Stirred ball mill and method for operating a stirred ball mill

Description

[0001] The present invention relates to a particularly horizontal stirred ball mill and a method for operating such a stirred ball mill according to the features of claims 1 and 9. State of the art

[0002] The present invention relates to a stirred ball mill, particularly a horizontal one, for grinding dry product. A stirred ball mill is a machine for coarse, fine, and ultrafine grinding or homogenization of materials. It consists of a non-rotating grinding chamber with a stirring shaft, usually arranged axially and centrally within the chamber, a bearing, and a drive unit. The grinding chamber is typically cylindrical and usually filled to 70% to 90% with grinding media. An agitator is provided within the grinding chamber, comprising a rotatably mounted stirring shaft with agitator elements attached to it, ensuring intensive movement of the grinding media. Known stirred ball mills are fed through a central opening in one of the end walls. Alternatively, the product can also be introduced directly radially or tangentially via the grinding cylinder.The material to be ground is continuously conveyed into and through the grinding chamber. During this process, the solids are reduced in size or dispersed by impact and shear forces between the grinding media. The discharge of the finished product depends on the design and typically occurs at the end of the mill. With relatively fine and free-flowing, usually spherical product particles, axial product transport within the grinding cylinder can be achieved solely by gravity. However, the product is generally conveyed through the grinding cylinder by means of a fluid, preferably a transport air stream. When the product and fluid are discharged from the stirred ball mill, the grinding media should remain within the milling chamber. This is achieved, in particular, by selectively separating the grinding media within the mill, for example, by using a suitable separating device.

[0003] German patent DE 10 2013 021 757 A1 discloses a stirred ball mill with a cantilevered rotor. The rotor has an axis of rotation and is cantilevered at a bearing, from which a free, unsupported rotor end is defined along the axis of rotation A. A plurality of spaced-apart stirring elements are provided on the stirring shaft, by means of which the grinding media located in the grinding chamber of the stirred ball mill are set into rotation. A gap is formed between the rotor end and the opposite rotor end, or the housing as the stator. Once the material has been ground, it can pass through the gap into the material outlet and thus leave the grinding chamber. A disadvantage, however, is that the cantilevered end is located at the material outlet and the end mounted at the bearing is located at the material inlet. Furthermore, there is a risk that, in addition to the material being ground, the grinding media themselves may also leave the grinding chamber through the gap.

[0004] DE 10 2015 112 760 B4 discloses a stirred ball mill with a separation device arranged upstream of the grinding material outlet. The separation device comprises a stationary sieve unit through which at least particles of at least one component of the product / grinding media mixture up to a certain diameter can pass. The separation device further comprises a classifying rotor with a support plate rigidly mounted on the agitator shaft of the stirred ball mill, with coupled attachments. The attachments form a rotor cage that rotates around the sieve unit, which is stationary upstream of the grinding material outlet. The rotor cage with the attachments helps to protect the sieve unit from the grinding media located in the grinding chamber and to ensure a specific flow behavior of the product / fluid mixture in the area of ​​the sieve unit. A comparatively similar stirred ball mill is disclosed in DE 10 2012 013 279 A1.

[0005] German patent application DE 22 34 076 A1 discloses a colloid mill with a conical vessel and a cooling jacket. Inside the conical vessel are a rotatable shaft with attached discs and a plurality of grinding media. The colloid mill comprises a separation device, which is attached to the outermost grinding disc by means of a flange and a sleeve, as well as a screen or filter, which is non-rotatably connected to the disc and the flange. Inside the screen or filter is a paddle wheel with scrapers, which is rigidly connected to the wall via a tube. The tube has openings through which the ground material passes into the annular space and from there through the openings into the discharge line.

[0006] In the separation device known from the prior art, a problem arises because the rotation of the agitator shaft forces the grinding media towards the inner wall of the grinding container, causing them to concentrate axially along this wall. This, naturally, combined with the superimposed internal flow direction of the product-fluid mixture and the associated drag forces on the grinding media, leads to an excessive concentration of the grinding media in the area around the support plate of the classifying rotor, and consequently to clogging of the product discharge and increased wear. Description

[0007] The invention is therefore based on the objective of providing a stirred ball mill and a method for operating a stirred ball mill in which the discharge of ground material can be improved compared to known solutions, in which wear on the sieve unit can be reduced and compaction of the grinding media located in the grinding chamber can be prevented.

[0008] The above problem is solved by a stirred ball mill with the features according to claim 1 and by a method for operating such a stirred ball mill. Further advantageous embodiments and developments of the invention are specified in the respective dependent claims.

[0009] To solve the aforementioned problem, the invention proposes a stirred ball mill with a grinding container, in particular a horizontal stirred ball mill with a grinding container, in particular a cylindrical one. The grinding container has a first end region with an inlet for the material to be ground and a second end region with an outlet for the material to be ground.

[0010] Preferably, a negative pressure can prevail in the grinding container or grinding chamber relative to the atmosphere, which can be generated and adjusted by appropriate vacuum pumps, suction blowers or the like.

[0011] The grinding container or grinding chamber can preferably be filled to 70% to 90% with grinding media, which are, for example, spherical in shape. Alternatively, the grinding media can have any other shape. The grinding media are essential for comminuting the material fed in via the grinding inlet and function as the comminuting tool. The grinding media can preferably be smaller than 20 mm, and in particular smaller than 12 mm.

[0012] The stirred ball mill comprises a shaft that rotates within the grinding container or grinding chamber by means of a drive unit. This shaft is designed, at least in sections, as a stirring shaft and is equipped with stirring elements. The shaft can extend, at least in sections, along the longitudinal axis of the grinding container and into the material inlet and / or outlet.

[0013] To separate the finished, crushed, or especially ground, material from the grinding media, the stirred ball mill includes a separation device, which is preferably arranged upstream of the material outlet. The separation device comprises a classifying rotor, which is arranged axially spaced from the material outlet on the agitator shaft and has a rotatable rotor cage. The rotor cage can help to move and / or fling the grinding media located in the area of ​​the separation device radially towards the inner wall of the grinding container.

[0014] In addition, the separation device includes a sieve unit arranged inside the rotor cage and attached to the classifying rotor.

[0015] According to the invention, the sieve unit has a smaller outer diameter on the side facing the inlet of the material being ground than on the side facing the outlet of the material being ground or the bearing-side boundary of the grinding chamber.

[0016] By attaching the screening unit to the classifying rotor, the screening unit is designed to rotate. Specifically, the screening unit can rotate together with the rotor cage; that is, the rotor cage and the screening unit can rotate at the same speed, since the rotational speed of the rotor cage can be transferred to the screening unit. Consequently, the finished ground material with a specific diameter, and alternatively also a fluid flow such as an initial fluid flow or at least a portion thereof, can exit the grinding container or grinding chamber via the screening unit, entering the material outlet, while the grinding media remain in the grinding container or grinding chamber.

[0017] The rotating sieve unit, in conjunction with the rotor cage, offers the advantage of preventing the grinding media from becoming rigidly compacted between the sieve unit and the inner wall of the grinding container. Instead, the grinding media are kept in constant motion, loosened, and flung radially towards the inner wall of the grinding container. This simultaneously reduces wear and / or damage to the sieve unit.

[0018] Preferably, the rotor cage with the attached sieve unit can be driven via the agitator shaft, so that the rotor cage with the sieve unit and the agitator shaft are driven at the same speed. For this purpose, torque transmission devices or the like can be provided, by means of which torque from the shaft or agitator shaft can be transferred to the rotor cage. Alternatively, the rotor cage can be assigned its own drive unit, so that the rotor cage with the sieve unit can be driven independently of the agitator shaft; that is, the rotor cage with the attached sieve unit and the agitator shaft can be driven or operated at different or the same speeds.

[0019] The sieve unit can, for example, be conical or star-folded conical. The inner diameter of the sieve unit can increase towards the material outlet, with a maximum inner diameter being less than 95% of the grinding chamber's inner diameter. The conical shape of the sieve unit provides a large sieve surface area, and in particular a large passage area in the region of the classifying rotor's support plate for the finished material. Alternatively, the sieve unit can be designed in any other shape that appears advantageous for use in the stirred ball mill according to the invention.

[0020] The drive unit of the agitator shaft can preferably be arranged at the second end region of the grinding container with the grinding material outlet, or on the side of the grinding material outlet. Preferably, the agitator shaft comprises a plurality of agitator elements, each arranged at a uniform distance from one another. In particular, the agitator elements can extend radially from an outer surface of the agitator shaft, with the distance between a free end of the agitator elements and an inner surface of the grinding container being, preferably across the entire circumference, at least two and a half times the diameter of the grinding media. The distance between the free end of the agitator elements and the inner surface of the grinding container can also be referred to as the grinding gap.

[0021] The agitator elements can preferably be attached to an outer surface of the agitator shaft in a rotationally secure manner. Preferably, the agitator elements can be attached to the outer surface of the agitator shaft by means of a force-fit and / or positive locking mechanism. The agitator elements can serve to set the grinding media located in the grinding chamber in motion and thus provide them with energy for grinding the material fed in via the grinding inlet.

[0022] In particular, the grinding media can be set in motion within so-called grinding zones, each defined as the space between two agitator elements. The material to be ground, fed in through the inlet, can pass through these grinding zones and be comminuted on its way from the inlet to the outlet. The feeding of the material to be ground and the discharge of the finished product create a flow. The agitator elements can be designed, for example, as discs such as solid discs, perforated discs with or without axial or radial protrusions, pins, or other elements.

[0023] The rotor cage may include a flange mounted on the agitator shaft with a support plate, i.e., the diameter of the classifying rotor may increase towards the grinding chamber outlet. The support plate may, in particular, be an end face of the classifying rotor with the smallest diameter. At least two rotor fingers may be attached to the support plate. Optionally, at least three, four, five, or more rotor fingers may be attached to the support plate. In particular, the at least two rotor fingers are each mechanically, and preferably detachably, attached to the support plate so that they can be replaced if necessary. The at least two rotor fingers may each be arranged at least approximately on the outer circumference of the support plate.It should also be noted that the rotor cage is formed by the support plate with at least two rotor fingers attached to it.

[0024] The at least two rotor fingers can be of equal length in the longitudinal direction, whereby a diameter and / or a width and / or a height of the at least two rotor fingers can increase or remain identical along their longitudinal extent. If the rotor fingers are of equal length in the longitudinal direction, at least one ring element, for example in the form of a disk, can be provided at the free end of the at least two rotor fingers. The at least one ring element can comprise a centrally arranged bore whose inner diameter is larger than an outer diameter of the shaft or agitator shaft. An outer diameter of the at least one ring element can be equal to or larger than at least one diameter or distance between the at least two rotor fingers.

[0025] Furthermore, the rotor cage may be provided with a stationary base, which is arranged on an inner side of the second end region of the grinding container. The stationary base may, for example, be a circular or tubular element which projects at least partially into the grinding chamber. Preferably, the stationary base can project at least approximately perpendicularly from an inner side of the second end region of the grinding container into the grinding chamber, i.e., the stationary base can extend at least partially parallel to the shaft, in particular to the classifying rotor.

[0026] The rotor cage, in particular the free end of the at least two rotor fingers or the end face of the at least one ring element facing the material outlet, can preferably be arranged relative to the stationary base, and in particular spaced apart, such that the distance or gap is less than 0.5 times, preferably less than 0.3 times, the diameter of the grinding media. This spacing prevents incompletely ground material and / or grinding media from entering the material outlet and clogging it and / or damaging the sieve unit.

[0027] Furthermore, it may be provided that the classifying rotor has a smaller diameter in the area of ​​the support plate than in the area of ​​the ring element.

[0028] Furthermore, the sieve unit can be fixed to the support plate of the flange. In particular, the sieve unit can be attached to the support plate by force-fit, form-fit, and / or material-fit, preferably detachably, meaning that the sieve unit can be easily replaced when worn. By fixing the sieve unit to the support plate, torque from the rotor cage can be transmitted to the sieve unit, meaning that the rotor cage and the sieve unit can rotate together, especially at the same speed. Consequently, the rotor cage can thus function as a type of torque transmission device.

[0029] To allow the finished ground material to pass through the sieve unit and into the outlet, the sieve unit can comprise a plurality of openings. These openings can have a round, oval, rectangular, or irregular cross-section. Preferably, the openings can be designed as axial elongated slots. The size of the openings in the sieve unit should be selected such that each opening is smaller than 70% of the diameter of the grinding media; that is, the openings can have a maximum width of 0.7 times the grinding media diameter and / or height and / or length. This prevents grinding media from entering the outlet.

[0030] Furthermore, it may be provided that a grinding material inlet chamber is located upstream of the grinding material inlet. In other words, the grinding material inlet chamber can lead into a grinding material inlet located downstream of the grinding material inlet chamber. The grinding material inlet can, for example, be designed in the form of an opening in the first end region of the grinding container.

[0031] Furthermore, it can be provided that a grinding material outlet is spatially downstream of the grinding material outlet; that is, the grinding material outlet can lead into a grinding material outlet downstream of the grinding material outlet. The grinding material outlet can, for example, be designed in the form of an opening in the second end region of the grinding container. The grinding material outlet can lead into a collection container so that the finished grinding material can be collected and temporarily stored until further processing.

[0032] In the broadest sense, the grinding material inlet chamber can be part of the grinding material inlet, and the grinding material outlet chamber can be part of the grinding material outlet. Therefore, when it is stated before and after that the shaft projects at least partially into the grinding material inlet and / or the grinding material outlet, this should also include, or at least not exclude, the possibility that the shaft may extend into the grinding material inlet chamber and / or the grinding material outlet chamber.

[0033] The grinding material outlet can be arranged at least partially parallel and / or perpendicular to the shaft. In particular, an opening can be provided in the second end region of the grinding container, which runs at least partially parallel and / or perpendicular to the shaft, i.e., the grinding material outlet can be arranged below and / or above the center of the shaft and extend downwards and / or laterally.

[0034] Furthermore, the shaft located in the grinding chamber can extend, at least partially, into the material inlet and / or outlet chambers. The shaft extending into the material inlet can, at least partially, be designed as the first screw conveyor, in particular as the first screw helix. This allows the material to be transported continuously or as needed into the grinding chamber. At the same time, this largely prevents the material inlet from becoming clogged with stuck and / or clumped material.

[0035] Furthermore, it may be provided that the shaft within the sieve unit and / or within the material outlet and / or within the material outlet chamber is designed, at least in sections, as a second screw conveyor, in particular as a second screw helix. With the aid of the second screw conveyor, the finished material can therefore be conveyed, at least in sections, along the material outlet to the material outlet chamber in order to prevent clogging of the material outlet.

[0036] A vertical grinding chamber arrangement is known in dry rear-mounted ball mills, but it has the problem that the grinding media become compacted by gravity in the lower part of the grinding cylinder, preventing product transport. Mill designs with separation of the product / grinding media mixture outside the grinding chamber have the disadvantage that grinding media must be constantly added to and removed from the product, which reduces the energy efficiency of the grinding cycle. Therefore, a horizontal grinding chamber is required. With known stirred ball mills featuring a horizontally oriented grinding chamber and a stationary screen unit positioned before the product outlet, the problem has been that the grinding media compact in the area of ​​the product outlet and screen unit, consequently damaging the screen unit and, in the worst case, rendering it impermeable to the finished product.The rotating sieve unit, along with the rotor cage, allows the grinding media to be kept in constant motion, ensuring that the sieve unit is accessible to the finished ground material at all times and is not damaged by compacted grinding media.

[0037] It is also possible for the shaft to be cantilevered within the grinding container. In particular, the material inlet can be located at the cantilevered end of the shaft and the material outlet at the bearing end. Preferably, the cantilevered end can be located at the first end region and the bearing end of the shaft at the second end region of the grinding container. Alternatively, a reversed mounting of the cantilevered shaft is also conceivable, whereby the cantilevered end is located at the material outlet and the bearing end at the material inlet.

[0038] Furthermore, it may be provided that a first fluid inlet opening is associated with the material inlet and / or the material inlet chamber, through which a first fluid flow, such as a first air volume flow or an inert or reactive gas, can be introduced into the material inlet or material inlet chamber and thus into the grinding chamber of the grinding container. The first fluid flow can be introduced into the material inlet or material inlet chamber in such a way that it mixes with the material being ground, forming a first material-fluid flow. The first fluid flow can thus serve as a transport flow, carrying the material being ground from the material inlet or material inlet chamber into the grinding chamber. It would also be conceivable that at least part of the first fluid flow also flows along the grinding chamber and carries the material to be ground and / or the finished ground material to the material outlet.In this way, along with the finished ground material, part of the initial fluid flow can also leave the grinding chamber via the grinding material outlet.

[0039] Furthermore, the system may be equipped with a second fluid inlet opening for the material being ground and / or the material being ground outlet, allowing a second fluid flow, such as a second air flow or an inert or reactive gas, to be supplied to the material being ground or the material being ground outlet. This second fluid flow can be introduced into the material being ground or the material being ground outlet in such a way that it mixes with the finished material being ground, creating a second fluid flow. This second fluid flow can then serve to carry and transport the finished material along the material being ground outlet.

[0040] Furthermore and / or additionally, it may be provided that the tubular element includes channels and / or bores through which the second fluid flow can flow.

[0041] According to an alternative embodiment, the channels and / or bores of the tubular element can constitute a third fluid inlet opening through which a third fluid flow, such as a third air volume flow, an inert gas, or the like, can flow. This third fluid flow can exit the grinding chamber, particularly via the grinding material outlet.

[0042] Preferably, the second and / or third fluid flow can be flushed through the gap or space formed between the stationary base and the rotor fingers in such a way that little or no finished ground material can penetrate the gap. Additionally, the second and / or third fluid flow can function as a rinsing fluid, by means of which the sieve unit can be cleaned and blown out.

[0043] The first, second and / or third fluid flow can each be generated by a separate or external fluid source, such as a separate or external air source, or by a common external fluid source, such as a common external air source or the like.

[0044] It can also be provided that at least one control element is assigned to each of the first, second, and / or third fluid inlet openings, so that the first, second, and / or third fluid flow can be regulated. For example, the control element can be used to vary the cross-section of the first, second, and / or third fluid inlet opening, thereby adjusting the flow of the first, second, and / or third fluid inlet opening. In particular, the at least one control element can be adjusted such that the negative pressure prevailing in the grinding chamber is maintained.

[0045] Furthermore, it may be provided that the first fluid flow flowing along the grinding material inlet is greater than 50% of the total fluid flow, whereby in particular the total fluid flow may be composed of the first, second and / or third fluid flow.

[0046] Preferably, the second and / or third fluid flow, which flows through the stationary base and the gap formed between the stationary base and the rotor fingers, may be smaller than 25% of the total fluid flow.

[0047] The invention further comprises a method for operating a previously described stirred ball mill. The stirred ball mill comprises a grinding chamber having a first end section with an inlet for the material to be ground and a second end section with an outlet for the material to be ground. The stirred ball mill further comprises a shaft rotatable within the grinding chamber or grinding chamber by means of a drive unit, which is at least partially designed as a stirring shaft and equipped with stirring elements.

[0048] To separate the finished ground material from the grinding media, a separation device is provided, which is preferably arranged axially to the ground material outlet. The separation device comprises a classifying rotor, which is arranged on the agitator shaft at an axial distance from the ground material outlet and has a rotatable rotor cage. A sieve unit is arranged inside the rotor cage and attached to the classifying rotor. When the classifying rotor is activated, the rotor cage is set into rotation. Since the sieve unit is attached to the classifying rotor and, in particular, to the rotor cage, a torque from the rotor cage is transmitted to the sieve unit, so that the rotor cage and sieve unit rotate together at the same speed. The rotation of the rotor cage serves to ensure that the material in the grinding container or...The grinding media located in the grinding chamber are flung radially towards the inner wall of the grinding container, while the finished ground material can pass through the sieve unit into the grinding material outlet. This separation and transport function is particularly effective when the grinding media have a higher specific gravity than the product being ground, as the density difference then causes the finished ground material to flow inwards through the sieve into the grinding material outlet.

[0049] While with a stationary screening unit, the grinding media can compact and stick together between the unit and the inner wall of the grinding chamber, potentially damaging the unit and obstructing or blocking the discharge of the ground material from the chamber, the placement of the screening unit on the agitator shaft prevents such compaction of the grinding media. This makes the agitator ball mill less susceptible to blockages in the discharge area. The maintenance effort and / or production downtime for cleaning the agitator ball mill are significantly reduced.

[0050] It should be expressly mentioned here that all aspects and embodiments explained in connection with the device according to the invention equally relate to, or can relate to, partial aspects of the method according to the invention. Therefore, whenever certain aspects, relationships, and / or effects are mentioned in the description or in the definitions of the claims relating to the device according to the invention, this applies equally to the method according to the invention. Conversely, the same applies, so that all aspects and embodiments explained in connection with the method according to the invention equally relate to, or can relate to, partial aspects of the device according to the invention.Therefore, if at any point in the description or in the claim definitions for the method according to the invention certain aspects and / or relationships and / or effects are mentioned, this applies equally to the device according to the invention. Character description

[0051] The following exemplary embodiments of the invention and its advantages will be explained in more detail with reference to the accompanying figures. The relative sizes of the individual elements in the figures do not always correspond to the actual relative sizes, as some shapes are simplified and others are enlarged for better illustration. Figure 1 shows a schematic view of a longitudinal section of an embodiment of the stirred ball mill according to the invention. Figure 2 shows a schematic detail view of the grinding material inlet from the in Figure 1 shown stirred ball mill. Figure 3shows a schematic detail view of the grinding material outlet with the separating device arranged in front of it, from the in Figure 1 shown stirred ball mill.

[0052] Identical reference numerals are used for identical or equivalently functioning elements of the invention. Furthermore, for the sake of clarity, only those reference numerals necessary for describing the respective figure are shown in the individual figures. The illustrated embodiments merely represent examples of how the device according to the invention can be configured and do not constitute an exhaustive limitation.

[0053] Figure 1Figure 1 shows a schematic longitudinal section view of an embodiment of the stirred ball mill 10 according to the invention. The stirred ball mill 10 comprises a grinding container 12, which is cylindrical and horizontally mounted. A vacuum is maintained in the grinding container 12 or in the grinding chamber 18, which is set by a suitable vacuum pump (not shown) or the like in the grinding container 12 or in the grinding chamber 18.

[0054] The grinding container 12 has a material inlet 14 and a material outlet 16, which are formed by corresponding openings in the grinding container 12. The material inlet 14 is located at a first end region of the grinding container 12 (left in the Figure 1 ) and the grinding material outlet 16 is located at a second end area opposite (on the right in the Figure 1 ) provided. A grinding material inlet chamber 68 is spatially arranged upstream of the grinding material inlet 14 (see ). Figure 2Furthermore, a grinding material outlet chamber 70 is spatially subordinate to the grinding material outlet 16 (see below). Figure 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.

[0055] The grinding container 12 is preferably filled to 70% to 90% with grinding media, which are preferably spherical, but can also be cylindrical, for example. The grinding media are essential for comminuting the material to be ground, which is fed in via the material inlet 14, and function as the grinding tool. The grinding media are preferably smaller than 12 mm.

[0056] The stirred ball mill 10 comprises a shaft 20, rotatable by means of a drive unit (not shown), 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 region of the grinding container 12.

[0057] The shaft 20 is cantilevered, with the bearing end of the shaft 20 located in the area of ​​the grinding material outlet 16 or grinding material outlet chamber 70 and the cantilevered end of the shaft 20 located in the area of ​​the grinding material inlet 14 or grinding material inlet chamber 68, i.e. the shaft 20 extends at least along the longitudinal extent of the grinding container 12 from the grinding material inlet chamber 68 or grinding material inlet 14 to the grinding material outlet chamber 70 or grinding material outlet 16.

[0058] The rotatable shaft 20 is designed, at least in sections, as a stirring shaft 22 and is equipped with stirring elements 24. The stirring elements 24 each extend radially from an outer surface of the stirring shaft 22, and each stirring element 24 is secured to the outer surface of the stirring shaft 22 in a rotationally secure manner, in particular mechanically. Specifically, the stirring elements 24 are arranged at uniform intervals from one another on the outer surface of the stirring shaft 22.

[0059] According to the present embodiment, the stirring elements 24 are designed as pins 25. However, it would also be conceivable to design the stirring elements 24 in the form of grinding discs or the like. The stirring elements 24 each serve to set the grinding bodies located in the grinding chamber 18 in motion and thus provide them with energy that serves to grind the material to be ground, which is supplied via the grinding inlet 14. In particular, the grinding bodies are set in motion in so-called grinding zones, which grinding zones are defined as the space between two pins. The material to be ground, supplied via the grinding inlet 14, passes through these grinding zones and is ground on its way from the grinding inlet 14 to the grinding outlet 16. Due to the supply of the material to be ground and the discharge of the finished ground material, the flow of the material to be ground is established from the grinding inlet 14 towards the grinding outlet 16.

[0060] The stirring elements 24 each have a free end 26, which is spaced apart from an inner wall 28 of the grinding container 12. The first distance A1 between the free end 26 of the stirring elements 24 and the inner wall 28 of the grinding container 12 corresponds to at least two and a half times the mean diameter of the grinding media. This first distance A1 between the free end and the inner wall 28 of the grinding container 12 is necessary so that the grinding media can pass through this area unhindered without compacting and / or clumping, as would otherwise occur if the distance between the free end of the stirring element and the inner wall 28 of the grinding container 12 were too small.

[0061] To separate the finished ground material from the grinding media, or to ensure that the grinding media remain in the grinding chamber 18 while the finished ground material leaves the grinding chamber 16, a separation device 30 is provided, which separation device 30 is preferably arranged axially upstream of the ground material outlet 16. The separation device 30 comprises a classifying rotor 32, which is arranged on the agitator shaft 22 at an axial distance from the ground material outlet 16, and has a rotatable rotor cage 34. The rotor cage 34 has a flange 36 mounted on the agitator shaft 22 with a support plate 38 (see Figure 3). Figure 3 ). From the Figure 1 or based on the in Figure 1The flange 36 shown clearly shows that the diameter of the classifying rotor 32 increases towards the grinding material outlet 16. The smallest diameter of the classifying rotor 32 is formed by the support plate 38 of the flange 36. At least two rotor fingers 40 are mechanically coupled to the outer circumference of the support plate 38.

[0062] The rotor fingers 40 are of equal size or length in the longitudinal direction, with their radial extent preferably varying along their length, i.e., the diameter of the rotor fingers 40 increases along their longitudinal extent. It is possible that the first diameter D1 of the rotor finger 40 is smaller than the second diameter D2 of the rotor finger 40. In particular, the rotor fingers 40 extend from the support plate 38 towards the material outlet 16. At least one ring element 44 in the form of a disk 46 is provided at the free end of the rotor fingers 40. The disk 46 comprises a centrally arranged bore whose inner diameter is larger than the outer diameter of the shaft 20 or the agitator shaft 22. The outer diameter of the disk 46 preferably corresponds to the diameter or distance between the at least two rotor fingers 40. The disk 46 forms the largest diameter of the classifying rotor 32.

[0063] Furthermore, the separation device 30 includes a sieve unit 42 arranged within the rotor cage 34 and attached to the classifying rotor 32. The finished ground material can exit the grinding chamber 18 through this sieve unit, while the grinding media are retained within the grinding chamber 18. Due to the attachment of the sieve unit 42 to the classifying rotor 32, the rotor cage 34, with the sieve unit 42 attached to it, rotates at the same speed as the agitator shaft 22. The rotational movement of the rotor cage 34 generates flows and forces that move or fling the grinding media radially towards the inner wall 28 of the grinding container 12. In this way, the area around the ground material outlet 16 is kept clear of the grinding media.

[0064] The sieve unit 42 comprises a plurality of openings, not shown here. The openings are preferably designed in the form of axial elongated holes. The elongated holes each have a cross-section smaller than the grinding media, so that only the finished ground material can pass through the openings of the sieve unit 42, while the grinding media remain in the grinding chamber 18. In particular, the openings have a cross-section that is smaller than 70% of the diameter of the grinding media.

[0065] The sieve unit 42 is conical in shape and arranged within the rotor cage 34 such that its outer diameter increases towards the grinding material outlet 16, with a maximum outer diameter of less than 95% of the grinding container's inner diameter. The conical shape of the sieve unit 42 provides a large surface area, particularly a large passage area for the finished grinding material. Of course, to further increase the surface area, the sieve unit 42 can, for example, consist of a star-shaped folded sieve plate with a conical outer surface.

[0066] Preferably, the end face of the sieve unit 42 facing the support plate 38 has two webs 48, 48' which are mechanically fixed to the support plate 38. In this way, the sieve unit 42 is fixed to the support plate 38. The fastening of the sieve unit 42 to the support plate 38 via the two webs 48, 48' can function like a kind of torque transmission device; that is, when the rotor cage 34 is set into rotation, a torque from the rotor cage 34 is automatically transmitted to the sieve unit 42, meaning that the sieve unit 42 automatically rotates at the same speed as the rotor cage 34.

[0067] The rotor cage 34 is further associated with a stationary base 50, which is arranged on an inner side of the second end region of the grinding container 12. The stationary base 50 is a circular or tubular element 52, which projects perpendicularly from the second end region of the grinding container 12, at least partially, into the grinding chamber 18. The circular or tubular element 52 has a bore through which the shaft 20 passes. An axial, second gap A2 or space is formed between the free end or face of the circular or tubular element 52 on the grinding chamber side and the disk 46. This second gap is preferably less than 0.3 times the diameter of the grinding media, i.e., the second gap A2 or space is designed such that no grinding media and / or incompletely ground material can enter the grinding material outlet 16 unlawfully.

[0068] Figure 2shows a schematic detail view of the grinding material inlet 14 from the in Figure 1 The illustrated stirred ball mill 10. The material to be ground is stored in a hopper 72, which is funnel-shaped and connected to the grinding inlet 14 via a grinding inlet chamber 68. A slide gate 74 is provided at the lowest point of the hopper 72 to feed the material stored in the hopper 72, via the grinding inlet chamber 68, into the grinding chamber 18 at the grinding inlet 14. Specifically, the material is fed to the grinding inlet 14 by gravity.

[0069] To control and support the feeding of the material to be ground, a first fluid inlet opening 54 is assigned to the material inlet 14, in particular to the material inlet chamber 68. A first fluid flow 56 (represented by arrows), such as a first air volume flow, is introduced through this opening into the material inlet 14 and thus into the grinding chamber 18. Alternatively, an inert or reactive gas could also be used. The first fluid flow 56 can mix with the material to be ground, so that a first material-fluid flow, in particular a first material-air volume flow, is formed. The first fluid flow 56 is metered so that the negative pressure prevailing in the grinding container 12 or in the grinding chamber 18 is not affected, but is sufficient to transport the material to be ground into the grinding container 12. The first fluid flow 56 is generated by an external fluid source, such as an air source, which is not shown here.

[0070] Optionally, the first fluid inlet opening 54 can be provided with at least one control element (not shown here) so that the first fluid flow 56 can be metered or regulated. For example, the cross-section of the first fluid inlet opening 54 can be changed by means of the at least one control element.

[0071] To support the transport of the material to be ground into the grinding chamber 18 and to prevent clogging of the material inlet 14, the shaft 20 projecting into the material inlet 14, in particular into the material inlet chamber 68, is designed at least partially as a first conveying screw 58, in particular as a first screw helix 66.

[0072] Figure 3 a schematic detail view of the grinding material outlet 16 with the separating device 30 arranged in front of it from the in Figure 1 shown stirred ball mill 10. In Figure 3It becomes clear that the shaft 20 projecting within the sieve unit 42 and into the material outlet 16 is designed, at least in sections, as a second screw conveyor 64, in particular as a second screw helix 67. This allows the material that has passed through the sieve unit 42 and is now ground to be moved and conveyed by the sieve unit 42 along the material outlet 16 or out of the material outlet 16.

[0073] The grinding material outlet 16 extends at least partially parallel above and / or below the shaft 20, in particular towards the second screw conveyor 64, and opens into a grinding material outlet chamber 70 spatially downstream of the grinding material outlet 16. The grinding material outlet chamber 70 is connected to a collection container for the finished grinding material, which is not shown here.

[0074] The material outlet 16, and in particular the material outlet chamber 70, is associated with a second fluid inlet opening 60, through which a second fluid flow 62 (represented by arrows), such as a second air volume flow, is introduced into the material outlet 16 and thus also into the material outlet chamber 70. Alternatively, an inert or reactive gas could also be used. The second fluid flow 62 serves, on the one hand, as a transport medium that mixes with the finished material, so that a second material-fluid flow, in particular a second material-air volume flow, is formed. The second fluid flow 62 thus supports the transport of the finished material along the material outlet 16 and the material outlet chamber 70. At the same time, it prevents the material outlet 16 from becoming clogged with material.

[0075] As already mentioned in Figure 1As mentioned, an axial, second gap A2 or space is formed between the free end or end face of the circular or tubular element 52 on the grinding chamber side and the disk 46. This gap is preferably less than 0.3 times the diameter of the grinding media. This space is preferably flushed through channels and / or bores (not shown) in the tubular element 52 by the second fluid flow and / or optionally by a third fluid flow (not shown), such as a third air flow, so that little or no finished grinding product can enter the gap.

[0076] Additionally, the second fluid flow 62 and / or third fluid flow also functions as a rinsing fluid, in particular as rinsing air, by means of which the sieve unit 42 can be cleaned. The rinsing fluid can also be used to clean and blow out the openings of the sieve unit 42, which are not shown here.

[0077] The second fluid flow 62 is generated via an additional external fluid source (not shown here), in particular an air source. Alternatively, the external fluid source can be the same fluid source used to generate the first fluid flow 56.

[0078] The third fluid flow can be provided, for example, by a fluid source not shown here, such as an air source. This third fluid source can be a separate or external additional fluid source, in particular an air source. Alternatively, this fluid source can be the same fluid source used to generate the first and / or second fluid flows 56, 62.

[0079] Optionally, the second fluid inlet opening 60 may include at least one further control element (not shown here) so that the second fluid flow 62 can be metered or regulated. For example, the control element can be used to change the cross-section of the second fluid inlet opening 60. It should be noted, however, that the supplied second fluid flow 62 is always selected such that the negative pressure prevailing in the grinding container 12 is not affected, but is sufficient to transport the finished ground material.

[0080] The embodiments, examples, and variants described in the preceding paragraphs, the claims, or the following description and the figures, including their various views or individual features, may be used independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, provided the features are not incompatible.

[0081] Although the figures are generally referred to as "schematic" representations and views, this does not imply that the figure representations and their descriptions are of minor importance with regard to the disclosure of the invention. A person skilled in the art is perfectly capable of extracting sufficient information from the schematic and abstract drawings to facilitate their understanding of the invention, without their understanding being impaired in any way by the drawn and potentially not exactly to-scale dimensions of the stirred ball mill and / or parts of the stirred ball mill or other drawn elements.The figures thus enable the expert as reader to derive a better understanding of the inventive concept formulated in the claims and in the general part of the description of general and / or abstract concepts, based on the more concretely explained implementations of the inventive method and the more concretely explained functioning of the inventive device.

[0082] The invention has been described with reference to a preferred embodiment. However, it is conceivable to a person skilled in the art that modifications or changes to the invention can be made without departing from the scope of protection of the following claims. Reference symbol list

[0083] 10 Stirred ball mill 12 Grinding hopper 14 Material inlet 16 Material outlet 18 Grinding chamber 20 Shaft 22 Agitator shaft 24 Agitator element 25 Pin 26 Free end 28 Inner wall of the grinding hopper 30 Separating device 32 Classifying rotor 34 Rotor cage 36 Flange 38 Support plate 40 Rotor finger 42 Screening unit 44 Ring element 46 Disc 48 Web 48' Web 50 Stationary base 52 Circular or tubular element 54 First fluid inlet opening 56 First fluid flow 58 First screw conveyor 60 Second fluid inlet opening 62 Second fluid flow 64 Second screw conveyor 66 First screw helix 67 Second screw helix 68 Inlet chamber 70 Outlet chamber 72 Storage container 74 Slide valve A1 First distance A2 Second distance D1 First diameter D2 Second diameter

Claims

1. An agitator ball mill (10) with an in particular horizontal grinding container (12), which has a first end region with a grinding material inlet (14) and a second end region with a grinding material outlet (16), comprising - a shaft (20), which is rotatable in the grinding container (12) or in the grinding chamber (18) by means of a drive unit and which is at least partly formed as agitator shaft (22) and which is equipped with agitator elements (24), - a separating device (30) comprising ∘ 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), as well as ∘ a screen unit (42), which is arranged within the rotor cage (34) and which is fastened to the classifier rotor (32), characterized in that the screen unit (42) has a smaller enveloping outer diameter on the side facing the grinding material inlet (14) than on the side facing the grinding material outlet (16) or the storage-side grinding chamber limitation.

2. The agitator ball mill according to claim 1, in the case of which the rotor cage (34) comprises a flange (36) sitting on the agitator shaft (22) with a support plate (38), to which at least two rotor fingers (40) are fastened or can be fastened.

3. The agitator ball mill according to claim 2, in the case of which the at least two rotor fingers (40) are formed of equal length in the longitudinal direction, wherein a diameter and / or a width and / or a height of the at least two rotor fingers (40) increases along the longitudinal extension thereof or is formed identically.

4. The agitator ball mill according to one of the preceding claims, in the case of which a stationary base (50) is assigned to the rotor cage (34), which stationary base is arranged on an inner side of the second end region of the grinding container (12) and protrudes at least partly into the grinding chamber (18).

5. The agitator ball mill according to claim 3, wherein the at least two rotor fingers (20) are formed of equal length in the longitudinal direction, wherein a diameter and / or a width and / or a height of the at least two rotor fingers (20) is formed so as to increase along the longitudinal extension thereof or is formed identically, wherein, with an equally sized formation in the longitudinal direction or equal length, respectively, at least one ring element is provided on the free end of the at least two rotor fingers (20), wherein the at least one ring element comprises a centrically arranged bore, the inner diameter of which is larger than an outer diameter of the shaft or agitator shaft, respectively, an outer diameter of the at least one ring element in particular corresponds to at least a diameter or a distance, respectively, between the at least two rotor fingers (40) or is formed to be larger.

6. The agitator ball mill according to one of claims 2 to 4, in the case of which the screen unit (42) is fixed to the support plate (38) of the flange (36).

7. The agitator ball mill according to one of the preceding claims, in the case of which the screen unit (42) comprises openings, which have at most 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 one of the preceding claims, in the case of which a grinding material inlet chamber (68) is arranged spatially upstream of the grinding material inlet (14), and / or in the case of which a grinding material outlet chamber (70) is arranged spatially downstream from the grinding material outlet (16).

9. A method for operating an agitator ball mill (10) according to one of claims 1 to 8.