Screen plates for separation devices for classifying bulk materials

Abstract

The present invention relates to a screen plate for a separator for classifying bulk material, comprising a profiled area whose contour comprises depressions and projections extending in the direction of the discharge side. The contour can be described by arcs of a first circle K1 and by arcs of a second circle K2, the circles K1 and K2 being arranged adjacent to each other, the arcs of the first circle K1 with a radius r1 describing the projections, and the arcs of the second circle K2 with a radius r2 describing the depressions. Each depression in the discharge area is transformed into a hole extending in the direction of the discharge side, wherein the hole has a hole edge whose width corresponds to the length of the radius r2 up to 2*r2.

Description

[0001] The subject of the invention is a screen plate for a separating device for mechanically classifying bulk material, more particularly polycrystalline silicon chunks.

[0002] Polysilicon is usually produced using the Siemens process, a chemical vapor deposition process. In a bell-shaped reactor (Siemens reactor), thin silicon filaments (thin rods) are heated by directly passing an electric current, and a reaction gas containing a silicon-containing component (e.g., monosilane or halosilane) and hydrogen is introduced. The surface temperature of the filaments is typically over 1000°C. At these temperatures, the silicon-containing components in the reaction gas decompose, and elemental silicon is deposited from the gas phase in the form of polysilicon on the rod surface, increasing the rod diameter. When the specified diameter is reached, the deposition is stopped and the resulting silicon rod is unloaded.

[0003] Polysilicon is the starting material for producing single-crystal silicon, which is produced, for example, by the Czochralski process (crucible pulling). Furthermore, polysilicon is required when producing multicrystalline silicon, for example using the block casting process. Both processes require that polysilicon rods be crushed to form individual blocks. These blocks are usually graded by size in a separation device. The separation device usually includes a screening machine that mechanically separates the polysilicon blocks into different size classes – that is, it grades them.

[0004] Polycrystalline silicon can also be produced in granular form in a fluidized bed reactor. This is achieved by fluidizing silicon seed particles using a gas stream in a fluidized bed, which is heated by a heating device. Adding a silicon-containing reaction gas causes a deposition reaction on the surface of the hot particles, depositing elemental silicon on the seed particles and increasing their diameter.

[0005] The polysilicon granules are usually also separated into two or more fractions (classification) by a screening device. The smallest fraction (undersize) can then be processed into seed particles in a grinding device and supplied to the reactor. The target fraction (product fraction) is usually packaged and shipped to the customer.

[0006] Screening machines are commonly used to separate solids based on particle size. Planar vibratory screening machines and shaker screening machines may differ in their kinematic characteristics. Screening machines are typically driven by electromagnetic forces or through unbalanced motors or gears. The motion of the sieve disc conveys the feed material longitudinally across the screen and facilitates the passage of undersize material through the mesh. Compared to planar vibratory screening machines, shaker screening machines exhibit both vertical and horizontal screen acceleration.

[0007] The multi-layer screening machine is capable of sorting multiple particle sizes simultaneously. The driving principle of the multi-layer flat screening machine is based on two unbalanced motors that run in opposite directions to generate linear vibration, and the sorted material moves linearly on the horizontal separation surface. Multiple screens can be assembled into screen stacks using a modular system. Therefore, different particle sizes can be produced in one machine without having to change the screen plates.

[0008] Classification is usually accomplished using perforated plate screens, bar screens, or profiled screens with ridges and valleys and possibly V-shaped holes on one side.

[0009] For example, classification using perforated plate screens of the type described in CN207605973U can become clogged during operation, and depending on the size and throughput of the material being fed, any blockages must be cleared regularly, leading to plant and production downtime. In the case of classification using bar screens (see EP 2 730 510 A1), the geometric arrangement of the bars can lead to clogging and blockage of the material being sorted, which can result in yield losses when separating the target product.

[0010] WO 2016 / 202473 A1 describes a profiled screen plate with a V-shaped profile and enlarged holes on the discharge side. However, the gradually tapering valleys and peaks can lead to blockage of the product flow and product fraction in the hole area (blocked bulk material can also be referred to as stuck particles). This can lead to deterioration of the classified material, as the undersize material to be separated passes through the stuck part into the target fraction. To prevent this, the stuck part must be regularly cleared, which results in longer downtimes.

[0011] WO 2018 / 108334 A1 represents an improvement to the sieve plate described in WO 2016 / 202473 A1. In this case, the holes on the discharge side have an additional widening. However, the sieve plate is quite poor at separating the coarse / product fraction from the fine fraction (separation accuracy). Due to the geometry of the screen, large particles can push the undersize material in front of them and prevent it from being separated.

[0012] The objects to be achieved by the present invention are derived from the above-mentioned problems.

[0013] This object is achieved by a sieve plate for a separator for classifying bulk material, the sieve plate comprising a profile region, the profile of which has depressions and elevations extending in the direction of the discharge side, wherein the profile can be described by an arc of a first circle K1 and by an arc of a second circle K2, the circles K1 and K2 being arranged adjacent to one another (and alternately as required), wherein the arc of the first circle K1 with a radius r1 describes the elevations and the arc of the second circle K2 with a radius r2 describes the depressions.

[0014] Each depression in the discharge area is transformed into a hole expanding in the discharge side direction, wherein the hole has a hole edge whose width corresponds to the length of the radius r2 to 2*r2. The width preferably corresponds to the radius r2.

[0015] It has been found that this rounded profile allows the undersize fraction (the fines to be separated) to be separated from the product fraction even more effectively. Due to the profiled area, a larger amount of the undersize fraction collects in the round recess. Larger lumps are conveyed into the recess by the undersize fraction on the screen plate, generally without coming into contact with the undersize fraction. This results in a higher-quality separation. The profile prevents larger lumps from becoming lodged in the recess due to blockage. In particular, the widened hole edge also prevents clogging by large lumps and, on the one hand, ensures unimpeded separation of the undersize fraction even if larger lumps become blocked.

[0016] The sieve plate of the present invention is more particularly a further development of the sieve plate described in WO 2018 / 108334 A1.

[0017] The circles K1 and K2 can touch each other at point T0 or be connected to each other by a common tangent, wherein the tangent touches the circle K1 at point T1 and touches the circle K2 at point T2. Accordingly, the contour is described by the tangent, which is optionally a circular arc. The circles K1 and K2 are preferably arranged adjacent to each other, provided that the depression and the contour always expand upwards (see Figure 2 B) The arc of the circle K1 describing the convexity of the profile extends from the vertex of the convexity to point T0 or T1. The arc of the circle K2 describing the concavity of the profile extends from the vertex of the concavity to point T0 or T2.

[0018] In principle, the two circles K1 and K2 can also be connected to one another via higher-order functions, hyperbolas or elliptical arcs, provided that the concavity of the contour always expands upwards.

[0019] The bulk material may include polysilicon chunks, such as crushed polysilicon rods from the Siemens process. The bulk material may also include polysilicon granules. The bulk material is typically applied to the screen deck in a loading zone, which is opposite the discharge zone.

[0020] The hole edge has a concave extent, thus arching into the inside of the sieve plate or arching in the direction of the feed area, and has a depth t, where t satisfies 0 < t ≤ 5*r2, preferably r2 to 5*r2, more preferably r2 to 4*r2, and more particularly 2*r2 to 3*r2. (See Figure 4 A).

[0021] According to another embodiment, the hole edge has a rectangular extent and has a depth t, where t satisfies 0 < t ≤ 5*r2, preferably r2 to 5*r2, more preferably r2 to 4*r2, and more particularly 2*r2 to 3*r2. (See Figure 4 B).

[0022] In order to remove bulk materials with small particle sizes (also known as screen undersize), the profile of the sieve plate preferably has two configurations described below. The bulk materials with small particle sizes herein refer to a part of the bulk material charge to be separated by the sieve plate. Therefore, the bulk materials with small particle sizes correspond to the part to be separated off.

[0023] The profile of the sieve plate for removing screen undersize preferably satisfies r2 < r1, where 0 < r2 / r1 < 1, preferably 0.2 < r2 / r1 < 0.4. In addition, r1 + r2 = e, where e corresponds to the distance between the center M1 of K1 and the center M2 of K2, where the circles K1 and K2 touch each other at the point T0, at which the circular arcs described in the profile meet.

[0024] In addition, 0° < α < 65°, preferably 0° < α < 25°, more preferably 5° < α < 20°, where α is the angle defining the position of M2 relative to M1 in the Cartesian coordinate system, if M1 and M2 are the vertices of a right triangle and e corresponds to the hypotenuse of the triangle (see Figure 5 ).

[0025] According to another embodiment for removing screen undersize, the sieve plate satisfies r2 < r1, where 0 < r2 / r1 < 1, preferably 0.2 < r2 / r1 < 0.4. In addition, r1 + r2 > e, where e is the distance between the center M1 of K1 and the center M2 of K2, and the circles K1 and K2 do not touch.

[0026] In addition, -65° < α < 65°, preferably -25° < α < 10°, more preferably -10° < α < 5°, where α is the angle defining the position of M2 relative to M1 in the Cartesian coordinate system, if M1 and M2 are the vertices of a right triangle and e corresponds to the hypotenuse of the triangle, and the circular arcs (or the circles K1 and K2) are connected to each other by a common tangent passing through the point T1 of K1 and the point T2 of K2 (see Figure 6 ).

[0027] In order to remove bulk materials with large particle sizes (also known as oversize materials), the profile of the sieve plate preferably has two configurations described below. The bulk materials with large particle sizes herein refer to a part of the bulk material charge to be separated by the sieve plate. Therefore, the bulk materials with large particle sizes correspond to the part to be separated. Oversize materials may cause blockage of individual depressions or damage to the sieve plate.

[0028] The profile of the sieve plate for removing oversize materials preferably satisfies r2 > r1, where 0 < r1 / r2 < 1, preferably 0.2 < r1 / r2 < 0.4.

[0029] In addition, r1 + r2 = e, where e corresponds to the distance between the center M1 of K1 and the center M2 of K2, and K1 and K2 are in contact at the point T0 where the arcs converge. Furthermore, -65° < α < 0°, preferably -20° < α < 0°, where α is the angle defining the position of M2 relative to M1 in the Cartesian coordinate system, if M1 and M2 are the vertices of a right triangle and e corresponds to the hypotenuse of the triangle (see Figure 7 ).

[0030] According to another embodiment for removing oversize materials, the sieve plate satisfies r2 > r1, where 0 < r1 / r2 < 1, preferably 0.2 < r1 / r2 < 0.4.

[0031] In addition, r1 + r2 > e, where e corresponds to the distance between the center point M1 of K1 and the center M2 of K2, and the circles K1 and K2 do not contact. Furthermore, -65° < α < 65°, preferably -20° < α < 0°, where α is the angle defining the position of M2 relative to M1 in the Cartesian coordinate system, if M1 and M2 are the vertices of a right triangle and e corresponds to the hypotenuse of the triangle, and the arcs are connected to each other by a common tangent passing through the point T1 of K1 and the point T2 of K2 (see Figure 8 ).

[0032] The sieve plate is preferably made of materials selected from plastics, ceramics, glass, diamond, amorphous carbon, silicon, metals, and combinations thereof.

[0033] The sieve plate or at least the part of the sieve plate in contact with the bulk materials can be lined or coated with materials selected from plastics, ceramics, glass, diamond, amorphous carbon, silicon, and combinations thereof.

[0034] More specifically, the sieve plate can have a coating of titanium nitride, titanium carbide, silicon nitride, silicon carbide, titanium aluminum nitride, or DLC (diamond-like carbon).

[0035] The plastics can be, for example, PVC (polyvinyl chloride), PP (polypropylene), PE (polyethylene), PU (polyurethane), PFA (perfluoroalkyl polymer), PVDF (polyvinylidene fluoride), and PTFE (polytetrafluoroethylene).

[0036] The screen plate is preferably made of hard metal.

[0037] Another aspect of the invention relates to a separating device for classifying bulk material, comprising at least one screen deck as described and at least one separating element arranged below the discharge region of the screen deck and having a separating edge.

[0038] The length of the separating element preferably corresponds to the length of the discharge side of the screen plate.The distance of the separating element from the discharge area is preferably variable.

[0039] The purpose of the separating element is to separate the undersize material or the oversize material from the target fraction.The separating element is preferably stationary and does not vibrate with the screen deck.

[0040] The separating element preferably has a triangular side profile, more particularly an acute-angled triangular side profile.

[0041] The separating edge of the separating element preferably has the same contour as the screen plate.The separating edge can also have a straight-line configuration, so that the separating element has a rectangular contour when viewed directly.

[0042] The separating element is preferably rotatable through an angle δ. This can be an advantage, particularly at relatively high conveying speeds, because in this case the drop-off curves of large and small chunks differ more significantly, and the fine fraction can be separated more effectively by the rotating separating edge. Due to the rotation, significantly fewer chunks bounce off the separating element and potentially enter the target product.

[0043] Figure 1 The screen plate of the present invention is shown in plan view and in elevation view.

[0044] Figure 2 Illustrate the description of the sieve plate profile.

[0045] Figure 3 Describe the description of the pore margins of the sieve plate.

[0046] Figure 4 Two embodiments of the screen plate in the area of ​​the hole edge are shown.

[0047] Figure 5 Displays the contours for removing undersize.

[0048] Figure 6 Another contour is shown for removing undersize.

[0049] Figure 7 Displays the contour for removing oversize.

[0050] Figure 8 Another contour is shown for removing oversize.

[0051] Figure 9 A separation device is shown.

[0052] Figure 10 、 11 1 and 12 respectively show another embodiment of the separation device.

[0053] List of reference numbers used

[0054] 10 Screen Plate

[0055] 10a Screen plate

[0056] 10b Screen

[0057] 11 Alien Area

[0058] 12 Discharging area

[0059] 13. Mount

[0060] 14 bulge

[0061] 15 Projection

[0062] 16 Depression

[0063] 17 hole edge

[0064] 18 holes

[0065] 19 Discharge side

[0066] 20 Loading area

[0067] 30 Separation elements

[0068] 30a Separation element

[0069] 30b Separation element

[0070] 32 Separation Edge

[0071] 40a Collection container

[0072] 40b Collection container

[0073] 40c collection container

[0074] 50 Blower

[0075] 100 Separation device

[0076] Figure 1A depicts a detail of a screen plate 10 according to the invention, having a profiled area 11 and a discharge area 12. The profiled area 11 has alternating projections 14 and depressions 16. The depressions 16 in the discharge area 12 transition into holes 18 through which the bulk material can fall, depending on its size. The transition between the depressions 16 and the holes 18 is formed by the hole edges 17, which are used Figure 3 and Figure 4 More precisely, the hole edge is described. The hole 18 widens in the direction of the discharge side 19 (dashed line). This contour is essentially retained in the discharge area 12, with the hole 18 preferably being milled or punched into the profiled area. The projection 15 formed in this way is correspondingly arched and forms a continuation of the projection 14. The discharge area 12 is essentially located between the hole edge 17 and the discharge side 19. It may be preferable for the hole edge 17 not to be at the same height.

[0077] Figure 1 B shows a straight view of the screen plate 10. In this view, there is no clear distinction between the discharge area 12 and the profiled area 11. The screen plate is arranged in a base 13 which extends at most to the aperture edge 17.

[0078] Figure 2 A shows a screen plate 10 (see Figure 1 ) is described by two adjacently arranged circles K1 and K2 that touch each other at point T0. The protrusion 14 is described by an arc of circle K1 (depicted in bold) with radius r1. The recess 16 is described by an arc of circle K2 (depicted in bold) with radius r2, and the arcs meet at the contact point T0. Repeatedly and alternately arranged adjacent to each other, the result is the profile of the screen plate 10. More specifically, K1 and K2 are arranged adjacent to each other so that the recess 16 is always expanded. This expansion is Figure 2 B. The depression 16 preferably obeys l0<l n <l 1+n .

[0079] Figure 3 A detailed view of the hole edge 17 is shown in plan view. In this exemplary embodiment, the width of the hole edge 17 corresponds to the circle K2 (see Figure 2 ) is twice the radius r2 of the circle K1. Similarly, the radius r1 of the circle K1 is depicted.

[0080] Figure 4 Two configurations of the screen plate 10 are shown, Figure 4 A depicts an embodiment with a concave hole edge 17, Figure 4 B depicts an embodiment with a rectangularly extended hole edge 17. Possible typical values ​​for r1, r2 and depth t are as follows: r1 = 15 mm; r2 = 5 mm; t = 5 mm.

[0081] Figure 5The profile of a screen plate 10 is shown, which is particularly suitable for removing bulk materials of small particle size (screen undersize). The relative positions of circles K1 and K2, where these circles touch each other at point T0, can be described by a right triangle, where the hypotenuse is the connecting line e between the center points M1 and M2 of the circles, and the adjacent side a extends parallel to the x-axis of the Cartesian coordinate system. The angle α (to the opposite side) together with the condition that the radius of K1 is greater than the radius of K2 authoritatively determine the profile of the screen plate 10. In this case, α is about 30°, resulting in the profile shown in bold.

[0082] Figure 6 The outline of a screening plate 10 is shown, which is also particularly suitable for removing undersize material. Figure 5 In contrast to the profile depicted in [ ], K1 and K2 do not touch each other but are connected by a common tangent through points T1 and T2. In this case, angle α is approximately 25°. Possible typical values ​​for r1, r2, and e are as follows: r1 = 15 mm; r2 = 5 mm; e = 30 mm. These dimensions are particularly suitable for sorting bulk material with block size 2 (CS 2, see examples).

[0083] Figure 7 and Figure 8 The profiles of the screen plates 10 are shown, which are particularly suitable for removing oversize material. The key difference compared to undersize removal is that circle K1 has a smaller radius r1 than circle K2. For other aspects, reference is made to the above description. Typical values ​​for α, r1, r2, and e are as follows: α = 45°; r1 = 5 mm; r2 = 25 mm; and e = 50 mm.

[0084] Figure 9 A shows a separation device 100 with a screen plate 10 and a separation element 30, which is arranged below the discharge area 12 and serves to separate the target portion from the oversize or undersize material. The separation element 30 has a profiled separation edge 32, the contour of which is Figure 9 B. The contour of the separating edge 32 preferably corresponds to the contour of the screen deck 10. The separating element can be rotated by an angle δ. On the side of the screen deck 10 opposite the discharge area 12, there is a loading area 20, which directly adjoins the profiled area but does not necessarily have any contour. A conveyor belt (not shown) is optionally used to transport the bulk material to the loading area.

[0085] Figure 10Another embodiment of a separation device 100 is shown, having two consecutive sieve decks 10A and 10B. Starting from the left, a first separation element 30A is located after the first sieve deck 10A. The separation element 30A can be rotated through an angle δ. The undersize material is then separated and collected in a collection container 40A. A blower 50, which can change its effective direction at an angle β, assists in removing the undersize material. The product fraction is further conveyed onto the second sieve deck 10B, where the oversize material is separated from the product fraction by the second separation element 30B. The product fraction is collected in a collection container 40B, and the oversize material is collected in a collection container 40C. Typical values ​​for the sieve deck 10A are as follows: r1 = 15 mm; r2 = 5 mm; t = 5 mm; and α = 15°. The angle δ of the separation element 30A can be 80°. The angle β of the blower 50A can be 30°.

[0086] Typical values ​​for the screen plate 10B are as follows: r1 = 5 mm; r2 = 25 mm; t = 25 mm, e = 50 mm; and α = 45°. The angle δ of the separating element 30A may be 90°.

[0087] Figure 11 and 12 Each shows another embodiment of the separation device 100. Figure 11 In the embodiment shown in FIG. 1 , two separating elements 30 are arranged directly after the screen deck 10. Thus, the screen deck 10 can be used to separate the oversize fraction (collection container 40C) and the fines fraction (collection container 40A) in only one step. Figure 12 Shows the Figure 10 Similar variants. However, in Figure 12 In the embodiment, the arrangement is switched so that the oversize material is first (collection container 40C) and subsequently, the fines are separated off by passing through the second screen deck 10A (collection container 40A). Figures 10 to 12 It can be expanded or transformed as needed. Example

[0088] Undersize removal

[0089] The bagged polysilicon material supplied by polysilicon manufacturers can typically include smaller ingots and an undersize fraction (screen material). Screen material, especially those with a particle size of less than 4mm, has an adverse effect on the pulling operation during the single crystal silicon production process and must therefore be removed before use. For this test, polysilicon with a crystal size of 2 (CS2) was used.

[0090] The size class of polysilicon blocks is defined as the longest distance between two points on the surface of the silicon block (corresponding to the maximum length):

[0091] CS 0 0.1 to 5 mm

[0092] CS1 3 to 15 mm

[0093] CS2 10 to 40 mm

[0094] CS 3 20 to 60 mm

[0095] CS 4 45 to 120 mm

[0096] CS 5 100 to 250 mm

[0097] The polysilicon material (CS2) used for the test was sieved using an analysis sieve (according to DIN ISO 3310-2) with a nominal aperture of W=4 mm (square holes) and used for the test. The removed undersize fraction (undersize material) was collected and weighed.

[0098] 10 kg of test material (without undersize fractions less than 4 mm) is applied to the conveyor. The test material is preferably loaded via a hopper. The container to be filled is located at the end of the sieve section above the first conveyor, making it easy to transfer the test material into the container.

[0099] The undersize fraction separated off beforehand was used for the test. When filling the conveyor, 2 g of undersize fraction was added per 2 kg of test material, resulting in a total of approximately 10 g of undersize fraction added.

[0100] Before the test run, the delivery rate was set to 3 kg ± 0.5 kg per minute. The removed undersize fraction was collected and weighed. Five experiments were performed for each setting.

[0101] Test 1:

[0102] The conveying device used comprises a convex hole edge with t=r2 (according to Figure 9 A and Figure 4 A) and according to Figure 5 The separating edge of the separating element does not have any profile.

[0103] Test 2:

[0104] The used transfer unit comprises a rectangular hole edge with t=r2 (according to Figure 9 A and Figure 4 B) and according to Figure 5 The separating edge of the separating element does not have any profile.

[0105] Test 3:

[0106] The conveying device used comprises a device having a convex hole edge (according to Figure 9 A and 4A) and according to Figure 6The separating edge of the separating element does not have any profile.

[0107] Test 4:

[0108] The conveying device used comprises a device having a convex hole edge (according to Figure 9 A and 4A) and according to Figure 5 The separating edge of the separating element has the same profile as the sieve plate. The separating edge is arranged relative to the profile of the sieve plate so that the protrusion of the separating edge points to the depression of the sieve plate.

[0109] Table 1 shows the average results compared with the results of WO 2018 / 108334 A01.

[0110]

[0111] Table 1

[0112] Example

[0113] Oversize removal

[0114] The polysilicon material in bags provided by the polysilicon manufacturer must not contain oversized pieces (oversize). Oversize can cause blockage and damage and must be removed before use. This is tested using the CS2.

[0115] All oversize lumps were manually removed from the polysilicon material (CS2) used for testing. The removed oversize was retained and weighed.

[0116] 10 kg of test material without oversize is applied to the conveyor. Filling is done via a hopper. The container to be filled is located at the end of the screening section above the first conveyor, into which the test material is transferred.

[0117] When filling the conveyor, 100 g of the removed oversize was added per 2 kg of test material, resulting in a total of 500 g of oversize added.

[0118] Before the test run, the conveyor rate was set to 15 kg ± 1 kg per minute. The removed oversize material was collected and weighed. Five tests were performed at each setting.

[0119] Test 1:

[0120] The conveying device used comprises a convex hole edge with t=r1 (according to Figure 9 A and Figure 4 A) and according to Figure 8A sieve plate with a profile of , wherein r1 = 10 mm, r2 = 25 mm, e = 55 mm and α = 45°, and with separating elements without a profile.

[0121] Test 2:

[0122] according to Figure 9 A, a double series of separation devices is used, each of the two sieve plates has a convex hole edge with t=r1 (see Figure 4 A), and in each case with a separating element without profile. The profile of the sieve plate is the product of the following values: r1 = 10 mm, r2 = 25 mm, e = 55 mm, and α = 45°.

[0123] Test 3:

[0124] according to Figure 9 A, a quadruple series of separation devices is used, each of the four sieve plates having a convex hole edge with t = r1 (see Figure 4 A), and in each case with a separating element without a profile. The profile of the sieve plate is the product of the following values: r1 = 10 mm, r2 = 25 mm, e = 55 mm and α = 45° (see Figure 8 ).

[0125] Test 4:

[0126] The conveying device used comprises a convex hole edge with t=r1 (according to Figure 9 A and Figure 4 A) and according to Figure 7 A sieve plate with a profile of , wherein r1 = 10 mm, r2 = 25 mm and α = 45°, and having separating elements without a profile.

[0127] Table 2 shows the average results for oversize removal:

[0128]

[0129]

[0130] Table 2.

Claims

1. A sieve plate (10) for removing undersize material of a separation device (100) for classifying bulk material, the sieve plate comprising a profiled area (11), the profile of which comprises depressions (16) and projections (14) extending in the direction of a discharge side (19), wherein the profile can be described by an arc of a first circle K1 and by an arc of a second circle K2, the first circle K1 and the second circle K2 being arranged adjacent to each other, wherein the arc of the first circle K1 with a radius r1 describes the projections (14) and the arc of the second circle K2 with a radius r2 describes the depressions (16), each depression (16) in the discharge area (12) transforms into a hole (18) extending in the direction of the discharge side (19), wherein the transition between the depression (16) and the hole (18) is formed by a hole edge (17), the width of the hole edge (17) corresponding to the length of the radius r2 to 2*r2, characterised in that The profile obeys r2 < r1, where 0 < r2 / r1 < 1, and r1 + r2 = e, where e corresponds to the distance between the center M1 of the first circle K1 and the center M2 of the second circle K2, and the first circle K1 and the second circle K2 are in contact at the point T0 where the arcs meet; and where 0° < α < 65°, where α is the angle defining the position of the center M2 relative to the center M1 in a Cartesian coordinate system, if the centers M1 and M2 are the vertices of a right triangle and e corresponds to the hypotenuse of the triangle; or ● r1 + r2 < e, and the first circle K1 and the second circle K2 do not contact each other; ● where the arcs are interconnected by a common tangent passing through the point T1 of the first circle K1 and the point T2 of the second circle K2, and where -65° < α < 65°.

2. The sieve plate according to claim 1, wherein When r1 + r2 = e, the angle α obeys 0° < α < 25°.

3. The sieve plate according to claim 1, wherein When r1 + r2 < e, the angle α obeys -25° < α < 10°.

4. A screen plate according to any one of the preceding claims, characterized in that r2 / r1 obeys 0.2 < r2 / r1 < 0.

4.

5. The sieve plate according to any one of claims 1 to 3, characterized in that The hole edge (17) has a concave region and has a depth t, where 0 < t ≤ 5*r2.

6. The sieve plate according to any one of claims 1 to 3, characterized in that The hole edge (17) has a rectangular region and has a depth t, where 0 < t ≤ 5*r2.

7. A sieve plate (10) for removing oversize material of a separation device (100) for classifying bulk material, the sieve plate comprising a profiled area (11), the profile of the profiled area having depressions (16) and projections (14) extending in the direction of a discharge side (19), wherein the profile can be described by an arc of a first circle K1 and by an arc of a second circle K2, the first circle K1 and the second circle K2 being arranged adjacent to each other, wherein the arc of the first circle K1 with a radius r1 describes the projections (14) and the arc of the second circle K2 with a radius r2 describes the depressions (16), each depression (16) in the discharge area (12) transforms into a hole (18) extending in the direction of the discharge side (19), wherein the transition between the depression (16) and the hole (18) is formed by a hole edge (17), the width of the hole edge (17) corresponding to the length of the radius r2 to 2*r2, characterized in that The profile obeys r2 > r1, where 0 < r1 / r2 < 1, and r1 + r2 = e, where e corresponds to the distance between the center M1 of the first circle K1 and the center M2 of the second circle K2, and the first circle K1 and the second circle K2 are in contact at the point T0 where the arcs meet; and where -65° < α < 0°, where α is the angle defining the position of the center M2 relative to the center M1 in a Cartesian coordinate system, if the centers M1 and M2 are the vertices of a right triangle and e corresponds to the hypotenuse; or r1 + r2 < e, and the first circle K1 and the second circle K2 do not contact each other; where the arcs are interconnected by a common tangent passing through the point T1 of the first circle K1 and the point T2 of the second circle K2, and where -65° < α < 65°.

8. The sieve plate according to claim 7, wherein r1 / r2 obeys 0.2 < r1 / r2 < 0.

4.

9. The sieve plate according to claim 7 or 8, wherein: The angle α obeys -20° < α < 0°.

10. A separation device (100) for classifying bulk material, comprising at least one screen plate (10) according to any one of claims 1 to 9 and at least one separating element (30) arranged below the discharge region (12) of the screen plate (10) and having a separating edge (32), characterized in that The separating edge (32) of the separating element (30) has the same profile as the sieve plate (10).

11. The separation device according to claim 10, characterized in that The separating element (30) is rotatable by an angle δ.

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