EP0410229B1 - Agitator mill for microgrinding - Google Patents
Agitator mill for microgrinding Download PDFInfo
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- EP0410229B1 EP0410229B1 EP90113421A EP90113421A EP0410229B1 EP 0410229 B1 EP0410229 B1 EP 0410229B1 EP 90113421 A EP90113421 A EP 90113421A EP 90113421 A EP90113421 A EP 90113421A EP 0410229 B1 EP0410229 B1 EP 0410229B1
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- European Patent Office
- Prior art keywords
- grinding
- grinding disks
- disks
- agitator mill
- agitator
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
- B02C17/16—Mills in which a fixed container houses stirring means tumbling the charge
- B02C17/163—Stirring means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
- B01F27/05—Stirrers
- B01F27/11—Stirrers characterised by the configuration of the stirrers
- B01F27/115—Stirrers characterised by the configuration of the stirrers comprising discs or disc-like elements essentially perpendicular to the stirrer shaft axis
Definitions
- the invention relates to an agitator mill for ultra-fine grinding of a grinding material dispersion consisting of solids or solid mixtures, which consists of a cylindrical container for holding grinding material and grinding media, in which a rotating stirrer shaft is provided, to which a plurality of circular grinding disks acting as stirring elements are attached, at least one of which Part of the grinding disks is attached directly to the agitator shaft off-center and offset in relation to one another in the axial direction, and the edge surfaces of the grinding disks are chamfered.
- Such an agitator mill is known for example from SU-A-1 384 332.
- agitator ball mills with vertically or horizontally arranged grinding troughs are used.
- Devices of this type consist of a vertically arranged grinding trough in which agitators are fitted, on which smooth disks, annular disks, perforated disks or stirring rods or the like are arranged. All of these designs have one fundamental disadvantage in common, which is that the high-speed mixing units have a continuously increasing peripheral speed from the center to the periphery. At the periphery, the peripheral speed is to be designed so that the grinding and dispersion effect is achieved, but that the grinding media themselves are not or only insignificantly stressed or even destroyed.
- the stress on the material to be ground and thus also on the grinding media essentially depends on the difference in speed between the stirring tool and the grinding media from.
- the grinding effect that can be achieved in the case of the continuously operating agitator mills that are mainly considered also depends on the fact that there are no zones of insufficient dispersing stress remaining on the millbase.
- the distance between the stirring discs and the inner wall of the grinding troughs must therefore be kept within certain limits.
- the grinding trough is double-walled for cooling purposes and has an inlet and an outlet for the material to be treated.
- a filter device for example in the form of a slot or sieve, is also provided, through which the grinding media are retained, but the treated product can pass through.
- Agitator mills with a hollow, cooled agitator shaft are also known, in particular for processing highly viscous and temperature-sensitive ground material.
- the outer edge design of the stirring disks has a non-circular shape deviating from the circular cross section of the grinding trough, for example tooth shape, wherein the outer edge of the stirring disks can have a bevel in the direction of the axis of the agitator shaft.
- DE-A-24 57 609 describes an agitator mill whose agitator shaft is formed by a conical hollow body which tapers downwards.
- DE-A-26 50 441 describes stirring disks, which are equipped with a Number of elongated openings, which are preferably circularly distributed around the central axis of the disk in question, are provided for taking the grinding media with them. A beveled leading edge is provided in the axial direction at each end of these elongated openings.
- DE-A-12 07 191 describes ring disks which act as stirring elements and which are fastened off-center on the agitator shaft and offset relative to one another as seen in the axial direction.
- these ring eccentrics have the disadvantage that, due to the centrifugal force, a cavity can arise in the interior of the grinding vessel, which considerably reduces the effectiveness of the fine grinding.
- DE-A-12 11 906 ring disks are known, which are designed as a helical surface. The same problems as described above occur with the fine grinding with these stirring elements.
- DE-A-21 64 286 describes eccentrically arranged circular stirring elements which have edges pointing upwards or downwards at the edges.
- SU-A-1 384 332 describes eccentrically mounted grinding disks with bevelled edges in one direction.
- From DE-A-16 07 533 eccentrically mounted solid disks are also known, which are provided on one or both outer surfaces with concentric bead-like ribs.
- the task was to enable an agitator mill of the generic type mentioned at the outset, even with a high degree of ball filling, by means of an optimized axial and radial conveyance of the ground material and the grinding media, without ball blocking. At the same time, this funding should take place in a mill cascade connected in series, if possible without additional pump systems.
- the grinding disk is provided on one or both sides with one or more eccentrically circumferential beveled active surfaces, as can be seen from FIGS. 1a to 1c.
- the grinding disc (1) according to the invention is a circular solid disc with an eccentrically mounted bore (5) for plugging onto the agitator shaft (6) (FIGS. 2a, 2b). This disc is manufactured as a turned part.
- the edge surfaces (2) of the disc (1) are beveled on one or both sides ( Figure 1c).
- the top and / or the underside of the disk is provided with circumferential, preferably circular-centered, zigzag-shaped tapered baffles (3, 4) inwards and / or outwards (FIG. 1b).
- the grinding disk is preferably equipped with these baffles on at least half of its outer surface.
- FIG. 1a due to the eccentric arrangement of the grinding disks, the grinding media hit the impact surfaces at different angles, as a result of which extremely good axial and radial conveyance of the grinding stock is achieved.
- FIG. 1b shows a particularly preferred embodiment of the grinding disc according to the invention, in which these active surfaces are arranged on both sides, that is to say on the top and bottom of the grinding disc.
- Steel, ceramic, low-pressure polyethylene or polyoxymethylene or others are used as the material for the grinding disc appropriate materials suitable. Since, as described above, the grinding disk is a turned part, in contrast to the prior art mentioned above, this requires a much simpler production.
- FIGS. 2a and 2b The arrangement of the grinding disks in relation to the stirrer shaft (6) is shown in FIGS. 2a and 2b.
- four disks (1, 1 ', 1 ⁇ , 1 axial) are axially seen helically offset from each other by 90 °, then follows as indicated in Figure 2b, the next series of 4 grinding disks.
- Each grinding disc covers the entire cross-section of the grinding trough with each revolution. This effect is now greatly enhanced by the staggered arrangement of the grinding disks.
- the grinding media are moved in the same direction, but at different speeds, which creates additional friction between the grinding media, which contributes to increasing the grinding work.
- the grinding media are from the prior art known grinding balls, for example steel, glass, aluminum oxide or ceramic balls can be used, the size of the grinding balls can be selected within wide limits, for example from 0.2 to 5 mm.
- the vertical distance between the individual grinding disks can be between 20 and 100 mm with a diameter of the grinding trough of 200 - 500 mm.
- a ball filling degree for example 0.8 mm ceramic balls, of up to 94% can be achieved, while ball filling degrees of up to about 80% are generally known from the prior art.
- agitator mills according to the invention have proven themselves particularly well in the very fine grinding of magnetic dispersions consisting of polymeric binder dissolved in an organic solvent and magnetic fine-particle pigments dispersed therein with a high viscosity of the millbase. It has been shown that the number of agitator mills connected in series could be reduced by about 1/3 for the fine grinding of such dispersions.
- the stirring elements are arranged in a vertical agitator ball mill in such a way that the grinding disks arranged at the lower shaft end consist of steel, while the grinding disks arranged in the middle and at the top preferably consist of plastic.
- the temperature profile in the grinding trough is taken into account, since, as is known to any person skilled in the art, the temperature due to the ball pressure in the lower part of the trough is significantly higher than in the upper part of the trough.
Description
Die Erfindung betrifft eine Rührwerksmühle zum Feinstmahlen einer aus Feststoffen oder Feststoffgemischen bestehenden Mahlgutdispersion, die aus einem zylindrischen Behälter zur Aufnahme von Mahlgut und Mahlkörpern besteht, in dem eine rotierende Rührwelle vorgesehen ist, an der mehrere als Rührelemente wirkende kreisförmige Mahlscheiben befestigt sind, wobei zumindest ein Teil der Mahlscheiben unmittelbar an der Rührwerkswelle außermittig und in Achsrichtung gesehen gegeneinander versetzt befestigt ist und wobei die Kantenflächen der Mahlscheiben abgeschrägt sind. Eine derartige Rührwerksmühle ist beispielsweise aus SU-A-1 384 332 bekannt.The invention relates to an agitator mill for ultra-fine grinding of a grinding material dispersion consisting of solids or solid mixtures, which consists of a cylindrical container for holding grinding material and grinding media, in which a rotating stirrer shaft is provided, to which a plurality of circular grinding disks acting as stirring elements are attached, at least one of which Part of the grinding disks is attached directly to the agitator shaft off-center and offset in relation to one another in the axial direction, and the edge surfaces of the grinding disks are chamfered. Such an agitator mill is known for example from SU-A-1 384 332.
Bei der Naßmahlung beispielsweise von magnetischen Dispersionen werden Rührwerkskugelmühlen mit vertikal oder horizontal angeordneten Mahltrögen verwendet. Man kennt Vorrichtungen dieser Art, die aus einem senkrecht angeordneten Mahltrog bestehen, in dem Rührwerke angebracht sind, auf denen glatte Scheiben, Ringscheiben, Lochscheiben oder Rührstäbe oder dergleichen angeordnet sind. Allen diesen Ausführungen ist ein grundsätzlicher Nachteil gemeinsam, der darin besteht, daß die hochtourig laufenden Mischwerke eine vom Zentrum bis zur Peripherie ständig steigende Umfangsgeschwindigkeit haben. An der Peripherie ist die Umfangsgeschwindigkeit so auszulegen, daß zwar der Effekt der Mahlung und Dispergierung erreicht wird, daß aber die Mahlkörper selbst nicht oder nur unwesentlich beansprucht oder gar zerstört werden. Die Beanspruchung des Mahlgutes und damit auch der Mahlkörper hängt wesentlich von der Differenzgeschwindigkeit zwischen Rührwerkzeug und den Mahlkörpern ab. Der erzielbare Mahleffekt hängt aber bei den hauptsächlich in Betracht kommenden kontinuierlich arbeitenden Rührwerksmühlen auch noch davon ab, daß dem Mahlgut keine Zonen mangelnder Dispergierbeanspruchung verbleiben. Der Abstand zwischen den Rührscheiben und der Innenwandung der Mahltröge muß deshalb innerhalb gewisser Grenzen gehalten werden.For wet grinding of magnetic dispersions, for example, agitator ball mills with vertically or horizontally arranged grinding troughs are used. Devices of this type are known which consist of a vertically arranged grinding trough in which agitators are fitted, on which smooth disks, annular disks, perforated disks or stirring rods or the like are arranged. All of these designs have one fundamental disadvantage in common, which is that the high-speed mixing units have a continuously increasing peripheral speed from the center to the periphery. At the periphery, the peripheral speed is to be designed so that the grinding and dispersion effect is achieved, but that the grinding media themselves are not or only insignificantly stressed or even destroyed. The stress on the material to be ground and thus also on the grinding media essentially depends on the difference in speed between the stirring tool and the grinding media from. However, the grinding effect that can be achieved in the case of the continuously operating agitator mills that are mainly considered also depends on the fact that there are no zones of insufficient dispersing stress remaining on the millbase. The distance between the stirring discs and the inner wall of the grinding troughs must therefore be kept within certain limits.
Der Mahltrog ist zu Kühlungszwecken doppelwandig ausgebildet und weist einen Einlaß und einen Auslaß für das zu behandelnde Mahlgut auf. Ebenso ist eine Filtervorrichtung zum Beispiel in Form eines Schlitzes oder Siebes vorgesehen, durch welche die Mahlkörper zurückgehalten werden, das behandelte Produkt jedoch hindurchtreten kann. Ebenso sind Rührwerksmühlen mit hohler gekühlter Rührwerkswelle, insbesondere für die Verarbeitung hochviskosen und temperaturempfindlichen Mahlguts bekannt.The grinding trough is double-walled for cooling purposes and has an inlet and an outlet for the material to be treated. A filter device, for example in the form of a slot or sieve, is also provided, through which the grinding media are retained, but the treated product can pass through. Agitator mills with a hollow, cooled agitator shaft are also known, in particular for processing highly viscous and temperature-sensitive ground material.
Bedingt durch den gewünschten hohen Energieeintrag, der mittels der sich drehenden Mahlscheiben in das Gemisch von Mahlkörpern und Mahlgut eingetragen wird, kommt es bei dichterer Kugelfüllung zum Verblocken der Mahlkörper. Dieses Verblocken führt zu hoher Temperaturentwicklung im Mahlgut und großem Kugelverschleiß mit hohem Energieverbrauch.As a result of the desired high energy input, which is introduced into the mixture of grinding media and grinding material by means of the rotating grinding disks, the grinding media are blocked when the balls are filled more densely. This blocking leads to high temperature development in the regrind and large ball wear with high energy consumption.
In der DE-A-12 11 905 wird vorgeschlagen, daß die Außenrandgestaltung der Rührscheiben eine vom Kreisquerschnitt des Mahltroges abweichende Unrundform beispielsweise Zahnform aufweist, wobei der Außenrand der Rührscheiben eine Abschrägung in Richtung zur Achse der Rührwerkswelle aufweisen kann. In der DE-A-24 57 609 ist eine Rührwerksmühle beschrieben, deren Rührwerkswelle von einem konischen, sich nach unten verjüngenden Hohlkörper gebildet ist. In der DE-A-26 50 441 sind Rührscheiben beschrieben, welche mit einer Anzahl vorzugsweise um die Mittelachse der betreffenden Scheibe herum kreisförmig verteilten länglichen Durchbrüche für die Mitnahme der Mahlkörper versehen sind. Dabei ist an jedem Ende dieser länglichen Durchbrüche eine abgeschrägte Anlaufkante in Axialrichtung vorgesehen.In DE-A-12 11 905 it is proposed that the outer edge design of the stirring disks has a non-circular shape deviating from the circular cross section of the grinding trough, for example tooth shape, wherein the outer edge of the stirring disks can have a bevel in the direction of the axis of the agitator shaft. DE-A-24 57 609 describes an agitator mill whose agitator shaft is formed by a conical hollow body which tapers downwards. DE-A-26 50 441 describes stirring disks, which are equipped with a Number of elongated openings, which are preferably circularly distributed around the central axis of the disk in question, are provided for taking the grinding media with them. A beveled leading edge is provided in the axial direction at each end of these elongated openings.
Die DE-A-12 07 191 beschreibt als Rührelemente wirkende Ringscheiben, welche unmittelbar an der Rührwerkswelle außermittig und in Achsrichtung gesehen gegeneinander versetzt befestigt sind. Diese Ringexzenter haben jedoch den Nachteil, daß infolge der Zentrifugalkraft im Inneren des Mahlgefäßes ein Hohlraum entstehen kann, der die Effektivität der Feinstmahlung erheblich reduziert. Aus der DE-A-12 11 906 sind Ringscheiben bekannt, die schraubenflächenförmig ausgebildet sind. Bei der Feinstmahlung mit diesen Rührelementen treten die gleichen Probleme auf wie oben geschildert.DE-A-12 07 191 describes ring disks which act as stirring elements and which are fastened off-center on the agitator shaft and offset relative to one another as seen in the axial direction. However, these ring eccentrics have the disadvantage that, due to the centrifugal force, a cavity can arise in the interior of the grinding vessel, which considerably reduces the effectiveness of the fine grinding. From DE-A-12 11 906 ring disks are known, which are designed as a helical surface. The same problems as described above occur with the fine grinding with these stirring elements.
In der DE-A-21 64 286 sind exzentrisch angeordnete kreisringförmige Rührorgane beschrieben, welche an den Kanten nach oben oder nach unten weisende Kanten aufweisen. Die SU-A-1 384 332 beschreibt exzentrisch gelagerte Mahlscheiben mit nach einer Richtung abgeschrägten Kanten. Aus der DE-A-16 07 533 sind gleichfalls exzentrisch gelagerte Vollscheiben bekannt, welche auf einer oder beiden Außenflächen mit konzentrischen wulstartigen Rippen versehen sind.DE-A-21 64 286 describes eccentrically arranged circular stirring elements which have edges pointing upwards or downwards at the edges. SU-A-1 384 332 describes eccentrically mounted grinding disks with bevelled edges in one direction. From DE-A-16 07 533 eccentrically mounted solid disks are also known, which are provided on one or both outer surfaces with concentric bead-like ribs.
Es bestand die Aufgabe, bei einer Rührwerksmühle der eingangs genannten gattungsmäßigen Art auch bei einem hohen Kugelfüllgrad durch eine optimierte axiale und radiale Förderung des Mahlgutes und der Mahlkörper eine gute Durchmischung ohne Kugelverblockung zu ermöglichen. Gleichzeitig soll diese Förderung bei einer in Reihe geschalteten Mühlenkaskade möglichst ohne zusätzliche Pumpsysteme geschehen.The task was to enable an agitator mill of the generic type mentioned at the outset, even with a high degree of ball filling, by means of an optimized axial and radial conveyance of the ground material and the grinding media, without ball blocking. At the same time, this funding should take place in a mill cascade connected in series, if possible without additional pump systems.
Gemäß der vorliegenden Erfindung wurde die Aufgabe gelöst mit einer Rührwerksmühle mit den im Kennzeichnenden Teil des Anspruchs 1 genannten Merkmalen. Weitere Einzelheiten der Erfindung gehen aus den Unteransprüchen, der Beschreibung und den Zeichnungen hervor.According to the present invention, the object was achieved with an agitator mill with the features mentioned in the characterizing part of
Die Erfindung wird nun anhand der Zeichnungen näher erläutert und zwar zeigen
- die Figuren 1a und 1b
- eine Draufsicht beziehungsweise einen Querschnitt einer erfindungsgemäßen Rührscheibe
- Figur 1c
- einen Querschnitt einer anderen erfindungsgemäßen Rührscheibe
- Figuren 2a und 2b
- eine Draufsicht beziehungsweise einen Querschnitt über die Anordnung der Rührscheiben an der Rührwerkswelle.
- Figures 1a and 1b
- a plan view or a cross section of a stirring disk according to the invention
- Figure 1c
- a cross section of another stirring disc according to the invention
- Figures 2a and 2b
- a plan view or a cross section on the arrangement of the agitator discs on the agitator shaft.
Erfindungswesentlich ist, daß die Mahlscheibe einseitig oder beidseitig mit einer oder mehreren exzentrisch umlaufenden angeschrägten Wirkflächen versehen ist, wie aus Figur 1a bis 1c zu ersehen. Die erfindungsgemäße Mahlscheibe (1) ist eine kreisrunde Vollscheibe mit einer exzentrisch angebrachten Bohrung (5) für das Aufstecken auf die Rührwelle (6) (Figur 2a, 2b). Diese Scheibe wird als Drehteil hergestellt. Die Kantenflächen (2) der Scheibe (1) sind nach einer oder nach beiden Seiten abgeschrägt (Figur 1c). Die Ober- und/oder die Unterseite der Scheibe ist in einer bevorzugten Ausführung mit umlaufenden vorzugsweise kreiszentrischen zickzackförmig verlaufenden angeschrägten Prallflächen (3, 4) nach innen und/oder nach außen versehen (Fig. 1b). Vorzugsweise ist die Mahlscheibe auf mindestens der Hälfte ihrer Außenfläche mit diesen Prallflächen ausgestattet. Wie aus Figur 1a zu erkennen, treffen infolge der außermittigen Anordnung der Mahlscheiben die Mahlkörper mit unterschiedlichem Winkel auf den Prallflächen auf, wodurch eine außerordentlich gute axiale und radiale Förderung des Mahlguts erreicht wird. In Figur 1b ist eine besonders bevorzugte Ausführung der erfindungsgemäßen Mahlscheibe dargestellt, bei der diese Wirkflächen beidseitig, das heißt auf der Ober- und Unterseite der Mahlscheibe, angeordnet sind. Als Material für die Mahlscheibe sind Stahl, Keramik, Niederdruckpolyethylen oder Polyoxymethylen oder andere entsprechende Werkstoffe geeignet. Da wie oben geschildert, die Mahlscheibe ein Drehteil ist, bedingt dies im Gegensatz zu dem vorstehend genannten Stand der Technik eine wesentlich einfachere Herstellung.It is essential to the invention that the grinding disk is provided on one or both sides with one or more eccentrically circumferential beveled active surfaces, as can be seen from FIGS. 1a to 1c. The grinding disc (1) according to the invention is a circular solid disc with an eccentrically mounted bore (5) for plugging onto the agitator shaft (6) (FIGS. 2a, 2b). This disc is manufactured as a turned part. The edge surfaces (2) of the disc (1) are beveled on one or both sides (Figure 1c). In a preferred embodiment, the top and / or the underside of the disk is provided with circumferential, preferably circular-centered, zigzag-shaped tapered baffles (3, 4) inwards and / or outwards (FIG. 1b). The grinding disk is preferably equipped with these baffles on at least half of its outer surface. As can be seen from FIG. 1a, due to the eccentric arrangement of the grinding disks, the grinding media hit the impact surfaces at different angles, as a result of which extremely good axial and radial conveyance of the grinding stock is achieved. FIG. 1b shows a particularly preferred embodiment of the grinding disc according to the invention, in which these active surfaces are arranged on both sides, that is to say on the top and bottom of the grinding disc. Steel, ceramic, low-pressure polyethylene or polyoxymethylene or others are used as the material for the grinding disc appropriate materials suitable. Since, as described above, the grinding disk is a turned part, in contrast to the prior art mentioned above, this requires a much simpler production.
Aus den Figuren 2a und 2b ist die Anordnung der Mahlscheiben in Bezug auf die Rührwelle (6) angegeben. Jeweils vier Scheiben (1, 1′, 1˝, 1‴) sind axial gesehen schraubenlinig jeweils um 90° gegeneinander versetzt, dann folgt wie in Figur 2b angedeutet, die nächste 4er-Serie von Mahlscheiben. Jede Mahlscheibe bestreicht bei jeder Umdrehung den gesamten Querschnitt des Mahltroges. Diese Wirkung wird nun noch außerordentlich durch die gegeneinander versetzte Anordnung der Mahlscheiben verstärkt. Die Mahlkörper werden zwar in gleicher Richtung bewegt, jedoch mit unterschiedlicher Geschwindigkeit, wodurch zusätzliche Reibung zwischen den Mahlkörpern entsteht, die zur Erhöhung der Mahlarbeit beiträgt.The arrangement of the grinding disks in relation to the stirrer shaft (6) is shown in FIGS. 2a and 2b. In each case four disks (1, 1 ', 1˝, 1 axial) are axially seen helically offset from each other by 90 °, then follows as indicated in Figure 2b, the next series of 4 grinding disks. Each grinding disc covers the entire cross-section of the grinding trough with each revolution. This effect is now greatly enhanced by the staggered arrangement of the grinding disks. The grinding media are moved in the same direction, but at different speeds, which creates additional friction between the grinding media, which contributes to increasing the grinding work.
Außerdem wurde gefunden, daß eine besonders intensive Durchmischung beziehungsweise Dispergierung dann erreicht wird, wenn bei einer senkrecht stehenden Rührwerkskugelmühle die untersten Mahlscheiben gemäß der vorliegenden Erfindung exzentrisch umlaufen und die Prallflächen (2, 3) lediglich an der Oberseite aufweisen, während die obersten exzentrisch umlaufenden Mahlscheiben Prallflächen (2, 4) lediglich an ihrer Unterseite aufweisen. In einem Mittelteil sind konventionell zylindrische Mahlscheiben beispielsweise mit Löchern, die nicht exzentrisch umlaufen, an der Rührwelle angebracht. Auf diese Weise wird eine gewisse Mahlkörperkompression in der Mitte erreicht, jedoch ohne Gefahr einer Kugelblockade, welche zu Kugelbruch führt.It has also been found that particularly intensive mixing or dispersion is achieved when the bottom grinding disks according to the present invention rotate eccentrically in a vertical agitator ball mill and the baffles (2, 3) only have on the top, while the top eccentrically rotating grinding disks Have impact surfaces (2, 4) only on their underside. Conventionally cylindrical grinding disks, for example with holes that do not rotate eccentrically, are attached to the agitator shaft in a central part. In this way, a certain grinding body compression is achieved in the middle, but without the risk of a ball blockage, which leads to ball breakage.
Als Mahlkörper sind die im übrigen aus dem Stand der Technik bekannten Mahlkugeln, beispielsweise Stahl-, Glas-, Aluminiumoxid- oder Keramik-Kugeln verwendbar, die Größe der Mahlkugeln ist in weiten Grenzen wählbar, beispielsweise von 0,2 bis 5 mm. Der senkrechte Abstand der einzelnen Mahlscheiben voneinander kann zwischen 20 und 100 mm bei einem Durchmesser des Mahltroges von 200 - 500 mm betragen.Incidentally, the grinding media are from the prior art known grinding balls, for example steel, glass, aluminum oxide or ceramic balls can be used, the size of the grinding balls can be selected within wide limits, for example from 0.2 to 5 mm. The vertical distance between the individual grinding disks can be between 20 and 100 mm with a diameter of the grinding trough of 200 - 500 mm.
Es hat sich gezeigt, daß mit der erfindungsgemäßen Rührwerksmühle ein Kugelfüllgrad, beispielsweise bei 0,8 mm Keramik-Kugeln, von bis zu 94 % erreichbar ist, während aus dem Stand der Technik im allgemeinen Kugelfüllgrade bis etwa 80 % bekannt sind.It has been shown that with the agitator mill according to the invention, a ball filling degree, for example 0.8 mm ceramic balls, of up to 94% can be achieved, while ball filling degrees of up to about 80% are generally known from the prior art.
Die vorstehend genannten erfindungsgemäßen Rührwerksmühlen haben sich insbesondere bei der Feinstmahlung von magnetischen Dispersionen, bestehend aus in einem organischen Lösungsmittel gelösten polymeren Bindemittel und darin dispergierten magnetischen feinteiligen Pigmenten bei hoher Viskosität des Mahlguts hervorragend bewährt. Es hat sich gezeigt, daß zur Feinstmahlung solcher Dispersionen die Anzahl der in Reihe geschalteten Rührwerksmühlen um etwa 1/3 reduziert werden konnte.The above-mentioned agitator mills according to the invention have proven themselves particularly well in the very fine grinding of magnetic dispersions consisting of polymeric binder dissolved in an organic solvent and magnetic fine-particle pigments dispersed therein with a high viscosity of the millbase. It has been shown that the number of agitator mills connected in series could be reduced by about 1/3 for the fine grinding of such dispersions.
In einer bevorzugten Ausführung sind die Rührelemente bei einer senkrecht stehenden Rührwerkskugelmühle so angeordnet, daß die am unteren Wellenende angeordneten Mahlscheiben aus Stahl bestehen, während die mittig und oben angeordneten Mahlscheiben vorzugsweise aus Kunststoff bestehen. Auf diese Weise wird dem Temperaturverlauf im Mahltrog Rechnung getragen, da wie jedem Fachmann bekannt ist, die Temperatur durch den Kugeldruck im Trogunterteil wesentlich höher ist als im Trogoberteil.In a preferred embodiment, the stirring elements are arranged in a vertical agitator ball mill in such a way that the grinding disks arranged at the lower shaft end consist of steel, while the grinding disks arranged in the middle and at the top preferably consist of plastic. In this way, the temperature profile in the grinding trough is taken into account, since, as is known to any person skilled in the art, the temperature due to the ball pressure in the lower part of the trough is significantly higher than in the upper part of the trough.
Claims (4)
- An agitator mill for microgrinding a ground-material dispersion consisting of solids or solid mixtures, which mill comprises a cylindrical container for receiving material to be ground and grinding media, in which container a rotating agitating shaft (6) is provided, on which a plurality of circular grinding disks (1), acting as agitating elements, are fastened, at least some of the grinding disks (1), acting as agitating elements, are fastened, at least some of the grinding disks (1) being fastened directly on the agitating shaft (6) off-center and, seen in the axial direction, offset with respect to one another, and the edge surfaces (2) of the grinding disks (1) being bevelled, wherein the grinding disks (1) are equipped on their upperside and/or underside with concentric ribs, wherein the cross section of the grinding disks (1) is designed in a zig-zagged shape (3, 4) and wherein the edge surfaces (2) of the grinding disks (1) are peripherally bevelled uniformly upward and downward.
- The agitator mill as claimed in claim 1, wherein, in the case of an upright agitator mill, the grinding disks (1) arranged at the lower shaft end (6) are made of steel and the grinding disks (1) arranged centrally or at the upper shaft end (6) are made of plastic.
- The agitator mill as claimed in claim 1, wherein, in the case of an upright agitator mill, the grinding disks (1) arranged at the lower shaft end are arranged off-center and have baffle surfaces (2, 3) only on their upper side, wherein the grinding disks (1) arranged off-center at the upper shaft end have baffle surfaces (2, 4) on the undersides and wherein conventional cylindrical perforated disks are arranged centrally in the central region of the agitating shaft (6).
- Process for microgrinding a magnetic dispersion, consisting of magnetic pigments, finely distributed in a polymeric binder, and further additives, wherein the dispersion runs once or more than once through at least one agitator mill as claimed in claims 1 to 3.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3924678 | 1989-07-26 | ||
| DE3924678A DE3924678A1 (en) | 1989-07-26 | 1989-07-26 | AGITATOR MILL FOR FINE GRINDING |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0410229A1 EP0410229A1 (en) | 1991-01-30 |
| EP0410229B1 true EP0410229B1 (en) | 1994-03-02 |
Family
ID=6385848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP90113421A Expired - Lifetime EP0410229B1 (en) | 1989-07-26 | 1990-07-13 | Agitator mill for microgrinding |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0410229B1 (en) |
| JP (1) | JPH0360747A (en) |
| DE (2) | DE3924678A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3725411B1 (en) * | 2019-04-18 | 2023-12-13 | Twee "R" Recyclinggroep B.V. | An apparatus for removing adhered substance from particulate material or for crushing material |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4234759C2 (en) * | 1992-10-15 | 2002-11-07 | Emtec Magnetics Gmbh | Agitator mill for very fine grinding |
| JP5326272B2 (en) * | 2007-12-13 | 2013-10-30 | アイシン精機株式会社 | Bubble refining device and bubble generating system using bubble refining device |
| DE102015101476A1 (en) * | 2015-02-02 | 2016-08-04 | Netzsch-Feinmahltechnik Gmbh | PULLER BALL MILL AND GRINDING DISK FOR EMPTY BALL MILLS |
| JP7111399B1 (en) * | 2021-12-10 | 2022-08-02 | 淺田鉄工株式会社 | Disperser |
| JP7138986B1 (en) * | 2021-12-10 | 2022-09-20 | 淺田鉄工株式会社 | Disperser |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1207191B (en) * | 1963-04-27 | 1965-12-16 | Netzsch Maschinenfabrik | Agitator mill for fine grinding and dispersion |
| DE1211905B (en) * | 1964-02-26 | 1966-03-03 | Draiswerke Ges Mit Beschraenkt | Agitator mill for the production of solid dispersions |
| DE1607533A1 (en) * | 1968-01-02 | 1969-10-02 | F B Lehmann Gmbh Maschinenfabr | Agitator mill for the finest grinding of suspensions such as paints, chemicals and cocoa |
| DE2164286C3 (en) * | 1971-12-23 | 1980-03-27 | Gebrueder Netzsch, Maschinenfabrik Gmbh & Co, 8672 Selb | Agitator mill |
| DE2457609B2 (en) * | 1974-12-05 | 1977-01-20 | Gustav Spangenberg Maschinenfabrik Gmbh, 6800 Mannheim | RUHRWERKSMÜHLE |
| ES222298Y (en) * | 1976-07-13 | 1977-05-01 | Oliver & Batlle, S. A. | PERFECTED DISC FOR GRINDING. |
| US4513917A (en) * | 1983-06-16 | 1985-04-30 | Morehouse Industries, Inc. | Sand mill rotor discs |
-
1989
- 1989-07-26 DE DE3924678A patent/DE3924678A1/en not_active Withdrawn
-
1990
- 1990-07-13 EP EP90113421A patent/EP0410229B1/en not_active Expired - Lifetime
- 1990-07-13 DE DE90113421T patent/DE59004741D1/en not_active Expired - Fee Related
- 1990-07-24 JP JP2194097A patent/JPH0360747A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3725411B1 (en) * | 2019-04-18 | 2023-12-13 | Twee "R" Recyclinggroep B.V. | An apparatus for removing adhered substance from particulate material or for crushing material |
Also Published As
| Publication number | Publication date |
|---|---|
| DE59004741D1 (en) | 1994-04-07 |
| EP0410229A1 (en) | 1991-01-30 |
| JPH0360747A (en) | 1991-03-15 |
| DE3924678A1 (en) | 1991-02-07 |
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