärtige Flotationsschntt (2) und
bei denen der Gutstoff (A1) des stromaufwärtigen Flotationsschrittes (1) in den stromabwärtigen Flotationsschritt (2) geführt wird,
dadurch gekennzeichnet,
dass der stromabwärtige Flotationsschritt (2) mit Hilfe der im Gutstoff (A1) des stromaufwärtigen Flotationsschrittes (1) enthaltenen Restluft und ohne weitere Luftzugabe betrieben wird.Process for removing impurities from an aqueous fiber suspension (S) with the aid of several selective flotation steps (1, 2), of which an upstream flotation step (1) is operated with a weaker force field than the immediately downstream flotation step (2) and
in which the accept (A1) of the upstream flotation step (1) is passed into the downstream flotation step (2),
characterized,
that the downstream flotation step (2) is operated with the aid of the residual air contained in the accept (A1) of the upstream flotation step (1) and without further air addition. Verfahren nach Anspruch 1,
dadurch gekennzeichnet,
dass der stromabwärtige Flotationsschritt (2) in einem Flotationszyklon durchgeführt wird.Method according to claim 1,
characterized,
that the downstream flotation step (2) is carried out in a flotation cyclone. Verfahren nach Anspruch 2,
dadurch gekennzeichnet,
dass die Zentrifugalbeschleunigung im Hydrozyklon auf Werte zwischen fünf und 200 Mal Erdbeschleunigung eingestellt werden.Method according to claim 2,
characterized,
that the centrifugal acceleration in the hydrocyclone is set to values between five and 200 times gravitational acceleration. Verfahren nach Anspruch 3,
dadurch gekennzeichnet,
dass die Zentrifugalbeschleunigung im Hydrozyklon auf Werte zwischen zehn und 100 Mal Erdbeschleunigung eingestellt werden.Method according to claim 3,
characterized,
that the centrifugal acceleration in the hydrocyclone is set to values between ten and 100 times gravitational acceleration. Verfahren nach Anspruch 1,
dadurch gekennzeichnet,
dass der Gutstoff (A1) zum stromabwärtigen Flotationsschritt (2) tangential in einen Zylinder (6) eingeführt wird.Method according to claim 1,
characterized,
that the accept (A1) is introduced tangentially into a cylinder (6) for the downstream flotation step (2). Verfahren nach Anspruch 2, 3, 4 oder 5,
dadurch gekennzeichnet,
dass sowohl der im stromabwärtigen Flotationsschritt (2) gebildete Flotationsschaum (R2) als auch der Gutstoff (A2) an der dem Einlauf axial gegenüberliegenden Seite aus der im stromabwärtigen Flotationsschritt (2) verwendeten Flotationsvorrichtung abgeführt werden.The method of claim 2, 3, 4 or 5,
characterized,
that both the flotation foam (R2) formed in the downstream flotation step (2) and the accept (A2) on the side axially opposite the inlet are removed from the flotation device used in the downstream flotation step (2). Verfahren nach Anspruch 2, 3, 4, 5 oder 6,
dadurch gekennzeichnet,
dass der im stromabwärtigen Flotationsschritt (2) gebildete Flotationsschaum (R2) axial an der Seite aus der verwendeten Flotationsvorrichtung abgeführt wird, an der sich auch der Einlauf befindet und der Gutstoff (A2) an der axial gegenüberliegenden Seite.The method of claim 2, 3, 4, 5 or 6,
characterized,
that the flotation foam (R2) formed in the downstream flotation step (2) is discharged axially on the side from the flotation device used, on which the inlet is also located, and the accept (A2) on the axially opposite side. Verfahren nach einem der voranstehenden Ansprüche,
dadurch gekennzeichnet,
dass das schwächere Kraftfeld das Erdschwerefeld ist.Method according to one of the preceding claims,
characterized,
that the weaker force field is the earth's gravity field. Verfahren nach einem der voranstehenden Ansprüche,
dadurch gekennzeichnet,
dass der Gutstoff (A1) vom stromaufwärtigen Flotationsschritt (1) direkt und büttenlos zum stromabwärtigen Flotationsschritt (2) geführt wird.Method according to one of the preceding claims,
characterized,
that the accepted material (A1) is led from the upstream flotation step (1) directly and without shoddy to the downstream flotation step (2).
EP00107633A 1999-05-04 2000-04-08 Method for removing impurities from an aqueous paper fiber suspension Expired - Lifetime EP1050342B1 (en)

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WO2006045378A1 (en) * 2004-10-21 2006-05-04 Voith Patent Gmbh Method for degassing and supplying a fibrous suspension to a headbox or a filter device, and degassing device
US7807020B2 (en) 2004-10-21 2010-10-05 Voith Patent Gmbh Method for degassing and supplying a fibrous suspension to a headbox or a filter device and degassing device
US8025761B2 (en) 2004-10-21 2011-09-27 Voith Patent Gmbh Method for degassing and supplying a fibrous suspension to a headbox or a filter device and degassing device
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EP1958697A1 (en) * 2005-12-07 2008-08-20 Taiheiyo Cement Corporation Apparatus for removing of unburned carbon from fly ash and relevant removing method
EP1958697A4 (en) * 2005-12-07 2013-06-26 Taiheiyo Cement Corp Apparatus for removing of unburned carbon from fly ash and relevant removing method

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