SEPARATOR FOR A BALL MILL OR STIRRING BALL MILL AS WELL AS BALL MILL OR STIRRING BALL MILL WITH SEPARATOR

Abstract

Separating device (20) for a ball mill or a stirred ball mill (1), wherein the ball mill or the stirred ball mill (1) comprises a material inlet (4) and a material outlet (7), wherein the separating device (20) can be arranged and / or assigned in the area of ​​the material outlet (7), characterized in that the separating device (20) is a cylinder (21), wherein the cylinder (21) consists of a plurality of first and second sieve segments (30, 40) with sieve openings (50) which are arranged alternately on a frame (60).

Description

[0001] The present invention relates to a separating device for a ball mill or stirred ball mill as well as a ball mill or stirred ball mill with a separating device according to the features of the preambles of claims 1 and 13. State of the art

[0002] The invention relates to a separating device for large, preferably horizontally oriented ball mills or stirred ball mills. A ball mill is a device for coarse, fine, and ultrafine grinding or homogenization of materials. It consists of a rotating grinding chamber in which the material is ground by grinding media. Ball mills are generally constructed from a horizontally rotatable, approximately circular cylindrical grinding chamber. The mills are filled through a central opening in one of the end walls. Discharge depends on the design and occurs, for example, through slots in the grinding chamber wall at the end of the mill, with the grinding media being retained by a separating device.

[0003] A special type of ball mill is the stirred ball mill. Stirred ball mills consist of a vertically or horizontally arranged, usually nearly cylindrical grinding chamber, which is 70–90% filled with grinding media. In stirred ball mills, the grinding chamber is generally stationary, not rotating. An agitator with suitable stirring elements ensures the intensive movement of the grinding media. The material suspension is continuously pumped through the grinding chamber. During this process, the suspended solids are comminuted or dispersed by impact and shear forces between the grinding media. At the mill's discharge, the material being ground and the grinding media are separated by a suitable separating device.

[0004] Such a separating device for retaining the grinding media typically consists of a sieve that allows only the ground product to pass through. The sieve can either be designed to rotate with the shaft or be statically arranged and is located in the grinding container in the outlet area for the processed product.

[0005] For example, dynamic separation devices for stirred ball mills are known, designed such that a gap is formed between a stator attached to the stationary part of the stirred ball mill and a rotor connected to the rotating part of the stirred ball mill, through which only the ground material can pass. A problem with such separation devices is that the grinding balls separated from or contained in the material accumulate in the edge region of the rotor and move with the rotor, causing rapid wear of both the rotor and the stator.

[0006] DE 4412408 A1 describes a stirred mill with grinding media. A conventional separator is positioned upstream of the material being ground outlet. A pre-classifying disc is arranged upstream of this separator, which preferentially conveys the grinding media entering its operating area radially outwards. The pre-classifying disc is part of a rotating cage that largely encloses the outlet body. The rotation of the cage largely prevents a radial flow of material and grinding media towards the outlet body. This largely protects the separator from impact by the grinding media, thereby reducing wear on the separator. Furthermore, the throughput of the stirred mill can be significantly increased.

[0007] DD 153331 A1 describes a stirred ball mill for the continuous comminution and dispersion of liquid-solid mixtures, equipped with a separation device. In this stirred ball mill, a build-up of grinding media in front of the separation screen is prevented, and the entire screen surface is covered by the grinding media movement. Furthermore, the separation screen can be replaced without emptying the grinding chamber. The separation device consists of a flat screen and is positioned parallel to the agitator shaft axis at its highest point, at the end of the grinding chamber, within the lid of the grinding chamber, which is designed as a screen housing. The separation device is covered by a grinding material collection hood equipped with an upwardly angled outlet nozzle.

[0008] DE 19830960 A1 describes a separating device for a stirred ball mill with a screen, wherein the screen has variable screen gaps. In particular, the separating device can be in a first operating position in which the elements limiting the screen gap are held at a first distance by at least partially non-elastic spacers. In a cleaning position, the elements assume a second distance that is greater than the first distance, so that blockages can be easily removed from the screen gap.

[0009] DE 102007012526 A1 shows a further separation device for grinding media of a stirred ball mill. DE 102010053484 A1 shows a stirred ball mill with a separation device consisting of at least two components. A first component is the separation device and a second component is a dynamic element for generating a material flow.

[0010] The object of the invention is to provide a separation device for a ball mill, in particular for a stirred ball mill, which is easy to assemble and can be quickly repaired or partially or completely replaced if necessary.

[0011] The above problems are solved by a separating device for a ball mill or stirred ball mill, and by a ball mill or stirred ball mill with a separating device, comprising the features in claims 1 and 13. Further advantageous embodiments are described in the dependent claims. Description

[0012] The invention relates to a separating device for a ball mill or an agitator ball mill. Hereinafter, the term "mill" is used for both ball mills with a rotating grinding chamber and agitator ball mills with stirring tools. In agitator ball mills, the grinding chamber can be mounted either rotatingly or non-rotatingly. The grinding chamber of mills has a first and a second end-face opening. In particular, the grinding chamber is a hollow cylinder that can be opened at least at one end, is arranged horizontally, and has a preferably circular opening at one of its free ends. Other geometries of the grinding chamber, for example, chambers with a largely symmetrical polygonal, in particular an octagonal, cross-section or similar, are also conceivable and are said to be encompassed by the invention. The second opening is closed with a second closing device, in particular with a lid.In stirred ball mills, the agitator is usually assigned to the second closing device of the second opening.

[0013] In the area of ​​the first end-face opening are a grinding material outlet and a separating device for separating the grinding media from the ground product. The first end-face opening is closed by a first closing device. The separating device is usually associated with the first closing device or is located in the area of ​​the grinding material outlet and / or associated with it.

[0014] According to the invention, the separating device comprises a plurality of first and second sieve segments with sieve openings. In particular, the separating device is designed as a cylinder, the cylinder consisting of a plurality of first and second sieve segments with sieve openings. The first and second sieve segments are arranged alternately on a frame. The arrangement of the first and second sieve segments on the frame forms the cylindrical shape of the separating device. For this purpose, the sieve segments each have at least one convexly curved outer surface. The sieve segments are arranged on the frame such that the convexly curved outer surfaces of all sieve segments together form a cylindrical outer shape of the separating device. The outer cylinder of the separating device preferably has a circular base.A particular advantage of the present invention is that the sieve openings can be machined into the respective sieve segments. In the separation devices for large mills known from the prior art, the sieve openings always had to be manually inserted (made), as such automation was neither possible nor practical.

[0015] According to a preferred embodiment of the invention, the sieve segments each comprise trapezoidal surfaces, in particular isosceles trapezoidal surfaces. A coating is preferably applied to the trapezoidal surfaces. The coating preferably has its greatest thickness in the region of an axis of symmetry of the isosceles trapezoidal surface and its smallest thickness in the region of the legs of the isosceles trapezoidal surface. In particular, the coating forms the convexly curved outer surface of the sieve segments with its greatest thickness in the region of an axis of symmetry of the isosceles trapezoidal surface. After the sieve segments are mounted on the frame, the coated side of the trapezoidal surfaces of the sieve segments forms the outer surface of the separating device cylinder.

[0016] According to one embodiment of the invention, the trapezoidal surfaces are designed as sieve plates with first openings for the material being ground. The coating has second openings for the material being ground, which are aligned with the first openings of the trapezoidal surfaces. The size of the openings is selected such that the grinding media are retained, while the ground material can be removed from the ball mill or stirred ball mill via the outlet.

[0017] The frame on which the sieve segments are arranged consists of two ring-shaped elements connected by transverse elements. The transverse elements are arranged at regular intervals; in particular, the distance between any two directly adjacent transverse elements is always identical.

[0018] The first and second screen segments preferably comprise trapezoidal surfaces with identical bases. The distance between the transverse elements of the frame largely corresponds to the average length of the base sides of the trapezoidal surfaces. The width of the transverse elements is preferably selected such that the trapezoidal legs of a first or second screen segment arranged between two transverse elements rest almost completely on the transverse elements. According to one embodiment of the invention, the areas of the coating extending beyond the trapezoidal legs rest on the transverse elements, while the trapezoidal surfaces are arranged between the transverse elements.

[0019] The first and second screen segments differ primarily in the arrangement of the fasteners and mounting elements used for attachment to the frame. These fasteners and mounting elements are located on the uncoated side of the trapezoidal surface. Specifically, a fastener is centrally located on the short base of the first screen segment, and a mounting element is centrally located in or adjacent to the long base of the first screen segment. The "central" position refers specifically to a position along the axis of symmetry of the isosceles trapezoidal surface. In contrast, a mounting element is centrally located in or adjacent to the short base of the second screen segment, and a fastener is centrally located on the long base of the second screen segment.Preferably, the first and second sieve segments are designed such that their respective basic shapes are mirror images of each other, with the arrangement of the receiving and connecting elements being specific to each sieve segment. This design makes it possible to manufacture the sieve segments from identical basic segments and to change only the arrangement of the receiving and connecting elements, particularly on the respective uncoated sides that define the interior of the separating device cylinder after assembly of the sieve segments.

[0020] Furthermore, the first annular element is equipped with mounting receptacles for the connecting elements of the first and second screen segments, and the second annular element of the frame is equipped with fastening devices for securing the first and second screen segments. The first and second screen segments are arranged and fastened to the second annular element via connecting elements that extend through the fastening devices and the mounting elements of the screen segments.

[0021] During the assembly of a separation device according to the invention, the sieve segments are attached to the frame, for example, to a steel base body (a so-called displacement body) that forms the sieve plate. A bolt is attached to one end of the sieve plate of the sieve segments, and a receptacle is formed on the other end. As described above, the different sieve segments differ in the arrangement of the bolt and receptacle. The bolt is inserted directly into the displacement body on the rear side, while on the front side, a separate bolt is pushed from the front through the steel base body or displacement body into the receptacle of the sieve segment's sieve plate. Furthermore, the rubber coating of the sieve segments is conically shaped in the axial direction so that the sieve segments can be pressed together, resulting in compression and thus a seal at the butt joints.

[0022] According to a preferred embodiment, the short base of the first sieve segments is configured as the bolt side and the long base side as the receiving side. In contrast, the short base of the second sieve segments is configured as the receiving side and the long base side as the bolt side. During assembly of the separating device, all second sieve segments are first inserted into the steel base body or displacement body using the bolts on their long base sides, leaving space between each second sieve segment for a first sieve segment. The first sieve segments are then inserted into these empty spaces. The last inserted first sieve segments can be manually pushed between the adjacent second sieve segments until the conical rubber surfaces or the trapezoidal legs abut each other.The adjacent rubber surfaces of the trapezoidal legs are in contact with each other, particularly through a form-fit and / or force-fit connection. The necessary axial displacement is then achieved by closing the lid, that is, the first locking device which closes the first opening at the end face of the grinding container, so that all sieve segments lie flush against each other in the axial direction. The lid, or rather the first locking device, is screwed onto the steel base body or displacement body and rests over the separately inserted bolts. It thus prevents the sieve segments from coming loose.

[0023] The number of screen segments in a separating device varies depending on the machine size. The convexity of one of the outer surfaces of the screen segments, particularly the convexity of the coating, must also be adapted to the number of screen segments and the machine size.

[0024] The modular design of the separation device according to the invention allows for easier assembly, particularly in large ball mills or stirred ball mills. Due to the modular design, it is possible to selectively replace only damaged areas or individual screen segments when worn. The individual components, especially the individual screen plates, are relatively small and therefore easier to handle, particularly in mills with large diameters, than separation systems known from the prior art.

[0025] The separating device according to the invention can be easily retrofitted to a first closure device or a lid of an existing mill. Thus, mills can be easily, quickly, and cost-effectively retrofitted with the separating device according to the invention.

[0026] The invention further relates to a ball mill or a stirred ball mill with a cylindrical grinding container having a first end-face opening and a second end-face opening, wherein the first and the second end-face openings can be closed by a first and a second closing device, respectively, wherein a material inlet is arranged in the region of the second end-face opening and a material outlet is arranged in the region of the first end-face opening, and wherein a separating device is associated with the material outlet. According to the invention, the ball mill or the stirred ball mill comprises a separating device and a plurality of first and second screen segments with screen openings, in particular a separating device with the features described above. Character description

[0027] 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. Fig. Figure 1 shows a schematic longitudinal section through a stirred ball mill. Fig. Figure 2 shows a separation device according to the invention for a mill, in particular for a large stirred ball mill. Fig. Figure 3 shows different views and detailed sections of the frame of the separating device according to the invention. Fig. Figure 4 shows different views of the first sieve segments. Fig. Figure 5 shows different views of the second sieve segment. Fig. Figure 6 shows different views of the separating device according to the invention, mounted and attached to a lid for closing the grinding container.

[0028] 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.

[0029] Fig. Figure 1 shows a schematic longitudinal section through a stirred ball mill 1 according to the prior art. This mill comprises a horizontally mounted grinding chamber 3. It is also evident that one end wall 10 has an outlet 7 for removing the material being ground, with a separation system 8. The other end wall 11 of the grinding chamber 3 is open and includes a grinding chamber flange 12. The open end wall 11 of the grinding chamber 3 is closed with a lid 13 with a lid flange 13*. Sealing elements are arranged on the chamber side of the lid 13 for a sealing connection. The material being ground inlet 4 is also associated with the lid 13, through which the material being ground 5 is introduced into the grinding chamber 3. The grinding chamber 3 is filled with grinding balls 6 and additionally includes stirring elements 14, which ensure the intensive movement of the grinding balls 6 while, for example, a material suspension 5* is continuously pumped through the grinding chamber of the grinding chamber 3.The stirring elements 14 are arranged, for example, on a common drive shaft 15, which is driven by a suitable drive means 16. The drive means 16 is, for example, an electric motor 17 and is arranged on the outside of the lid 13.

[0030] Fig. Figure 2 shows a separation device 20 according to the invention for a mill, in particular for a large stirred ball mill 1 (compare Figure 2). Fig. 1) The separating device 20 is designed as a type of sieve cylinder 21, wherein the size of the sieve openings 50 is selected such that the grinding aids 6 (compare Fig. 1) be retained, while the ground material 5, 5* can be removed from the mill or stirred ball mill 1 via a grinding material outlet 7 (compare Fig. 1) The sieve cylinder 21 is composed of a plurality of individual sieve segments 30, 40, the number of which varies depending on the machine size. The sieve segments 30, 40 are arranged in a circular pattern and mounted on a frame 60, so that together they form the separating device 20 in the form of a cylinder with a circular base.

[0031] Fig. Figures 3 show different views and detailed sections of the frame 60 of the separating device 20 according to the invention. In particular, they show Fig. 3A a perspective view and Fig. Figure 3B shows a side view. The frame 60 consists of two annular frame elements 61-1 and 61-2, which are connected to each other by transverse elements 62. The transverse elements 62 each project at least partially beyond the outer diameter of the annular frame elements 61-1 and 61-2 and form projecting bearing surfaces 63 in this area. The first annular frame element 61-1 includes a mounting receptacle 70 for connecting elements of the sieve segments 30, 40, located centrally between two transverse elements 62, and the second annular frame element 61-1 includes a fastening device 72 for connecting elements of the sieve segments 30, 40, also located centrally between two transverse elements 62. Preferably, the mounting receptacles 70 and the fastening devices 72 are arranged opposite each other. The transverse elements 62 are preferably arranged parallel to each other between the two annular frame elements 61-1 and 61-2.

[0032] In the illustrated embodiment, the two ring-shaped frame elements 61-1, 61-2 are connected to each other by twelve evenly spaced transverse elements 62, i.e. the transverse elements 62 are each offset at an angle of α = 30° along the circumference of the ring-shaped frame elements 61-1, 61-2 or the transverse elements 62 are each arranged at a distance A from each other along the circumference of the ring-shaped frame elements 61-1, 61-2.

[0033] Fig. 3C shows a cross-sectional view along the in Fig. Section line AA shown in 3B with top view of the first ring-shaped frame element 61-1 with fastening receptacles 70, each arranged centrally between two adjacent crossbars 62. Fig. 3D shows a top view of the second ring-shaped frame element 61-2 with fastening devices 72, each arranged centrally between two adjacent crossbars 62. Fig. 3E to 3G each show a cross-sectional view along the line in the Fig. 3D representation of the section line BB, CC or DD.

[0034] Fig. Figure 4 shows different views of the first sieve segments 30 and Fig. Figure 5 shows different views of the second sieve segment 40. In particular, the Fig. 4A, Fig. 5A each a top view of a sieve segment 30, 40, the Fig. 4B, Fig. Figures 5B each show a side view of a sieve segment 30, 40; the Fig. 4C, Fig. 5C each show a cross-sectional view along the respective in Fig. 4A or Fig. Section line AA shown in 5A. Fig. 4D, Fig. 4E, Fig. 5D, Fig. Figures 5E each show different perspective views of sieve segments 30 and 40.

[0035] The sieve segments 30, 40 consist of largely flat sieve plates 80 made of metal, in particular steel, or another suitable material. The sieve plates 80 each have the shape of an isosceles trapezoid.

[0036] The sieve segments 30, 40 each comprise connecting elements 82 and receiving elements 84. The connecting elements 82 are, for example, designed as bolts 83, and the receiving elements 84 are, for example, designed as screw receptacles 85 or similar receptacles. According to the preferred embodiment shown, in the first sieve segments 30, the short base side 31 of the sieve plate 80-1 is designed as the bolt side; in particular, the connecting element 82 is centrally located on the short base side 31 of the sieve plate 80. Adjacent to the long base side 32, the receiving element 84 is also centrally located, in particular on the axis of symmetry S between the legs 33. Furthermore, in the second sieve segments 40, the short base side 31 of the sieve plate 80-2 is designed as the bolt side; in particular, the connecting element 82 is centrally located on the short base side 31 of the sieve plate 80-2.Adjacent to the long base side 32, the receiving means 84 is also arranged centrally, in particular on the axis of symmetry S between the legs 33.

[0037] The sieve segments 30, 40 have a coating 87 on one side with an elastic material, in particular rubber or similar. Preferably, the coating 87 is at least largely radius-shaped in the radial direction. Considering the Fig. 4C, Fig. 5C then makes it clear that the coating 87 has the greatest thickness dmax in the region of the axis of symmetry S between the two trapezoidal legs 33, while the coating 87 has the smallest thickness dmin in the region of the legs 33. This means that, starting from the axis of symmetry S, the coating 87 tapers in cross-section on both sides.

[0038] The sieve plate 80 and the coating 87 each have passage openings 81, 88. The passage openings 81, 88 are arranged such that a first passage opening 81 of the sieve plate 80 and a second passage opening 88 of the coating 87 are aligned with each other and thus form a sieve opening 50.

[0039] Especially in the Fig. 4A, Fig. 4C, Fig. 4D and Fig. 5A, Fig. 5C and Fig. In 5D it is clearly visible that the coating 87 extends laterally beyond the legs 33 of the sieve plates 80 and forms a conical coating side 89.

[0040] Fig. Figure 6 shows different views of the separating device 20 according to the invention, mounted and attached to a lid 90 for closing the grinding container.

[0041] The illustrated separating device consists of six first and six second sieve segments 30, 40, which are arranged alternately on the frame 60, wherein the trapezoidal legs 33, 43 each rest on the transverse elements 62 of the frame 60 and preferably abut one another. That is, the width of the transverse elements 62 is selected such that the trapezoidal legs 33, 43 of a first or second sieve segment 30, 40 arranged between two transverse elements 62 rest almost completely on the transverse elements 62. The distance A between two adjacent transverse elements 62 (compare Fig. 3A) of frame 60 largely corresponds to the mean value of the lengths of the base sides 31, 32 of the trapezoidal faces. Preferably, A=½ X(Length of short base + Length of long base).

[0042] By arranging and attaching the first and second sieve segments 30,40 to the frame 60 (compare Fig. 3) with coating 87 facing outwards, the commonly known outer cylindrical shape of the fully assembled separating device 20 is achieved.

[0043] In particular, the sieve segments 30, 40 are attached to the frame 60 by inserting them, with their connecting element 82 or bolt 83, into the mounting receptacles 70 of the first annular frame element 61-1 of the frame 60. On the opposite side, a separate bolt 75 or other suitable connecting element is pushed through the mounting device 72 of the second annular frame element 61-1 of the frame 60 into the receiving element of the sieve plate 80 of the sieve segment 30, 40. In particular, the second sieve segments 40 are first arranged on the frame 60, leaving space between each second sieve segment 40 for a first sieve segment 30. The first sieve segments 30 are then inserted into the free spaces and attached to the frame and via separate bolts 75 to the fastening devices 72 of the second ring-shaped frame element 61-1 of the frame 60.

[0044] Due to their respective trapezoidal shapes, the sieve segments 30, 40 are conically shaped in the axial direction of the formed separating device cylinder 20. In particular, the coating 87 extends uniformly over the trapezoidal legs 33 of the sieve plate 80 so that the sieve segments 30, 40 can be pressed together, resulting in compression and thus a seal at the abutting edges or the trapezoidal legs 33, 43 (compare Fig. 4 and Fig. 5).

[0045] The first sieve segments 30, which were inserted last, can be pushed by hand between the adjacent second sieve segments 40 until the conical coating sides 89 (compare Fig. 4 and Fig.5) or the trapezoidal legs 33 abut each other. The remaining necessary axial displacement is achieved by closing the grinding cylinder with a cover 90, so that all sieve segments 30, 40 lie flush against each other in the axial direction. The cover 90 is screwed onto the frame 60 and rests over the separately inserted bolts 75. It thus prevents the sieve segments 30, 40 from coming loose.

[0046] 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 alterations of the invention can be made without departing from the scope of protection of the following claims. Reference symbol list 1 stirred ball mill 3 grinding containers 4. Grinding material inlet 5 Milling material 5* Milling suspension 6 grinding balls 7 Grinding material outlet 8 Separation system 10 first front wall 11 second front wall 12 Grinding container flange 13 lids 13* Lid flange 14 Stirring element 15 Drive shaft 16 propulsion devices 17 Electric motor 20 separating device 21 sieve cylinders 30 first sieve segment 31 short base 32 long base 33 Trapezoidal legs 40 second sieve segment 50 sieve opening 60 frames 61 Ring element 62 transverse element 70 first mounting point 72 Fastening device 75 bolts 80 sieve plate 81 first passage opening 82 Fasteners 83 bolts 84 recording devices 85 Screw mount 87 Coating 88 second passage opening 89 conical coating side 90 lids A distance α Angle between transverse elements d thickness S axis of symmetry

Claims

[1] Separating device (20) for a ball mill or a stirred ball mill (1), wherein the ball mill or the stirred ball mill (1) comprises a material inlet (4) and a material outlet (7), wherein the separating device (20) can be arranged and / or assigned in the area of ​​the material outlet (7), characterized by , that the separating device (20) is a cylinder (21) wherein the cylinder (21) consists of a plurality of first and second sieve segments (30, 40) with sieve openings (50) arranged alternately on a frame (60). [2] Separating device (20) according to claim 1, wherein the first and second sieve segments (30, 40) each have a convexly curved outer surface, wherein the first and second sieve segments (30, 40) are arranged on the frame (60) such that the outer surfaces of the entirety of all first and second sieve segments (30, 40) form a cylindrical shape with a circular base. [3] Separating device (20) according to one of the preceding claims, wherein the first and second sieve segments (30, 40) each comprise trapezoidal surfaces (80), in particular isosceles trapezoidal surfaces. [4] Separating device (20) according to one of the preceding claims, wherein the first and second sieve segments (30, 40) each comprise a coating (87). [5] Separating device (20) according to claim 4, wherein the coating (87) is applied to the trapezoidal surfaces (80). [6] Separating device (20) according to claim 5, wherein the coating (87) has a maximum thickness (dmax) in the region of an axis of symmetry (S) of the isosceles trapezoidal surface (80) and a minimum thickness (dmin) in the region of the legs (33, 43) of the isosceles trapezoidal surface (80), in particular wherein the coating (87) forms a convexly outwardly curved outer surface with a maximum thickness (dmax) in the region of an axis of symmetry (S) of the isosceles trapezoidal surface (80). [7] Separating device (20) according to one of claims 4 to 6, wherein the trapezoidal surfaces (80) are designed as sieve plates with first passage openings (81) for the material to be ground and wherein the coating (87) has second passage openings (88) for the material to be ground, which are aligned with the first passage openings (81) of the trapezoidal surfaces (80). [8] Separating device (20) according to one of the preceding claims, wherein the frame (60) consists of two ring-shaped elements (61-1, 61-2) which are connected to each other by transverse elements (62). [9] Separating device (20) according to claim 8, wherein the first and second sieve segments (30, 40) comprise trapezoidal surfaces (80) with identical base areas and wherein the distance (A) between the transverse elements (62) of the frame largely corresponds to the mean value of the lengths of the base sides (31, 32) of the trapezoidal surfaces (80). [10] Separating device (20) according to one of claims 3 to 9, wherein a connecting means (82) is centrally assigned to the short base side (31) of the first sieve segments (30) and a receiving means (84) is centrally assigned in the area or adjacent to the long base side (32) of the first sieve segments (30) and wherein a receiving means (84) is centrally assigned in the area or adjacent to the short base side (31) of the second sieve segments (40) and wherein a connecting means (82) is centrally assigned to the long base side (32) of the second sieve segments (40). [11] Separating device (20) according to claim 10, wherein the first annular element (61-1) of the frame (60) is associated with fastening receptacles (70) for the connecting means (82) of the first and second sieve segments (30, 40) and wherein the second annular element (61-2) of the frame (60) is associated with fastening devices (72) for fastening the first and second sieve segments (30, 40). [12] Separating device (20) according to claim 11, wherein the first and second sieve segments (30, 40) can be attached to the second annular element (61-2) by means of connecting means (75) passing through the fastening devices (72) and the receiving means (84) of the sieve segments (30, 40). [13] Ball mill or stirred ball mill (1) with a cylindrical grinding container (2) having a first end-face opening (10) and a second end-face opening (11), wherein the first and the second end-face opening (10, 11) can be closed by a first and a second closing device (13), wherein a grinding material inlet (4) is arranged in the region of the second end-face opening (11) and a grinding material outlet (7) is arranged in the region of the first end-face opening (10), wherein a separating device (20) is associated with the grinding material outlet (7), wherein the ball mill or the stirred ball mill (1) comprises a cylindrical separating device (20, 21) characterized by, that , wherein the cylindrical separating device (21) consists of a plurality of first and second sieve segments (30, 40) with sieve openings (50) arranged alternately on a frame (60). [14] Ball mill or stirred ball mill (1) according to claim 13, wherein the ball mill or stirred ball mill (1) comprises a separating device (20) according to any one of claims 1 to 12.

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