EP0627262B1 - Continuously working agitator ball mill for fine and ultrafine milling of material - Google Patents

Description

The invention relates to an agitator ball mill and a Process for fine and very fine grinding of a good, namely one Agitator ball mill according to the preamble of claim 1 and a method according to the preamble of claim 10.

Agitator ball mills are used, for example, for comminution and dispersing solids in a liquid phase or used to digest microorganisms.

Known on the market and for continuous operation The proposed agitator ball mills have a cylindrical one or conical, horizontal or vertical axis grinding chamber, whose housing consists of one longitudinal wall and two on the two Ends of the longitudinal wall arranged end walls is formed. One end wall has one for feeding the Grist-serving good inlet and the other end wall a good outlet for removing the goods. In the The grinding chamber is also an agitator that can be rotated around the axis of the chamber arranged radially around the grinding media presented in the mill to the agitator shaft and thereby continuously material passed through the grinding chamber through impact and Crush shear forces. The agitators have the known agitator ball mills several, coaxial to the chamber axis rotating agitators. These have the shape, for example a disc with a substantially circular orbit and are in through slots opening into the orbit tapering, extending in the tangential direction Tines divided.

Another well-known agitator ball mill is known from GB-A 1,340,385. This reveals one for fine and Fine grinding of a good serving, continuously working Agitator ball mill with a cylindrical, for holding of grinding media serving, one on one Arranged end of the grinding chamber and in the interior of the Grinding chamber opening good inlet and one at the other end of the Grinding chamber arranged Gut outlet and one more Agitator with agitators and coaxial to the chamber axis. In this case, the agitators of the agitator each have a circular partition plate and on each side of the partition plate a circular disc, the latter a central one Have opening through which the grinding media and the well-formed mixture can flow through. The Separating plate divides the gap between the two disks two slots, namely a lower and an upper one Slot, which, as will be explained in more detail, the grinding effect reinforced. When operating this known agitator ball mill is continuously a part of the mixture mentioned flow through the central opening into the gap between the disks and radially over the edge of the two discs transported outside.

The two discs of the agitators have mutually arcuate edge sections, which is a reduction in Gap or slot widths in the edge area, i.e. an increase the flow rate of the exiting from the stirring elements Mixture. The slot width is chosen so that they are only slightly larger in the area of the pane edges is, as the diameter of the grinding media, thereby a proportionate to achieve good grinding effect. The between the separating plate arranged on both disks finally has the Purpose to increase the frequency of particle collisions what together with the particle acceleration in the edge area an improved Grinding effect.

Research has now shown that when increasing of the total circulation, i.e. with the increase in the mixture acting centrifugal forces a strong concentration of the mixture occurs on the inside wall of the mill. The mixture will pressed so tightly in the area of the inner wall that the Good to be ground is no longer fully absorbed and in There are too few grinding media in the center of the container. By the tight packing of the grinding media in the area of the inner wall and the narrow gap also has a useless abrasion effect and Wear the grinding media.

In the continuous operation of the above, horizontal and vertical axis agitator ball mills are the Grinding media through the flow of the material to be ground in the direction the good outlet dragged, whereby the grinding media in Accumulate the area of the good outlet and its grinding and dispersing effect by losing from being through the Agitators of the agitator are moved. Which during the Grinding and dispersing process in the area of the good outlet Grinding media also hinder continuous leakage of the product flow, resulting in an increase in the internal chamber pressure has the consequence. For mills in a standing version due to the centrifugal pressure and the upward movement of the grinding media an overflow of the mill also favors, which not only the Maximum throughput of the mill limits but also an increase of the internal chamber pressure. This increase in Finally, the internal chamber pressure has the effect that, in particular, the Grinding media during the grinding and / or dispersing process exposed to relatively large mechanical wear are and that to maintain a uniform from the grinding chamber leaking product streams for the movement of the stirring elements necessary agitator power must be increased. The accumulation of grinding media in the area of the good outlet ultimately causes also an increase in the grinding temperature, which is disadvantageous affect the quality of the product to be manufactured can. Additional wear of the grinding media occurs in the from GB-A 1,340,285 known mill finally through the relatively narrow gap.

The invention is now based on GB-A 1,340,285 The underlying task of creating a new agitator ball mill, which does not have the aforementioned disadvantages and with which good can be ground gently and evenly, for what in particular a uniform axial distribution of the grinding media is kept in the grinding chamber.

According to the invention, this object is achieved by an agitator ball mill solved with the features of claim 1.

The invention further relates to a with this agitator ball mill feasible process by the characteristics of claim 10 is defined.

Advantageous embodiments of the agitator ball mill and of the method emerge from the dependent claims.

die Figur 1 einen Längsschnitt durch einen Teil einer zylindrischen Mahlkammer,

die Figur 2 eine Draufsicht auf ein in der Figur 1 dargestelltes Rührorgan,

die Figur 3 einen Längsschnitt durch eine zweite Mahlkammer,

die Figur 4 eine Draufsicht auf ein in der Figur 3 dargestelltes Rührorgan,

die Figur 5 einen Längsschnitt durch eine dritte Mahlkammer,

die Figur 6 eine Draufsicht auf ein Teil eines in der Figur 5 dargestellten Rührorganes,

die Figur 7 eine Draufsicht auf ein anderes in der Figur 5 dargestelltes Rührorgan;

die Figuren 8 und 9 zeigen eine Draufsicht auf zwei weitere Ausführungsformen eines Rührorganes.

Exemplary embodiments of the invention are described below with reference to the drawing. In the drawing shows

1 shows a longitudinal section through part of a cylindrical grinding chamber,

FIG. 2 shows a plan view of a stirring element shown in FIG. 1,

3 shows a longitudinal section through a second grinding chamber,

FIG. 4 shows a top view of a stirring element shown in FIG. 3,

5 shows a longitudinal section through a third grinding chamber,

FIG. 6 shows a plan view of part of a stirring element shown in FIG. 5,

FIG. 7 shows a top view of another stirrer shown in FIG. 5;

FIGS. 8 and 9 show a top view of two further embodiments of a stirring element.

The only partially shown in Figure 1 and as a whole with 1 designated grinding chamber of an agitator ball mill has a housing 2 with a horizontal axis 3. The Housing 2 has an elongated, substantially cylindrical Longitudinal wall 4 and two at both ends of the longitudinal wall 4th arranged end walls 5 and 6, of which the end wall 5 a feed inlet for feeding the regrind 8 and the end wall 6 one for removing the goods Good outlet 9 has.

In the interior 7, an agitator 10 is also arranged four paddlewheel-like agitators distributed along axis 3 12 and by a not shown in the drawing Drive device can be rotated. The axis 3 coaxial shaft 11 of the agitator 10 is with its the end wall 6 piercing end on the drive device attached.

As can be seen from Figures 1 and 2, each has Agitator 12 a disc 12a facing the end wall 6, a parallel to this, facing the end wall 5 annular disc 12b with a coaxial to the axis 3 Opening 12d and several, the two disks 12a and 12b interconnecting and designed as blades 12c Funding elements. The latter are arcuate in longitudinal section and connect the disks 12a and 12b together.

Finally, in the end wall 6 of the grinding chamber 1 a via an outlet line 15 connected to the outlet 9, here there is a separating mechanism designed as an annular gap 14, which is dimensioned so that the ground material from the interior 7 can flow out, the grinding media used for grinding 13 however be withheld.

When operating an agitator ball mill having the grinding chamber 1 is through the inlet 8 to be ground or Good to be dispersed in a liquid in liquid form continuously transported into the interior 7 of the grinding chamber 1 and led to outlet 9 in this. This can be, for example around dye suspensions, lacquer colors, printing inks, Agrochemicals, filler suspensions, video tape coatings, Cosmetics, food or microorganisms act. The grinding media present in the interior 7 of the grinding chamber 1 13 grind and / or disperse during operation the agitator ball mill continuously through the grinding chamber 1 passed through, whereupon that in the grinding chamber produced this product - in a continuous flow of liquid - Leaves through the separation mechanism 14.

Which during the grinding and / or dispersing process Stirring elements 12 rotating in the direction of arrow 16 are now designed in this way and measure that part of that from the Grinding bodies 13 and the one to be ground and / or to be dispersed Well-formed mixture radially in the direction of arrow 17 is transported outside, whereupon at least part of the mixture in the direction of arrow 18 to the opening 12d and back from there in the space between the two disks 12a and 12b flows, or is sucked into it. Through this and through that the speed at which the said mixture is moved radially, preferably greater than the speed of the material passed through the grinding chamber 1 - thereby entraining grinding media 13 through the axial flowing material is avoided - can be a uniform distribution of the grinding media 13 in the interior 7 to adjust. The speed at which the grinding media 13 radially can be moved, for example, by about one Be three to seven times faster than speed, with which the material to be ground flows through the grinding chamber 1.

The shown in Figures 3 and 5 and as a whole 21 designated grinding chamber is similar to that based on the figure 1 described grinding chamber 1 is formed and has like this one from a longitudinal wall 23 and two end walls 24 and 25 formed housing 22 and a horizontally mounted agitator 26 on.

In FIG. 3, the agitator 26 has a plurality of paddlewheel-like ones Stirring elements 27, each consisting of an essentially circular disc 27a, one arranged parallel to this Disc 27b and more between discs 27a and 27b arranged blades 27c exist. That in Figure 4 in view Stirring member 27 shown differs from that Agitator 12 in that the discs 27a and 27b to the end wall 24 are inclined towards and that the good inlet 8 facing disc 27b has the central opening 27d, so that when the agitator ball mill is operated, this is done by the agitators radially moving mixture on the end wall 24 suction side of the stirring elements 27 sucked becomes. The curved shape of the stirring elements 27 now has the additional one Advantage that when turning the stirring elements 27 in the direction arrow 28 the grinding media sucked in through hole 27d in the direction of arrow 29 from the agitator 27 - that is, in the direction of flow the opposite direction - ejected be, so that this is also proportionate large axial speed of the to be ground and / or good to be dispersed in a liquid Adjust the distribution of the grinding media 13 in the interior 7 can.

In Figure 5, the agitator 26 has two different Stirring elements, namely a propeller-like stirring element 30 and a paddle wheel-type agitator 36.

The stirring element 30 is composed of a propeller 31 and two circular discs 32 and 33 together. Latter are on the inner wall of the grinding chamber 21 by means of holding arms 34 attached and each have a coaxial to the chamber axis hole 32a and 33a through which the shaft of the agitator 26 passes. The propeller 31 shown in view in FIG. 6 has four wings 31a designed as conveying elements, through which during the operation of the agitator ball mill in the Grinding chamber submitted mixture is transported to the disk 32. The diameter of the hole 33a facing the good inlet Disk 33 is in the embodiment shown in Figure 5 preferably larger than the diameter of the drive shaft, for example twice as big as this that at least continuously during the operation of the agitator ball mill part of the propeller carried to wall 32 Mixtures are deflected radially and back in the direction of arrow 35 in the space between the two disks 32 and 33 can flow.

It should also be noted that the agitator 30 in different can be changed. So you can choose at least one of the two disks 32 or 33 - instead of the inner wall of the grinding chamber 21 - also on the shaft of the agitator 26 be attached. One for sucking the in the grinding chamber 21 submitted mixture serving disc without Holding arms 34 is attached, has - in contrast to in 5 shown disk 33 - at least one central Bore or several, for example arranged in a circle Single holes on. Furthermore, there is also the Possibility of connecting several propeller-like stirring elements together combine their propellers with opposite directions of conveyance produce.

The paddle wheel type shown in view in FIG. 7 Stirring member 36 differs from the stirring member 12 and 27 in that there are three arranged parallel to each other Discs 37, 38 and 39 has that between two each Disks, namely between the disks 37 and 38 and the Disks 38 and 39 the blades 40 are arranged that the two outer disks 37 and 39 each have a central opening 37a and 39a and that the stirring member 36 by means of middle disc 38 attached to the shaft of the agitator 26 is.

During the grinding and / or dispersing process it turns the agitator 36 in the direction of arrow 41, so that continuously Part of the grinding media and that to be ground and / or dispersing well-formed mixture through the two holes 37a and 39a sucked in, radially from the blades 40 outside and radially again over the edges of the disks 37 and 39 is transported inwards, so that it affects both Sides of the agitator 36 shown by the arrows 42 Circulation.

Two further embodiments of stirring elements, the serve the same purpose as the stirring elements described above 12, 27, 30 and 36 are shown in Figures 8 and 9, respectively. The paddle wheel type shown in these figures Stirring elements 43 and 44 are essentially the same designed as the stirrer shown in Figures 1 and 2 12, but differ from this in that the Disks 43b arranged on both sides of the blades 43a and 44a and 43c or 44b and 44c each have at least one hole, so that during the grinding and / or dispersing process, that is in the interior existing mixture sucked in on both sides of the grinding chamber the blades 43a and 44a radially outwards, over the edges of the two discs radially inwards and then again into the space between the two disks 43b and 43c or 44b and 44c is conveyed.

The agitator ball mill according to the invention now faces the known agitator ball mills have the advantage that during the entire grinding and / or dispersing process even distribution, not compressed towards the exit the grinding media remains in the grinding chamber and that means that a disadvantageous pressure for the manufacture of the product - and temperature increase in the area of the good outlet as well an increased wear of the equipment largely avoided can be.

At this point it should be noted that the of Figures 1 to 7 described grinding chambers and stirring elements just a selection of several possible embodiments represent the invention and changed in various respects can be.

For example, those described above Stirrers as desired with each other or with other stirrers be combined.

In addition, for example, those facing away from axis 3 Outer surfaces 12e of those shown in Figures 1 and 2 Blade 12c with the inner surface of the disc 12b a pointed Form angles so that the grinding media moved by the stirring element 12 13 - similar to the agitator 27 - in the direction of flow of the good in the opposite direction become.

Finally, the longitudinal wall of the grinding chamber can still be closed additionally be encased by a cylindrical jacket that with together a space with a circular cross-section limited to cool or warm the interior a good cooling or heating fluid is introduced can be.

Claims (11)

1. Continuously operating agitator ball mill serving for the fine and ultrafine milling of a material and with a cylindrical or conical milling chamber (1, 21) serving for the reception of milling bodies (13), a material inlet (8) arranged at one end (5, 24) of the milling chamber (1, 21) and opening into the interior chamber (7) of the milling chamber (1, 21) and a material outlet (9) arranged at the other end (6, 25) of the milling chamber (1, 21) and leading out of the interior chamber (7) as well as a stirring mechanism (10, 26), which is co-axial with the chamber axis (3) and comprises several stirring organs (12, 27, 30, 36, 43, 44), wherein each stirring organ (12, 27, 30, 36, 43, 44) comprises at least two mutually parallel circular discs (12a, 12b; 27a, 27b; 32, 33, 43b, 43c; 44b, 44c) for moving the milling bodies (13), characterised thereby, that the stirring organs are constructed in the manner of bucket wheels or propellers and comprise several conveying elements, that the two discs (12a, 12b; 27a, 27b; 32, 33, 43b, 43c; 44b, 44c) are arranged at both sides of the conveying elements, that at least one of the two discs (12b, 27b) has a central opening (12d, 27d) through which the mixture formed of the milling bodies (13) and the stock to be milled can flow and that the stirring organs (12, 27, 30, 36, 43, 44) are constructed and dimensioned in such a manner that, in operation of the agitator ball mill, a part of the mixture flows continuously over the rim of the disc (12b, 27b, 33, 43b, 44b, 44c) with the central opening radially inwards to the central opening (12d, 27d, 33a) and from there back into the gap between the discs (12a, 12b; 27a, 27b; 32, 33, 43b, 43c; 44b, 44c) and that a uniform axial distribution of the milling bodies in the interior space (7) of the milling chamber (1, 21) remains maintained thereby.
2. Agitator ball mill according to claim 1, characterised thereby, that the stirring organ (12, 27, 43, 44) comprises several vanes (12c, 27c, 40, 43a, 44a), which are arcuate in longitudinal section and extend towards the disc rims in tangential direction and which form an integral body with the two discs (12a, 12b; 27a, 27b; 43b, 43c, 44b, 44c).
3. Agitator ball mill according to claim 2, characterised thereby, that the two circular discs (12a,12b) are arranged perpendicularly to the chamber axis (3).
4. Agitator ball mill according to claim 2 or 3, characterised thereby, that the disc (12b, 27b) facing the material inlet (8) has the central opening (12d, 27d).
5. Agitator ball mill according to claim 2 or 3, characterised thereby, that the two discs each have a respective central opening.
6. Agitator ball mill according to one of the claims 2 to 5, characterised thereby, that the vanes (12c, 27c) stand perpendicularly to the two discs (12a, 12b; 27a, 27b).
7. Agitator ball mill according to one of the claims 2 to 5, characterised thereby, that outward surface of the vane, which is remote from the chamber axis (3), forms an acute angle with the inward surface of the disc facing the material inlet.
8. Agitator ball mill according to claim 1, characterised thereby, that the stirring organ (36) comprises at least three discs (37, 38, 39), that several vanes (40), which are arcuate in longitudinal section and extend towards the disc rims in tangential direction, are arranged between each two discs (37, 38; 38, 39) and that the two outer discs (37, 39) each have a respective central opening (37a, 39a).
9. Agitator ball mill according to claim 1, characterised thereby, that the discs (32, 33) arranged at both sides of the conveying elements of a stirring organ each have a hole (33a), which is co-axial with the chamber axis and through which the shaft of the stirring mechanism (26) leads and that the discs (32, 33) are fastened by means of retaining arms selectably at the inward wall of the milling chamber (21) or at the mentioned shaft.
10. Method for the fine and ultrafine milling of a material in an agitator ball mill according to one of claims 1 to 9, wherein the stirring organs (12, 27, 30, 36, 43, 44) are rotated in that direction which has the consequence of a radially outward movement of the milling bodies (13), characterised thereby, that the speed at which the milling bodies (13) are moved radially is greater than the speed at which the stock to be milled is led through the milling chamber (1, 21).
11. Method according to claim 10, characterised thereby, that the speed at which the milling bodies (13) are moved radially is greater by about a factor of three to seven than the speed at which the stock to be milled is led through the milling chamber (1, 21).

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