EP0290840B1 - Gap-ball mill for continuously grinding, especially disintegrating microorganisms, and dispersing solids in fluids - Google Patents

Abstract

Three mill units are mounted axially in series in a mill housing with a cover. Each mill unit has a rotor disc between two stator discs. The rotor discs are secured to the rotor shaft at their radially interior region. The stator discs are secured to the housing wall at their radially outer region. Individual pulverization gaps are formed between the stator discs, which gaps run around the rotor discs and in longitudinal cross section extend sequentially with a serpentine shape. The outer parts of the pulverization gaps form individual gap loops the inner ends of which are connected or "short-circuited" via ball return channels. During operation, the grinding elements are accelerated outward by centrifugal forces, and are concentrated into the gap loops. The grinding elements in each of the individual stages may be kept separated from the grinding elements in other stages; and they may have different sizes from stage to stage. The individual mill stages can be replaced as units. Alternatively, the rotor discs and stator discs which are rotationally symmetric can be replaced individually. They can have different axial cross sections, containing a single bend or multiple bends. The processing pressure for the material being pulverized which is passed through the serpentine pulverization gap system can be set accurately based on the rotational speed (rpm), so that microorganisms are recovered without the hyaloplasm leaking out or being worked into (i.e. intermixing with or being forced into intercalation with) the other materials.

Description

Ball mills of this type are known in various designs. The term "balls" should not be understood exclusively to mean the preferred, precisely spherical grinding media, but basically all grinding media of a similar configuration which are suitable for comminuting the solid particles of the material to be ground by rolling them against one another and on the boundary surfaces of the grinding chamber.

As a rule, finely ground balls made of hard wear-resistant steel, hard metal, glass or ceramic are used, but grinding media made of other materials are also used. In the past, grains of sand were used, which could often only be made sufficiently passable during the pre-grinding process.

CH-PS 639 567 already discloses a split ball mill set up for continuous operation which engages a cross-sectionally wedge-shaped displacement body of the rotor, which surrounds the mill axis at a radial distance, in an equally shaped grinding chamber of the stator. The regrind rotates around the entire displacement body attached to a rotor disk in a long acceleration phase around the wedge nose and is guided inwards by half the radius of rotation to the outlet.

The grinding media, which basically rotate in the same direction as the material to be ground, are separated out before the outlet by a separating device and conveyed back through a ball return channel, which is passed obliquely outwards through the rotor disk, under centrifugal force into the inlet area of the material, from where they return to their closed orbit.

In this way, high energy density is concentrated in a small area or in a small space, which enables high grinding performance with small mill dimensions and low manufacturing costs. However, the design of the separating device and the ball return device requires special care in order to avoid the risk of a ball jam. Especially since the interacting parts such as rotor and stator are made in one piece and can only be replaced as a whole or given for repair.

There are other known designs, in particular in the case of annular gap mills, with active grinding parts being provided interchangeably, such as according to DE-PS 35 26 724, but this leads to particular problems in the changing process and in the holding of the interchangeable mill elements, especially in high-speed mills. In this way, even multi-stage and possibly different grinding processes can be connected in series, and rotor and stator disks with axial openings are provided. In the case of large throughput, however, all grinding media to be circulated must be be stopped by a single separator. The large number of grinding media can be easily compacted and block the mill.

However, while in the aforementioned CH-PS 639 567 relatively large orbital paths are selected on the top of the rotor, which results in only a limited increase in the ball pressure, short paths with a high rate of increase are used here, the grinding media always being in the extension of the ball return channel connecting the inner surface against the outer cone ring, which enables a high-performance grinding with increased pressing and grinding performance, which also enables the creation of very fine, uniform dispersions in a short time.

Finally, it is also known from DE-A 1 913 147 an agitator ball mill with a vertical mill axis, the agitator of which has at least two agitating elements rotating one above the other in a container and a plurality of funnel-like ring disks which are connected by deflecting elements, so that the ground material from above into one Grinding insert can be initiated, flows through to the lower end of the container and is pumped up from there again. Here, too, the grinding media are freely movable again at larger intervals, so that only slight contact forces can be applied between the grinding media during the grinding process. In addition, the build-up of higher press forces takes a relatively long time there and is generally not sufficiently controllable. Especially when microbes are opened, however, certain predetermined pressing forces are required, which are to be built up and used in an exact size. So far, this has not been adequately achieved with agitator mills.

The invention is based on the gap ball mill defined at the outset and pursues the task of developing this mill, primarily for the disintegration of microorganisms, in the simplest possible manner in such a way that it is without danger and disadvantages of a ball jam formation for a variety of tasks, in particular for breaking up extremely solid microbes with correspondingly large pressing forces, and can also be easily maintained, that is to say, requires little downtime.

• a) In einem Mühlengehäuse (1) sind zentrisch zur Mühlenachse (5) erste und zweite Statorscheiben (17,18) leicht auswechselbar mit ihrem Außenrand festgelegt und
• b) einander wenigstens paarweise so zugeordnet und angepaßt, daß sie zwischen sich eine von der Mühlenachse (5) etwa radial erstreckte Statoreinheit (16) mit einer rotationssymmetrischen Mahlraumeinheit (19) bilden.
• c) Die Statorscheiben (17,18) haben jeweils einen zur Mühlenachse (5) geneigten kegelförmigen Teil (171,182), an den sich bei der ersten Statorscheibe (17) innen ein S-förmiger Teil (172) anschließt.
• d) In der Mahlraumeinheit (19) ist zentrisch zur Mühlenachse (5) mindestens eine rotierbar angetriebene tellerartige Rotorscheibe (20) gelagert, die zum Außenrand hin einen kegelartig geformten Ringteil (Kegelring 28) aufweist.
• e) Vorder- und Rückseite (71,72) der Rotorscheibe (20) bilden mit zwei Statorscheiben (17,18) in der Mahlraumeinheit (19) gemeinsam einen die Rotorscheibe (20) umschließenden Mahlspalt (36), der sich von der Mühlenachse (5) aus allseits etwa radial erstreckt.
• f) Im inneren Teil der Mahleinheit (2) ist eine um den Kegelring (28) gelegte Spaltschleife (37,37') nach außen durch mindestens zwei Kugelrückführkanäle (47,47') kurzgeschlossen,
• g) die als Zentrifugal-Leitelemente von der Mühlenachse (5) weg radial nach außen erstreckt sind.

A split ball mill for continuous grinding, in particular for disintegrating microorganisms and dispersing solids in liquid, has the following features according to the invention:

• a) In a mill housing (1), the first and second stator disks (17, 18) are easily exchangeable with their outer edge and centered on the mill axis (5)
• b) assigned and adapted to one another at least in pairs so that they form between them a stator unit (16) which extends approximately radially from the mill axis (5) and has a rotationally symmetrical grinding chamber unit (19).
• c) The stator disks (17, 18) each have a conical part (171, 182) inclined to the mill axis (5), to which an S-shaped part (172) adjoins the inside of the first stator disk (17).
• d) In the grinding chamber unit (19) at least one rotatably driven plate-like rotor disk (20) is mounted centrally to the mill axis (5) and has a cone-shaped ring part (cone ring 28) towards the outer edge.
• e) The front and rear sides (71, 72) of the rotor disk (20) together with two stator disks (17, 18) in the grinding chamber unit (19) together form a grinding gap (36) which surrounds the rotor disk (20) and which extends from the mill axis ( 5) extends approximately radially from all sides.
• f) in the inner part of the grinding unit (2), a split loop (37, 37 ') placed around the cone ring (28) is short-circuited to the outside by at least two ball return channels (47, 47'),
• g) which, as centrifugal guide elements, extend radially outward from the mill axis (5).

First of all, all parts essential for the grinding process, in particular the stator disks and the rotor disks, are provided as easily replaceable as a whole. This not only reduces the loss times in the case of repairs, but also enables the targeted use of special materials according to the local stresses, which despite the use of expensive materials in individual places, possibly in the form of thin surface layers, proves to be inexpensive. Above all, however, a recirculating ball area is installed in the middle part of the grinding unit and thus the grinding media are kept at a distance from the outlet of the unit. For safety's sake, a type of separating device in the form of a friction gap or the like is again provided, but it is avoided that the mass of the grinding media collects in front of such a separating device and can thus compact in the mill.

The design of individual, partly identical, partly individually or in groups interchangeable components within a grinding unit also has the advantage that almost any number of individual grinding units can be easily joined together, which only requires different, possibly again composed of unit elements mill housing with drive shafts . In principle, one or more grinding units can be operated in a larger housing, each with its own closed grinding media circulation. The individual grinding stages can therefore be loaded with grinding media of different sizes, for example in such a way that in the first grinding unit larger grinding media are used, in the subsequent grinding units in each case with gradually thinner grinding media. This in turn enables an increase in the intensity and uniformity of the shredding processes at least on average increased energy density and thus higher output with reduced mill volume.

But this can easily be achieved if you only ensure that by designing the different flow paths of grinding media and regrind at the separation point, appropriately differentiated and differently directed forces come into play, the rejection of the grinding media being primarily caused by correspondingly increased centrifugal forces and the deflection angle is so large that, following inertia and pressure drop, the regrind continues to flow on the specified path. It is even better to separate the grinding media of the individual grinding units using mechanical separation devices such as friction gaps.

The design is also still relatively simple, since it is primarily about rotational shapes on stator disks and rotor disks, which can be accomplished inexpensively by conventional manufacturing methods. The flow paths can be made relatively long in the smallest space and therefore the exposure time can be made relatively long.

In addition, the rotor disks in particular can be given a relatively large cross section with a corresponding thickness, which increases the breaking strength even in the case of material which is sensitive to bending and sensitive, such as ceramic.

The split ball mill according to the invention is particularly suitable for disrupting microorganisms or microbes, the evaluation of which is of particular importance for biotechnology. Such microbes consist of a capsule-like cell with a cell fluid that has a species-specific active ingredient that should be obtained as completely as possible. Wet grinding in agitator ball mills has already been proposed for mechanical extraction. The one scored there However, yield is still limited. The percentage of recovery is largely determined by the pressure applied during the grinding process. Due to the rubber-like elasticity of the cell wall, the cell remains intact if the pressure is too low and is deformed elastically. If the pressure is too high, the cell wall, cell fluid and active substance are often processed so strongly that the separation to be carried out later is made more difficult. In the case of the split ball mill according to the invention, however, the pressure to be applied can be largely predetermined and possibly adjusted in order to achieve optimal digestion and extraction ratios.

Especially for biotechnology, the possibility of intensive sterilization of the surfaces that come into contact with the regrind is of considerable importance. The subject matter of the invention is very largely worked with large smooth surfaces which have no sharp-edged parts, angular corners, grooves or the like, which allow the formation of contamination nests. These surfaces can therefore be sterilized easily and thoroughly.

Further refinements and advantages of the invention are set out in the subclaims and will now be explained in more detail with reference to the drawing.

Fig. 1

einen Längsschnitt durch eine erfindungsgemäße Spalt-Kugelmühle,

Fig. 2

eine Ansicht einer Rotorscheibe von links in Fig. 1 gesehen,

Fig. 3

einen der Fig. 1 entsprechenden Axialschnitt mit geänderter Mahlspaltform,

Fig. 4

den zugehörigen Längsschnitt durch eine Rotorscheibe und

Fig. 5

eine weitgehend der Fig. 2 entsprechende Stirnansicht einer solchen Rotorscheibe.

The drawing shows a preferred embodiment of the invention, for example. Show it:

Fig. 1

2 shows a longitudinal section through a split ball mill according to the invention,

Fig. 2

2 shows a view of a rotor disk from the left in FIG. 1,

Fig. 3

1 corresponding axial section with modified grinding gap shape,

Fig. 4

the associated longitudinal section through a rotor disk and

Fig. 5

a largely similar to FIG. 2 front view of such a rotor disk.

The split ball mill shown in FIGS. 1 and 2 consists essentially of a mill housing (1), which receives three grinding units (2) from a multi-part stator (3) and a likewise multi-part rotor (4), which the mill axis (5th ) rotates and is driven by a particularly controllable electric motor (6).

This motor (6) is flanged to the stationary mill housing (1). The motor pin (7) engages in a rotationally fixed manner with a wedge (8) in the bore (9) in the rotor shaft (10) made at the left end in FIG. 1. The other end sits with a journal bearing (11) in an outer cover (12), which closes the pot-like mill housing (1) and receives the product outlet (13).

Each of the three grinding units (2) comprises a stator unit (16) with a first stator disc (17) and a second stator disc (18). These each form a grinding chamber unit (19) between them, in which a rotor disk (20) designed as a friction disk rotates.

The individual rotor disks (20) of the multi-stage rotor (4) sit with their hubs (21), separated by spacer bushings (23), one behind the other on the rotor shaft (10) between their shoulder (24) and that screwed towards the journal bearing (11) Mother (25). The spacer bushes (23) can in principle have the same length, but are preferably kept in stock in slightly different lengths in order to be able to precisely determine the position of the rotor disks (20).

Individual, polygonal profile driving bolts (26), which are matched to the length of the hubs (21) and are seated in a continuous longitudinal, approximately semi-cylindrical groove (27) of the rotor shaft (10), are used for torque transmission. The first stator disks (17) have a central, conical part (171) with an inclination of 60 ° to the mill axis (5). An S-shaped part (172) follows on the inside and an approximately cylindrical partial flange (173) on the outside. In contrast, every second stator disk (18) has an inner, approximately flat part (181) with an outer conical part (182), the surface line of which in turn encloses an angle of 60 ° with the mill axis (5). They each end inside and outside in radial surfaces and are sealed there against each other and against the mill housing (1) by sealing rings (33, 34) and support rings (35), the latter in particular ensuring a flexible and damping support effect.

Each rotor disc (20) widens from its hub (21) initially by means of an approximately flat intermediate part (22) to form an outer conical ring (28), which is largely in the center of the grinding chamber unit (19) between conical parts (171, 182) of the two stator discs (17, 18) comes to rest, whereby a grinding gap (36) of approximately the same width is formed around the entire rotor disc (20), which forms a gap loop (37) which is closed towards the outside around the cone ring (28). The gap loop (37) is connected via approximately radially extending connecting gaps (38, 39) with connecting gaps (40, 41) and thereby with the radial end faces (42) of the stators of the individual grinding units (2) formed by the stator disks (17, 18) Connection.

Close to the inner surface (46) of the conical ring (28) are the upper ends of the connecting gaps (38, 39), each connected by at least two ball return channels (47) which can also be inclined by approximately 60 ° to the rotor axis (5) or run spirally according to FIG. As a result, larger centrifugal forces are exerted on heavy particles, in particular on the grinding media (48), than on the solid particles of the grinding material which are conveyed further under pump pressure. To increase this effect, the grinding media (48) are preferably made of ceramic. However, they can also consist of specifically particularly heavy rock. In this way it can be achieved that the grinding media, as shown in the middle grinding unit in FIGS. 1 and 1a, rotate on a spatial ring path closed by at least two ball return channels (47), that is to say they remain in the respective grinding unit.

The separation process can also be influenced by changing an angle, such as the inclination of the intermediate gap (49) of the inner edge surface of the cone ring (28).

The grinding media (48) can also be filled separately into each grinding unit through a filling tube (51), which is placed in a holding bush (52) in the mill housing (1) and directly in a bore (53) of the ring flange (173) covering the loop (37) ) sits. The filling tube (51) is normally closed by a stopper (54) which is held by a screwed-on union nut (55). Instead of the stopper (54), a probe or a measuring device (56), for example for pressure, temperature, viscosity or the like, of the material to be ground can also be inserted or attached.

The product inlet (13), like the product outlet (14), is closed off from the adjacent grinding gap by a friction gap ring (57) which is inserted between the housing web (59) or the outer cover (12) and the spacer bush (23) present there . The friction gaps (58) formed in this way, which widen outwards, serve to secure against the loss of grinding media for some reason, for example when starting off, have left their orbit in the gap loop (37). If the mill comes to a standstill in the meantime, such grinding media collect in the bottom of the gap loop (37) and are thrown outwards again during start-up and are thus distributed in the grinding loop.

Spacer rings (61) can be inserted between adjacent stators (17, 18) in order to be able to influence the axial distances between the stators, but also between the stator and rotor disks. In contrast to the embodiment shown with spacer rings and the like, devices for continuous adjustment by means of pressure screws or the like can also be used. For example, the screws (62) on the outer cover (12) can also be used for such adjustment processes.

At the longitudinal ends of the mill, cooling spaces (64, 65) are provided on the outside, and annular cooling spaces (64) are also provided between adjacent grinding units (2). These are individually connected to jacket cooling chambers (85), which are each formed between the jacket of the mill housing (1) and the ring flange (172) of the associated first stator disk (17).

In the spacer rings (61) there are approximately radial openings for connecting the jacket cooling spaces (85) to the coolant circuit. Instead of a coolant, another heat transfer medium can also be used, for example for heating or for optional cooling and / or heating. All cold rooms are e.g. Connected to a cold and / or heat source via two manifolds (66) offset at 180 ° to the mill axis (5) in order to be able to adjust the operating temperature during the grinding process as required.

Stator disks (17, 18) and rotor disks (20) are made of sintered ceramic material with high temperature resistance and abrasion resistance. The compressive strength of these materials is sufficient for the stresses that occur. However, in order to compensate for the tensile stress caused in particular by centrifugal forces, on the one hand the rotor disks can be designed as prestressed construction elements in a manner known per se. On the other hand, the pressure of the cooling liquid is dimensioned much higher than is the case with comparable cooling systems. As a result, the stators are pressed radially inward out of the jacket cooling spaces (85) in order to at least compensate for the expansion deformations resulting from centrifugal forces and the like. The stator disks can also be mechanically preloaded.

In order to obtain small diameters, the use of two or more, possibly up to five or more grinding units is recommended. As a result, a relatively large number of identical individual elements is required, which enables production in a larger series and thus a reduction in price even with complicated technology.

Before commencing operations, the processing of contamination-sensitive goods, for example for the food and pharmaceutical industries or biotechnology, the grinding rooms or grinding gaps and other surfaces that come into contact with the material to be ground, as well as the rooms that contain the cooling or tempering agents, should be largely sterilized. After the previous cleaning processes, this is mainly done by passing steam through these rooms at a pressure which is about 1 bar higher than the usual grinding pressure, the temperature being constantly increased to a maximum value of about 140.degree. This maximum value is maintained for a certain time, which depends on various operating factors and is expediently determined by tests.

After the motor (6) has started, regrind is fed continuously to the inlet and flows through the serpentine annular gap from one grinding unit to the next until it comes from the second friction gap (58) to the material outlet (14), which leads to the motor through a mechanical seal (68) is completed.

The grinding media, which may be provided in different sizes, are filled while the mill is at a standstill, they usually have a diameter of 0.3 to 3 mm and are classified, for example in the right grinding unit with a diameter of 3 mm, in the middle with 1.5 mm and in the left with 0.8 mm. When starting up, the balls, which have initially accumulated at the bottom of the gap loop (37), are distributed to the remaining part of the ring-shaped gap loop and cyclically flung outwards and concentrated in the area of the grinding loop by the centrifugal forces. Instead of a single return channel (47) there are expediently provided a plurality - six according to FIG. 2 - distributed uniformly around the circumference, depending on the rotational speed of the balls with regard to the processed material.

During the circulation, the grinding media are always pressed against the outer conical ring (28) on the inner surface (46), which is an extension of the ball return channel, whereby a kind of high-performance grinding action is brought about, while when returning from the gap loop (37) to the intermediate gap (49) reduce the plant forces and, with a lower specific grinding capacity, the grinding process is evened out and completed. Three grinding cycles, which are largely independent of one another and also different, are run through until the ground material reaches the outlet (14). It is therefore possible to create extremely fine and particularly uniform dispersions in a relatively short time.

3 to 5 are in the modified embodiment Identify the same components with the same reference numerals, modified versions being identified by a prime.

The difference of this second embodiment compared to the first described is in principle that in the cross section of each grinding gap (36 '), in particular the gap loop (37'), an additional ring bead or deflection is attached in both flow branches, with the end faces (71) and (72) for example of the rotor, alternate annular elevations (73) and depressions (74). The end faces here, as a whole, in particular the outer part of the rotor disk (20) are designed in a zigzag cross section. They can also have a wave-like shape. If possible, however, the mutually assigned surfaces, for example the end surfaces (76) and (77) leading to the outer edge (75), should run at least approximately parallel to one another and, if appropriate, also have constant distances. This also applies to the end faces (78) and (79) provided on the stator disks (17 ') and (18'). The outer cone ring (28) according to FIG. 1 thus becomes a Z flange (80) with the cross-sectional shape of a rune. The gap loop (37 ') of the two arms of the grinding gap (36') surrounding the Z flange is designed accordingly.

These two grinding gap arms are connected by ball return channels (47 ') attached to the lower end of the Z-flange. The grinding balls are also first introduced in the direction of flow and sharply deflected outwards at the exit from the ball return channel (47 '), so that they remain concentrated in their gap loop (37'), ie in the two outer parts of the grinding gap arms, during operation. Here, the ball return channels (47 ') as the parts and arrangements not mentioned are formed in the same manner as in Figs. 1 and 2, so that on the remaining parts of the second embodiment need not be discussed.

The illustrated embodiments can be modified in various ways without leaving the scope of the invention. For example, the grinding gap loop (37), for example of the conical surfaces provided with straight surface lines, can be formed by concave and / or convexly curved conical barrel surfaces or the like, so that the loop has an approximately egg-shaped or elliptical cross-section. The angles of the surface line to the mill axis can be chosen to be the same or different, and the rotor disks can form a rotational connection with the rotor shaft over the entire circumference, for example that they form a polygonal cross section, in particular triangular and with rounded corners or with side surfaces curved transversely to the rotor axis.

Claims (24)

1. Gap-ball mill for continuously grinding, in particular disintegrating, microorganisms and dispersing solids in fluid and having the following features:

   a) first and second stator discs (17, 18) are secured in a mill housing (1) centrally relative to the mill axis (5) such that they can be easily interchanged; and

   b) are associated with and adapted to one another at least in pairs such that they form between them a stator unit (16) which extends approximately radially from the mill axis (5) and has a rotationally symmetrical grinding chamber unit (19);

   c) the stator discs (17, 18) in each case have a conical section (171, 182) which is inclined towards the mill axis (5) and which is adjoined at the interior by an S-shaped section (172) in the case of the first stator disc (17);

   d) in the grinding chamber unit (19) there is mounted centrally relative to the mill axis (5) at least one rotatably driven plate-like rotor disc (20) which comprises a conically shaped annular section (tapered ring 28) towards the outer edge;

   e) the front and rear (71, 72) of the rotor disc (20) together with two stator discs (17, 18) in the grinding chamber unit (19) form a grinding gap (36) which surrounds the rotor disc (20) and extends approximately radially on all sides from the grinding axis (5);

   f) in the interior of the grinding unit (2) a gap loop (37, 37') which is disposed about the tapered ring (28) is short circuited outwardly by at least two ball return ducts (47, 47');

   g) which extend radially outwards from the grinding axis (5) as centrifugal guide elements.
2. Gap-ball mill according to Claim 1, characterised in that the ball return ducts (47) are inserted in the gap loop (37) in such a way that the grinding medium (48) enters the outwardly directed flow of material at least approximately tangentially but is thrown back abruptly and radially outwards at the inlet to the ball return duct (47) from the inwardly directed flow of material there.
3. Gap-ball mill according to Claim 1 or 2, characterised in that the ball return duct (47) is in each case disposed in the extension of a generated surface (28, 46) of an inner gap section and is curved helically approximately in the manner of a centrifugal pump duct (Figure 2).
4. Gap-ball mill according to any one of Claims 1 to 3, characterised in that the ball return duct (47) forms an angle of 50 to 67° in each case with the mill axis (5) and merges at the point of deflection of the short inner loop section (intermediate gap 49) into the associated approximately radial connection gap (38, 39).
5. Gap-ball mill according to Claim 4, characterised in that the angle between the ball return duct (47) and the mill axis (5) is approximately 60 to 62°.
6. Gap-ball mill according to Claim 4 or 5, characterised in that the angle of inclination of the centre section (28) of at least a first stator disc (17) is approximately 60° relative to the mill axis (5).
7. Gap-ball mill according to any one of Claims 1 to 6, characterised in that a plurality of grinding units (2) consisting of a stator unit (16) and a rotor disc (20) in each case are joined together along the mill axis (5) and form between the material inlet (13) and material outlet (14) a continuous grinding gap (36) which in cross-section is in the shape of a multi-stage serpentine loop.
8. Gap-ball mill according to Claim 7, characterised by spacer sleeves (26) secured on the rotor shaft (10) between the rotor discs (20) for adjusting the width of the grinding gap (36).
9. Gap-ball mill according to any one of Claims 1 to 8, characterised in that the stator discs (17, 18) are delimited on at least one side in each case by a cooling chamber (64, 65) through which a heat exchanger medium flows.
10. Gap-ball mill according to Claim 9, characterised in that at least one annular casing-cooling chamber (85) is also formed between the radial outer surface of the stator (3) and the inner surface of the mill housing (1).
11. Gap-ball mill according to Claim 9 or 10, characterised in that one stator disc (17) in each case is provided, in particular integrally, with an outer annular flange (173) which inwardly delimits the annular casing-cooling chamber (85) and is sealed by means of at least two annular seals (34) with respect to a second stator disc (18) acting as a cover for the grinding chamber unit (19).
12. Gap-ball mill according to Claim 10 or 11, characterised in that the pressure at least in the annular casing-cooling chamber (85) is at least one bar greater than in the grinding gap (36) and is in particular 2 to 3 bars.
13. Gap-ball mill according to any one of Claims 1 to 12, characterised in that each grinding gap of a grinding unit (2) comprises, closely about the rotor shaft (10), two connection gaps (40, 41) which face in opposite directions and each end in a primarily radial end surface (45) for radially outwardly extending connection gaps (38, 39) which extend to the grinding gap loop (37) provided with the ball return duct (47).
14. Gap-ball mill according to any one of Claims 1 to 13, characterised in that the grinding gap loops (37) are disposed such that they are predominantly inclined towards the mill axis (5) and are formed by at least approximately parallel, preferably obtuse-angled, conical gaps.
15. Gap-ball mill according to any one of Claims 1 to 14, characterised in that friction gap rings (57) forming a friction gap (58) are disposed at the material inlet (13) and material outlet (14) in a sealing manner in order to retain the grinding medium (48).
16. Gap-ball mill according to Claim 15, characterised in that retaining devices such as friction gap rings (57) for the grinding medium (48) are also provided between adjacent grinding units (2) in the grinding gap (36).
17. Gap-ball mill according to Claim 8 or 16, characterised in that the spacer sleeves (23) are sealed with respect to one another and with respect to the rotor shaft (10).
18. Gap-ball mill according to any one of the preceding claims, characterised in that a ball filler duct extending in a sealed manner through the casing-cooling chamber (85) is associated with each grinding chamber unit (2).
19. Gap-ball mill according to Claim 18, characterised in that the ball filler duct comprises a filler pipe (51) which is mounted interchangeably in an insertion sleeve (52) which is sealed with respect to the mill housing (1) and the annular flange (172).
20. Gap-ball mill according to Claim 18 or 19, characterised in that the filler pipe (51) can be closed by a plug (54) and optionally accommodates instead of the plug a measuring gauge (60) for operating values, such as pressure, temperature or the like for example.
21. Gap-ball mill according to any one of Claims 1 to 20, characterised in that at least the rotor disc (20) which acts as the friction disc and additionally the stator discs (17, 18) in particular are made of sintered material.
22. Gap-ball mill according to Claim 21, characterised in that at least the rotor disc (20) consists of ceramic material with non-abrasive granular material.
23. Gap-ball mill according to Claim 21 or 22, characterised in that the rotor discs (20) are mounted with a noncircular, edge-free aperture on the likewise noncircular rotor shaft (10).
24. Gap-ball mill according to Claim 23, characterised in that the cross-section of contact between the rotor discs (20) and the rotor shaft (10) is built on the basic shape of a polygon, in particular a triangle.

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