Agitator Ball Mill and Method for Operating an Agitator Ball Mill

Abstract

An agitator ball mill including an in particular horizontal grinding container, which has a first end area having a grinding material inlet and a second end area having a grinding material outlet, and a method for operating an agitator ball mill. The agitator ball mill includes a shaft, which can be rotated in the grinding container or in the grinding chamber, respectively, by means of a drive unit and which is formed as agitator shaft at least in sections and which is equipped with agitator elements, as well as a separating device. The separating device includes a classifier rotor, which is arranged on the agitator shaft axially spaced apart from the grinding material outlet and has a rotatable rotor cage, as well as a screen unit, which is arranged within the rotor cage and which is fastened to the classifier rotor.

Claims

1. An agitator ball mill comprising a horizontal grinding container, which has a first end area having a grinding material inlet and a second end area having a grinding material outlet, including: a shaft, which can be rotated in the grinding container or in the grinding chamber, respectively, by means of a drive unit and which is formed as agitator shaft at least in sections and which is equipped with agitator elements, a separating device including: a classifier rotor, which is arranged on the agitator shaft axially spaced apart from the grinding material outlet and has a rotatable rotor cage, as well as a screen unit, which is arranged within the rotor cage and which is fastened to the classifier rotor.

2. The agitator ball mill according to claim 1, in the case of which the rotor cage comprises a flange, which sits on the agitator shaft, including a support plate, to which at least two rotor fingers are fastened or can be fastened, respectively.

3. The agitator ball mill according to claim 2, in the case of which the at least two rotor fingers are formed of identical length in the longitudinal direction, wherein a diameter and/or a width and/or a height of the at least two rotor fingers along the longitudinal extension thereof increases or is formed identically.

4. The agitator ball mill according to claim 1, in the case of which the rotor cage is assigned a stationary base, which is arranged on an inner side of the second end area of the grinding container and protrudes into the grinding chamber at least in sections.

5. The agitator ball mill according to claim 3, in the case of which the classifier rotor has a smaller diameter in the area of the support plate than in the area of the ring element.

6. The agitator ball mill according to claim 2, in the case of which the screen unit is fixed to the support plate of the flange.

7. The agitator ball mill according to claim 1, in the case of which the screen unit comprises openings, which maximally have 0.7-times the opening width of the grinding body diameter and/or of the grinding body length and/or of the grinding body height.

8. The agitator ball mill according to claim 1, in the case of which the screen unit has a smaller enveloping outer diameter on the side facing the grinding material inlet than on the side facing the grinding material outlet or the bearing-side grinding chamber limitation, respectively.

9. The agitator ball mill according to claim 1, in the case of which a grinding material inlet chamber is arranged spatially upstream of the grinding material inlet and/or in the case of which a grinding material outlet chamber is arranged spatially downstream from the grinding material outlet.

10. The agitator ball mill according to claim 1, in the case of which the shaft arranged in the grinding container extends into the grinding material inlet or grinding material inlet chamber, respectively, and/or into the grinding material outlet or grinding material outlet chamber at least in sections.

11. The agitator ball mill according to claim 1, in the case of which the shaft within the grinding material inlet and/or grinding material inlet chamber is formed as first screw conveyor, in particular as screw helix, at least in sections, and/or in the case of which the shaft within the screen unit and/or the grinding material outlet and/or the grinding material outlet chamber is formed as second screw conveyor, in particular as screw helix, at least in sections.

12. The agitator ball mill according to claim 1, in the case of which the shaft is cantilever-mounted, wherein in particular the grinding material inlet is arranged at the cantilevered end of the shaft and the grinding material outlet at the bearing-side end of the shaft.

13. The agitator ball mill according to claim 1, in the case of which the grinding material inlet and/or the grinding material inlet chamber is assigned a first fluid inlet opening, via which a first fluid flow can be supplied to the grinding material inlet chamber and/or to the grinding material inlet.

14. The agitator ball mill according to claim 1, in the case of which the grinding material outlet and/or the grinding material outlet chamber is assigned a second fluid inlet opening, via which a second fluid flow can be supplied to the grinding material outlet chamber and/or to the grinding material outlet.

15. The agitator ball mill according to claim 1, in the case of which at least one control element is in each case assigned to the first and/or second fluid inlet opening, so that a cross section of the first and/or second fluid inlet opening can be set and the first and/or second fluid flow can thus be regulated.

16. The agitator ball mill according to claim 1, in the case of which the first fluid flow through the grinding material inlet chamber is larger than 50% of the entire fluid flow.

17. The agitator ball mill according to claim 1, in the case of which a third fluid flow, which passes through the stationary base, is smaller than 25% of the entire fluid flow.

18. A method for operating an agitator ball mill comprising a horizontal grinding container, which has a first end area having a grinding material inlet and a second end area having a grinding material outlet, including the steps of: rotating a shaft in the grinding container or in the grinding container, with a drive unit and which is formed as agitator shaft at least in sections and which is equipped with agitator elements, separating with a classifier rotor, which is arranged on the agitator shaft axially spaced apart from the grinding material outlet and has a rotatable rotor cage, as well as a screen unit, which is arranged within the rotor cage and which is fastened to the classifier rotor.

19. The agitator ball mill according to claim 2, in the case of which the rotor cage is assigned a stationary base, which is arranged on an inner side of the second end area of the grinding container and protrudes into the grinding chamber at least in sections.

20. The agitator ball mill according to claim 3, in the case of which the screen unit is fixed to the support plate of the flange.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Exemplary embodiments are to describe the invention and its advantages in more detail below by means of the enclosed figures. The size ratios of the individual elements relative to one another in the figures do not always correspond to the actual size ratios, because some forms are illustrated in a simplified manner and other forms are illustrated in an enlarged manner in relation to other elements for better visualization.

[0050] FIG. 1 shows a schematic view of a longitudinal section of an embodiment of the agitator ball mill according to the invention.

[0051] FIG. 2 shows a schematic detail view of the grinding material inlet of the agitator ball mill shown in FIG. 1.

[0052] FIG. 3 shows a schematic detail view of the grinding material outlet comprising the separating device arranged upstream thereof from the agitator ball mill shown in FIG. 1.

DETAILED DESCRIPTION

[0053] Identical reference numerals are used for elements of the invention, which are identical or have an identical effect. Furthermore, only reference numerals, which are required for the description of the respective figure, are illustrated in the individual figures for the sake of clarity. The illustrated embodiments only represent examples for how the device according to the invention could be designed, and do not represent a conclusive limitation.

[0054] FIG. 1 shows a schematic view of a longitudinal section of an embodiment of the agitator ball mill 10 according to the invention. The agitator ball mill 10 comprises a grinding container 12, which is formed cylindrically and which is supported horizontally. A negative pressure, which is set by means of a suitable vacuum pump or the like, which is not illustrated here, prevails in the grinding container 12 or in the grinding chamber 18, respectively.

[0055] The grinding container 12 has a grinding material inlet 14 and a grinding material outlet 16, which are formed by corresponding openings in the grinding container 12. The grinding material inlet 14 is provided at a first end area of the grinding container 12 (on the left in FIG. 1), and the grinding material outlet 16 is provided at an opposite second end area (on the right in FIG. 1). A grinding material inlet chamber 68 is arranged spatially upstream of the grinding material inlet 14 (see FIG. 2). A grinding material outlet chamber 70 is furthermore arranged spatially downstream from the grinding material outlet 16 (see FIG. 3). In the broadest sense, the grinding material inlet chamber 68 is an area of the grinding material inlet 14 and the grinding material outlet chamber 70 is an area of the grinding material outlet 16.

[0056] Up to between 70% and 90% of the grinding container 12 is preferably filled with grinding bodies, which are preferably formed spherically, but which can also be formed cylindrically, for example. The grinding bodies are essential for the comminution of the grinding material, which is supplied via the grinding material inlet 14, and act as comminution tool. The grinding bodies are preferably formed to be smaller than 12 mm.

[0057] The agitator ball mill 10 comprises a shaft 20, which can be rotated by means of a drive unit, which is not illustrated here and which is arranged in the grinding container 12. The drive unit of the rotatable shaft 20 is preferably located in the area of the grinding material outlet 16 or at the second end area of the grinding material container 12, respectively.

[0058] The shaft 20 is cantilever-mounted, wherein the bearing-side end of the shaft 20 is arranged in the area of the grinding material outlet 16 or grinding material outlet chamber 70, respectively, and the cantilevered end of the shaft 20 is arranged in the area of the grinding material inlet 14 or grinding material inlet chamber 68, respectively, i.e. the shaft 20 extends at least along the longitudinal extension of the grinding container 12 from the grinding material inlet chamber 68 or grinding material inlet, respectively, to the grinding material outlet chamber 70 or grinding material outlet 16, respectively.

[0059] The rotatable shaft 20 is formed as agitator shaft 22 at least in sections and is equipped with agitator elements 24. The agitator elements 24 each extend radially from an outer jacket surface of the agitator shaft 22, wherein the agitator elements 24 are each fastened to the outer jacket surface of the agitator shaft 22 in a rotationally fixed manner, in particular mechanically. The agitator elements 24 are in particular arranged evenly spaced apart from one another on the outer jacket surface of the agitator shaft 22.

[0060] According to the present embodiment, the agitator elements 24 are formed as pins 25. It would also be conceivable, however, to form the agitator elements 24 in the shape of grinding disks or the like. The agitator elements 24 in each case serve the purpose of setting the grinding bodies, which are located in the grinding chamber 18, in motion, and to thus provide them with energy, which serves to comminute the grinding material supplied via the grinding material inlet 14. The grinding bodies are set in motion in particular in so-called grinding zones, which grinding zones are in each case defined as space between two pins. The grinding material to be ground, which is supplied via the grinding material inlet 14, in each case passes through these grinding zones and is comminuted on the way from the grinding material inlet 14 to the grinding material outlet 16. By supplying the grinding material to be ground and discharging the completely ground grinding material, the flow of the grinding material is set from the grinding material inlet 14 in the direction of the grinding material outlet 16.

[0061] The agitator elements 24 each have a free end 26, which is in each case arranged at a distance from an inner wall 28 of the grinding container 12. The first distance A.sub.1 between the free end 26 of the agitator elements 24 and the inner wall 28 of the grinding container 12 corresponds to at least two and a half times the average diameter of the grinding bodies. The first distance A.sub.1 between the free end and the inner wall 28 of the grinding container 12 is thus required, so that the grinding bodies can pass through this area unhindered, without compressing and/or sticking together, as it would otherwise be the case in the case of a distance, which is selected to be too small, between free end of the agitator element and inner wall 28 of the grinding container 12.

[0062] To separate the completely ground grinding material from the grinding bodies or to ensure that the grinding bodies remain in the grinding chamber 18, respectively, while the completely ground grinding material leaves the grinding chamber 16, a separating device 30 is provided, which separating device 30 is preferably arranged axially upstream of the grinding material outlet 16. The separating device 30 comprises a classifier rotor 32, which is arranged on the agitator shaft 22 axially spaced apart from the grinding material outlet 16, and has a rotatable rotor cage 34. The rotor cage 34 has a flange 36 resting on the agitator shaft 22 comprising a support plate 38 (see FIG. 3). It becomes clear from FIG. 1 or by means of the flange 36 shown in FIG. 1, respectively, that a diameter of the classifier rotor 32 increases in the direction of the grinding material outlet 16. A smallest diameter of the classifier rotor 32 is formed by the support plate 38 of the flange 36. At least two rotor fingers 40 are mechanically coupled on the outer circumference of the support plate 38.

[0063] The rotor fingers 40 are formed of identical size or of identical length, respectively, in the longitudinal direction, wherein the radial extension thereof across the length thereof preferably changes, i.e. a diameter of the rotor fingers 40 increases along the longitudinal extension thereof. It can apply thereby that a first diameter D.sub.1 of the rotor finger 40 is smaller than the second diameter D2 of the rotor finger 40. The rotor fingers 40 extend in particular from the support plate 38 in the direction of the grinding material outlet 16. At the free end of the rotor fingers 40, at least one ring element 44 is provided in the shape of a disk 46. The disk 46 comprises a centrically arranged bore, the inner diameter of which is larger than an outer diameter of the shaft 20 or of the agitator shaft 22, respectively. An outer diameter of the disk 46 preferably corresponds to the diameter or distance, respectively, between the at least two rotor fingers 40. A largest diameter of the classifier rotor 32 is formed by the disk 46.

[0064] The separating device 30 furthermore comprises a screen unit 42, which is arranged within the rotor cage 34 and which is fastened to the classifier rotor 32, and via which the completely ground grinding material can leave the grinding chamber 18 and the grinding bodies are retained in the grinding chamber 18. Due to the fastening of the screen unit 42 to the classifier rotor 32, the rotor cage 34 comprising the screen unit 42 fastened thereto rotates at the same speed as the agitator shaft 22. Due to the rotational movement of the rotor cage 34, flows and forces are created, so that the grinding bodies are moved or centrifuged, respectively, radially in the direction of the inner wall 28 of the grinding container 12. The area round the grinding material outlet 16 is kept free from the grinding bodies in this way.

[0065] The screen unit 42 comprises a plurality of openings, which are not illustrated here. The openings are preferably formed in the shape of axial elongated holes. The elongated holes each have a cross section, which is smaller than the grinding bodies, so that only the completely ground grinding material can pass through the openings of the screen unit 42, while the grinding bodies, in contrast, remain in the grinding chamber 18. The openings in particular have a cross section, which is formed to be smaller than 70% of the diameter of the grinding bodies.

[0066] The screen unit 42 is formed conically and is arranged within the rotor cage 34 in such a way that an outer diameter of the screen unit 42 increases in the direction of the grinding material outlet 16, wherein a maximum outer diameter of the screen unit 42 is formed to be smaller than 95% of the inner diameter of the grinding material container. Due to the spherical shape of the screen unit 42, a large surface, in particular a large passage surface, is provided for the completely ground grinding material. It goes without saying that in order to increase the surface, the screen unit 42 can consist, e.g., of a screen plate, which is folded in a star-shaped manner and the outer sleeve surface of which is formed to be conical.

[0067] The end face of the screen unit 42 pointing towards the support plate 38 preferably has two webs 48, 48, which are mechanically fixed to the support plate 38. The screen unit 42 is fixed to the support plate 38 in this way. The fastening of the screen unit 42 to the support plate 38 via the two webs 48, 48 can act in the manner of a torque transmission device, i.e. a torque of the rotor cage 34 is automatically transmitted to the screen unit 42 when the rotor cage 34 is set in rotation, i.e. the screen unit 42 rotates automatically at the same speed as the rotor cage 34.

[0068] The rotor cage 34 is furthermore assigned a stationary base 50, which is arranged on an inner side of the second end area of the grinding container 12. The stationary base 50 is a circular element or tubular element 52, respectively, which protrudes perpendicularly from the second end area of the grinding container 12 into the grinding chamber 18 at least in sections. The circular or tubular element 52, respectively, has a bore, through which the shaft 20 is guided. An axial, second distance A2 or gap, respectively, which is preferably smaller than 0.3-times the diameter of the grinding body, is formed between the grinding chamber-side free end or end face, respectively, of the circular or tubular element 52, respectively, and the disk 46, i.e. the second distance A2 or gap, respectively, is formed in such a way that no grinding bodies and/or grinding material, which is not completely ground, reach into the grinding material outlet 16 without authorization.

[0069] FIG. 2 shows a schematic detail view of the grinding material inlet 14 from the agitator ball mill 10 shown in FIG. 1. The grinding material to be ground is stored in a storage container 72, which is formed in a funnel-shaped manner and which is connected to the grinding material inlet 14 via a grinding material inlet chamber 68. A gate 74 is provided at the lowest point of the storage container 72, in order to supply the grinding material stored in the storage container 72 to the grinding material inlet 14 in the grinding chamber 18 via the grinding material inlet chamber 68. The grinding material is in particular supplied to the grinding material inlet 14 by means of gravity.

[0070] To control and to support the supply of the grinding material, the grinding material inlet 14, in particular the grinding material inlet chamber 68, is assigned a first fluid inlet opening 54, via which a first fluid flow 56 (illustrated by arrows), such as, for example, a first air volume flow, is supplied into the grinding material inlet 14 and thus into the grinding chamber 18. It would alternatively also be conceivable to use an inert or reactive gas. The first fluid flow 56 can mix with the grinding material, so that a first grinding material fluid flow, in particular a first grinding material air volume flow, is formed. The first fluid flow 56 is metered in such a way that the negative pressure, which prevails in the grinding container 12 or in the grinding chamber 18, respectively, is not impacted, but is sufficient for transporting the grinding material into the grinding container 12. The first fluid flow 56 is created via an external fluid source, such as, for example, an air source, which is not illustrated here.

[0071] It can optionally be provided that the first fluid inlet opening 54 comprises at least one control element, which is not illustrated here, so that the first fluid flow 56 can be metered or regulated, respectively. A cross section of the first fluid inlet opening 54 can be changed, for example by means of the at least one control element.

[0072] To support the transport of the grinding material into the grinding chamber 18 and to prevent a clogging of the grinding material inlet 14, the shaft 20 in the grinding material inlet 14, which protrudes in particular into the grinding material inlet chamber 68, is formed as first screw conveyor 58, in particular as first helical screw 66, at least in sections.

[0073] FIG. 3 shows a schematic detail view of the grinding material outlet 16 comprising the separating device 30 arranged upstream thereof from the agitator ball mill 10 shown in FIG. 1. It becomes clear in FIG. 3 that the shaft 20, which protrudes within the screen unit 42 and into the grinding material outlet 16, is formed as second screw conveyor 64, in particular as second helical screw 67, at least in sections. The grinding material, which is allowed to pass through the screen unit 42 and which is ground completely, is thus moved and conveyed from the screen unit 42 along the grinding material outlet 16 or out of the grinding material outlet 16, respectively.

[0074] The grinding material outlet 16 extends parallel above and/or below the shaft 20 at least in sections, in particular towards the second screw conveyor 64, and leads into a grinding material outlet chamber 70 arranged spatially downstream from the grinding material outlet 16. Here, the grinding material outlet chamber 70 communicates with a non-illustrated collection container for the completely ground grinding material.

[0075] The grinding material outlet 16, in particular the grinding material outlet chamber 70, is assigned a second fluid inlet opening 60, via which a second fluid flow 62 (illustrated by arrows), such as, for example a second air volume flow, is supplied into the grinding material outlet 16 and thus also into the grinding material outlet chamber 70. It would alternatively also be conceivable to use an inert or reactive gas. On the one hand, the second fluid flow 62 serves as transport medium, which mixes with the completely ground grinding material, so that a second grinding material fluid flow, in particular a second grinding material air volume flow, is formed. The transport of the completely ground grinding material along the grinding material outlet 16 and of the grinding material outlet chamber 70 is thus supported by means of the second fluid flow 62. A clogging of the grinding material outlet 16 with grinding material is prevented at the same time.

[0076] As already mentioned in FIG. 1, an axial, second distance A2 or gap, respectively, which is preferably smaller than 0.3-times the diameter of the grinding body, is formed between the grinding chamber-side free end or end face, respectively, of the circular or tubular element 52, respectively, and the disk 46. This gap is preferably flushed through channels and/or bores in the tubular element 52, which are not illustrated here, by means of the second fluid flow and/or optionally by means of a third fluid flow (not illustrated here), such as, for example, a third air volume flow, so that no ground product or hardly completely ground product can penetrate into the gap.

[0077] In addition, the second fluid flow 62 and/or third fluid flow also acts as flushing fluid, in particular as flushing air, by means of which the screen unit 42 can be cleaned. In particular the openings of the screen unit 42, which are not illustrated here, can also be cleaned and blown out with the help of the flushing fluid.

[0078] The second fluid flow 62 is created via an external further fluid source, which is not illustrated here, in particular by means of an air source. The external fluid source can optionally be the same fluid source, which serves to create the first fluid flow 56.

[0079] The third fluid flow can be provided, for example, via a fluid source, which is not illustrated here, such as, for example, air source. The third fluid source can be a separate or external further fluid source, in particular air source. This fluid source can optionally be the same fluid source, which serves to create the first and/or second fluid flow 56, 62.

[0080] It can optionally be provided that the second fluid inlet opening 60 comprises a further control element, which is not illustrated here, so that the second fluid flow 62 can be metered or regulated, respectively. A cross section of the second fluid inlet opening 60 can be changed for example by means of the control element. It is important to point out in particular, however, that the supplied second fluid flow 62 is in each case selected in such a way that the negative pressure, which prevails in the grinding container 12, is not impacted, but is sufficient for transporting the completely ground grinding material.

[0081] The embodiments, examples and alternatives of the preceding paragraphs, the claims or the following description and the figures, including the different views thereof or respective individual features can be used independently of one another or in any combination. Features, which are described in combination with an embodiment, can be applied for all embodiments, unless the features are incompatible.

[0082] When, in connection with the figures, reference is generally made to schematic illustrations and views, this does in no way suggest that the figure illustrations and the description thereof with regard to the disclosure of the invention are to be of minor importance. The person of skill in the art is in fact able to gather sufficient information from the illustrations, which are drawn schematically and in an abstract manner, which make it easier for him to understand the invention, without his understanding being impacted in any way from the illustrated and possibly not exactly true-to-scale size ratios of the agitator ball mill and/or parts of the agitator ball mill or other illustrated elements. The figures thus make it possible to the person of skill in the art, as reader, to derive a better understanding for the inventive idea, which is worded more generally and/or more abstractly in the claims as well as in the general part of the description, on the basis of the concretely described implementations of the method according to the invention and the concretely described mode of operation of the device according to the invention.

[0083] The invention has been described with reference to a preferred embodiment. A person of skill in the art can envision, however, that modifications or changes can be made to the invention, without thereby leaving the scope of protection of the claims below.