EP4200085B1 - Screen plate for a separating device for classifying bulk material - Google Patents

Description

The subject of the invention is a sieve plate for a separating device for mechanically classifying bulk material, in particular polycrystalline silicon fragments.

Polycrystalline silicon (polysilicon) is commonly produced using the Siemens process - a chemical vapor deposition process. Thin filament rods (thin rods) made of silicon are heated in a bell-shaped reactor (Siemens reactor) by direct current passage, and a reaction gas containing a silicon-containing component (e.g. monosilane or halosilane) and hydrogen is introduced. The surface temperature of the filament rods is usually more than 1000°C. At these temperatures, the silicon-containing component of the reaction gas decomposes, and elemental silicon separates from the gas phase as polysilicon on the rod surface, increasing the rod diameter. After a predetermined diameter is reached, the deposition is stopped and the silicon rods obtained are removed.

Polysilicon is the starting material in the production of single-crystalline silicon, which is produced, for example, using the Czochralski process (crucible drawing). Furthermore, polysilicon is required for the production of multicrystalline silicon, for example using ingot casting processes. For both processes, the polysilicon rods must be crushed into fragments. These are usually classified according to size in separators. The separating devices are usually screening machines that mechanically sort or classify the polysilicon fragments into different size classes.

Polysilicon can also be produced in the form of granules in a fluidized bed reactor. This is done by fluidizing silicon seed particles using a gas flow in a fluidized bed, which is heated using a heating device. By adding a silicon-containing reaction gas, a deposition reaction occurs on the hot particle surface, whereby elemental silicon is deposited on the seed particles with an increase in diameter.

The polysilicon granulate is also usually divided into two or more fractions using a screening system (classification). The smallest fraction (undersized sieve) can then be processed into germ particles in a grinding plant and fed to the reactor. The target fraction (product grain) is usually packaged and transported to the customer.

Sieving machines are generally used to separate solids according to grain sizes. Depending on the movement characteristics, a distinction can be made between vibrating screen machines and vibrating screen machines. The screening machines are usually driven electromagnetically or by unbalanced motors or gears. The movement of the sieve lining serves to further transport the feed material in the longitudinal direction of the sieve and to allow the sieve undersize to pass through the sieve openings. In contrast to vibrating screen machines, vibrating screen machines have both horizontal and vertical screen acceleration.

Multi-deck screening machines can fractionate several grain sizes at the same time. The drive principle in multi-deck flat screen machines is based on two counter-rotating unbalance motors that generate a linear vibration, with the broken material moving in a straight line over a horizontal separating surface. Using a modular system, a large number of screen decks can be put together to form a screen stack. This means that different Grain sizes can be produced in a single machine without the need to change screen decks.

Classification usually takes place either using perforated screens, bar screens or profiled screen plates with elevations and valleys and, if necessary, V-shaped openings on one side.

When classifying using perforated sieves, such as those in the CN207605973U As described, blockages can occur during the process, which must be removed at regular intervals depending on the size of the feed material and the throughput, which leads to system and production downtimes. When classifying using bar sieves (cf. EP 2 730 510 A1 ), due to the geometric arrangement of the rods, jamming and clogging by broken material can occur, which can lead to loss of yield when separating the target product.

WO 2016/202473 A1 describes a profiled sieve plate with a V-profile, which has enlarging openings on one removal side. However, the tapered depressions and elevations can cause jamming of product grain (jammed bulk material can also be referred to as stuck grain) in the product flow and in the opening area. This can lead to a deterioration in the classifying quality, as the undersize fraction to be separated passes through the plug grain into the target grain. To prevent this, the plug grain must also be removed regularly, which results in longer service life.

WO 2018/108334 A1 represents an improvement in WO 2016/202473 A1 described sieve plate. Here the openings on the removal side had an additional widening. However, the sieve plate has rather poor separation of coarse grain/target grain and fine grain (selectivity). Due to the sieve geometry, large particles can push the undersize ahead of them and prevent the undersize from being separated. EP1079939 A1 discloses a sieve plate for a separating device according to the preamble of claims 1 and 5.

The task of the invention arose from this problem.

The task is solved by claims 1 and 5.

It has been shown that this rounded profile enables the undersize fraction (fines to be separated) to separate even better from the product grain. The profiled area causes larger amounts of undersized particles to collect in the rounded depressions. Larger fragments are transported away on the sieve plate above the undersize fraction in the depressions, usually without coming into contact with the undersize fraction. This leads to a high separation quality. The profile prevents larger fragments from getting stuck in the recesses due to jamming. In particular, the widened opening edge, on the one hand, prevents large fragments from jamming, and on the other hand, it ensures unhindered separation of the undersize fraction if a larger fragment gets jammed.

In particular, the sieve plate according to the invention is a further development of the one in WO 2018/108334 A1 described sieve plate.

The circles K1 and K2 may touch at a point T0, or they may be connected to each other by a common tangent, the tangent touching the circle K1 at a point T1 and the circle K2 at a point T2. Accordingly, the tangent describes the profile with the circular arcs if necessary. The circles K1 and K2 are preferably arranged next to one another with the proviso that the depressions of the profile always widen upwards (cf. Fig. 2B ). The circular arc of the circle K1 describing the elevations of the profile extends from the apex of the elevation to point T0 or T1. The circular arc of the circle K2 describing the depressions of the profile extends from the apex of the depression to the point T0 or T2.

In principle, the two circles K1 and K2 can also be connected to one another via the points T1 and T2 by a higher-order function, a hyperbola or an elliptical arc; However, taking into account the proviso that the depressions in the profile always widen upwards.

The bulk material can be broken polysilicon material, for example crushed polysilicon rods from the Siemens process. The bulk material can also be polysilicon granules. In general, the bulk material is placed in a feed area, which lies opposite the removal area, is placed on the sieve plate.

The opening edge is preferably concave, i.e. curved into the interior of the sieve plate or in the direction of the feed area, and has a depth t, where t is 0 <t ≤ 5*r2, preferably r2 to 5*r2, particularly preferably r2 to 4 *r2, especially 2*r2 to 3*r2. (see. Fig. 4A ).

According to a further embodiment, the opening edge is rectangular and has a depth t, where t is 0 <t ≤ 5*r2, preferably r2 to 5*r2, particularly preferably r2 to 4*r2, in particular 2*r2 to 3*r2 . (see. Fig. 4B ).

For the removal of small-sized bulk material (also referred to as undersized particles), the profile of the sieve plate can preferably have the two configurations described below. Small-sized bulk material should be understood to mean a subset of the quantity of bulk material fed in, which is to be separated using the sieve plate. The small-sized bulk material therefore corresponds to the fraction to be separated.

According to the invention, the profile of the sieve plate for removing undersize is r2 <r1, where 0 <r2/r1 <1, preferably 0.2 <r2/r1 <0.4. Furthermore, r1 + r2 = e, where e corresponds to the distance between the circle center M1 of K1 and the circle center M2 of K2, and where the circles K1 and K2 touch each other at a point T0, in which the circular arcs describing the profile merge into one another.

Furthermore, 0° <α <65°, preferably 0° <α <25°, particularly preferably 5° <α <20°, where α is an angle that defines the position from M2 to M1 in a Cartesian coordinate system when M1 and M2 are vertices of a right-angled triangle and e corresponds to the hypotenuse of the triangle (cf. Fig. 5 ).

According to a further embodiment for removing undersize, r2 < r1 applies to the sieve plate, where 0 < r2 / r1 < 1, preferably 0.2 < r2 / r1 < 0.4. Furthermore, r1 + r2 > e, where e corresponds to the distance between the center of the circle M1 from K1 and M2 from K2, and the circles K1 and K2 do not touch each other.

Furthermore, -65° <α <65°, preferably -25° <α <10°, particularly preferably -10° <α <5°, where α is an angle that defines the position from M2 to M1 in a Cartesian coordinate system , if M1 and M2 are vertices of a right-angled triangle and e corresponds to the hypotenuse of the triangle, where the circular arcs (or the circles K1 and K2) are connected to one another by a common tangent through the points T1 of K1 and T2 of K2 (cf. Fig. 6 ).

For the removal of large bulk material (also referred to as oversize), the profile of the sieve plate can preferably have the two configurations described below. Large-scale bulk material should be understood to mean a subset of the quantity of bulk material fed in, which is to be separated using the sieve plate. The large bulk material therefore corresponds to the fraction to be separated. Oversize particles can clog individual recesses or damage the sieve plate.

According to the invention, the profile of the sieve plate for removing oversized particles is r2 > r1, where 0 < r1/r2 < 1, preferably 0.2 < r1/r2 < 0.4.

Furthermore, r1 + r2 = e, where e corresponds to the distance between the circle center M1 of K1 and the circle center M2 of K2, and K1 and K2 touch each other at a point T0 in which the circular arcs merge into one another. Furthermore, -65° < α < 0°, preferably -20° < α < 0°, where α is an angle that defines the position from M2 to M1 in a Cartesian coordinate system if M1 and M2 are corner points of a rectangular triangle and e corresponds to the hypotenuse of the triangle (cf. Fig. 7 ).

According to a further embodiment for removing oversized particles, r2 > r1 applies to the sieve plate, where 0 < r1/r2 < 1, preferably 0.2 < r1/r2 < 0.4.

Furthermore, r1 + r2 > e, where e corresponds to the distance between the circle center M1 of K1 and the circle center M2 of K2, and the circles K1 and K2 do not touch each other. Furthermore, -65° < α < 65°, preferably -20° < α < 0°, where α is an angle that defines the position of M2 to M1 in a Cartesian coordinate system when M1 and M2 are vertices of a right-angled triangle and e corresponds to the hypotenuse of the triangle, where the circular arcs are connected to each other by a common tangent through the points T1 of K1 and T2 of K2 (cf. Fig. 8 ).

Preferably, the sieve plate is made of a material selected from the group consisting of plastic, ceramic, glass, diamond, amorphous carbon, silicon, metal and combinations thereof.

The sieve plate or at least the part of the sieve plate that comes into contact with the bulk material can be lined or coated with a material selected from the group consisting of plastic, ceramic, glass, diamond, amorphous carbon, silicon and combinations thereof.

In particular, the sieve plate can have a coating made of titanium nitride, titanium carbide, silicon nitride, silicon carbide, aluminum titanium nitride or DLC (Diamond Like Carbon).

The plastic can be, for example, PVC (polyvinyl chloride), PP (polypropylene), PE (polyethylene), PU (polyurethane), PFA (perfluoroalkoxy polymer), PVDF (polyvinylidene fluoride) and PTFE (polytetrafluoroethylene).

The sieve plate preferably consists of a hard metal.

A further aspect of the invention relates to a separating device for classifying bulk material, comprising at least one of the sieve plates described and at least one separating element with a separating edge arranged below the removal area of the sieve plate.

The length of the separating element preferably corresponds to the length of the removal side of the sieve plate. The distance of the separating element from the removal area is preferably variable.

The separating element is used to separate undersized or oversized particles from the target fraction. Preferably, the separating element is static and does not vibrate with the sieve plate.

The separating element preferably has a triangular side profile, in particular the side profile of an acute-angled triangle.

The separating edge of the separating element preferably has the same profile as the sieve plate. The separating edge can also be designed to be straight, so that the separating element has the contour of a rectangle in front view.

Fig. 1

zeigt eine erfindungsgemäße Siebplatte in Draufsicht und Fronansicht.

Fig. 2

verdeutlicht die Beschreibung des Profils der Siebplatte.

Fig. 3

verdeutlicht die Beschreibung der Öffnungskante der Siebplatte.

Fig. 4

zeigt zwei Ausführungsformen der Siebplatte im Bereich der Öffnungskante.

Fig. 5

zeigt einen Profilverlauf zur Abtrennung von Unterkorn.

Fig. 6

zeigt einen weiteren Profilverlauf zur Abtrennung von Unterkorn.

Fig. 7

zeigt einen Profilverlauf zur Abtrennung von Überkorn.

Fig. 8

zeigt einen weiteren Profilverlauf zur Abtrennung von Überkorn.

Fig. 9

zeigt eine Trennvorrichtung.

Fig. 10, 11 und 12

zeigen jeweils eine weitere Ausführungsform der Trennvorrichtung.

The separating element is preferably pivotable through an angle δ . This can be particularly advantageous at higher conveying speeds, as the fall curve of large and small fragments then differs more clearly and the fine fraction can be separated better with a pivoted separating edge. By pivoting, there are significantly fewer fragments that bounce off the separating element and possibly end up in the target product.

Fig. 1

shows a sieve plate according to the invention in top view and front view.

Fig. 2

clarifies the description of the profile of the sieve plate.

Fig. 3

clarifies the description of the opening edge of the sieve plate.

Fig. 4

shows two embodiments of the sieve plate in the area of the opening edge.

Fig. 5

shows a profile course for separating undersized particles.

Fig. 6

shows another profile course for separating undersized particles.

Fig. 7

shows a profile course for separating oversize particles.

Fig. 8

shows another profile course for separating oversize particles.

Fig. 9

shows a separating device.

10, 11 and 12

each show a further embodiment of the separating device.

List of reference symbols used

10

Sieve plate

11

Profile area

12

Collection area

13

bracket

14

survey

15

head Start

16

deepening

17

opening edge

18

opening

19

withdrawal side

20

Area of responsibility

30

Separator

32

Separating edge

40

Collection container

41

Collection container

42

Collection container

50

fan

100

Separating device

In the Figure 1A a section of a sieve plate 10 according to the invention with a profile area 11 and a removal area 12 is shown. The profile area 11 has alternating elevations 14 and depressions 16. The depressions 16 merge into openings 18 in the removal area 12, through which the bulk material can fall depending on its size. The transition between recess 16 and opening 18 is formed by an opening edge 17, which is based on the 3 and 4 is described in more detail. The openings 18 widen towards a removal side 19 (dashed line). The profiling is basically maintained in the removal area 12, with the openings 18 preferably being punched or milled into a profile area. The projections 15 formed in this way are correspondingly curved and form a continuation of the elevations 14. The removal area 12 basically lies between the opening edges 17 and the removal side 19. If necessary, it may be preferred that the opening edges 17 are not at the same height.

The Figure 1B shows a front view of the sieve plate 10. The removal area 12 cannot be distinguished from the profile area 11 from this perspective. The sieve plate is arranged in a holder 13, the holder 13 extending maximally up to the opening edges 17.

The Figure 2A shows how the profile of the sieve plate 10 (cf. Fig 1 ) can be written with the help of two circles K1 and K2 arranged next to each other, which touch each other at a point T0. The elevations 14 are described by a circular arc of the circle K1 shown in bold with the radius r1. The Depressions 16 are described with a circular arc of the circle K2 shown in bold with the radius r2, the circular arcs merging into one another at the contact point T0. Arranged repeatedly and alternately next to one another, the profile of the sieve plate 10 results. In particular, K1 and K2 are arranged next to one another in such a way that the depressions 16 always widen. This expansion is in Fig 2B shown as an example. It should preferably apply to the depressions 16 that l ₀ <l _n <l _1+n .

The Figure 3 shows a detailed view of the opening edge 17 in a top view. In this exemplary embodiment, the opening edge 17 has a width that corresponds to twice the radius r2 of the circle K2 (cf. Fig. 2 ). Also shown is the radius r1 of the circle K1.

The Figure 4 shows two configurations of the sieve plate 10, where Fig. 4A an embodiment with a concave opening edge 17 and Fig. 4B represents an embodiment with a rectangular opening edge 17. Typical values for r1, r2 and the depth t can be: r1 = 15 mm; r2 = 5mm; t = 5mm.

The Figure 5 illustrates a profile of the sieve plate 10, which is particularly suitable for separating small-sized bulk material (undersized particles). The position of the circles K1 and K2 relative to each other, which touch each other at a point T0, can be described by a right-angled triangle, where the hypotenuse is the connecting line e between the circle centers M1 and M2 and where the adjacent a is parallel to the x-axis of a Cartesian Coordinate system runs. In addition to the requirement that the radius of K1 is larger than that of K2, the angle α (to the countercathete) significantly determines the profile course of the sieve plate 10. Here α is approximately 30°, which results in the profile course indicated in the form of the bold line .

The Figure 6 shows the profile of a sieve plate 10, which is also particularly suitable for separating undersized particles. In contrast to that in the Fig. 5 In the profile shown, K1 and K2 do not touch each other, but are connected via a common tangent through the points T1 and T2. The angle α here is approx. 25°. Typical values for r1, r2 and e can be: r1 = 15 mm; r2 = 5mm; e = 30mm. These dimensions are particularly suitable for classifying bulk material of fraction size 2 (BG 2, see example).

The Figures 7 and 8 each show a profile of a sieve plate 10, which is particularly suitable for separating oversize particles. The main difference compared to the separation of undersized particles is that the circle K1 has a smaller radius r1 than the circle K2. Furthermore, reference can be made to the above statements. Typical values for α , r1, r2 and e can be: α = 45°; r1 = 5mm; r2 = 25mm; e = 50mm.

The Figure 9A shows a separating device 100 with a sieve plate 10 and a separating element 30, which is arranged below the removal area 12 and is intended to separate the target fraction from oversize or undersize particles. The separating element 30 has a profiled separating edge 32, the profiling being in the Figure 9B can be recognized. The profiling of the separating edge 32 preferably corresponds to the profiling of the sieve plate 10. The separating element can be pivoted through an angle δ . On the side of the sieve plate 10 opposite the removal area 12 is a feed area 20, which directly adjoins the profile area, but does not necessarily have to have a profiling. If necessary, the bulk material is brought to the feed area using a conveyor belt (not shown).

The Figure 10 shows a further embodiment of a separating device 100, which has two sieve plates 10A, 10B arranged one after the other. Starting from the left, the first separating element 30A is located after the first sieve plate 10A. The separating element 30A can be pivoted through an angle δ . At this point, the sieve undersize is separated and collected in the collecting container 40A. The undersize separation is supported by a blower 50, which can change its direction of action by an angle β. The product grain is further conveyed to the second sieve plate 10B, and there the oversize is separated from the product grain by means of a second separating element 30B. The product grain is collected in the collecting container 40B, the oversize in the collecting container 40C. Typical values for the sieve plate 10A are: r1 = 15 mm; r2 = 5mm; t = 5 mm and α = 15°. The angle δ of the separating element 30A can be 80°. The angle β of the fan 50A can be 30°.

Typical values for the sieve plate 10B are: r1 = 5 mm;
r2 = 25mm; t = 25 mm, e = 50 mm and α = 45°. The angle δ of the separating element 30A can be 90°.

The Figures 11 and 12 each show a further embodiment of the separating device 100. In the Figure 11 Two separating elements 30 are arranged directly after a sieve plate 10. This makes it possible to use a sieve plate 10 to separate the oversize fractions (collection container 40C) and fines (collection container 40A) in just one step. The Figure 12 shows a similar variant as Figure 10 . In Figure 12 However, the arrangement is reversed and first the oversize (collection container 40C) and then the fine fraction (collection container 40A) are separated using a second sieve plate 10A. The

Figures 10 to 12 can be expanded or changed as desired.

Example Undersize separation

In general, the polysilicon material delivered in a bag by a polysilicon manufacturer may also contain smaller fragments and an undersize fraction (undersize). The undergrain, especially with grain sizes smaller than 4 mm, has a negative influence on the drawing process in the production of single-crystalline silicon and for this reason must be removed before use. Polysilicon with fracture size 2 (BG 2) was used for the test.

The size class of polysilicon fragments is defined as the longest distance between two points on the surface of a silicon fragment (equivalent to the maximum length): BG 0 0.1 to 5mm BG 1 3 to 15mm BG2 10 to 40mm BG 3 20 to 60mm BG 4 45 to 120mm BG 5 100 to 250mm

The polysilicon material (BG 2) used for the test was screened using an analysis sieve (according to DIN ISO 3310-2) with a nominal hole width W = 4 mm (square hole) and made available for the tests. The separated undersize fraction (undersize) was collected and weighed.

10 kg of the test material (without undersize fraction < 4 mm) were placed on a conveyor unit. The test material is preferably added via a funnel. The container to be filled is positioned at the end of the screening section above the first conveyor unit so that the test material can be conveyed into the container without any problems.

The undersize fraction separated in advance is used for this test. When filling the conveyor unit, 2 g of undersize fraction are added to every 2 kg of test material, so that a total of approx. 10 g of undersize fraction was added.

The delivery rate was set to 3 kg ± 0.5 kg per minute before the test run. The removed undersize fraction was collected and weighed. The experiments were carried out five times per setting.

Test 1:

A conveyor unit with a sieve plate with a convex opening edge (according to Fig. 9A and 4A ) with t = r2 and a profile according to Fig. 5 with the values for r1 = 15 mm, r2 = 5 mm and α = 15°. The separating edge of the separating element had no profile.

Test 2:

A conveyor unit with a sieve plate with a rectangular opening edge (according to Fig. 9A and 4A ) and according to a profile Fig. 5 with the values for r1 = 15 mm, r2 = 5 mm and α = 15°. The separating edge of the separating element had no profile.

Test 3:

A conveyor unit with a sieve plate with a convex opening edge (according to Fig. 9A and 4A ) and according to a profile Fig. 6 with the values for r1 = 15 mm, r2 = 5 mm, e = 30 mm and α = -15°. The separating edge of the separating element had no profile.

Test 4:

A conveyor unit with a sieve plate with a convex opening edge (according to Fig. 9A and 4A ) and according to a profile Fig. 5 with the values for r1 = 15 mm, r2 = 5 mm and α = 15° used. The separating edge of the separating element had the same profiling as the sieve plate. The separating edge is arranged in relation to the profile of the sieve plate in such a way that the elevations of the separating edge point towards the recesses of the sieve plate.

Table 1 shows the mean results compared to the results from the WO 2018/108334 A1 . Table 1 test Test material [kg] Addition of undersize [g] Removed undersize [g] Removal rate [%] WO2018/108334 (1) 10 10 8.3 83 1 10 10 9.5 95 2 10 10 9.0 90 3 10 10 9.2 92 4 10 10 9, 6 96

Example Oversize separation

The polysilicon material delivered in the bag by the polysilicon manufacturer must not contain any excessively large fragments (oversize particles). The oversize can cause blockages and damage and must therefore be removed before use. The BG 2 was used for the test.

All oversize fragments were manually removed from the polysilicon material (BG 2) used for the test. The removed oversize material was saved and weighed.

10 kg of the test material without oversize was placed on the conveyor unit. Posting was done via a funnel. The container to be filled is positioned at the end of the screening section above the first conveyor unit so that the test material can be conveyed into the container.

When filling the conveyor unit, 100 g of the separated oversize are added to every 2 kg of test material, so that a total of 500 g of oversize was added.

The delivery rate was set to 15 kg ± 1 kg per minute before the test run. The removed oversize was collected and weighed. The experiments were carried out five times per setting.

Test 1:

A conveyor unit with a sieve plate with a convex opening edge (according to Fig. 9A and 4A ) with t = r1 and a profile according to Fig. 8 with the values for r1 = 10 mm, r2 = 25 mm, e = 55 mm and α = 45° and a separating element without a profile.

Test 2:

A double series-connected separating device was developed according to Fig. 9A used, whereby each of the two sieve plates has a convex opening edge with t = r1 (cf. Fig. 4A ) and each had a separating element without a profile. The profile of the sieve plates resulted from: r1 = 10 mm, r2 = 25 mm, e = 55 mm and α = 45 °.

Test 3:

A four-fold series-connected separating device was used in accordance with Fig. 9A used, whereby each of the four sieve plates has a convex opening edge with t = r1 (cf. Fig. 4A ) and each had a separating element without a profile. The profile of the Sieve plates resulted from: r1 = 10 mm, r2 = 25 mm, e = 55 mm and α = 45° (cf. Fig. 8 ).

Test 4:

A conveyor unit with a sieve plate with a convex opening edge (according to Fig. 9A and 4A ) with t = r1 and a profile according to Fig. 7 with the values for r1 = 10 mm, r2 = 25 mm and α = 45° and a separating element without a profile.

Table 2 shows the average results for oversize separation: Table 2 test Test material [kg] Addition of oversize [g] Removed oversize [g] Removal rate [%] 1 10 500 380 76 2 10 500 440 88 3 10 500 500 100 4 10 500 300 60

Claims (11)

1. Screen plate (10) for removing undersize for a separating device (100) for classifying bulk material, comprising a profile region (11) which has a profile having depressions (16) and elevations (14) extending in the direction of a takeoff side (19), where the profile is describable by a circle arc of a first circle K1 and by a circle arc of a second circle K2, and the circles K1 and K2 are disposed adjacent to one another, where the circle arc of the first circle K1 with a radius r1 describes the elevations (14) and the circle arc of the second circle K2 with a radius r2 describes the depressions (16), with each depression (16) in a takeoff region (12) undergoing transition into an opening (18) which expands in the direction of the takeoff side (19), where the transition between depression (16) and opening (18) is formed by an opening edge (17) with a width corresponding to the length of the radius r2 to 2*r2, where either

   - r1 + r2 = e, where e corresponds to the distance between the circle center point M1 of K1 and the circle center point M2 of K2, and K1 and K2 contact one another at a point T0 at which the circle arcs merge, and where 0° < α < 65°, where α is an angle which defines the position of M2 relative to M1 in a cartesian coordinate system, if M1 and M2 are vertices of a right-angled triangle and e corresponds to the hypotenuse of the triangle; or

   - r1 + r2 < e and K1 and K2 do not contact one another, where the circle arcs are joined to one another by a common tangent through a point T1 of K1 and a point T2 of K2, and where -65° < α < 65°,

   characterized in that the profile is subject to r2 < r1, with 0 < r2/r1 < 1.
2. Screen plate according to Claim 1, characterized in that when r1 + r2 = e, the angle α is subject to 0° < α < 25°, preferably 5° < α < 20°.
3. Screen plate according to Claim 1, characterized in that when r1 + r2 < e, the angle α is subject to -25° < α < 10°, preferably -10° < α < 5°.
4. Screen plate according to any of the preceding claims, characterized in that r2/r1 is subject to 0.2 < r2/r1 < 0.4.
5. Screen plate (10) for removing oversize for a separating device (100) for classifying bulk material, comprising a profile region (11) which has a profile having depressions (16) and elevations (14) extending in the direction of a takeoff side (19), where the profile is describable by a circle arc of a first circle K1 and by a circle arc of a second circle K2, and the circles K1 and K2 are disposed adjacent to one another, where the circle arc of the first circle K1 with a radius r1 describes the elevations (14) and the circle arc of the second circle K2 with a radius r2 describes the depressions (16), with each depression (16) in a takeoff region (12) undergoing transition into an opening (18) which expands in the direction of the takeoff side (19), where the transition between depression (16) and opening (18) is formed by an opening edge (17) with a width corresponding to the length of the radius r2 to 2*r2, where either

   - r1 + r2 = e, where e corresponds to the distance between the circle center point M1 of K1 and the circle center point M2 of K2, and K1 and K2 contact one another at a point T0 at which the circle arcs merge and where - 65° < α < 0°, where α is an angle which defines the position of M2 relative to M1 in a cartesian coordinate system, if M1 and M2 are vertices of a right-angled triangle and e corresponds to the hypotenuse; or

   - r1 + r2 < e and K1 and K2 do not contact one another, where the circle arcs are joined to one another by a common tangent through a point T1 of K1 and a point T2 of K2, and where -65° < α < 65°,

   characterized in that the profile is subject to r2 > r1, with 0 < r1/r2 < 1.
6. Screen plate according to Claim 5, characterized in that rl/r2 is subject to 0.2 < rl/r2 < 0.4.
7. Screen plate according to Claim 5 or 6, characterized in that the angle α is subject to -20° < α < 0°.
8. Screen plate according to any of the preceding claims, characterized in that the opening edge (17) has a concave extent and has a depth t for which 0 < t ≤ 5*r2, preferably r2 to 5*r2, more preferably r2 to 4*r2, more particularly 2*r2 to 3*r2.
9. Screen plate according to any of Claims 1 to 7, characterized in that the opening edge (17) has a rectangular extent and has a depth t for which 0 < t ≤ 5*r2, preferably r2 to 5*r2, more preferably r2 to 4*r2, more particularly 2*r2 to 3*r2.
10. Separating device (100) for classifying bulk material, comprising at least one screen plate (10) according to at least one of Claims 1 to 9 and at least one separating element (30) disposed beneath the takeoff 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 a profile like the screen plate (10).
11. Separating device according to Claim 10, characterized in that the separating element (30) is swivelable by an angle δ.

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