(19)
(11)EP 2 674 220 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
18.04.2018 Bulletin 2018/16

(21)Application number: 13169354.1

(22)Date of filing:  27.05.2013
(51)International Patent Classification (IPC): 
B02C 17/22(2006.01)

(54)

Wear-resistant lining for mills

Verschleißfeste Auskleidung für Mühlen

Revêtement résistant à l'usure pour broyeurs


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 11.06.2012 IT MO20120151

(43)Date of publication of application:
18.12.2013 Bulletin 2013/51

(73)Proprietor: Certech S.P.A. A Socio Unico
41049 Sassuolo (Modena) (IT)

(72)Inventor:
  • Palladini, Alberto
    42035 Castelnovo ne' Monti (Reggio Emilia) (IT)

(74)Representative: Casadei, Giovanni et al
Bugnion S.p.A. Via Vellani Marchi, 20
41124 Modena
41124 Modena (IT)


(56)References cited: : 
DE-A1- 19 847 920
US-A- 5 814 273
SU-A1- 679 240
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The subject matter of the present invention is a wear-resistant lining for ball mills. The grinding balls or bodies constituting the grinding charge are made of hard materials. For example in the grinding of materials for the ceramics industry, they are frequently made of alumina. However, they may also be made of steel, steatite and even pebbles.

    [0002] The mill lining may be total or partial.

    [0003] Linings made of various materials are known in the prior art.

    [0004] For example, there are known linings made of hard materials, for example alumina-based materials, and obtained by arranging actual bricks side by side and cemented one to the other so as to cover all of the internal walls of the mill chambers. This is actual masonry requiring very long amounts of time for assembly and reconditioning.

    [0005] There are also known wear-resistant rubber linings that are realized with modular elements constituted by sheets and pieces of rubber of various dimensions. These types of executions require relatively little time for installation and offer the positive feature of enabling replacement of individual worn-out sheets or elements somewhat easily. However, the linings made of wear-resistant rubber require replacement of the entire lining, or even only part of it, with a certain frequency. In fact, there are parts of these linings that owing to the geometrical and operating characteristics of the mills are more susceptible to wear than others. Therefore, in these cases, it is necessary to stop the mill in order to proceed with replacement only of some worn-out parts of the lining and not of the entire lining.

    [0006] All of this is the cause of evident inconveniences and diseconomies that have negative repercussions on the entire production cycle of which the mill is a part.

    [0007] These disadvantages are more accentuated in the case of continuous mills.

    [0008] There are also known wear-resistant linings such as that illustrated in the Italian patent No. 1287434, which describes a wear-resistant lining for mills that comprises a rubber base, in which plates of hard material are stably inserted, with part of the external surface thereof appearing at the surface of the lining that undergoes wear.

    [0009] Although they are capable of performing their function advantageously with respect to prior linings, wear-resistant linings such as that described above, which can be realized by incorporating small bricks of wear-resistant material such as alumina in the rubber base, are not, however, without defects and drawbacks that substantially originate from the manufacturing technique, which in any case provides for the inclusion of the wear-resistant bricks in the mass of a rubber base by means of pressing and vulcanizing operations and the subsequent assembly of the various portions of the lining thus formed so as to form the complete lining.

    [0010] Examples of prior art lining are known from US 5814273 and SU 679240.

    [0011] The present invention, as defined by the claims and described, proposes to overcome the drawbacks and shortcomings of the prior art illustrated above, particularly regarding the construction of the wear-resistant lining obtained by stably incorporating the hard materials in the mass of the rubber base.

    [0012] The principal aim of the present invention is to overcome the said limits of the prior art, proposing the realization of a wear-resistant lining for ball mills as stated in the claims and the description.

    [0013] An advantage of the invention consists in the structural capacity thereof of requiring solely the arrangement and the assembly of the base of the lining, leaving the formation of the complete lining, comprising the insertion of hard bodies or inserts in the base, to a brief initial operating step preferably carried out without a load to be ground, and only with the charge of balls or grinding bodies.

    [0014] Another advantage of the invention consists in it enabling the realization of a base of the lining provided with an extremely regular distribution of cavities and composed of panels that are geometrically regular in shape and easy to transport and mount.

    [0015] A further advantage is represented by less use of material and thus lower weight of the lining.

    [0016] These aims and advantages, as well as others still, are all achieved by the invention at hand, as described and defined by the claims appended herein below.

    [0017] Further characteristics and advantages of the present invention will become more apparent from the following detailed description of some embodiments of the invention at hand, these embodiments being illustrated by way of nonlimiting example in the accompanying figures, in which:

    Figure 1 shows part of a schematic perspective overview of the invention;

    Figure 2 shows a portion of the lining appearing in Figure 1, at an enlarged scale;

    Figure 3 shows, at an enlarged scale, part of a cross section taken along a plane normal to the work surface of the lining;

    Figure 4 shows, on the same scale as Figure 3, part of a cross section taken along a plane normal to the work surface of the lining and relating to an embodiment not forming part of the invention;

    - Figure 5 shows, on the same scale as Figures 3 and 4, part of a cross section taken along a plane normal to the work surface of the lining and relating to an embodiment not forming part of the invention. With reference to the figures cited, the number "1" schematically indicates a ball mill used for the fine grinding of materials utilized in the ceramics industry. The mill is constituted by a rotating drum, provided with an adequate resistant structure, the internal compartment of which is designed to comprise the grinding balls or bodies 6 together with the load of material to be ground, and has walls covered by a lining indicated in its entirety as "2". The latter proves to be made up of a base 3, which is made of a material that is elastically deformable. The most frequently used material is rubber (natural and wear-resistant), but all materials, even synthetic materials, can be used as long as they have similar characteristics as regards elastic deformability, abrasion resistance, water resistance and resistance to the main chemical agents.



    [0018] A plurality of cavities or hollows 5 suitable for accommodating therein bodies of hard material, in the manner of inserts, are afforded at the work surface 4 subjected to wear, which is the surface designed to come into contact with the grinding balls or bodies 6 and with the load of material to be ground. The insertion of these bodies of hard material serves the purpose of giving substance to a "composite" surface that is particularly resistant in that it performs the function of imparting particular wear resistance to the work surface 4.

    [0019] Once inserted stably in the cavities or hollows 5, these bodies serve the function of coming into contact with the grinding bodies or balls 6 of hard material, which are still free and constitute the grinding charge (which, in the performance of the milling action, moves together with the load of materials to be ground). The hard bodies stably inserted in the cavities or hollows 5 are thus utilized to "absorb" a good part of the overall level of wear transmitted to the lining 2 of the mill.

    [0020] In the case in point, the cavities or hollows 5 of at least part of the plurality of cavities or hollows 5 arranged at the work surface 4 are dimensioned and proportioned so that each of them is suitable for accommodating therein at least one of the grinding bodies or balls 6, which, at least initially, are part of the grinding charge in operation in the mill.

    [0021] In particular, the cavities or hollows 5 are shaped and dimensioned in relation to the shape and size of the grinding bodies or balls 6 so that upon completion of the insertion and coupling of a pre-established part of the grinding bodies or balls 6 in the respective cavities or hollows 5, there is defined an operative configuration distinguished by the fact that said grinding bodies or balls 6 are stably housed in the respective cavities 5.

    [0022] According to a first embodiment, at least one portion of each grinding body or ball 6 stably housed in the respective cavity 5 protrudes externally at least in part from said work surface 4.

    [0023] In another embodiment, the cavities 5 are shaped and dimensioned in relation to the shape and size of the grinding bodies or inserts 6 so that when insertion and coupling are completed, at least a portion of each of said grinding bodies or balls 6 is situated at the same level as the work surface 3 so as not to protrude therefrom.

    [0024] According to a further embodiment, the cavities 5 are shaped and dimensioned in relation to the shape and size of the grinding bodies or balls 6 so that when insertion and coupling are completed, the grinding bodies or balls 6 or part thereof are situated below the level established by the work surface 3. According to the invention, each cavity or hollow 5 appears in the form of a cavity defined by the spherical surface portion of a spherical segment whose depth is not less than the radius of the corresponding sphere or grinding body 6 that is to be housed therein.

    [0025] Preferably, this depth is slightly greater than the measurement of the radius of the grinding ball or body 6. Once insertion has taken place, this enables stable locking.

    [0026] These grinding bodies or balls 6, in the initial, non-worn state, preferably have mutually equal diameters. In particular, these diameters, or more in general, the sizes of the grinding bodies or balls 6, in the initial, non-worn state, are determined so as to enable a coupling by interference of a grinding body or ball 6 in a cavity or hollow 5.

    [0027] In another embodiment, not forming part of the invention, each cavity or hollow 5 is in the form of an essentially cylindrical cavity or hollow 50 thus delimited by a lateral cylindrical surface with an axis perpendicular to the work surface 4 and having a diameter such as to enable a coupling by interference with one grinding body or ball 6 in the initial, non-worn state.

    [0028] Moreover, each cylindrical cavity or hollow 50 has a depth that is not less than the diameter of one of the grinding bodies or balls 6 in the initial, non-worn state.

    [0029] This means that the transverse dimension (diameter) of the cavity is slightly smaller than the diameter of the grinding ball or body 6 and that the depth thereof is smaller by a pre-established amount so as to enable the grinding ball or body to protrude from the work surface 4.

    [0030] Further embodiments comprise the use of bases 3 having cavities of different shapes, suitable for accommodating grinding bodies of different shapes and sizes.

    [0031] In particular, the lining may be made up of a base 3 having cavities of different shapes and sizes, suitable for accommodating a number of grinding bodies packed tightly side by side.

    [0032] There is also provided the use of cavities shaped so as to house not only a number of grinding bodies, but also a number of grinding bodies differing in shape and size (see Figure 5).

    [0033] The option of utilizing grinding bodies that are not particularly regular in terms of size is also provided.

    [0034] Once the internal lining of the mill has been completed with the base 3, insertion of the hard inserts, constituted by part of the grinding balls or bodies 6, in the same lining, may be carried out in a first step in which the mill is started and rotated, with the sole charge of grinding balls or bodies 6. Owing to the action exerted on the lining 2, the latter tend to enter the cavities 5 and insertion takes place.

    [0035] During the actual milling step, the insertion remains active and subject to continuous regeneration.


    Claims

    1. A wear-resistant lining for ball mills comprising a base (3) made of a material that is elastically deformable at the work surface (4) subjected to wear from which it is obtained, a plurality of cavities or hollows (5) suitable for accommodating bodies of hard material inside them; the presence of said bodies of hard material having the function of imparting particular wear resistance to the work surface (4) in that they are suitable for coming into contact with the grinding bodies or balls (6) made of hard material which are used in the mill, characterized in that the cavities or hollows (5) of at least part of said plurality are dimensioned and proportioned so that each of them is suitable for accommodating at least one of said grinding bodies or balls (6) inside it; said cavities or hollows (5) being shaped and dimensioned in relation to the shape and size of the grinding bodies or balls (6) so that when insertion and coupling are completed, there is defined an operative configuration distinguished by the fact that said grinding bodies or balls (6) are stably housed in the respective cavities (5); each of said cavities or hollows (5) appears in the form of a cavity defined by the spherical surface portion of a spherical segment whose depth is not less than the radius of the corresponding sphere.
     
    2. The wear-resistant lining according to the preceding claim, comprising a plurality of grinding bodies or balls (6), wherein at least a portion of each grinding body or ball (6) stably housed in the respective cavity (5) protrudes externally at least in part from said work surface (4).
     
    3. The wear-resistant lining according to claim 1, comprising a plurality of grinding bodies or balls (6), wherein the cavities (5) are shaped and dimensioned in relation to the shape and size of the grinding bodies or inserts (6) so that when insertion and coupling are completed, at least a portion of each of said grinding bodies or balls (6) is situated at the same level as the work surface (3) so as not to protrude therefrom.
     
    4. The wear-resistant lining according to claim 1, comprising a plurality of grinding bodies or balls (6), wherein the cavities (5) are shaped and dimensioned in relation to the shape and size of the grinding bodies or balls (6), so that when insertion and coupling are completed, the grinding bodies or balls (6) or part thereof are situated below the level established by the work surface (3).
     
    5. The wear-resistant lining according to claim 1, comprising a plurality of grinding bodies or balls (6), wherein in the initial, non-worn state, said grinding bodies or balls (6) have mutually equal diameters.
     
    6. The wear-resistant lining according to the claim 1, comprising a plurality of grinding bodies or balls (6), wherein in the initial, non-worn state, said grinding bodies or balls (6) have diameters which enable a coupling by interference of a grinding body or ball (6) in a cavity or hollow (5).
     
    7. The wear-resistant lining according to claim 1, characterized in that it comprises a base (3) having cavities of different shapes and sizes, suitable for accommodating grinding bodies of different shapes and sizes.
     


    Ansprüche

    1. Verschleißfeste Auskleidung für Kugelmühlen, umfassend eine Basis (3) aus einem Material, das an der Arbeitsfläche (4) elastisch verformbar ist, das einem Verschleiß unterworfen ist, aus der es gewonnen wird, eine Vielzahl von Aussparungen oder Hohlräumen (5), die geeignet sind, Körper aus hartem Material in ihrem Inneren aufzunehmen; wobei die Anwesenheit der Körper aus hartem Material die Funktion hat, der Arbeitsfläche (4) eine besondere Verschleißfestigkeit zu verleihen, damit sie geeignet sind, mit den Mahlkörpern oder Kugeln (6) aus hartem Material, die in der Mühle verwendet werden, in Kontakt zu kommen, dadurch gekennzeichnet, dass die Aussparungen oder Hohlräume (5) mindestens eines Teils der Vielzahl so dimensioniert und proportioniert sind, dass jeder von ihnen geeignet ist, mindestens einen der Mahlkörper oder Kugeln (6) darin aufzunehmen; wobei die Aussparungen oder Hohlräume (5) in Bezug auf die Form und Größe der Mahlkörper oder Kugeln (6) so geformt und dimensioniert sind, dass nach Abschluss des Einführens und Koppelns eine funktionsfähige Konfiguration definiert wird, die dadurch gekennzeichnet ist, dass die Mahlkörper oder Kugeln (6) stabil in den jeweiligen Aussparungen (5) untergebracht sind; jeder der Aussparungen oder Hohlräume (5) erscheint in Form einer Aussparung, die durch einen sphärischen Oberflächenabschnitt eines sphärischen Segments definiert wird, dessen Tiefe nicht kleiner als der Radius der entsprechenden Kugel ist.
     
    2. Verschleißfeste Auskleidung nach dem vorhergehenden Anspruch, umfassend eine Vielzahl von Mahlkörpern oder Kugeln (6), wobei mindestens ein Teil jedes Mahlkörpers oder Kugel (6), die stabil in der jeweiligen Aussparung (5) untergebracht ist, mindestens teilweise nach aussen aus der Arbeitsfläche (4) herausragt.
     
    3. Verschleißfeste Auskleidung nach Anspruch 1, umfassend eine Vielzahl von Mahlkörpern oder Kugeln (6), wobei die Aussparungen (5) in Bezug auf die Form und Größe der Mahlkörper oder Einsätze (6) so geformt und dimensioniert sind, dass nach Abschluss des Einführens und Koppelns mindestens ein Teil jedes der Mahlkörper oder Kugeln (6) auf derselben Höhe wie die Arbeitsfläche (3) angeordnet ist, um aus dieser nicht herauszuragen.
     
    4. Verschleißfeste Auskleidung nach Anspruch 1, umfassend eine Vielzahl von Mahlkörpern oder Kugeln (6), wobei die Aussparungen (5) in Bezug auf die Form und Größe der Mahlkörper oder Kugeln (6) geformt und dimensioniert sind, so dass sich die Mahlkörper oder Kugeln (6) oder ein Teil davon nach Abschluss des Einführens und Koppelns unterhalb der durch die Arbeitsfläche (3) festgelegten Ebene befinden.
     
    5. Verschleißfeste Auskleidung nach Anspruch 1, umfassend eine Vielzahl von Mahlkörpern oder Kugeln (6), wobei die Mahlkörper oder Kugeln (6) im anfänglichen, nicht verschliessenen Zustand gegenseitig gleiche Durchmesser aufweisen.
     
    6. Verschleißfeste Auskleidung nach Anspruch 1, umfassend eine Vielzahl von Mahlkörpern oder Kugeln (6), wobei die Mahlkörper oder Kugeln (6) im anfänglichen, nicht verschliessenen Zustand Durchmesser aufweisen, die eine Kopplung durch Interferenz eines Mahlkörpers oder einer Kugel (6) in einer Aussparung oder einem Hohlraum (5) ermöglichen.
     
    7. Verschleißfeste Auskleidung nach Anspruch 1, dadurch gekennzeichnet, dass sie eine Basis (3) mit Aussparungen unterschiedlicher Form und Größen aufweist, die zur Aufnahme von Mahlkörpern unterschiedlicher Form und Größen geeignet ist.
     


    Revendications

    1. Revêtement résistant à l'usure pour broyeurs à sphères comprenant une base (3) composée d'un matériau élastiquement déformable au niveau de la surface de travail (4) sujette à usure à partir de laquelle elle est obtenue, une pluralité de cavités ou creux (5) pouvant loger à l'intérieur des corps de matériau dur ; la présence desdits corps de matériau dur ayant la fonction de fournir une résistance particulière à l'usure à la surface de travail (4), puisqu'ils sont adaptés à entrer en contact avec les corps de broyage ou sphères (6) à base de matériau dur utilisés dans le broyeur, caractérisé en ce que les cavités ou creux (5) d'au moins une partie de ladite pluralité sont dimensionnés et proportionnés pour que chacun d'entre eux puisse loger à l'intérieur au moins l'un desdits corps de broyage ou sphères (6) ; lesdites cavités ou lesdits creux (5) étant formés et dimensionnés par rapport à la forme et à la taille des corps de broyage ou sphères (6) de sorte que, après insertion et accouplement, soit définie une configuration opérationnelle se caractérisant par le fait que lesdits corps de broyage ou sphères (6) sont logés de façon stable dans les cavités respectives (5) ; chacune desdites cavités ou chacun desdits creux (5) se présente sous la forme d'une cavité déterminée par la portion de surface sphérique d'un segment sphérique dont la profondeur n'est pas inférieure au rayon de la sphère correspondante.
     
    2. Revêtement résistant à l'usure selon la revendication précédente, comprenant une pluralité de corps de broyage ou sphères (6), dans lequel au moins une portion de chaque corps de broyage ou sphère (6) logés de façon stable dans la cavité correspondante (5) dépasse sur l'extérieur au moins en partie de ladite surface de travail (4).
     
    3. Revêtement résistant à l'usure selon la revendication 1, comprenant une pluralité de corps de broyage ou sphères (6), dans lequel les cavités (5) sont formées et dimensionnées par rapport à la forme et à la taille des corps de broyage ou inserts (6) de sorte que, après insertion et accouplement, au moins une portion de chacun desdits corps de broyage ou sphères (6) se situe au même niveau que la surface de travail (3) pour ne pas en dépasser.
     
    4. Revêtement résistant à l'usure selon la revendication 1, comprenant une pluralité de corps de broyage ou sphères (6), dans lequel les cavités (5) sont formées et dimensionnées par rapport à la forme et à la taille des corps de broyage ou sphères (6) de sorte que, après insertion et accouplement, les corps de broyage ou sphères (6) ou une partie d'eux se situent sous le niveau déterminé par la surface de travail (3).
     
    5. Revêtement résistant à l'usure selon la revendication 1, comprenant une pluralité de corps de broyage ou sphères (6), dans lequel à l'état initial de non-usure, lesdits corps de broyage ou sphères (6) ont des diamètres égaux entre eux.
     
    6. Revêtement résistant à l'usure selon la revendication 1, comprenant une pluralité de corps de broyage ou sphères (6), dans lequel à l'état initial de non-usure, lesdits corps de broyage ou sphères (6) ont des diamètres autorisant un accouplement par interférence d'un corps de broyage ou d'une sphère (6) dans une cavité ou un creux (5).
     
    7. Revêtement résistant à l'usure selon la revendication 1, caractérisé en ce qu'il comprend une base (3) ayant des cavités de différentes formes et tailles, pouvant loger des corps de broyage de différentes formes et tailles.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description