Agitating Mill

Abstract

An agitator mill, in particular an agitator bead mill having a mill housing, in which an agitator shaft, preferably bearing agitator elements, circulates in such a way that a grinding chamber is configured between the agitator shaft and the mill housing, and into the chamber the grist is fed, transported by a fluid carrier substance, as a rule in the form of a suspension, wherein the grinding chamber is partially filled with grinding media, which are set in motion by the circulating agitator shaft and thereby the grist, carried through the grinding chamber by a fluid carrier substance, is crushed, wherein the grist, transported by the fluid carrier substance, is discharged together with the carrier substance through a sieve, which retains grinding media that arrive as far as the area of the sieve, wherein the sieve consists of several sieve elements arranged one after the other along the longitudinal axis of the agitator mill, the sieve elements being penetrated in parallel manner, with their surfaces flowing from the grinding chamber, and extend diagonally or radially to the axis, around which the agitator shaft circulates.

Claims

1. An agitator mill, in particular an agitator mill having a mill housing, in which an agitator shaft, preferably bearing agitator elements, circulates in such a way that a grinding chamber is configured between the agitator shaft and the mill housing, and into said chamber the grist is fed, transported by a fluid carrier substance, as a rule in the form of a suspension, wherein the grinding chamber is partially filled with grinding media, which are set in motion by the circulating agitator shaft and thereby the grist, carried through the grinding chamber by a fluid carrier substance, is crushed, wherein the grist, transported by the fluid carrier substance, is discharged together with the carrier substance through a sieve, which retains grinding media that arrive as far as the area of the sieve, wherein the sieve consists of several sieve elements arranged one after the other along the longitudinal axis of the agitator mill, said sieve elements being penetrated in parallel manner, with their surfaces flowing from the grinding chamber, and extend diagonally or radially to the axis, around which the agitator shaft circulates.

2. The agitator mill according to claim 1, wherein every sieve element configures a front surface of a sieve carrier closed on its peripheral side, wherein every sieve element is preferably constructed of steel, ideally stainless steel.

3. The agitator mill according to claim 2, wherein the agitator mill comprises sieve carriers, both of whose front surfaces are configured by sieve elements.

4. The agitator mill according to claim 1, wherein the agitator mill comprises sieve carriers whose outer ring includes a closed peripheral enclosure surface.

5. The agitator mill according to claim 4, wherein the outer ring is constructed of ceramic or whose peripheral enclosing surface bears a coating to reduce abrasion, in particular a ceramic layer.

6. The agitator mill according to claim 1, wherein the outer ring of the sieve carrier is connected by means of spokes with a hub sleeve of the sieve carrier.

7. The agitator mill according to claim 1, wherein the hub of the sieve carrier includes at least one, preferably several discharge openings for the fluid carrier and the grist carried by it.

8. The agitator mill according to claim 1, wherein the sieve carriers are carried by a drain pipe into which the fluid carrier substance and the grist transported by it are carried out of the sieve carrier.

9. The agitator mill according to claim 1, wherein the at least two, better at least six, especially preferred at least 10 and ideally at least 15 sieve carriers are arranged along the longitudinal axis one after the other.

10. The agitator mill according to claim 1, wherein the sieve or the sieve carriers which constitute it are arranged in a sieve chamber in the agitator shaft.

11. The agitator mill according to claim 1, wherein the grinding chamber is connected by rotary openings with the sieve chamber, preferably in the form of slits whose main extending axes run parallel to the longitudinal axis.

12. The agitator mill according to claim 1, wherein the sieve carriers rotate during operation, ideally by being carried by a drain pipe, which in turn also rotates.

13. The agitator mill according to claim 12, wherein the drain pipe carries at least one and preferably several compensation channels through which the fluid carrier substance with grist is conveyed and is discharged into the at least one intermediate space, wherein each compensation channel is preferably configured by a tube that is disposed between the drain tube and the hub sleeves and as a rule is held by the latter.

14. The agitator mill according to claim 1, wherein the individual sieve openings of a sieve element, which preferably rotates with the agitator shaft, have, on the side flowing from the grinding chamber, a greater diameter than the grinding media.

15. The agitator mill according to claim 14, wherein the aforementioned sieve openings are each narrowed in a funnel shape toward the inside.

16. The agitator mill according to claim 15, wherein the funnel-shaped narrowing area of a sieve opening leadspreferably abruptlyinto a channel whose diameter can be less than the diameter of the grinding media.

17. The agitator mill according to claim 14, wherein on the downstream side of the sieve openings, on the inner surface of the sieve element situated there, a separator panel is disposed at a distance therefrom, preferably constructed of sheet metal, so that a gap is configured between the inner surface of the sieve element and the separator panel, and the fluid carrier substance with the grist transported by it must pass through the said gap at the connection to the narrowest point of the sieve opening, and where the gap preferably has a gap height which is at least 30% smaller than the diameter of the smallest grinding media.

18. The agitator mill according to claim 17, wherein the separator panel in turn has openings whose opening longitudinal axis runs parallel to the longitudinal axis of the agitator bead mill, wherein the openings of the separator panel and the corresponding openings of the sieve element are disposed at a distance from one another, as seen in the radial and/or in the peripheral direction, so that the fluid carrier substance with the grist transported by it must pass through a gap between the inner surface of the sieve element and the separator panel, in order to flow out from a sieve opening through an opening of a separator panel, wherein the gap preferably has a gap height at least 30% smaller than the diameter of the smallest grinding media.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] FIG. 1 shows a schematic depiction of an agitator mill.

[0075] FIG. 2 shows the sieve of an inventive agitator mill in a longitudinal section.

[0076] FIG. 2a shows an enlarged section from FIG. 2.

[0077] FIG. 2b shows a perspective view of the arrangement shown in FIG. 2.

[0078] FIG. 3 shows an isometric explosion depiction of a sieve carrier with assembled sieve element and a drain tube.

[0079] FIG. 4 shows the sieve of an inventive agitator mill with compensation channel in longitudinal section, that is, of a second, especially preferred embodiment.

[0080] FIG. 4a shows a perspective view of the ensemble shown in FIG. 4.

[0081] FIG. 5 shows the sieve illustrated in FIG. 4 in cross-section with bent cutting sequence.

[0082] FIG. 6 shows a section with sieve carriers whose sieve elements are equipped with specially configured, preferred funnel-shaped sieve openings.

[0083] FIG. 6a shows an enlarged section from the left-hand sieve carrier of FIG. 6.

[0084] FIG. 6b shows a section enlargement from the right-hand sieve carrier of FIG. 6.

[0085] FIG. 7 shows a variant of the ensemble of FIG. 6, which now is equipped with pump vanes.

[0086] FIG. 8 shows a section with sieve carriers, which employs sieve elements with additional separator plates.

DETAILED DESCRIPTION

[0087] The functioning of the invention is explained by way of example with reference to FIGS. 2 through 8.

[0088] FIG. 2 depicts in a lengthwise sectional view a first embodiment of an inventive agitator mill 1 having a sieve 4.

[0089] The sieve 4 is situated in a sieve chamber 21. The sieve chamber 21 is configured by a section of the agitator shaft 3 which is configured as a hollow shaft. It is also possible here, instead, that a rotary cage, which configures the sieve chamber 21, is fastened to the agitator shaft 3. Agitator elements 8 are also preferentially situated on the non-facing side of the section of the agitator shaft 3 configuring the sieve chamber 21. The said elements 8 set the grinder media in motion. The result is that the grist transported by the carrier substance in the direction of the sieve 4 is crushed by the grinding media in passing the agitator elements 8.

[0090] Because the grinding media are set into a motion in the peripheral direction of the agitator shaft by the agitator shaft 3 and the agitator elements 8, they are in principle kept distant from the sieve 4 by the thereby arising centrifugal forces. In addition, the portion of the agitator shaft 3 configuring the sieve chamber 21 and the mill housing 2 together form a channel, which must be traversed by the carrier substance and the grist as well as by the grinding media if the latter stream in the direction of the sieve 4. Even when the agitator shaft 3 is stationary, the grinding media do not therefore automatically advance as far as the sieve 4.

[0091] The sieve 4 is made up of several sieve carriers 15 (compare in particular the enlarged sectional view, FIG. 2a), on each of which one or two sieve elements 12 are mounted. By means of hubs 17, the sieve carriers 15 here are mounted in a parallel row on a drain tube 20.

[0092] To safeguard the sieve carriers 15 axially against slipping, one of the sieve carriers 15 is contiguous with the mill housing 2 when in assembled state. In addition, distancing sleeves 26 are provided between the individual sieve carriers 15. The sieve carrier 15 mounted on the free end of the drain tube 20, in addition, is secured by an axial safety device 29.

[0093] The first and last sieve carriers 15 preferably each carry only a single sieve element 12 on their free front surface. The sieve carriers 15 situated between the first and last sieve carriers 15 each carry a sieve element 12 on their two free front surfaces.

[0094] The sieve elements 12 comprise sieve openings 13 (compare here, in particular, FIG. 2b). The diameters of the sieve openings 13 are of such a size that only the carrier substance coming out of the mill chamber 7 together with the ground grist is able to pass through them. The grinding media, on the other hand, cannot pass through the sieve openings 13.

[0095] After the carrier substance, together with the grist, has passed through a sieve element 12 into the interior of a sieve carrier 15, they can flow by way of the respective discharge openings 19 of the hubs 17 of the sieve carriers 15 and by way of the discharge openings 27 of the drain tube 20 into the drain tube 20. From there, finally, they flow out of the mill housing 2.

[0096] Because the sieve 4 is situated in the sieve chamber 21, the grinding media are, in principle, kept at a distance from the sieve 4. However, it can also happen that grinding media arrive in the sieve chamber 21 through the channel between the agitator shaft 3 forming the sieve chamber 21 and the mill housing 2. Because of the rotating motion of the portion of the agitator shaft 3 forming the sieve chamber 21, however, the grinding media situated in the sieve chamber 21 are also set in rotating motion about the longitudinal axis of the agitator shaft 3. To ensure that the grinding media are moved out of the sieve chamber 21 by the resulting centrifugal forces, slits 22 are provided in the portion of the agitator shaft 3 forming the sieve chamber 21. The sieve elements 12 are thus barely in contact with moved grinding media. Formations of abrasive wear, caused by the grinding media on the sieve elements 12, are thus avoided to the maximum possible extent. On the outer rings 16 of the sieve carriers 15, however, there can occur increased contact with the grinding media when so many grinding media are situated in the sieve chamber 21 that they accumulate in the region of the slits 22 before they can proceed out of the sieve chamber 21 by way of the slits 22 as a result of centrifugal forces. For this reason, the outer rings 16 are preferably made of abrasion-resistant, often ceramic material.

[0097] Because the individual components of the grist have a markedly lower weight than the grinding media, the centrifugal forces acting on the grist on the other hand are not sufficient to overcome the suction that prevails on the sieve elements 12.

[0098] FIG. 3 depicts a single sieve carrier 15 together with a sieve element 12; in the foreground the drain tube 20 is shown. The sieve element 12 here is shown in partial sectional view in order to be able to indicate the interior of the sieve carrier 15.

[0099] As can be seen, a sieve element is preferably designed as essentially or completely level. A sieve element preferably has the form of a disc extending with its surfaces completely or at least essentially in the radial direction.

[0100] The outer ring 16 of the sieve carrier 15 is connected with the hub 17 by means of spikes 18. Accordingly, the interior of the sieve carrier 15 offers considerable space for the carrier substance flowing in through the sieve element 12 and the grist. The carrier substance together with the grist can thus flow into the drain tube 20 through the discharge openings 19 of the hub 17, which in assembled state are congruent with the discharge openings 27 of the drain tube 20.

[0101] An additional embodiment is shown in FIGS. 4, 4a and 5. It foresees in addition one or at most several compensation chambers 23. The compensation chambers 23 are configured by tubes which when mounted run between the drain tube 20 and the hub 17 of the sieve carriers 15. The pressure adjustment discussed above can occur by means of the compensation channels 23. For this purpose, the compensation channels 23 comprise the openings 30. The latter, when assembled, are congruent with the openings 28 in the distancing hubs 26 situated between the sieve carriers 15.

[0102] Shown in FIGS. 6 through 8 are various embodiments of the sieve openings 13 in the sieve elements 12.

[0103] In FIGS. 6 and 6a, at least a few of the sieve openings 13 on the side of the sieve element 12, through which the carrier substance together with the grist flows into the sieve carrier 15, have a greater diameter than on the side of the sieve element 12, which is situated inside the sieve carrier 15. The transition from the greater diameter to the smaller diameter here is preferably funnel-shaped or conical. In such a configuration of the sieve openings 13, besides the grist, grinding media can also, at least partly, stream into the sieve opening 13. The greatest diameter A of the sieve opening 13 is accordingly greater than the diameter of the grinding media. This has the advantage that the grinding media cannot strike with pressure against the edge of a sieve opening 13 that is relevant to the functioning of the sieve, because beforehand they penetrate the respective sieve opening 13. The grinding media not only come into contact with the edges, but also with the sieve opening 13 rather extensively, thus further reducing abrasion.

[0104] Here the smallest diameter B, or the smallest thin cross-section of the sieve opening 13, can be smaller than the grinding media, so that the latter cannot pass through the respective sieve opening 13. Alternatively, this configuration, in accordance with FIGS. 6 and 6a, can also be such that the said smallest diameter is also greater than the grinding mediadepending on whether this is a matter of a dynamic or a static design in the aforementioned sense.

[0105] The configuration illustrated here contributes to making the grinding media nevertheless unable to pass through, particularly when stationary, because they thus, after their penetration into a sieve opening, fall back down the slope toward the outside under the impact of their weight, and thus back into the sieve space.

[0106] Easily recognizable in FIGS. 6 and 6a is the abrasion-resistant layer VSS, which encloses or encircles the peripheral enclosure surface of a sieve carrier 15.

[0107] In at least a few or even all of the sieve openings 13 of the embodiment shown in FIG. 6 (compare FIG. 6b), the diameter of the sieve opening 13 starting from the side of the sieve element 12 at which the carrier substance flows into the sieve carrier 15, likewise decreases like a funnel or conically and then suddenly grows smaller. From the point where the diameter suddenly decreases, it finally forms a channel 14 having a primarily constant diameter. At that point the diameter of the channel 14 is finally smaller than the median diameter of the grinding media. Until reaching this channel 14, accordingly, the grinding media can penetrate the sieve opening 13. However, the channel 14 is situated so far inside the sieve opening 13 that a grinding medium that has penetrated must leave its regular motion path in order to reach that point. Consequently, the grinding medium reaches the channel 14 only with a reduced mobile energy and thus causes no appreciable damage to the channel 14.

[0108] The embodiment according to FIG. 7 corresponds completely to the one shown in FIG. 6. There is just one difference. Bridges or pump vanes PF are provided between immediately neighboring sieve carriers. They are configured in such a way that they produce a pumping effect that propels the grinding media outward or supports the outward impetus.

[0109] In the embodiment shown in FIG. 8 (left-hand side) the sieve openings 13 optionally also comprise a cross-section that tapers in the manner of a funnel or cone or trapezoid. Its smallest diameter or slender cross-section C can thus be greater than that of the grinding media. On the side of the sieve element 12, which is situated inside the sieve carrier 15, in addition, a separator plate 24 is disposed on the sieve element 12 in such a way that the sieve openings 13 are covered. However, between the separator plate 24 and the sieve element 12, a distancing brace 26 is provided. Accordingly, a small air gap is situated between the separator plate 24 and the sieve element 12. This air gap is of such a size that grinding media that have penetrated the sieve opening 13 cannot pass through it. On the other hand, the carrier substance together with the grist can proceed through the air gap into the interior of the sieve carrier 15. With this embodiment as well, the grinding medium can no longer cause abrasive effects once it has advanced into the sieve opening 13 as far as the separator plate 24.

[0110] In the embodiment shown in FIG. 8 (right-hand side), the sieve openings 13 have a conical cross-section. They could also have a constant cross-section, however. In either case, a separator plate 24 is provided here on the sieve element 12 side that is situated inside the sieve carrier 15. The plate is situated immediately contiguous with the sieve element 12 and covers the sieve openings 13. However, the otherwise preferred, circularly insulated separator plate 24 likewise has at least one opening 25, such openings being set off from the sieve openings 13. The width of the sieve element 12 in the region of the setoff, between a sieve opening 13 and an opening 25 of the separator plate 24, is reduced in such a way that a gap remains between the separator plate 24 and the sieve element 12. The carrier substance together with the grist can stream through this gap into the interior of the sieve carrier 15. The grinding media, however, cannot pass through the gap. Here as well, however, the grinding media can cause no further abrasive friction effect once they have penetrated the sieve opening 13 as far as the separator plate 24.

[0111] Optionally, it is possible eventually to claim protection also for the following aspects, either for each separately or more broadly to include additional technical features from the description and/or the drawings and/or expanded by individual features or all features of one or more already stated subsidiary claims, regardless of their reference to the already existing claims.

[0112] An agitator mill 1, in particular an agitator bead mill having a mill housing, in which an agitator shaft, preferably bearing agitator elements, circulates in such a way that a grinding chamber is configured between the agitator shaft and the mill housing, and into said chamber the grist is fed, transported by a fluid carrier substance, as a rule in the form of a suspension, wherein the grinding chamber is partially filled with grinding media, wherein the grist, transported by the fluid carrier substance, is discharged together with the carrier substance through a sieve, which retains grinding media, wherein the sieve either consists only of a single sieve element, ideally extending essentially radially or in rare cases diagonally, dispensing with a sieve element, which configures a peripheral enclosure surface; or essentially consisting of several, preferably at least 10 sieve elements flowing in parallel, one after the other, along the longitudinal axis of the agitator mill.