SCREEN PLATE FOR A SEPARATING DEVICE FOR CLASSIFYING BULK MATERIAL

Abstract

Subject-matter of the invention is a screen plate for a separating device for classifying bulk material. The screen plate comprises a profile region having a profile having depressions and elevations extending in a direction of a takeoff side, the profile being describable by a circle arc of a first circle K1 and a circle arc of a second circle K2, and the circles K1 and K2 being disposed adjacent to one another, with the circle arc of the first circle K1 with a radius r1 describing elevations and the circle arc of the second circle K2 with a radius r2 describing the depressions. Each depression undergoes transition, in a takeoff region, into an opening which expands in the direction of the takeoff side, the opening having an opening edge with a width corresponding to the length of the radius r2 to 2*r2.

Claims

1-15. (canceled)

16. A screen plate for a separating device for classifying bulk material, comprising: wherein said screen plate has a profile region which has a profile having depressions and elevations extending in the direction of a takeoff side, wherein 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, wherein the circle arc of the first circle K1 with a radius r1 describes the elevations and the circle arc of the second circle K2 with a radius r2 describes the depressions, with each depression in a takeoff region undergoing transition into an opening which expands in the direction of the takeoff side, wherein the transition between the depression and the opening is formed by an opening edge with a width corresponding to the length of the radius r2 to 2*r2, characterized in that the profile is subject to r2<r1, with 0<r2/r1<1; wherein r1+r2=e or r1+r2<e; wherein when r1+r2=e, 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 wherein 0°<α<65°, wherein a 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 wherein e corresponds to the hypotenuse of the triangle; and wherein when 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°.

17. The screen plate of claim 16, wherein when r1+r2=e, the angle α is subject to 0°<α<25°, preferably 5°<α<20°.

18. The screen plate of claim 16, wherein when r1+r2<e, the angle α is subject to −25°<α<10°, preferably −10°<α<5°.

19. The screen plate of claim 16, wherein r2/r1 is subject to 0.2<r2/r1<0.4.

20. The screen plate of claim 16, wherein the opening edge 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.

21. The screen plate of claim 16, wherein the opening edge 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.

22. A screen plate for a separating device for classifying bulk material, comprising: wherein the screen plate has a profile region which has a profile having depressions and elevations extending in the direction of a takeoff side, wherein 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, wherein the circle arc of the first circle K1 with a radius r1 describes the elevations and the circle arc of the second circle K2 with a radius r2 describes the depressions, with each depression in a takeoff region undergoing transition into an opening which expands in the direction of the takeoff side, wherein the transition between the depression and the opening is formed by an opening edge with a width corresponding to the length of the radius r2 to 2*r2; wherein the profile is subject to r2>r1, with 0<r1/r2<1, and wherein either r1+r2=e or r1+r2<e; wherein when r1+r2=e, 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°, wherein a 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; and wherein when 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 Ti of K1 and a point T2 of K2, and where −65°<α<65°.

21. The screen plate of claim 22, wherein r1/r2 is subject to 0.2<r1/r2<0.4.

22. The screen plate of claim 22, wherein the angle a is subject to −20°<α<0°.

23. The screen plate of claim 22, wherein the opening edge 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.

24. The screen plate of claim 22, wherein the opening edge 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.

25. A separating device for classifying bulk material, comprising: at least one screen plate and at least one separating element; wherein the at least one screen plate has a profile region which has a profile having depressions and elevations extending in the direction of a takeoff side, wherein 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, wherein the circle arc of the first circle K1 with a radius r1 describes the elevations and the circle arc of the second circle K2 with a radius r2 describes the depressions, with each depression in a takeoff region undergoing transition into an opening which expands in the direction of the takeoff side, wherein the transition between the depression and the opening is formed by an opening edge with a width corresponding to the length of the radius r2 to 2*r2, characterized in that the profile is subject to r2<r1, with 0<r2/r1<1; wherein r1+r2=e or r1+r2<e; wherein when r1+r2=e, 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 wherein 0°<α<65°, wherein a 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 wherein e corresponds to the hypotenuse of the triangle; and wherein when 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°; wherein the at least one separating element is disposed beneath the takeoff region of the at least one screen plate and has a separating edge; and wherein the separating edge of the at least one separating element has a profile like the at least one screen plate.

26. The separating device of claim 25, wherein the separating element is swivelable by an angle δ.

27. A separating device for classifying bulk material, comprising: at least one screen plate and at least one separating element; wherein the screen plate has a profile region which has a profile having depressions and elevations extending in the direction of a takeoff side, wherein 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, wherein the circle arc of the first circle K1 with a radius r1 describes the elevations and the circle arc of the second circle K2 with a radius r2 describes the depressions, with each depression in a takeoff region undergoing transition into an opening which expands in the direction of the takeoff side, wherein the transition between the depression and the opening is formed by an opening edge with a width corresponding to the length of the radius r2 to 2*r2; wherein the profile is subject to r2>r1, with 0<r1/r2<1, and wherein either r1+r2=e or r1+r2<e; wherein when r1+r2=e, 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°, wherein a 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; and wherein when 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°; wherein the at least one separating element is disposed beneath the takeoff region of the at least one screen plate and has a separating edge; and wherein the separating edge of the at least one separating element has a profile like the at least one screen plate.

28. The separating device of claim 27, wherein the separating element is swivelable by an angle δ.

Description

[0042] The separating element is preferably swivelable by an angle δ. At relatively high transport speeds in particular, this may be an advantage, since in that case there is a greater difference in the drop curves of large and small chunks, and the fine fraction can be separated off more effectively with a swiveled separating edge. As a result of the swivel, there are far fewer chunks which rebound from the separating element and possibly enter the target product.

[0043] FIG. 1 shows a screen plate of the invention in plan view and straight-on view.

[0044] FIG. 2 illustrates the description of the profile of the screen plate.

[0045] FIG. 3 illustrates the description of the opening edge of the screen plate.

[0046] FIG. 4 shows two embodiments of the screen plate in the region of the opening edge.

[0047] FIG. 5 shows a profile for the removal of undersize.

[0048] FIG. 6 shows a further profile for the removal of undersize.

[0049] FIG. 7 shows a profile for the removal of oversize.

[0050] FIG. 8 shows a further profile for the removal of oversize.

[0051] FIG. 9 shows a separating device.

[0052] FIGS. 10, 11 and 12 each show a further embodiment of the separating device.

LIST OF REFERENCE NUMERALS USED

[0053] 10 Screen plate

[0054] 11 Profile region

[0055] 12 Takeoff region

[0056] 13 Mount

[0057] 14 Elevation

[0058] 15 Projection

[0059] 16 Depression

[0060] 17 Opening edge

[0061] 18 Opening

[0062] 19 Takeoff side

[0063] 20 Charging region

[0064] 30 Separating element

[0065] 32 Separating edge

[0066] 40 Collecting container

[0067] 41 Collecting container

[0068] 42 Collecting container

[0069] 50 Blower

[0070] 100 Separating device

[0071] FIG. 1A depicts a detail of a screen plate 10 of the invention, with a profile region 11 and a takeoff region 12. The profile region 11 has elevations 14 and depressions 16 in alternation. The depressions 16 in the takeoff region 12 transition into openings 18, through which the bulk material can fall as a function of its size. The transition between depression 16 and opening 18 is formed by an opening edge 17, which is described more precisely using FIGS. 3 and 4. The openings 18 expand in the direction of a takeoff side 19 (dashed line). The profiling is fundamentally retained in the takeoff region 12, with the openings 18 preferably being milled or punched into a profile region. The projections 15 which are formed in this way are correspondingly arched and form a continuation of the elevations 14. The takeoff region 12 is situated fundamentally between the opening edges 17 and the takeoff side 19. It may possibly be preferable for the opening edges 17 not to be situated at the same height.

[0072] FIG. 1B shows a straight-on view of the screen plate 10. In this perspective there is no apparent difference between the takeoff region 12 and the profile region 11. The screen plate is disposed in a mount 13, with the mount 13 extending at most to the

[0073] FIG. 2A shows how the profile of the screen plate 10 (cf. FIG. 1) can be described by means of two adjacently disposed circles K1 and K2 which contact one another at a point T0. The elevations 14 are described by a circle arc—depicted in bold—of the circle K1 having the radius r1. The depressions 16 are described by a circle arc—depicted in bold—of the circle K2 having the radius r2, and the circle arcs merge at the contact point T0. Disposed repeatedly and alternatingly adjacent to one another, the result is the profile of the screen plate 10. More particularly, K1 and K2 are disposed adjacent to one another in such a way that the depressions 16 always expand. This expansion is depicted illustratively in FIG. 2B. The depressions 16 are preferably to be subject to I.sub.0<I.sub.n<I.sub.+n.

[0074] FIG. 3 shows a detail view of the opening edge 17 in plan view. In this illustrative embodiment, the opening edge 17 has a width which corresponds to twice the radius r2 of the circle K2 (cf. FIG. 2). Likewise depicted is the radius r1 of the circle K1.

[0075] FIG. 4 shows two configurations of the screen plate 10, with FIG. 4A depicting an embodiment with a concave opening edge 17, and FIG. 4B depicting an embodiment with a rectangularly extending opening edge 17. Possible typical values for r1, r2 and the depth t are as follows: r1=15 mm, r2=5 mm, t=5 mm.

[0076] FIG. 5 illustrates a screen plate profile 10 which is suitable in particular for the removal of bulk material of small particle size (undersize). The position of the circles K1 and K2 relative to one another, these circles contacting one another at a point T0, may be described by a right-angled triangle, with the hypotenuse being the connecting line e between the circle center points M1 and M2, and the adjacent side a extending parallel to the x-axis of a cartesian coordinate system. The angle α (to the opposite side), along with the proviso that the radius of K1 is greater than that of K2, authoritatively determines the profile of the screen plate 10. In this case a is around 30°, thereby producing the profile indicated in the form of the bold line.

[0077] FIG. 6 shows the profile of a screen plate 10 which is likewise particularly suitable for removing undersize. In contrast to the profile depicted in FIGS. 5, K1 and K2 do not contact one another, instead being joined via a common tangent through the points T1 and T2. The angle α in this case is around 25°. Possible typical values of r1, r2 and e are as follows: r1=15 mm; r2=5 mm; e=30 mm. These dimensions are especially suitable for classifying bulk material of chunk size 2 (CS 2, cf. example).

[0078] FIGS. 7 and 8 each show a profile of the screen plate 10 which is especially suitable for removing oversize. The key difference by comparison with the removal of undersize is that the circle K1 has a smaller radius r1 than the circle K2. Reference may otherwise be made to the observations above. Possible typical values for α, r1, r2 and e are as follows: α=45°; r1=5 mm; r2=25 mm; e=50 mm.

[0079] FIG. 9A shows a separating device 100 having a screen plate 10 and a separating element 30 which is disposed beneath the takeoff region 12 and is intended to separate target fraction from oversize or undersize. The separating element 30 has a profiled separating edge 32, with the profiling being apparent in FIG. 9B. The profiling of the separating edge 32 preferably corresponds to the profiling of the screen plate 10. The separating element can be swiveled by an angle δ. On the side of the screen plate 10 opposite the takeoff region 12 there is a charging region 20, which directly adjoins the profile region, but need not necessarily have any profiling. The bulk material is conveyed to the charging region optionally using a conveyor belt (not depicted).

[0080] FIG. 10 shows a further embodiment of a separating device 100, which hast wo successive screen plates 10A and 10B. Starting from the left, the first separating element 30A is located after the first screen plate 10A. The separating element 30A can be swiveled by an angle δ. At this point the screen undersize is separated off and collected in the collecting container 40A. The removal of undersize is assisted by a blower 50, which is able to change its effective direction by an angle β. The product fraction is carried further on a second screen plate 10B, where the oversize is separated from the product fraction by means of a second separating element 30B. The product fraction is collected in the collecting container 40B, the oversize in the collecting container 40C. Typical values for the screen plate 10A are as follows: r1=15 mm, r2=5 mm, t=5 mm, and α=15°. The angle δ of the separating element 30A may be 80°. The angle β of the blower 50A may be 30°.

[0081] 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°.

[0082] FIGS. 11 and 12 each show a further embodiment of the separating device 100. In FIG. 11, two separating elements 30 are disposed directly after a screen plate 10. As a result of this it is possible to separate the oversize fraction (collecting container 40C) and the fines fraction (collecting container 40A) using a screen plate 10 in only one step. FIG. 12 shows a variant similar to that of FIG. 10. In FIG. 12, however, the arrangement is switched round, and first the oversize (collecting container 40C) and subsequently, by means of a second screen plate 10A, the fines (collecting container 40A) are separated off. FIGS. 10 to 12 may be extended or transposed as desired.

EXAMPLE

[0083] Undersize Removal

[0084] The polysilicon material supplied in a bag by a polysilicon manufacturer may generally include smaller chunks and an undersize fraction (undersize). The undersize, more particularly having particle sizes smaller than 4 mm, has an adverse effect on the pulling operation during the production of monocrystalline silicon, and for that reason must be removed prior to use. For the test, polysilicon of chunk size 2 (CS 2) was used.

[0085] The size class of polysilicon chunks is defined as the longest distance between two points on the surface of the silicon chunk (corresponding to the maximum length):

TABLE-US-00001 CS 0 0.1 to 5 mm   CS 1  3 to 15 mm CS 2 10 to 40 mm CS 3 20 to 60 mm CS 4  45 to 120 mm CS 5 100 to 250 mm

[0086] The polysilicon material used for the test (CS 2) was screened using an analytical screen (according to DIN ISO 3310-2) with a nominal hole size W=4 mm (square hole) and was made available for the tests. The undersize fraction removed (undersize) was collected and weighed.

[0087] 10 kg of the test material (without undersize fraction <4 mm) were applied to a conveying unit. The test material is charged preferably via a hopper. The container to be filled is positioned at the end of the screen section above the first conveying unit, allowing the test material to be readily conveyed into the container.

[0088] The undersize fraction separated off in advance is used for this test. Upon filling of the conveying unit, 2 g of undersize fraction is added per 2 kg of test material, resulting in the addition overall of around 10 g of undersize fraction.

[0089] The conveying rate was set prior to the test run at 3 kg±0.5 kg per minute. The undersize fraction removed was collected and weighed. The experiments were performed five times per setting.

[0090] Test 1:

[0091] The conveying unit used comprised a screen 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 of r1=15 mm, r2=5 mm and α=15°. The separating edge of the separating element did not have any profile.

[0092] Test 2:

[0093] The conveying unit used comprised a screen plate with a rectangular opening edge (according to FIG. 9A and 4A) with t=r2 and a profile according to FIG. 5 with the values of r1=15 mm, r2=5 mm and α=15°. The separating edge of the separating element did not have any profile.

[0094] Test 3:

[0095] The conveying unit used comprised a screen plate with a convex opening edge (according to FIG. 9A and 4A) and a profile according to FIG. 6 with the values of r1=15 mm, r2=5 mm, e=30 mm and α=−15°. The separating edge of the separating element did not have any profile.

[0096] Test 4:

[0097] The conveying unit used comprised a screen plate with a convex opening edge (according to FIG. 9A and 4A) and a profile according to FIG. 5 with the values of rl=15 mm, r2=5 mm and α=15°. The separating edge of the separating element had the same profiling as the screen plate. The separating edge here is disposed relative to the profile of the screen plate such that the elevations of the separating edge point to the depressions of the screen plate.

[0098] Table 1 shows the average results in comparison to the results from WO 2018/108334 A1.

TABLE-US-00002 TABLE 1 Test Undersize Removal material Addition of removed rate Test [kg] undersize [g] [g] [%] WO2018/108334 10 10 8.3 83 (1) 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

[0099] Oversize Removal

[0100] The polysilicon material supplied in bags by the polysilicon manufacturer must not contain excessively sized chunks (oversize). The oversize may result in clogging and damage and must therefore be removed prior to use. The test was carried out using CS 2.

[0101] All of the oversize chunks were removed manually from the polysilicon material (CS 2) used for the test. The oversize material removed was retained and weighed.

[0102] 10 kg of the test material without oversize were applied to the conveying unit. Charging took place by a hopper. The container to be filled is positioned at the end of the screening section over the first conveying unit, allowing the test material to be conveyed into the container.

[0103] Upon filling of the conveying unit, 100 g of the removed oversize are added per 2 kg of test material, resulting in the overall addition of 500 g of oversize.

[0104] The conveying rate was set ahead of the test run at 15 kg±1 kg per minute. The oversize removed was collected and weighed. The tests were performed five times per setting.

[0105] Test 1:

[0106] The conveying unit used comprised a screen 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 of r1=10 mm, r2=25 mm, e=55 mm and α=45°, and with a separating element without a profile.

[0107] Test 2:

[0108] A separating device in twofold series was used, according to FIG. 9A, with each of the two screen plates having a convex opening edge with t=r1 (cf. FIG. 4A) and in each case a separating element without a profile. The profile of the screen plates was the product of the following values: r1=10 mm, r2=25 mm, e=55 mm, and α=45°.

[0109] Test 3:

[0110] A separating device in fourfold series was used, according to FIG. 9A, with each of the four screen plates having a convex opening edge with t=r1 (cf. FIG. 4A) and in each case a separating element without a profile. The profile of the screen plates was the product of the following values: r1=10 mm, r2=25 mm, e=55 mm, and α=45° (cf. FIG. 8).

[0111] Test 4:

[0112] The conveying unit used comprised a screen 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 of r1=10 mm, r2=25 mm, and α=45°, and with a separating element without a profile.

[0113] Table 2 shows the average results for the oversize removal:

TABLE-US-00003 TABLE 2 Test Oversize Removal material Addition of removed rates Test [kg] oversize [g] [g] [%] 1 10 500 380 76 2 10 500 440 88 3 10 500 500 100 4 10 500 300 60