EP0173271B1 - Annular gap pebble mill - Google Patents

Annular gap pebble mill Download PDF

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Publication number
EP0173271B1
EP0173271B1 EP85110652A EP85110652A EP0173271B1 EP 0173271 B1 EP0173271 B1 EP 0173271B1 EP 85110652 A EP85110652 A EP 85110652A EP 85110652 A EP85110652 A EP 85110652A EP 0173271 B1 EP0173271 B1 EP 0173271B1
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EP
European Patent Office
Prior art keywords
grinding
gap
ball mill
annular
type ball
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP85110652A
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German (de)
French (fr)
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EP0173271A2 (en
EP0173271A3 (en
Inventor
Peter Fabian
Karl-Heinz Hoffmann
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Cessione erich Netzsch & Co Holding KG GmbH
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Reimbold und Strick GmbH and Co
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Priority to AT85110652T priority Critical patent/ATE39066T1/en
Publication of EP0173271A2 publication Critical patent/EP0173271A2/en
Publication of EP0173271A3 publication Critical patent/EP0173271A3/en
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Publication of EP0173271B1 publication Critical patent/EP0173271B1/en
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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
    • 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
    • B02C17/166—Mills in which a fixed container houses stirring means tumbling the charge of the annular gap type

Definitions

  • the invention relates to an annular gap ball mill for continuous fine grinding, in particular of mineral hard materials, with a standing grinding container closed by a lid, in which a rotor is arranged, the conical outer surface of which, with the conical inner surface of the grinding container, delimits a grinding gap which is connected to a feed opening and which contains grinding beads, the rotor having an upper part, the shape of which is matched to the inner surface of the cover and in the region of which an outlet opening is arranged.
  • Mineral hard materials such as corundum, zirconium dioxide, aluminum oxide, silicon carbide and similar substances, have so far been mainly crushed in ball mills with iron balls. This requires considerable dwell times of the material in the grinding chamber, and all parts that come into contact with the material to be ground and the iron balls are subject to very heavy wear. In addition, the grinding process is associated with annoying noise. Another disadvantage of such ball mills is that the abrasion of the iron balls gets into the regrind and has to be washed out in chemical washing processes in a complicated and expensive manner.
  • Annular gap ball mills of the type mentioned at the beginning (DE-OS 2848479) are said to be an improvement over the conventional ball mills, but are not very suitable for the fine grinding of mineral hard materials and only for the grinding of very much softer materials, e.g. Chalk and the like, economically. This is primarily due to the behavior of the grinding balls or grinding beads in the grinding gap.
  • the grinding beads which are pumped into the grinding gap through the feed opening from below or through a hollow shaft of the rotor from above, initially move through the pressure of the feed pump, with which the grinding material suspension is pressed into the annular gap ball mill, and through the rotational movement of the Rotors upwards in the grinding gap, but sink when the pump pressure decreases due to gravity and do not allow a grinding process to take place in the upper part of the grinding gap. If you want to prevent this, the feed pump pressure or the regrind flow must be increased in such a way that the grinding beads are also held in the upper part of the grinding gap; then there is the danger that the grinding beads are discharged together with the regrind, which in turn reduces the grinding performance.
  • the vane pump wheel only reinforces another disadvantage of this annular gap ball mill, which is that grinding beads that do not sag down are increasingly pumped to the outlet opening with the material to be ground and are therefore also lost to the grinding process.
  • the vane pump wheel is subject to heavy wear from grinding beads and regrind. Sieves are sometimes used to hold back the grinding beads in the grinding gap, but these can hinder and even prevent the regrind discharge if they are clogged with regrind and grinding beads.
  • a comparatively high collecting space above the rotor should ensure a uniform flow of regrind through the grinding chamber, which is limited by the convexly curved end face of the upper part of the rotor and the correspondingly convexly curved inner surface of the cover of the grinding container and with which the outlet opening is directly connected. This collection room cannot make any contribution to the retention of the grinding beads in the grinding gap.
  • annular gap ball mill (DE-OS-2811 899) has a regrind container, the inner surface of which delimits a grinding chamber into which a conical driver body is immersed, the inner surface of the regrind container and the displacement body being designed as an annular double cone.
  • the surfaces delimiting the grinding chamber can be roughened or raised or depressed, such as Ribs, grooves, pins and the like, provided, but this would lead to unacceptable wear especially when grinding hard materials.
  • the annular gap ball mill itself nor this special design are therefore suitable for the fine comminution of mineral hard materials.
  • the invention is based on the object of improving an annular gap ball mill of the type mentioned at the outset in such a way that, by increasing the performance of the grinding beads in the grinding gap, it is also possible to economically and technically optimally fine comminute mineral hard materials.
  • This object is achieved in that the upper part of the rotor and the cover are conical and delimit an annular outlet gap, the lower end of the largest diameter opening into an annular chamber at the open upper end of the largest diameter of the grinding gap.
  • any mineral hard material such as corundum, zirconium dioxide, aluminum oxide, silicon carbide and the like, can be finely ground economically, because the entire height of the grinding gap is used for the active grinding process of the grinding beads. This is due to the fact that hydrodynamics and centrifugal force, as a result of the conical design of the rotor and its upper part, generate a suction force which counteracts the gravity of the grinding beads and prevents them from sinking into the grinding gap.
  • the grinding gap is used 100% for the grinding process because it is penetrated by grinding pearls in its entire height and width even with a slowly rotating rotor and because discharge of grinding pearls with the ground material through the outlet opening and thus a reduction in the quantity of grinding pearls or the grinding effect is effectively prevented.
  • the latter is due to the fact that a predetermined excess of grinding pearls is located in the radial annular chamber at the upper end of the grinding gap, i.e. in the area of the largest rotor diameter, collects and forms a floating barrier layer there, which retains the active grinding beads in the grinding gap without preventing the finely ground material from escaping from the grinding gap in the direction of the outlet opening in the manner of a sieve or the like.
  • the regrind moved upwards to the outlet opening after the annular chamber through the narrow outlet gap between the upper rotor part and the lid contains practically no milling beads, so that a subsequent separation of milling beads and milling material is not necessary. Even if the width of the outlet gap is larger than the millbead diameter, the millbeads are not conveyed upward through the outlet gap because they are retained in the radial annular chamber by gravity or centrifugal force.
  • the annular gap ball mill according to the invention results in longer dwell times because lower circumferential speeds of the rotor and lower feed pump output can be used.
  • the millbase between the millbeads moves upwards very slowly, and the grain size of the millbase is narrow.
  • the annular gap ball mill according to the invention works extremely well with grinding beads of various sizes, the coarse, heavier grinding beads preferably grinding coarse parts of the ground material in the grinding gap below and the fine, lighter grinding pearls preferably grinding finer parts in the grinding gap above, because the centrifugal force and thus the buoyancy of the lighter particles increases upwards. If the material now remains in the grinding gap for a sufficiently long time, the hard material is ground in a short time into powder of the desired fineness and discharged in a continuous stream. Corresponding to the higher filling in the grinding gap, the utilization of the energy supplied to the rotor is greater and the operation of the annular gap ball mill is more economical.
  • the upper part and the inner surface of the cover have the shape of a truncated cone.
  • the grinding gap and the discharge gap are each formed with a parallel surface and that the grinding gap is wider than the discharge gap.
  • Further configurations of the grinding gap and the run-up gap can, however, be expedient for adaptation to the mineral hard material to be ground.
  • the grinding gap can widen upwards, while the outlet gap has a parallel surface. It is also possible that the grinding gap and the discharge gap each widen upwards. Furthermore, the grinding gap can widen upwards, while the outlet gap narrows upwards. In all cases there is an annular chamber which, in conjunction with the counter-rotating cone of the upper rotor part, picks up the barrier layer of grinding beads and prevents active grinding beads from being discharged from the grinding gap.
  • the annular chamber is advantageously located in the region of the dividing joint of the grinding container and the lid, so that after removing the lid, the grinding beads can be removed from the open half of the chamber.
  • the annular chamber is equipped with at least one opening for the inlet of grinding beads, so that these are separately added to the ground material introduced into the grinding gap from above. This helps prevent the grinding beads from sagging to the bottom of the grinding container.
  • the annular chamber has essentially parallel walls and on its circumferential end face che is rounded convex.
  • This shape of the chamber offers an adaptation to the spherical shape of the grinding beads in such a way that their abrasion is minimized.
  • the ratio of the height of the upper part to the total height of the rotor and upper part is 0.2 to 0.5: 1. So the top is shorter than the rotor.
  • the conical outer surface of the rotor expediently runs at an angle of 40 ° to 85 °, preferably 60 ° to 80 °, in particular 70 ° to 80 ° to the vertical.
  • the cone inclination of the rotor is adapted to the type of hard material to be shredded, and the cone inclination of the upper part results from the ratio of its height to the total height.
  • the inner surface of the grinding container and the lid as well as the outer surface of the rotor and its upper part have fine-rough surfaces. This means that under no circumstances should they be particularly smooth, nor should they be particularly rough.
  • the fine roughness can be achieved by a suitable coating of the surfaces, for example with polyurethane, which serves as a corrosion and wear protection layer.
  • the inside of the rotor can be ventilated.
  • the grinding container and the lid can be surrounded by a cooling liquid jacket. Exemplary embodiments of the invention are shown schematically in the drawing. 1 shows a longitudinal section of an annular gap ball mill, FIGS. 2, 3 and 4 longitudinal sections of an annular gap ball mill with different designs of the grinding gap and the outlet gap.
  • an annular gap ball mill 1 is suspended via an arm 11, which essentially consists of a stationary truncated cone-shaped grinding container 12 and a truncated cone-shaped rotor 13, which at its wide upper end is flush with the wide lower end of a truncated cone-shaped upper part 14 is whose height is less than the height of the rotor 13.
  • the upper part 14 is covered at a short distance from a lid 15 which is releasably attached to the grinding container 12 and is adapted to the conical inclination of the upper part 14.
  • the upper end of the upper part 14 engages with a vertical shaft 16, which bores the rotor 13 and upper part 14 in the grinding container 12 and transfers the drive of a motor 17 to the upper part 14 and rotor 13.
  • the entire inner surface of the grinding container 12 and the lid 15 is provided with a wear and corrosion-resistant lining 18, 19 which has a fine-rough surface and e.g. can consist of polyurethane.
  • the outer surface of the rotor 13 and its upper part 14 is equipped with a correspondingly fine-rough surface, which is not shown for the sake of clarity.
  • a parallel-walled annular grinding gap 20 is provided, which is connected via a horizontal space 22 between the flat bottoms of the grinding container 12 and the rotor 13 to a lower central feed opening 21 for the ground material.
  • an outlet gap 23 with a parallel surface, the width of which is smaller than the width of the grinding gap 20 and which extends over the entire height of the upper part 14.
  • the lower end of the downwardly diverging outlet gap 23 and the upper end of the upwardly diverging grinding gap 20 open into an annular chamber 24 which is essentially worked out in the linings 18 and 19.
  • top and bottom walls are flat and parallel to each other; its outer end face 25 is convexly curved. Since the chamber 24 lies on the dividing joint between the cover 15 and the grinding container 12, it can be opened by removing the cover 15.
  • a spacer 27 is inserted into the division joint 26, which can be exchanged for a spacer of a different thickness in order to raise or lower the grinding container 12 more or less with respect to the rotor 13 in order to change the width of the grinding gap 20.
  • the chamber 24 is accessible through an opening 28 in the cover flange. Through this opening 28 grinding beads are introduced into the grinding gap 20 when the rotor 13 rotates with the upper part 14 and mineral hard materials to be comminuted through the feed opening 21 have been introduced into the grinding gap 20 from below.
  • the shaft 16 passes through a discharge chamber 29 in a nozzle 30 which is flanged to the cover 15.
  • a nozzle 30 which is flanged to the cover 15.
  • In the wall of the nozzle 30 there is an outlet opening 31 for the finely ground material, which is pressed out of the outlet gap 23 into the discharge chamber 29.
  • baffles 32, 33 are arranged, which form ventilation slots.
  • the grinding container 12 is enclosed by a housing 34 which has a cooling water inlet 35 and a cooling water outlet 36.
  • the cover 15 is also surrounded by a housing 37 which is provided with a cooling water inlet 38 and a cooling water outlet 39.
  • the motor 17 When operating the annular gap ball mill 1, the motor 17 first rotates the rotor 13 with the upper part 14, then grinding material (slip) is introduced into the grinding gap 20 through the feed opening 21, and then 28 grinding beads are added through the opening, which result from the same material as the material to be shredded, so that the abrasion of the grinding beads does not contaminate the material to be ground and high-purity substances are generated. Since the conical design of the rotor 13 and its upper part 14 at the upper end of the grinding gap 20 achieves the highest circumferential speed, this results in an upward suction effect which prevents the grinding beads from falling in the grinding gap 20. An excess of grinding beads is collected in the chamber 24, so that a floating barrier layer is formed, which prevents grinding beads from escaping from the grinding gap 20.
  • the be in the grinding gap 20 sensitive grinding beads fill the grinding gap 20 over its entire height, so that it is 100% used for the grinding process and the ground material is exposed to a maximum grinding attack during its residence time in the grinding gap 20.
  • Grinding beads which have become so small due to abrasion, for example, that they fit into the outlet gap 23, are returned to the chamber 24 by the centrifugal force, so that the powder emerging from the outlet opening 31 contains no grinding beads and without aftertreatment such as washing or sieving in it desired final state is present. Since the grinding beads are reliably prevented from sedimentation in the grinding gap, the risk of starting difficulties or blocking of the rotor is averted. The wear of the parts is correspondingly low.
  • the degree of comminution can be influenced by the size of the grinding beads, which can be different if necessary, whereby a gradual comminution is achieved because coarse grinding beads in the lower part of the annular gap ball mill preferably grind the coarse parts and finer grinding beads in the upper part preferably comminute the finer parts .
  • annular gap ball mills 2, 3, 4 should essentially correspond to the construction according to FIG. 1. Only possible modifications of the cross sections of grinding gap and outlet gap are shown in the diagram, which can be advantageous depending on the type of mineral hard material to be comminuted.
  • annular radial chamber 24 which receives the grinding-pearl barrier layer and is located at the transition between grinding gap 20a, 20b, 20c to outlet gap 23a, 23b, 23c. This transition is essentially identical to the equator line between rotor 13a, 13b, 13c and upper part 14a, 14b, 14c.
  • the grinding gap 20a widens upwards, while the outlet gap 23a has a parallel surface.
  • the grinding gap 20b is wider at the top than at the bottom, and the outlet gap 23b also widens upwards.
  • FIG. 4 shows a further possible embodiment, according to which the grinding gap 20c widens upwards like the grinding gaps 20a and 20b, but the outlet gap 23c narrows upwards and opens into the chamber 24 with a wider lower end.
  • the angle of the bevel of the rotor 13, 13a, 13b, 13c to the vertical is advantageously 70 ° to 80 °. The best grinding results are achieved with this inclination.

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  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Crushing And Grinding (AREA)
  • Disintegrating Or Milling (AREA)
  • Milling Processes (AREA)
  • Hydrogenated Pyridines (AREA)
  • Heat Treatment Of Articles (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)

Abstract

The annular gap-type ball mill for the continuous pulverization in particular of hard mineral substances comprises a closed grinding container (12) driven rotatingly and accommodating a rotor (13) driven in opposite direction. The outer surface of the rotor defines with the inner face of the grinding container (12) a grinding gap (20) which may contain grinding pellets.

Description

Die Erfindung betrifft eine Ringspalt-Kugelmühle zum kontinuierlichen Feinstzerkleinern insbesondere von mineralischen Hartstoffen mit einem von einem Deckel verschlossenen, stehenden Mahlbehälter, in dem ein Rotor angeordnet ist, dessen kegelförmige Aussenfläche mit der kegelförmigen Innenfläche des Mahlbehälters einen Mahlspalt begrenzt, der mit einer Speiseöffnung verbunden ist und der Mahlperlen enthält, wobei der Rotor ein Oberteil aufweist, dessen Form der Innenfläche des Deckels angeglichen ist und in dessen Bereich eine Auslassöffnung angeordnet ist.The invention relates to an annular gap ball mill for continuous fine grinding, in particular of mineral hard materials, with a standing grinding container closed by a lid, in which a rotor is arranged, the conical outer surface of which, with the conical inner surface of the grinding container, delimits a grinding gap which is connected to a feed opening and which contains grinding beads, the rotor having an upper part, the shape of which is matched to the inner surface of the cover and in the region of which an outlet opening is arranged.

Mineralische Hartstoffe (Mohssche Härte >5), wie Korund, Zirkoniumdioxid, Aluminiumoxid, Siliciumcarbid und ähnliche Stoffe, werden bisher vorwiegend in Kugelmühlen mit Eisenkugeln feinzerkleinert. Hierbei sind beträchtliche Verweilzeiten des Gutes im Mahlraum erforderlich, und alle mit dem Mahlgut und den Eisenkugeln in Berührung kommenden Teile unterliegen sehr starkem Verschleiss. Ausserdem ist der Mahlvorgang mit störender Geräuschentwicklung verbunden. Ein weiterer Nachteil solcher Kugelmühlen besteht darin, dass der Abrieb der Eisenkugeln in das Mahlgut gelangt und in chemischen Waschprozessen auf komplizierte aufwendige Weise herausgewaschen werden muss.Mineral hard materials (Mohs hardness> 5), such as corundum, zirconium dioxide, aluminum oxide, silicon carbide and similar substances, have so far been mainly crushed in ball mills with iron balls. This requires considerable dwell times of the material in the grinding chamber, and all parts that come into contact with the material to be ground and the iron balls are subject to very heavy wear. In addition, the grinding process is associated with annoying noise. Another disadvantage of such ball mills is that the abrasion of the iron balls gets into the regrind and has to be washed out in chemical washing processes in a complicated and expensive manner.

Ringspalt-Kugelmühlen der eingangs erwähnten Art (DE-OS 2848479) sollen zwar gegenüber den herkömmlichen Kugelmühlen eine Verbesserung darstellen, sind zum Feinzerkleinern von mineralischen Hartstoffen aber wenig geeignet und nur bei der Zerkleinerung von sehr viel weicheren Stoffen, z.B. Kreide und dergleichen, wirtschaftlich. Dies ist vor allem auf das Verhalten der Mahlkugeln oder Mahlperlen in dem Mahlspalt zurückzuführen. Die zusammen mit dem Mahlgut durch die Speiseöffnung von unten oder durch eine Hohlwelle des Rotors von oben in den Mahlspalt eingepumpten Mahlperlen bewegen sich zwar zunächst durch den Druck der Speisepumpe, mit der die Mahlgutsuspension in die Ringspalt-Kugelmühle gedrückt wird, sowie durch die Rotationsbewegung des Rotors in dem Mahlspalt nach oben, sacken jedoch bei Nachlassen des Pumpendruckes durch Schwerkraft nach unten und lassen einen Mahlvorgang im oberen Teil des Mahlspaltes gar nicht stattfinden. Will man dies verhindern, muss der Speisepumpendruck bzw. der Mahlgutdurchfluss derart erhöht werden, dass zwar die Mahlperlen auch im oberen Teil des Mahlspaltes gehalten werden; dann besteht aber die Gefahr, dass die Mahlperlen zusammen mit dem Mahlgut ausgetragen werden, was wiederum die Mahlleistung reduziert. Erfahrungsgemäss wird daher bei einer mittleren Durchflussgeschwindigkeit des Mahlgutes nur etwa die untere Hälfte des Mahlspaltes für den Mahlvorgang ausgenutzt, und die theoretisch erzielbare Mahlleistung ist demgemäss nur etwa zur Hälfte realisiert. Ausserdem bewirkt die hohe Packungsdichte der Mahlperlen im unteren Teil des Mahlspaltes einen hohen Abrieb an der Oberfläche des Rotors und des Mahlbehälters, und es kann, insbesondere nach einer kurzen Stillstandszeit des Rotors oder der Speisepumpe, sogarzu Blockierungen des Rotors kommen. Dieses Risiko soll bei der vorgenannten Ringspalt-Kugelmühle dadurch reduziert werden, dass der Rotor an seinem unteren Ende mit einem Flügelpumpenrad versehen ist. Das Flügelpumpenrad verstärkt jedoch nur einen weiteren Nachteil dieser Ringspalt-Kugelmühle, der darin besteht, dass Mahlperlen, die nicht nach unten sacken, mit dem Mahlgut verstärkt zur Auslassöffnung gepumpt werden und auch dadurch für den Mahlvorgang verloren sind. Überdies unterliegt das Flügelpumpenrad einem starken Verschleiss durch Mahlperlen und Mahlgut. Bisweilen werden zur Zurückhaltung der Mahlperlen in dem Mahlspalt Siebe benutzt, die jedoch den Mahlgutaustrag behindern und sogar verhindern können, wenn sie mit Mahlgut und Mahlperlen zugesetzt sind.Annular gap ball mills of the type mentioned at the beginning (DE-OS 2848479) are said to be an improvement over the conventional ball mills, but are not very suitable for the fine grinding of mineral hard materials and only for the grinding of very much softer materials, e.g. Chalk and the like, economically. This is primarily due to the behavior of the grinding balls or grinding beads in the grinding gap. The grinding beads, which are pumped into the grinding gap through the feed opening from below or through a hollow shaft of the rotor from above, initially move through the pressure of the feed pump, with which the grinding material suspension is pressed into the annular gap ball mill, and through the rotational movement of the Rotors upwards in the grinding gap, but sink when the pump pressure decreases due to gravity and do not allow a grinding process to take place in the upper part of the grinding gap. If you want to prevent this, the feed pump pressure or the regrind flow must be increased in such a way that the grinding beads are also held in the upper part of the grinding gap; then there is the danger that the grinding beads are discharged together with the regrind, which in turn reduces the grinding performance. Experience has shown that at an average flow rate of the material to be ground, only about the lower half of the grinding gap is used for the grinding process, and the theoretically achievable grinding capacity is accordingly only about half realized. In addition, the high packing density of the grinding beads in the lower part of the grinding gap causes a high level of abrasion on the surface of the rotor and the grinding container, and the rotor may even become blocked, especially after the rotor or the feed pump has come to a short standstill. This risk is to be reduced in the aforementioned annular gap ball mill by providing the rotor with a vane pump wheel at its lower end. The vane pump wheel, however, only reinforces another disadvantage of this annular gap ball mill, which is that grinding beads that do not sag down are increasingly pumped to the outlet opening with the material to be ground and are therefore also lost to the grinding process. In addition, the vane pump wheel is subject to heavy wear from grinding beads and regrind. Sieves are sometimes used to hold back the grinding beads in the grinding gap, but these can hinder and even prevent the regrind discharge if they are clogged with regrind and grinding beads.

Für eine einheitliche Mahlgutströmung durch den Mahlraum soll bei der erwähnten Ringspalt-Kugelmühle ein verhältnismässig hoher Sammelraum über dem Rotor sorgen, der durch die konvex gekrümmte Stirnfläche des Oberteiles des Rotors und die entsprechend konvex gekrümmte Innenfläche des Deckels des Mahlbehälters begrenzt wird und mit dem die Auslassöffnung direkt verbunden ist. Zur Zurückhaltung der Mahlperlen im Mahlspalt kann dieser Sammelraum keinen Beitrag leisten.For the above-mentioned annular gap ball mill, a comparatively high collecting space above the rotor should ensure a uniform flow of regrind through the grinding chamber, which is limited by the convexly curved end face of the upper part of the rotor and the correspondingly convexly curved inner surface of the cover of the grinding container and with which the outlet opening is directly connected. This collection room cannot make any contribution to the retention of the grinding beads in the grinding gap.

Die durch Verdichtung der Mahlperlen am unteren Ende eines zur Senkrechten schräg gerichteten, ringförmigen Mahlspaltes bewirkte Erschwerung des Anfahrens des Rotors und das Einschleifen von Verschleissmarkierungen an Rotor und Mahlbehälter sollen bei einer anderen Ringspalt-Kugelmühle (DE-OS 3022809) dadurch verhindert werden, dass Rotor und Mahlbehälter im Bedarfsfalle zur Verbreiterung des Mahlspaltes axial auseinandergezogen werden. Zu diesem Zweck sind komplizierte technische Vorkehrungen nötig, die die Ringspalt-Kugelmühle verteuern. Eine Erhöhung der Leistung der Mahlperlen in dem Mahlspalt, d.h. die Ausnutzung der gesamten Mahlspalthöhe für den Mahlvorgang, wird jedoch hiermit nur in geringem Umfang erzielt; denn die in dem abwärts/auswärts gerichteten Mahlspalt befindlichen Mahlperlen folgen dem Mahlgutstrom und wirken nicht, wie in dem aufwärts gerichteten Mahlspalt, diesem entgegen, so dass in diesem Teil des Mahlspaltes nur geringe Arbeit geleistet wird.The aggravation of the start-up of the rotor caused by the compaction of the grinding beads at the lower end of an annular grinding gap which is inclined to the vertical and the grinding in of wear marks on the rotor and grinding container are to be prevented in another annular gap ball mill (DE-OS 3022809) by preventing the rotor and the grinding container are pulled apart axially if necessary to widen the grinding gap. For this purpose, complicated technical measures are required, which make the annular gap ball mill more expensive. An increase in the performance of the grinding beads in the grinding gap, i.e. the utilization of the entire grinding gap height for the grinding process, however, is only achieved to a small extent with this; because the grinding beads located in the downward / outward grinding gap follow the grinding material flow and do not counteract it, as in the upward grinding gap, so that only little work is done in this part of the grinding gap.

Eine andere bekannte Ringspalt-Kugelmühle (DE-OS-2811 899) weist einen Mahlgutbehälter auf, dessen Innenfläche einen Mahlraum begrenzt, in den ein kegelförmiger Mitnahmekörper eintaucht, wobei die Innenfläche des Mahlgutbehälters und der Verdrängungskörper als ringförmige Doppelkegel ausgebildet sind. Als eventuelle weitere Ausführungsform können die den Mahlraum begrenzenden Flächen mit Aufrauhungen bzw. Erhebungen oder Vertiefungen, wie Rippen, Rillen, Stiften und dergleichen, versehen sein, doch würde dies gerade beim Mahlen von Hartstoffen zu einem untragbaren Verschleiss führen. Weder die Ringspalt-Kugelmühle selbst noch diese spezielle Ausführungsart sind somit zur Feinzerkleinerung von mineralischen Hartstoffen geeignet.Another known annular gap ball mill (DE-OS-2811 899) has a regrind container, the inner surface of which delimits a grinding chamber into which a conical driver body is immersed, the inner surface of the regrind container and the displacement body being designed as an annular double cone. As a possible further embodiment, the surfaces delimiting the grinding chamber can be roughened or raised or depressed, such as Ribs, grooves, pins and the like, provided, but this would lead to unacceptable wear especially when grinding hard materials. Neither the annular gap ball mill itself nor this special design are therefore suitable for the fine comminution of mineral hard materials.

Der Erfindung liegt demgegenüber die Aufgabe zugrunde, eine Ringspalt-Kugelmühle der eingangs erwähnten Art so zu verbessern, dass sie durch Erhöhung der Leistung der Mahlperlen in dem Mahlspalt eine wirtschaftlich und technisch optimale Feinstzerkleinerung auch von mineralischen Hartstoffen ermöglicht. Diese Aufgabe wird dadurch gelöst, dass das Oberteil des Rotors und der Deckel kegelförmig gestaltet sind und einen ringförmigen Auslaufspalt begrenzen, dessen unteres Ende grössten Durchmessers in eine ringförmige Kammer am offenen oberen Ende grössten Durchmessers des Mahlspaltes mündet.In contrast, the invention is based on the object of improving an annular gap ball mill of the type mentioned at the outset in such a way that, by increasing the performance of the grinding beads in the grinding gap, it is also possible to economically and technically optimally fine comminute mineral hard materials. This object is achieved in that the upper part of the rotor and the cover are conical and delimit an annular outlet gap, the lower end of the largest diameter opening into an annular chamber at the open upper end of the largest diameter of the grinding gap.

Mit einer in dieser Weise ausgebildeten Ringspalt-Kugelmühle kann beliebiges mineralisches Hartmaterial, wie Korund, Zirkoniumdioxid, Aluminiumoxid, Siliciumcarbid und dergleichen, wirtschaftlich feinstzermahlen werden, weil die gesamte Höhe des Mahlspaltes für den aktiven Mahlvorgang der Mahlperlen ausgenutzt wird. Dies ist darauf zurückzuführen, dass Hydrodynamik und Zentrifugalkraft als Folge der konischen Ausbildung des Rotors und seines Oberteils eine Saugkraft erzeugen, die der Schwerkraft der Mahlperlen entgegenwirkt und deren Absinken in den Mahlspalt verhindert. Der Mahlspalt wird 100%ig für den Mahlvorgang ausgenutzt, weil er sogar bei langsam rotierendem Rotor in seiner gesamten Höhe und Breite von Mahlperlen durchsetzt ist und weil eine Austragung von Mahlperlen mit dem Mahlgut durch die Auslassöffnung und damit eine Reduzierung der Mahlperlenmenge bzw. der Mahlwirkung wirksam verhindert wird. Letzteres ist darauf zurückzuführen, dass ein vorgegebener Mahlperlenüberschuss sich in der radialen ringförmigen Kammer am oberen Ende des Mahlspaltes, d.h. im Bereich des grössten Rotordurchmessers, sammelt und dort eine schwimmende Sperrschicht bildet, die die aktiven Mahlperlen im Mahlspalt zurückhält, ohne nach der Art eines Siebes oder dergleichen den Austritt des feinstgemahlenen Stoffes aus dem Mahlspalt in Richtung der Auslassöffnung zu behindern. Das nach der ringförmigen Kammer durch den schmalen Auslaufspalt zwischen Rotoroberteil und Deckel nach oben zur Auslassöffnung bewegte Mahlgut enthält praktisch keine Mahlperlen, so dass eine nachträgliche Trennung von Mahlperlen und Mahlgut entfällt. Selbst wenn die Breite des Auslaufspaltes grösser ist als der Mahlperlendurchmesser, werden die Mahlperlen nicht durch den Auslaufspalt nach oben gefördert, weil sie durch die Schwerkraft bzw. Zentrifugalkraft in der radialen ringförmigen Kammer zurückgehalten werden. Bei der erfindungsgemässen Ringspalt-Kugelmühle ergeben sich verlängerte Verweilzeiten, weil mit niedrigeren Umfangsgeschwindigkeiten des Rotors und geringerer Speisepumpenleistung gearbeitet werden kann. Das Mahlgut zwischen den Mahlperlen bewegt sich entsprechend ganz langsam nach oben, und es ergibt sich ein enges Kornspektrum des Mahlgutes. Die erfindungsgemässe Ringspalt-Kugelmühle arbeitet ausserordentlich gut mit Mahlperlen verschiedener Grösse, wobei die groben, schwereren Mahlperlen unten im Mahlspalt vorzugsweise grobe Teile des Mahlgutes vermahlen und die feinen, leichteren Mahlperlen oben im Mahlspalt vorzugsweise feinere Teile vermahlen, weil die Zentrifugalkraft und damit der Auftrieb der leichteren Partikel nach oben zunimmt. Bei nunmehr ausreichend langer Verweilzeit des Gutes in dem Mahlspalt wird das Hartmaterial in kurzer Zeit in Pulver gewünschter Feinheit zermahlen und in kontinuierlichem Strom ausgetragen. Entsprechend der höheren Füllung im Mahlspalt ist auch die Ausnutzung der dem Rotor zugeführten Energie grösser und der Betrieb der Ringspalt-Kugelmühle wirtschaftlicher.With an annular gap ball mill designed in this way, any mineral hard material, such as corundum, zirconium dioxide, aluminum oxide, silicon carbide and the like, can be finely ground economically, because the entire height of the grinding gap is used for the active grinding process of the grinding beads. This is due to the fact that hydrodynamics and centrifugal force, as a result of the conical design of the rotor and its upper part, generate a suction force which counteracts the gravity of the grinding beads and prevents them from sinking into the grinding gap. The grinding gap is used 100% for the grinding process because it is penetrated by grinding pearls in its entire height and width even with a slowly rotating rotor and because discharge of grinding pearls with the ground material through the outlet opening and thus a reduction in the quantity of grinding pearls or the grinding effect is effectively prevented. The latter is due to the fact that a predetermined excess of grinding pearls is located in the radial annular chamber at the upper end of the grinding gap, i.e. in the area of the largest rotor diameter, collects and forms a floating barrier layer there, which retains the active grinding beads in the grinding gap without preventing the finely ground material from escaping from the grinding gap in the direction of the outlet opening in the manner of a sieve or the like. The regrind moved upwards to the outlet opening after the annular chamber through the narrow outlet gap between the upper rotor part and the lid contains practically no milling beads, so that a subsequent separation of milling beads and milling material is not necessary. Even if the width of the outlet gap is larger than the millbead diameter, the millbeads are not conveyed upward through the outlet gap because they are retained in the radial annular chamber by gravity or centrifugal force. The annular gap ball mill according to the invention results in longer dwell times because lower circumferential speeds of the rotor and lower feed pump output can be used. The millbase between the millbeads moves upwards very slowly, and the grain size of the millbase is narrow. The annular gap ball mill according to the invention works extremely well with grinding beads of various sizes, the coarse, heavier grinding beads preferably grinding coarse parts of the ground material in the grinding gap below and the fine, lighter grinding pearls preferably grinding finer parts in the grinding gap above, because the centrifugal force and thus the buoyancy of the lighter particles increases upwards. If the material now remains in the grinding gap for a sufficiently long time, the hard material is ground in a short time into powder of the desired fineness and discharged in a continuous stream. Corresponding to the higher filling in the grinding gap, the utilization of the energy supplied to the rotor is greater and the operation of the annular gap ball mill is more economical.

In vorteilhafter Ausgestaltung der Erfindung ist vorgesehen, dass das Oberteil und die Innenfläche des Deckels Kegelstumpfform aufweisen.In an advantageous embodiment of the invention it is provided that the upper part and the inner surface of the cover have the shape of a truncated cone.

Es hat sich als optimal erwiesen, dass Mahlspalt und Auslaufspalt jeweils parallelflächig ausgebildet sind und dass der Mahlspalt breiter ist als der Auslaufspalt. Weitere Ausgestaltungen des Mahlspaltes und des Auflaufspaltes können jedoch zur Anpassung an den zu mahlenden mineralischen Hartstoff zweckmässig sein. Es kann sich der Mahlspalt nach oben verbreitern, während der Auslaufspalt parallelflächig ist. Auch ist es möglich, dass der Mahlspalt und der Auslaufspalt sich jeweils nach oben verbreitern. Ferner kann der Mahlspalt sich nach oben verbreitern, während der Auslaufspalt sich nach oben verengt. In allen Fällen ist die ringförmige Kammer vorhanden, die in Verbindung mit dem gegenläufigen Konus des Rotoroberteils die Sperrschicht von Mahlperlen aufnimmt und den Austrag von aktiven Mahlperlen aus dem Mahlspalt verhindert.It has proven to be optimal that the grinding gap and the discharge gap are each formed with a parallel surface and that the grinding gap is wider than the discharge gap. Further configurations of the grinding gap and the run-up gap can, however, be expedient for adaptation to the mineral hard material to be ground. The grinding gap can widen upwards, while the outlet gap has a parallel surface. It is also possible that the grinding gap and the discharge gap each widen upwards. Furthermore, the grinding gap can widen upwards, while the outlet gap narrows upwards. In all cases there is an annular chamber which, in conjunction with the counter-rotating cone of the upper rotor part, picks up the barrier layer of grinding beads and prevents active grinding beads from being discharged from the grinding gap.

Vorteilhafterweise befindet sich die ringförmige Kammer im Bereich der Teilungsfuge von Mahlbehälter und Deckel, so dass nach Abnahme des Deckels die Mahlperlen aus der offenen Hälfte der Kammer herausgenommen werden können. Die ringförmige Kammer ist mit mindestens einer Öffnung zum Einlass von Mahlperlen ausgestattet, so dass diese separat dem in den Mahlspalt eingeführten Mahlgut von oben zugegeben werden. Hierdurch wird die Verhinderung des Absackens der Mahlperlen auf den Boden des Mahlbehälters unterstützt. Ausserdem wird eine Erleichterung bei der Beschickung der Ringspalt-Kugelmühle mit dem zu zerkleinernden Gut erzielt, weil dieses nicht, wie bisher nötig, erst mit den Mahlperlen vermischt und dann mit diesen gemeinsam eingespeist werden muss.The annular chamber is advantageously located in the region of the dividing joint of the grinding container and the lid, so that after removing the lid, the grinding beads can be removed from the open half of the chamber. The annular chamber is equipped with at least one opening for the inlet of grinding beads, so that these are separately added to the ground material introduced into the grinding gap from above. This helps prevent the grinding beads from sagging to the bottom of the grinding container. In addition, there is a relief in the loading of the annular gap ball mill with the material to be comminuted, because this does not have to be mixed with the grinding beads first and then fed in together with these.

Es hat sich als vorteilhaft erwiesen, dass die ringförmige Kammer im wesentlichen parallelwandig und an ihrer umfangsmässigen Stirnfläche konvex abgerundet ist. Diese Form der Kammer bietet eine Anpassung an die Kugelform der Mahlperlen derart, dass deren Abrieb minimiert wird.It has proven to be advantageous that the annular chamber has essentially parallel walls and on its circumferential end face che is rounded convex. This shape of the chamber offers an adaptation to the spherical shape of the grinding beads in such a way that their abrasion is minimized.

Das Verhältnis der Höhe des Oberteiles zur Gesamthöhe von Rotor und Oberteil beträgt 0,2 bis 0,5:1. Das Oberteil ist also kürzer als der Rotor. Zweckmässigerweise verläuft die konische Aussenfläche des Rotors unter einem Winkel von 40° bis 85°, vorzugsweise 60° bis 80°, insbesondere 70° bis 80° zur Senkrechten. Die Konusneigung des Rotors wird der Art des zu zerkleinernden Hartstoffes angepasst, und die Konusneigung des Oberteiles ergibt sich durch das Verhältnis seiner Höhe zur Gesamthöhe entsprechend.The ratio of the height of the upper part to the total height of the rotor and upper part is 0.2 to 0.5: 1. So the top is shorter than the rotor. The conical outer surface of the rotor expediently runs at an angle of 40 ° to 85 °, preferably 60 ° to 80 °, in particular 70 ° to 80 ° to the vertical. The cone inclination of the rotor is adapted to the type of hard material to be shredded, and the cone inclination of the upper part results from the ratio of its height to the total height.

Die Innenfläche des Mahlbehälters und des Deckels sowie die Aussenfläche des Rotors und seines Oberteiles weisen feinrauhe Oberflächen auf. Dies bedeutet, dass sie keinesfalls besonders glatt sein dürfen, aber auch nicht besonders rauh sein sollten. Die Feinrauhigkeit kann durch eine geeignete Beschichtung der Oberflächen, beispielsweise mit Polyurethan, erzielt werden, die als Korrosions- und Verschleissschutzschicht dient. Zur Vermeidung von Wärmestaus kann der Rotor innen belüftet sein. Ausserdem können der Mahlbehälter und der Deckel von einem Kühlflüssigkeitsmantel umgeben sein. In der Zeichnung sind Ausführungsbeispiele der Erfindung schematisch dargestellt. Es zeigen: Fig. 1 einen Längsschnitt einer Ringspalt-Kugelmühle, Fig. 2, 3 und 4 Längsschnitte von Ringspalt-Kugelmühlen mit anderen Gestaltungen des Mahlspaltes und des Auslaufspaltes.The inner surface of the grinding container and the lid as well as the outer surface of the rotor and its upper part have fine-rough surfaces. This means that under no circumstances should they be particularly smooth, nor should they be particularly rough. The fine roughness can be achieved by a suitable coating of the surfaces, for example with polyurethane, which serves as a corrosion and wear protection layer. To avoid heat build-up, the inside of the rotor can be ventilated. In addition, the grinding container and the lid can be surrounded by a cooling liquid jacket. Exemplary embodiments of the invention are shown schematically in the drawing. 1 shows a longitudinal section of an annular gap ball mill, FIGS. 2, 3 and 4 longitudinal sections of an annular gap ball mill with different designs of the grinding gap and the outlet gap.

An einem beliebigen Gestell 10 ist über einen Arm 11 eine Ringspalt-Kugelmühle 1 aufgehängt, die im wesentlichen aus einem stillstehenden kegelstumpfförmigen Mahlbehälter 12 und einem kegelstumpfförmigen Rotor 13 besteht, der an seinem breiten oberen Ende bündig mit dem breiten unteren Ende eines kegelstumpfförmigen Oberteiles 14 zusammengesetzt ist, dessen Höhe geringer als die Höhe des Rotors 13 ist. Das Oberteil 14 wird mit geringem Abstand von einem Deckel 15 abgedeckt, der lösbar auf dem Mahlbehälter 12 befestigt und der konischen Schrägneigung des Oberteiles 14 angepasst ist. Das obere Ende des Oberteils 14 greift an eine senkrechte Welle 16 an, die Rotor 13 und Oberteil l4freifliegend in dem Mahlbehälter 12 lagert und den Antrieb eines Motors 17 auf Oberteil 14 und Rotor 13 überträgt. Die gesamte Innenfläche des Mahlbehälters 12 und des Deckels 15 ist mit einer verschleiss- und korrosionsfesten Auskleidung 18, 19 versehen, die eine feinrauhe Oberfläche hat und z.B. aus Polyurethan bestehen kann. Die Aussenfläche des Rotors 13 und seines Oberteiles 14 ist mit einer entsprechend feinrauhen Oberfläche ausgestattet, die der Deutlichkeit halber nicht gezeichnet ist.On any frame 10, an annular gap ball mill 1 is suspended via an arm 11, which essentially consists of a stationary truncated cone-shaped grinding container 12 and a truncated cone-shaped rotor 13, which at its wide upper end is flush with the wide lower end of a truncated cone-shaped upper part 14 is whose height is less than the height of the rotor 13. The upper part 14 is covered at a short distance from a lid 15 which is releasably attached to the grinding container 12 and is adapted to the conical inclination of the upper part 14. The upper end of the upper part 14 engages with a vertical shaft 16, which bores the rotor 13 and upper part 14 in the grinding container 12 and transfers the drive of a motor 17 to the upper part 14 and rotor 13. The entire inner surface of the grinding container 12 and the lid 15 is provided with a wear and corrosion-resistant lining 18, 19 which has a fine-rough surface and e.g. can consist of polyurethane. The outer surface of the rotor 13 and its upper part 14 is equipped with a correspondingly fine-rough surface, which is not shown for the sake of clarity.

Zwischen der Aussenfläche des Rotors 13 und der Innenfläche des Mahlbehälters 12 ist ein parallelwandiger ringförmiger Mahlspalt 20 vorgesehen, der über einen waagerechten Zwischenraum 22 zwischen den ebenen Böden des Mahlbehälters 12 und des Rotors 13 mit einer unteren zentralen Speiseöffnung 21 für das Mahlgut in Verbindung steht. Zwischen dem Oberteil 14 und dem Deckel 15 bzw. seiner Beschichtung 19 ist ein ebenfalls parallelflächiger Auslaufspalt 23 vorhanden, dessen Breite geringer ist als die Breite des Mahlspalts 20 und der sich über die ganze Höhe des Oberteiles 14 erstreckt. Das untere Ende des nach unten divergierenden Auslaufspaltes 23 und das obere Ende des nach oben divergierenden Mahlspaltes 20 münden in eine ringförmige Kammer 24, die im wesentlichen in den Auskleidungen 18 und 19 ausgearbeitet ist. Ihre obere und untere Wand sind eben und zueinander parallel; ihre äussere Stirnfläche 25 verläuft konvex gekrümmt. Da die Kammer 24 auf der Teilungsfuge zwischen Deckel 15 und Mahlbehälter 12 liegt, lässt sie sich durch Abnahme des Deckels 15 öffnen. In die Teilungsfuge 26 ist eine Distanzscheibe 27 eingesetzt, die gegen eine Distanzscheibe anderer Dicke ausgetauscht werden kann, um zur Änderung der Breite des Mahlspaltes 20 den Mahlbehälter 12 in bezug auf den Rotor 13 mehr oder weniger anzuheben oder abzusenken. Die Kammer 24 ist durch eine Öffnung 28 im Deckelflansch zugänglich. Durch diese Öffnung 28 werden Mahlperlen in den Mahlspalt 20 eingeführt, wenn der Rotor 13 mit Oberteil 14 rotiert und durch die Speiseöffnung 21 zu zerkleinernde mineralische Hartstoffe von unten in den Mahlspalt 20 eingebracht worden sind.Between the outer surface of the rotor 13 and the inner surface of the grinding container 12, a parallel-walled annular grinding gap 20 is provided, which is connected via a horizontal space 22 between the flat bottoms of the grinding container 12 and the rotor 13 to a lower central feed opening 21 for the ground material. Between the upper part 14 and the cover 15 or its coating 19 there is also an outlet gap 23 with a parallel surface, the width of which is smaller than the width of the grinding gap 20 and which extends over the entire height of the upper part 14. The lower end of the downwardly diverging outlet gap 23 and the upper end of the upwardly diverging grinding gap 20 open into an annular chamber 24 which is essentially worked out in the linings 18 and 19. Its top and bottom walls are flat and parallel to each other; its outer end face 25 is convexly curved. Since the chamber 24 lies on the dividing joint between the cover 15 and the grinding container 12, it can be opened by removing the cover 15. A spacer 27 is inserted into the division joint 26, which can be exchanged for a spacer of a different thickness in order to raise or lower the grinding container 12 more or less with respect to the rotor 13 in order to change the width of the grinding gap 20. The chamber 24 is accessible through an opening 28 in the cover flange. Through this opening 28 grinding beads are introduced into the grinding gap 20 when the rotor 13 rotates with the upper part 14 and mineral hard materials to be comminuted through the feed opening 21 have been introduced into the grinding gap 20 from below.

Die Welle 16 durchquert eine Austragkammer 29 in einem Stutzen 30, der an den Deckel 15 angeflanscht ist. In der Wand des Stutzens 30 befindet sich eine Auslassöffnung 31 für das feingemahlene Gut, das aus dem Auslaufspalt 23 in die Austragkammer 29 hineingedrückt wird. Am oberen Ende des Stutzens 30 sind Leitbleche 32, 33 angeordnet, die Entlüftungsschlitze bilden.The shaft 16 passes through a discharge chamber 29 in a nozzle 30 which is flanged to the cover 15. In the wall of the nozzle 30 there is an outlet opening 31 for the finely ground material, which is pressed out of the outlet gap 23 into the discharge chamber 29. At the upper end of the nozzle 30 baffles 32, 33 are arranged, which form ventilation slots.

Der Mahlbehälter 12 wird von einem Gehäuse 34 umschlossen, das einen Kühlwasserzulauf 35 und einen Kühlwasserauslass 36 aufweist. Auch der Deckel 15 ist von einem Gehäuse 37 umgeben, das mit einem Kühlwasserzulauf 38 und einem Kühlwasserauslass 39 versehen ist.The grinding container 12 is enclosed by a housing 34 which has a cooling water inlet 35 and a cooling water outlet 36. The cover 15 is also surrounded by a housing 37 which is provided with a cooling water inlet 38 and a cooling water outlet 39.

Beim Betrieb der Ringspalt-Kugelmühle 1 versetzt zunächst der Motor 17 den Rotor 13 mit Oberteil 14 in Drehung, dann wird durch die Speiseöffnung 21 Mahlgut (Schlicker) in den Mahlspalt 20 eingeführt, und anschliessend werden durch die Öffnung 28 Mahlperlen zugegeben, die aus dem gleichen Material wie das zu zerkleinernde Gut bestehen können, damit der Abrieb der Mahlperlen das Mahlgut nicht verunreinigt und hochreine Stoffe erzeugt werden. Da durch die konische Ausbildung des Rotors 13 und seines Oberteils 14 am oberen Ende des Mahlspaltes 20 die höchste Umfangsgeschwindigkeit erreicht wird, ergibt sich ein nach oben gerichteter Saugeffekt, der ein Absinken der Mahlperlen im Mahlspalt 20 verhindert. Ein Überschuss an Mahlperlen wird in der Kammer 24 gesammelt, so dass eine schwimmende Sperrschicht entsteht, die einen Austritt von Mahlperlen aus dem Mahlspalt 20 verhindert. Die im Mahlspalt 20 befindlichen Mahlperlen füllen den Mahlspalt 20 über seine ganze Höhe aus, so dass dieser 100%ig für den Mahlvorgang ausgenutzt wird und das Mahlgut während seiner Verweilzeit im Mahlspalt 20 einem maximalen Mahlangriff ausgesetzt ist. Mahlperlen, die beispielsweise durch Abrieb so klein geworden sind, dass sie in den Auslaufspalt 23 passen, werden durch die Zentrifugalkraft in die Kammer 24 zurückgeführt, so dass das aus der Auslassöffnung 31 austretende Pulver keine Mahlperlen enthält und ohne Nachbehandlung wie Waschen oder Sieben in seinem gewünschten Endzustand vorliegt. Da die Mahlperlen zuverlässig an einer Sedimentation im Mahlspalt gehindert werden, ist die Gefahr von Anlaufschwierigkeiten oder Blockierung des Rotors gebannt. Der Verschleiss der Teile ist entsprechend gering. Mit geringer Energieaufnahme werden hohe Mahlleistungen bei mineralischen Hartstoffen erzielt, wobei die Länge der Verweilzeit des Gutes in dem Mahlspalt durch passende Wahl der Umfangsgeschwindigkeit und der Breite des Mahlspaltes eingestellt werden kann. Der Zerkleinerungsgrad lässt sich durch die Grösse der Mahlperlen beeinflussen, die gegebenenfalls unterschiedlich sein kann, wodurch eine stufenweise Zerkleinerung erreicht wird, weil grobe Mahlperlen im unteren Teil der Ringspalt-Kugelmühle vorzugsweise die groben Teile mahlen und feinere Mahlperlen im oberen Teil vorzugsweise die feineren Teile zerkleinern.When operating the annular gap ball mill 1, the motor 17 first rotates the rotor 13 with the upper part 14, then grinding material (slip) is introduced into the grinding gap 20 through the feed opening 21, and then 28 grinding beads are added through the opening, which result from the same material as the material to be shredded, so that the abrasion of the grinding beads does not contaminate the material to be ground and high-purity substances are generated. Since the conical design of the rotor 13 and its upper part 14 at the upper end of the grinding gap 20 achieves the highest circumferential speed, this results in an upward suction effect which prevents the grinding beads from falling in the grinding gap 20. An excess of grinding beads is collected in the chamber 24, so that a floating barrier layer is formed, which prevents grinding beads from escaping from the grinding gap 20. The be in the grinding gap 20 sensitive grinding beads fill the grinding gap 20 over its entire height, so that it is 100% used for the grinding process and the ground material is exposed to a maximum grinding attack during its residence time in the grinding gap 20. Grinding beads, which have become so small due to abrasion, for example, that they fit into the outlet gap 23, are returned to the chamber 24 by the centrifugal force, so that the powder emerging from the outlet opening 31 contains no grinding beads and without aftertreatment such as washing or sieving in it desired final state is present. Since the grinding beads are reliably prevented from sedimentation in the grinding gap, the risk of starting difficulties or blocking of the rotor is averted. The wear of the parts is correspondingly low. With low energy consumption, high grinding capacities are achieved with mineral hard materials, and the length of the residence time of the material in the grinding gap can be adjusted by appropriately selecting the peripheral speed and the width of the grinding gap. The degree of comminution can be influenced by the size of the grinding beads, which can be different if necessary, whereby a gradual comminution is achieved because coarse grinding beads in the lower part of the annular gap ball mill preferably grind the coarse parts and finer grinding beads in the upper part preferably comminute the finer parts .

Bei den Beispielen der Figuren 2, 3 und 4 soll die Ausbildung der Ringspalt-Kugelmühlen 2, 3, 4 im wesentlichen der Konstruktion nach Fig. 1 entsprechen. Es sind lediglich mögliche Abwandlungen der Querschnitte von Mahlspalt und Auslaufspalt im Schema dargestellt, die je nach der Art des zu zerkleinernden mineralischen Hartstoffes vorteilhaft sein können. In allen Fällen ist die ringförmige radiale Kammer 24 vorhanden, die die Mahlperlensperrschicht aufnimmt und sich am Übergang zwischen Mahlspalt 20a, 20b, 20c zum Auslaufspalt 23a, 23b, 23c befindet. Dieser Übergang ist im wesentlichen identisch mit der Äquatorlinie zwischen Rotor 13a, 13b, 13c und Oberteil 14a,14b,14c.In the examples of FIGS. 2, 3 and 4, the formation of the annular gap ball mills 2, 3, 4 should essentially correspond to the construction according to FIG. 1. Only possible modifications of the cross sections of grinding gap and outlet gap are shown in the diagram, which can be advantageous depending on the type of mineral hard material to be comminuted. In all cases there is an annular radial chamber 24, which receives the grinding-pearl barrier layer and is located at the transition between grinding gap 20a, 20b, 20c to outlet gap 23a, 23b, 23c. This transition is essentially identical to the equator line between rotor 13a, 13b, 13c and upper part 14a, 14b, 14c.

Bei dem Beispiel der Fig. 2 verbreitert sich der Mahlspalt 20a nach oben, während der Auslaufspalt 23a parallelflächig ist.In the example of FIG. 2, the grinding gap 20a widens upwards, while the outlet gap 23a has a parallel surface.

Gemäss Fig. 3 ist der Mahlspalt 20b oben breiter als unten, und der Auslaufspalt 23b verbreitert sich ebenfalls nach oben.According to FIG. 3, the grinding gap 20b is wider at the top than at the bottom, and the outlet gap 23b also widens upwards.

Fig. 4 zeigt eine weitere Ausgestaltungsmöglichkeit, nach der der Mahlspalt 20c sich wie die Mahlspalte 20a und 20b nach oben verbreitert, der Auslaufspalt 23c jedoch nach oben enger wird und mit einem breiteren unteren Ende in die Kammer 24 mündet.FIG. 4 shows a further possible embodiment, according to which the grinding gap 20c widens upwards like the grinding gaps 20a and 20b, but the outlet gap 23c narrows upwards and opens into the chamber 24 with a wider lower end.

Der Winkel der Abschrägung des Rotors 13, 13a, 13b, 13c zur Senkrechten beträgt vorteilhafterweise 70° bis 80°. Bei dieser Neigung werden die besten Mahlergebnisse erreicht.The angle of the bevel of the rotor 13, 13a, 13b, 13c to the vertical is advantageously 70 ° to 80 °. The best grinding results are achieved with this inclination.

Claims (14)

1. Annular gap-type ball mill (1) for continuously pulverizing in particular mineral hard materials comprising an upright grinding container (12) closed by a cover (15), and accomodating a rotor (13) whose cone-shaped outer surface defines with the inner cone-shaped surface of the grinding container (12) a grinding gap (20) communicating with a feed aperture (21), and containing grinding pellets, the rotor (13) having a top portion (14) being adapted in its shape to the inner surface of the cover (15) and including in its range an outlet opening (31), characterized in that the top portion (14, 14a, 14b, 14c) of said rotor (13, 13a, 13b, 13c) and said cover (15) are cone-shaped and define an annular discharge gap (23,23a, 23b, 23c) whose lower, maximum diameter end terminates in an annular chamber (24) at the open upper, maximum diameter end of the grinding gap (20, 20a, 20b, 20c).
2. Annular gap-type ball mill according to claim 1 characterized in that the shape of the top portion (14, 14a, 14b, 14c) and of the inner surface of the cover (15) is frusto-conical.
3. Annular gap-type ball mill according to claim 1 or 2, characterized in that the grinding gap (20) and the discharge gap (23) are each of a parallel-sided design, and that the grinding gap (20) is broader than the discharge gap (23).
4. Annular gap-type ball mill according to claim 1 or 2, characterized in that the grinding gap (20 a) is flared to the top and that the discharge gap (23a) is parallel-sided.
5. Annular gap-type ball mill according to claim 1 or 2, characterized in that the grinding gap (20 b) and the discharge gap (23 b) are each flared to the top.
6. Annular gap-type ball mill according to claim 1 or 2, characterized in that the grinding gap (20 c) is flared to the top and the discharge gap (23 c) is contracted to the top.
7. Annular gap-type ball mill according to one of claims 1 to 6, characterized in that the annular chamber (24) is within the range of the partition joint (26) of the grinding container (12) and the cover (15).
8. Annular gap-type ball mill according to one of claims 1 to 7, characterized in that the annular chamber (24) contains at least one opening (28) for the inlet of the grinding pellets.
9. Annular gap-type ball mill according to one of claims 1 to 8, characterized in that the annular chamber (24) is substantially parallel-walled and its peripheral end face is rounded convexly.
10. Annular gap-type ball mill according to one of claims 1 to 9, characterized in that the ratio of the height of the top portion (14, 14a, 14b, 14c) to the overall height of rotor (13, 13a, 13b, 13c) and top portion (14,14a, 14b, 14c) is 0.2 to 0.5:1.
11. Annular gap-type ball mill according to one of claims 1 to 10, characterized in that the conical outer surface of the rotor (13, 13a, 13b, 13c) extends at an angle of 40° to 85°, preferably of 60° to 80°, in particular of 70° to 80° relative to the vertical line.
12. Annular gap-type ball mill according to one of claims 1 to 11, characterized in that the inner surface of the grinding container (12) and of the cover (15) and the outer surface of the rotor (13, 13a, 13b, 13c) and of its top portion (14,14a,14b,14c) are provided with fine roughened surfaces.
13. Annular gap-type ball mill according to one of claims 1 to 12, characterized in that the upper end of the discharge gap (23) terminates in a discharge chamber (29) to which the discharge opening (31) is connected.
14. Annular gap-type ball mill according one of to claims 1 to 13, characterized in that a cooling liquid jacket encloses the grinding container (12) and the cover (15).
EP85110652A 1984-08-29 1985-08-24 Annular gap pebble mill Expired EP0173271B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85110652T ATE39066T1 (en) 1984-08-29 1985-08-24 RING GAP BALL MILL.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3431636A DE3431636C1 (en) 1984-08-29 1984-08-29 Annular gap ball mill
DE3431636 1984-08-29

Publications (3)

Publication Number Publication Date
EP0173271A2 EP0173271A2 (en) 1986-03-05
EP0173271A3 EP0173271A3 (en) 1986-08-20
EP0173271B1 true EP0173271B1 (en) 1988-12-07

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EP85110652A Expired EP0173271B1 (en) 1984-08-29 1985-08-24 Annular gap pebble mill

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US (2) US4703896A (en)
EP (1) EP0173271B1 (en)
JP (1) JPS6168145A (en)
KR (1) KR900000548B1 (en)
AT (1) ATE39066T1 (en)
AU (1) AU555884B2 (en)
BR (1) BR8504117A (en)
CA (1) CA1244392A (en)
DD (1) DD236462A5 (en)
DE (2) DE3431636C1 (en)
ES (1) ES8700577A1 (en)
FI (1) FI74631C (en)
IN (1) IN165878B (en)
ZA (1) ZA856616B (en)

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Also Published As

Publication number Publication date
BR8504117A (en) 1986-04-22
JPS6168145A (en) 1986-04-08
KR900000548B1 (en) 1990-01-31
ZA856616B (en) 1986-05-28
DE3566619D1 (en) 1989-01-12
KR860001614A (en) 1986-03-20
FI853276A0 (en) 1985-08-27
DE3431636C1 (en) 1985-10-17
ES546469A0 (en) 1986-10-16
EP0173271A2 (en) 1986-03-05
DD236462A5 (en) 1986-06-11
US4703896A (en) 1987-11-03
CA1244392A (en) 1988-11-08
AU4667885A (en) 1986-04-10
EP0173271A3 (en) 1986-08-20
ATE39066T1 (en) 1988-12-15
FI74631B (en) 1987-11-30
IN165878B (en) 1990-02-03
FI853276L (en) 1986-03-01
US4776522A (en) 1988-10-11
AU555884B2 (en) 1986-10-16
ES8700577A1 (en) 1986-10-16
JPH0152062B2 (en) 1989-11-07
FI74631C (en) 1988-03-10

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