METHOD AND DEVICE FOR THE PRODUCTION OF FLOUR AND / OR SEMOLINA

Description

[0001] The present invention relates to a method for producing a milled product consisting of flour and / or semolina and to a high-pressure roller mill according to the preambles of the independent claims.

[0002] Methods and devices for producing flour and / or semolina are known per se. For example, EP 0 335 925 B1 discloses a method and device for producing ground grain products such as flour, semolina, or semolina based on the multi-roll milling principle. The ground material is repeatedly roller milled and repeatedly sieved. In this process, the ground material is passed through double-roll milling stages, with the ground material being passed through at least two such milling stages and being passed between the individual stages without sieving. Following the double milling, it is then sifted through each stage.

[0003] However, such devices have the disadvantage that they require a great deal of equipment, which is expensive, due to the need for multiple grinding stages. Furthermore, the use of multiple grinding mills requires large buildings for the mill, which further increases the cost of constructing a mill.

[0004] From DE 1 757 093 A1 a roller mill for fine grinding of brittle material is known, whereby depending on the material feed and the contact pressure of the rollers required for comminution, a roller gap width is set which is larger than the grain size of the essential part of the feed material.

[0005] WO 2010 / 000811 A1 discloses a process for producing flour and / or semolina using a high-pressure roller mill with a variable gap. The gap is adjusted depending on the quantity and type of grain to be milled, as well as the pressure exerted on the rollers in the direction of the gap.

[0006] However, this previously known method and the corresponding device have the disadvantage that larger particles in the ground material are not reliably ground, and vibrations of the rollers can occur due to the material being processed, which often includes particles approximately the size of the roller gap. Furthermore, such high-pressure roller mills hardly introduce heat into the ground material, which is desirable in the production of certain types of flour.

[0007] It is therefore an object of the present invention to avoid the disadvantages of the known method, in particular to provide a method and apparatus with which flour can be reliably produced from a milling material containing finer and coarser milling material. A further object of the present invention is to provide a device and a method with which flour can be produced from a material in a cost-effective and energy-efficient manner, wherein, in particular, sufficient heat is also supplied to the flour during milling.

[0008] These objects are achieved by a method and a device according to the independent claims.

[0009] The inventive method for producing a milled product consisting of flour and / or semolina from a material selected from the group consisting of cereals, cocoa, sunflower seeds and rice or combinations thereof comprises the following steps: Providing a material bed roller mill comprising a feed opening and a discharge opening. The material bed roller mill comprises a first roller and a second roller, wherein at least one of the two rollers is movably mounted in a direction substantially perpendicular to the direction of rotation of the other of the two rollers for adjusting a grinding gap between the first and second rollers. The bed of material is provided and consists of particles with a size distribution, wherein a first portion of the bed of material consists of finer ground material and a second portion of the bed of material consists of coarser ground material.In a further step, which can also be carried out before the above step, the grinding gap is adjusted such that, when used as intended, the first and second rollers do not oscillate relative to one another, with the first portion of the bed containing finer ground material forming a packed particle bed in the grinding gap. Furthermore, the adjustment is carried out such that individual particles of the second portion of the bed containing coarser ground material are in contact with the first roller and the second roller of the material bed roller mill. A material bed is then created in the intake area between the rollers from an excess of material by means of a filled material chute or hopper, so that the first and second rollers can draw the material from the intake area into the grinding gap.The bulk material is then ground by exerting pressure on the first and second rollers in the direction of the grinding gap of the high-pressure roller mill to produce the ground product. Following grinding, the ground product is discharged through the discharge opening. Following grinding of the bulk material, the ground product is conveyed to a separation stage for separation into finer ground product and coarser ground product, and the ground product is then conveyed back to the feed opening.

[0010] For the purposes of this application, goods are understood to mean cereals, cocoa, sunflower seeds and rice or any combination thereof.

[0011] The cereals used in the process according to the invention are preferably bread wheat, durum wheat, maize and buckwheat or any combination thereof.

[0012] In particular, a pressure in the direction of the grinding gap on the rollers is preset and / or adjustable, for example in conjunction with the damping.

[0013] For the purposes of this application, a material bed roller mill is understood to be a roller mill in which a material bed is formed in the intake area between the rollers when the material bed roller mill can draw in an excess of material, e.g., via a filled material chute or hopper. For the finer material to be ground, the material bed comminution is based on a packed bed of particles in the grinding gap.

[0014] In the context of the present application, a direction of rotation is understood to be the vector perpendicular to the plane of rotation in the mathematical sense.

[0015] For the purposes of the present application, damping with respect to a deflection in the direction in which the roller is movably mounted is understood to mean damping for suppressing vibrations, as is possible, for example, with shock absorbers or adjustable hydraulic and / or pneumatic damping, with hydraulic damping preferably being used.

[0016] The use of such adjustable damping with respect to deflection is particularly advantageous when a force-controlled roller mill is used, in which, for example, mechanically preloaded springs or hydraulically coupled gas pressure accumulators are used to generate force and pressure is exerted on the rollers in the direction of the grinding gap. With such a design, a grinding gap forms between these rollers depending on the quantity and type of material to be ground in the grinding gap as well as the set pressure. Fluctuations in the composition of the material to be ground or a certain proportion of coarser material to be ground that is in contact with both rollers can, for example, cause the material bed roller mill to vibrate. These vibrations can then be reduced or even completely suppressed with the adjustable damping.

[0017] When using a fixed grinding gap, damping is preferably avoided, since the rollers are locked to each other and therefore do not vibrate with each other.

[0018] For the purposes of the present application, a size distribution of particles, in particular ground material, is understood to mean the distribution of the largest dimension of the particles of the ground material.

[0019] For the purposes of the present application, a grinding gap is understood to mean the gap between the two rollers and, in particular, the smallest roller spacing during operation of the material bed roller mill, whereby only the area of ​​the rollers which is in contact with the material to be ground during normal use is taken into account.

[0020] The method according to the invention has the advantage that the finer material to be ground is ground in a material bed, while the coarser material to be ground is also comminuted and, in particular, subjected to significant stress, so that the coarser material to be ground is already comminuted in a single pass. This largely avoids the use of multiple grinding stages, while also achieving the highest possible energy efficiency of the grinding process.

[0021] Preferably, the first roller and the second roller rotate at different speeds. In particular, the speed ratio is greater than 1.1:1 and, more particularly, greater than 2:1.

[0022] This has the advantage that the material to be ground is ground more efficiently, since greater shear forces occur in the material to be ground when operating at different speeds.

[0023] A further advantage is that the adjustment of the speed ratio (i.e., the rotational speed ratio) of the rollers is an additional parameter for optimizing the milling process for flour production, thus allowing the process to be more effectively optimized. Furthermore, a lower pressure can be used in the milling gap, as the grinding process is supported by the particularly strong shear forces resulting from the different roller speeds. This leads to lower pressures and thus better dissolvability for further separation of the milled product after milling.

[0024] For the purposes of the present application, the speed at which a roller rotates is understood to mean the speed of the roller surface in the tangential direction.

[0025] Particularly preferably, at least one of the two rollers is designed as a profile roller. The profile roller has, in particular, a recess in the roller surface, in particular substantially parallel to the longitudinal axis of the respective roller.

[0026] For the purposes of the present application, the roller surface is understood to be the surface which is radially furthest away from the longitudinal axis, whereby only the part which is in contact with the grinding material during operation and when used as intended is taken into account.

[0027] This has the advantage of allowing a smaller grinding gap to be set for reliable grinding of coarser material, which is subjected to greater stress and therefore ground to a greater degree. At least in the recessed sections, a material bed is formed between the rollers, in which even the smaller particles are reliably ground into a tightly packed bed of particles.

[0028] Most preferably, the profile of the profile roller is designed to be substantially self-cleaning, in particular at least during the rotation of the profile roller.

[0029] In the context of the present application, "self-cleaning" means that at least during rotation, i.e. during operation of the rollers, the ground material does not remain in the section-wise depressions, but reliably falls out of them and can be further processed in the downstream devices.

[0030] This self-cleaning design of the section-wise depressions has the advantage that the feed of grinding material into the material bed roller mill can be carried out reliably over the long term during operation, which is often not the case with non-self-cleaning section-wise depressions.

[0031] The self-cleaning design of the sectional depressions can be achieved by selecting the geometry of the sectional depressions and / or by selecting the appropriate surface roughness.

[0032] According to the invention, following the grinding of the material, the ground product is conveyed to a separation stage for separation into a finer ground product and a coarser ground product. In particular, the coarser ground product is conveyed back into the feed opening.

[0033] Such separation stages such as zigzag sifters, semolina purifiers, plan sifters, turbo sifters, spreader disc sifters or cross-flow sifters are known from the prior art, as described for example in WO 2010 / 000811 A2.

[0034] Zig-zag sifters, for example, separate the product to be separated into finer product and coarser product due to the different specific gravity and / or size of the particles in the product.

[0035] Plan sifters, for example, separate the product to be separated into finer product and coarser product by sieving, essentially based on the size of the particles in the product.

[0036] This separation of the ground product into finer and coarser fractions has the advantage that the respective fractions can be used for different purposes. Returning the coarser ground product to the feed opening of the high-pressure roller mill has the advantage that the plant can be operated in closed-loop mode, thus reducing the number of high-pressure roller mills or other grinding stages, leading to cost and energy savings.

[0037] Particularly preferably, a further high-pressure roller mill is arranged downstream of the separation stage for further grinding of the finer ground product.

[0038] This has the advantage that the additional high-pressure roller mill can have other process parameters, such as the speed of the rollers or the grinding gap, for optimal grinding of the finer ground product.

[0039] A further aspect is directed to a material-bed roller mill for carrying out a method as described above. This material-bed roller mill comprises a first roller and a second roller, wherein at least one of the two rollers is designed as a profile roller with at least one section-wise depression in the roller surface. This section-wise depression is formed, in particular, substantially parallel to the longitudinal axis of the profile roller. The section-wise depression is self-cleaning, at least during rotation of the profile roller.

[0040] As already explained above, the self-cleaning property of the sectional recess is achieved by the geometric design and / or by the surface properties of the sectional recess.

[0041] As explained above, this has the advantage that even when using a profile roller, the feed of grinding material into the grinding gap is permanently reliable during operation.

[0042] Preferably, the section-wise depression extends at least over the entire length of the profile roller, which is in contact with the grinding material during intended use. In other words, the section-wise depression is designed as a section-wise depression in the circumferential direction.

[0043] To adjust the grinding gap between the two rollers during operation, at least one of the two rollers is preferably mounted so as to be movable in a direction substantially perpendicular to the direction of rotation of one of the two rollers. Damping with respect to a deflection in the direction in which the roller is movably mounted is adjustable, and / or the grinding gap is fixed.

[0044] In the context of the present application, a fixed setting of the grinding gap means infinite damping, since with a fixed setting of the grinding gap, essentially no vibrations of the rollers relative to each other are possible when used as intended.

[0045] Particularly preferably, at least one section of the recess in the circumferential direction of the profile roller has an average width in the range of 0.5 mm to 20 mm. In particular, this average width is in the range of 2 mm to 10 mm, and more particularly in the range of 4 mm to 6 mm.

[0046] For the purposes of the present application, the mean width is understood to mean the mean value of the width along the longitudinal direction, i.e. the longest extent of the sectional depression.

[0047] Most preferably, the at least one section-wise depression of the profile roller has an average depth in the range of 0.3 mm to 10 mm in the radial direction of the roller. The depth is preferably in the range of 0.5 mm to 5 mm, and particularly preferably in the range of 0.7 mm to 1.8 mm.

[0048] For the purposes of the present application, the mean of a depth of the sectional depression is understood to be the mean value of the deepest point along the greatest extent of the sectional depression.

[0049] Preferably, the roller surface with the at least one section-wise depression of the profile roller has an average internal angle of 100° to 170° in a section between the roller surface and the surface of the depression that intersects the roller surface. Preferably, the roller surface forms an angle of 120° to 150° with the at least one section-wise depression, and particularly preferably, of 130° to 140°.

[0050] For the purposes of the present application, an interior angle is understood to be an angle facing the longitudinal axis of the profile roller on the inside of the roller surface in a sectional plane perpendicular to the longitudinal axis.

[0051] For the purposes of the present application, an average of an interior angle is understood to mean a mean value along a section between the roller surface and the section-wise depression.

[0052] This design as described above with regard to one of the parameters width, depth and internal angle or combinations thereof has the advantage that the section-wise recess is self-cleaning, at least during rotation of the profile roller, whereby operation can be reliable in the long term and, moreover, complex cleaning devices, which are costly, are not required.

[0053] Particularly preferably, the profile roller has at least two circumferentially spaced-apart, section-wise depressions. These circumferentially spaced-apart section-wise depressions have an average spacing in the range of 0.15 mm to 10 mm, preferably from 0.15 mm to 5 mm, and particularly preferably from 0.15 mm to 0.5 mm.

[0054] The mean distance between the sectional depressions is understood to be the mean distance along the longest extent of the sectional depression, whereby the distance is determined between the two mutually facing sides of the sectional depressions.

[0055] This design with at least two section-wise depressions has the advantage that the grinding of the coarser material to be ground can take place reliably on the roller surface and a material bed situation can be created in the depressions for the grinding of the finer material to be ground.

[0056] Most preferably, the sectioned depression of the profile roller has a flat surface section. This surface section is preferably arranged substantially perpendicular to the radius of the profile roller.

[0057] For the purposes of the present application, a flat surface section does not include curved or bent surface sections, although such a surface section with a usual surface roughness and / or damage that usually occurs during operation, such as scratches, is also considered to be flat.

[0058] This has the advantage of further improving the self-cleaning of the section-by-section depression.

[0059] Preferably, the first roller and / or the second roller of the material bed roller mill has a diameter in the range from 400 mm to 1000 mm and preferably from 600 mm to 800 mm.

[0060] This large diameter, in contrast to conventional roller mills, has the advantage of improving product feed.

[0061] A further aspect is directed to the use of a high-pressure roller mill as described above for producing flours and / or semolina from cereals, cocoa, sunflower seeds and rice or any combinations thereof according to the process described above.

[0062] This use has the advantages described above.

[0063] An additional aspect of the present invention is directed to a material bed roller mill having an inlet opening, a discharge opening, a first roller and a second roller, wherein at least one of the two rollers is mounted so as to be movable in a direction substantially perpendicular to the direction of rotation of one of the two rollers for adjusting a grinding gap between the two rollers, wherein the rollers can be locked relative to one another in such a way that, during intended use, essentially no vibrations of the rollers relative to one another are possible, wherein the material bed roller mill further comprises a material chute or hopper for generating a material bed in the intake area between the rollers, and wherein the discharge opening is connected to the inlet opening via a separation stage by means of a return arrangement.

[0064] The alternative material bed roller mill can in particular be combined with the embodiments disclosed for this material bed roller mill.

[0065] A further aspect relates to a surface segment for forming a particularly profiled roller surface of a roller. In particular, a roller for a material bed roller mill is formed as described above. The surface segment can be releasably fastened to a roller body to form the roller by means of a fastening means. In the circumferential direction of the roller body, the surface segment covers an angular range of 22° to 90°, preferably 30° to 45°, and particularly preferably 32° to 40°.

[0066] The modular design of the roller, consisting of a roller body and surface segments, has the advantage that the surface segments serve as wear parts that can be replaced cost-effectively and with little effort. Furthermore, the surface segments offer the advantage that, depending on the diameter of the roller body, the angular range covered by the surface segments can be selected, so that the surface segments are easy to handle and not too heavy due to their appropriate size.

[0067] In particular, the roller comprising surface segments and roller body can be used as a first roller and / or second roller in a high-pressure roller mill as described above.

[0068] Preferably, the surface segment is formed in cross-section substantially in the shape of a ring segment.

[0069] In this case, the cross-section through a surface segment is understood to mean that the cut is made perpendicular to the longitudinal axis of the roller when the surface segment is used as intended.

[0070] Ring segment-shaped surface segments have the advantage that less material is used to manufacture the surface segments, which makes the surface segments more cost-effective and lighter, which facilitates handling, especially during assembly or disassembly.

[0071] Particularly preferably, the surface segment is operatively connectable to a torque transmission device such that a torque can be transmitted from the roller body to the surface segment.

[0072] For the purposes of this application, a "torque transmission device" is understood to mean a device such that the torque exerted on the roller body during operation for driving the roller can be reliably transmitted to the surface segments, so that the surface segments are not inadvertently detached from the roller body during operation due to the forces occurring during operation. Typically, the surface segments are attached to the roller body with fastening means in the form of screws. However, the screws may not be sufficiently stable, so that surface segments can become detached when large shear forces occur during operation, which should be avoided. In such a case, an additional torque transmission device leads to more reliable and thus more cost-effective operation.

[0073] Most preferably, the surface segment has a surface segment groove on the side facing the roller body for engagement by the torque transmission device.

[0074] This has the advantage that the engagement of the torque transmission device in the surface segment groove enables a reliable transmission of the torque from the roller body to the surface segment, since the area for the operative connection between the roller body and the surface segment for the torque transmission is increased, which avoids overloads and therefore makes operation more reliable.

[0075] Particularly preferably, the surface segment groove runs substantially parallel to the longitudinal axis of the roller when used as intended.

[0076] This has the advantage of further reducing point peak loads on the surface segment, making operation even more reliable.

[0077] An additional aspect relates to a set comprising surface segments as described above for forming a closed roller surface of a roller. The set comprises 4 to 16, preferably 8 to 12, particularly preferably 9 to 11, and most particularly preferably 10 surface segments.

[0078] For the purposes of this application, the formation of a "closed" roller surface is understood to mean a surface that is essentially circumferentially uninterrupted. In other words, in the area of ​​the roller that comes into contact with the material during intended use, the roller body is completely covered by surface segments.

[0079] The set preferably comprises a torque transmission device between the roller body and the surface segment. In particular, the set comprises the same number of torque transmission devices as surface segments. Furthermore, the torque transmission device is designed as a rod for engaging in a surface segment groove of the surface segment, wherein the rod is preferably angular in cross-section, at least in sections, and in particular wedge-shaped or rectangular.

[0080] A further aspect relates to a roller comprising at least one surface segment as described above and a roller body. The surface segment is releasably attached to the roller body by means of a fastening means. The roller comprises a torque transmission device for transmitting torque from the roller body to the surface segment.

[0081] Preferably, the roller body has a roller groove in which the torque transmission device can be releasably fastened.

[0082] This has the advantage of reliably transmitting the torque from the roller body to the torque transmission device while avoiding the generation of point peak loads, which makes the operation of the roller more reliable.

[0083] Particularly preferably, the torque transmission device is designed as a rod for simultaneous engagement in the roller groove and a surface segment groove of the surface segment.

[0084] Most preferably, the rod is angular in cross-section at least in sections and is preferably wedge-shaped or rectangular.

[0085] This has the advantage of particularly reliable transmission of the torque from the roller body to the rod and from the rod to the surface segment, in whose surface segment groove the rod engages.

[0086] The term "angular" in the context of the present application means that the bar has at least one right angle, one acute angle or one obtuse angle or any combination thereof in its cross-section.

[0087] Preferably, the roller body comprises a balancing device.

[0088] This has the advantage that an asymmetrical weight distribution relative to the longitudinal axis of the roller body, around which the roller rotates during operation, can lead to high bearing loads or vibrations, which can be compensated for using the balancing device. This makes operation more reliable with less wear, thus reducing costs.

[0089] Particularly preferably, the balancing device is designed as a recess arranged at least partially in the roller body. The recess is in particular designed as a bore.

[0090] The recess is arranged essentially parallel to the longitudinal axis of the roller body, and at least one balancing weight can be inserted into the recess. In particular, the balancing weight is made of lead.

[0091] In particular, the roller has recesses spaced apart from one another in the circumferential direction, such that corresponding balancing weights can be inserted into the respective recesses for balancing the roller.

[0092] For a better understanding, further features and advantages of the invention are explained in more detail below using exemplary embodiments, without limiting the invention to the exemplary embodiments. They show: Figure 1: Schematic side view of a material-bed roller mill according to the invention with bulk material; Figure 2: Schematic top view of an alternative material-bed roller mill according to the invention with bulk material; Figure 3: Schematic representation of a profile of a profile roller; Figure 4: Alternative profile of a profile roller in a schematic representation; Figure 5: Schematic representation of a material-bed roller mill according to the invention with a separation stage and product feed; Figure 6: Alternative arrangement of a material-bed roller mill according to the invention with a dissolver, separation stage, and product return; Figure 7: Flow diagram of a method according to the invention using two material-bed roller mills; Figure 8: Schematic representation of an enlarged section of a material-bed roller mill according to the invention with two profile rollers and bulk material; Figure 9: Schematic side view of an alternative material-bed roller mill according to the invention with a level sensor in the feed hopper;Figure 10: Arrangement of a material-bed roller mill according to the invention with multiple separation stages. Figure 11: Perspective view of a roller consisting of a roller body and surface segments in a partially exploded view; Figure 12: Section along the longitudinal axis through a roller according to; Figure 11 ; Figure 13: Front view parallel to the longitudinal axis of the roller according to Figure 11 ; Figure 14: Sectional view of a roller according to Figure 12 along the section plane B; Figure 15: Perspective view of a surface segment with visible roller surface; Figure 16: Perspective view of the surface segment according to Figure 15 from underneath.

[0093] In Figure 1 A material bed roller mill 9 is shown in a schematic side view. A bed 6 comprises finer ground material 5 and coarser ground material 7, which is drawn into the grinding gap d by the rotation in direction r of the two rollers 10 and 11.

[0094] The roller 10 is movably mounted in direction s, dh perpendicular to the direction of rotation, whereby a grinding gap d can be adjusted. The rollers 10 and 11 both have a diameter w of 600 mm and are mounted for rotation in the direction r by means of bearings 20. The rollers have a smooth roller surface 19. To prevent vibrations, the bearing 20 has a damping device 26, which is designed as a pneumatic damper.

[0095] In the present case, the grinding gap d is variable depending on the drawn-in bulk material 6, with a pressure acting in the direction of the grinding gap d by the rollers 10 and 11 being adjusted such that the finer grinding material 5 is ground by means of a packed bed of particles in the grinding gap d, and the coarser grinding material 7 is comminuted in the grinding gap d by direct contact with the rollers 10 and 11. The material bed roller mill 9 has the damping device 26, known per se to those skilled in the art, in order to prevent the occurrence of vibrations between the rollers.

[0096] Roller 10 has a peripheral speed of 1 m / s, and roller 11 has a peripheral speed of 1.5 m / s. The speed ratio between rollers 10 and 11 is therefore 1.5:1.

[0097] During operation, the rollers rotate in the direction r, and the bulk material 6, including finer ground material 5 and coarser ground material 7, is drawn into the material bed roller mill 9. Between the two rollers in the grinding gap d, which is set here to a value of 1 mm, a packed bed of particles is formed with regard to the finer ground material, whereby the finer ground material is ground.

[0098] The coarser ground material 7 touches the first roller 10 and the second roller 11 at least in the area of ​​the grinding gap d, so that this coarser ground material is greatly crushed.

[0099] After grinding, the grinding product 17, which may be flour, for example, is discharged from the high-pressure roller mill.

[0100] In Figure 2 is a schematic representation of a plan view of a material bed roller mill 9 essentially according to Figure 1 shown.

[0101] From here on and in the following, like reference symbols refer to like components in the figures.

[0102] In contrast to the high-pressure roller mill 9 according to Figure 1 Here both rollers are mounted movably in the direction s. During grinding operation, the rollers are rotatable about the longitudinal axis 21 by means of the bearings not shown here, both of which comprise a damping device designed as a shock absorber, not shown here.

[0103] In contrast to Figure 1 Here, the grinding gap d is set to a fixed value of 1 mm during operation. In this case, grain 1 is milled as the coarser material, and semolina 3 is milled as the finer material.

[0104] In this case, roller 10 has a peripheral speed of 0.8 m / s, and roller 11 has a peripheral speed of 2.4 m / s. This results in a speed ratio of 3:1.

[0105] Another difference to the Figure 1is that the roller 10 in the present case is designed as a profile roller with a profile not shown here.

[0106] In Figure 3 A section of a roller profile is shown in a schematic representation.

[0107] The profile has two fully illustrated, sectioned depressions 18 with an average depth t of 1.2 mm, with the sectioned depressions 18 having a flat surface section 27 perpendicular to the radius of the profiled roller. The flat surface section 27 thus forms an angle p = 90° with the radius of the roller, indicated by a dashed line. The width b of the depression 18 is 4.3 mm, and the distance k between the sectioned depressions on the roller surface 19 is 0.2 mm. The interior angle a is 135°.

[0108] On both sides of the section-wise depressions 18, as shown in Figure 3, the roller has further section-wise depressions not shown here.

[0109] In Figure 4 An alternative profile of a profile roller is shown as a section. The profile roller has a recess 18 with a width b of 7 mm and a depth t of 1.8 mm. The section-wise recess 18 is, in contrast to Figure 3 not symmetrical and has an angle a of 120° on one side in the circumferential direction and an angle a' of 140° on the other side in the circumferential direction.

[0110] In Figure 5 is shown schematically a plant 24 comprising a material bed roller mill 9 with two rollers 10 and 11. The rollers 10 and 11, which are both profile rollers with a profile according to Figure 3are designed to a fixed grinding gap d of 0.1 mm. The high-pressure roller mill 9 has a feed opening 15 for the bulk material 6, here rice, and a discharge opening 16 for the ground product 17. The ground product 17 is conveyed by means of a conveying arrangement 25 into a separation stage 14, which is designed here as a zigzag sifter. In the zigzag sifter, the ground product 17 is separated into finer ground product 12 and coarser ground product 13. This separation occurs essentially on the basis of the physical properties of the particles, such as the size, suspension properties and specific gravity or combinations of these properties. By means of a return arrangement 23, the coarser ground product 13 is conveyed back into the feed opening 15 of the high-pressure roller mill 9. Finer ground product 12 is discharged from the arrangement 24 here as flour.

[0111] In Figure 6A further arrangement 24 according to the invention is shown, which has a plan sifter as the separation stage 14 and, additionally, a dissolver 22 between the material bed roller mill 9 and the separation stage 14. The dissolver 22 is designed as an impact dissolver, as is known to the person skilled in the art, for example, from WO 2010 / 000811 A1. Cocoa is used as the bulk material 6 here.

[0112] In Figure 7 A flow diagram of a process according to the invention is shown. Bulk material 6, The resulting product, in this case sunflower seeds, is fed to a high-pressure roller mill 9 and ground therein. The ground product is fed to a separation stage 14, where it is separated into a finer ground product 12 and a coarser ground product 13. The coarser ground product 13 is returned to the high-pressure roller mill 9.

[0113] In this case, the finer ground product 12 is fed to another high-pressure roller mill 9, which is followed by another separation stage 14. In this stage, the ground product from the other high-pressure roller mill 9 is again separated into finer ground product 12 and coarser ground product 13, with the coarser ground product 13 being returned to the other high-pressure roller mill 9. The finer ground product 12 can now be further processed as flour.

[0114] In Figure 8 A schematic representation of a material bed roller mill 9 is shown. The first roller 10 and the second roller 11 are each provided with profiles according to Figure 3 The rollers rotate in the direction of rotation r, with roller 10 having a peripheral speed of 3 m / s and roller 11 having a peripheral speed of 0.5 m / s, ie the rollers have a speed ratio of 6:1.

[0115] The grinding gap d is fixed at 0.8 mm, with no damping device provided. The distance k is 0.3 mm.

[0116] The bulk material 6 includes semolina as finer ground material and shell parts 4 as well as grain not shown here as coarser ground material, which as Figure 1 described is ground.

[0117] In Figure 9 is a high-pressure roller mill 9 according to Figure 1 shown. Ground material 8 is located in a feed hopper 31, forming a bed. The feed of ground material 8 into the feed hopper 31 is not shown here.

[0118] The feed hopper 31 comprises a level sensor 30 for measuring the level of grinding material 8 in the feed hopper 31. Based on the measured level of grinding material 8 in the feed hopper 31, for example, the peripheral speed of at least one of the rollers 10 or 11 can be adjusted.

[0119] If, for example, the level of ground material 8 falls below a predetermined value, the level of ground material 8 in the feed hopper 31 can be increased by reducing the peripheral speed of at least one of the rollers 10 or 11, since this measure reduces the throughput through the material bed roller mill 9, while ground material 8 continues to be fed into the feed hopper 31.

[0120] By increasing the peripheral speed of at least one of the rollers 10 or 11, the level of grinding material 8 in the feed hopper 31 can be reduced, since this measure increases the throughput through the material bed roller mill 9, while grinding material 8 continues to be fed into the feed hopper 31.

[0121] It is also possible, based on the measurement with the level sensor 30, to control the feed of grinding material 8 into the feed hopper 31 in order to increase or decrease the level in the feed hopper 31 at a constant throughput through the material bed roller mill 9.

[0122] A difference to Figure 1 is that the rollers 10 and 11 are designed as profile rollers with a profile not shown here.

[0123] In Figure 10 a further alternative arrangement 24 according to the invention is shown, which has a plan sifter and a zigzag sifter as separation stages 14.

[0124] Above a high-pressure roller mill 9 is a hopper 6 containing a mixture of rice and grain. The material is ground in the high-pressure roller mill 9 into a ground product, which is then conveyed to the plansifter.

[0125] In the plansifter, the milled product is separated into a finer milled product 12, a medium milled product 29, and a coarser milled product 13. In addition, a further fraction is discharged from the plansifter as flour 2. The medium milled product 29 is conveyed to a further separation stage 14, which is designed here as a zigzag sifter. The medium milled product 29 is separated in the zigzag sifter into finer milled product and coarser milled product 13, with the zigzag sifter being adjusted so that the finer milled product essentially contains bran 28. The mass fraction of bran 28 in the milled product is in the range of 1 wt.% to 10 wt.% and in particular in the range of 3 wt.% to 5 wt.%, based on the milled product.

[0126] The finer ground product 12 and the coarser ground product 13 from the plan sifter as well as the coarser ground product 13 from the zigzag sifter are conveyed back into the material bed roller mill 9 by means of the return arrangement 23.

[0127] In Figure 11 A perspective view with a partial exploded view shows a roller 32 consisting of a roller body 42 and several surface segments 33. On the side facing away from the roller body 42, the surface segments 33 have a roller surface 19.

[0128] The roller 32 has a balancing device 36 formed by a plurality of bores substantially parallel to the longitudinal axis of the roller 32. Lead balancing weights (not shown here) can be inserted into the bores, and after the balancing weights have been inserted, the bores can be closed by means of closure caps 41.

[0129] The roller body 42 has a roller groove 37 into which a torque transmission device 34, designed as a rod, can be inserted. The rod can be releasably secured in the roller groove 37 by means of a transmission fastening device 40 designed as a screw. The rod is designed such that, after being inserted into the roller groove 37, it protrudes radially from the roller groove 37.

[0130] The surface segments 33 have a surface segment groove 38 on the side facing the roller body 42, into which the rod, i.e., the torque transmission device 34, can engage. Additionally, fastening means 35 designed as screws are provided, by means of which the surface segment can be releasably connected to the roller body 42. In the assembled state, the rod engages in the surface segment groove 38, thereby ensuring reliable torque transmission during operation from the roller body 42 to the surface segment 33.

[0131] In Figure 12 the roller 32 is according to Figure 11 shown in a sectional view parallel to the longitudinal axis. A segment length o of the surface segments 33 is approximately 400 mm.

[0132] In Figure 13 is a front view parallel to the longitudinal axis 21 of the roller 32 according to Figure 11 shown.

[0133] The roller 32 comprises 10 surface segments 33. The torque transmission device 34, designed as a rod, is accommodated in the area formed by the surface segment groove and roller groove.

[0134] In Figure 14 is in a sectional view parallel to the axis B according to Figure 12 the roller 32 is shown.

[0135] The roller 32 comprises 10 surface segments 33, each covering an angular range m of 36°. The surface segments 33 are detachably connected to the roller body 42, with a rectangular rod serving as a torque transmission device 34 being accommodated in the area formed by the roller groove 37 and surface segment groove 38.

[0136] Figure 15 shows a perspective view of a surface segment 33 with roller surface 19. In Figure 16 is the surface segment 33 according to Figure 15 shown in a further perspective from below, in which the surface segment groove 38 is visible.

Claims

1. A method of manufacturing a milled product (1) consisting of flour (2) and / or semolina (3) from a material (6) selected from the group consisting of cereals, cocoa, sunflower seeds and rice or combinations thereof, comprising the following steps: - Providing a high-pressure roller mill (9) comprising a feed opening (15) and an outlet opening (16), - a first roller (10) and a second roller (11), wherein at least one of the two rollers (10, 11) is mounted movably in a direction (s) substantially perpendicular to the direction of rotation of the other of the two rollers (10, 11), and so that the milling gap (d) between the first and second rollers (10, 11) can be adjusted, - Providing a bulk material (6), which consists of particles with a size distribution, wherein a first partial amount of the bulk material (6) consists of finer material to be milled (5) and a second partial amount of the bulk material (6) consists of coarser material to be milled (7); - setting the milling gap (d) in such a way that, when used as intended, the first and second rollers (10, 11) do not oscillate relative to one another, wherein: the first partial amount of the bulk material (6) containing finer material to be milled (5) forms a packed particle bed in the milling gap (d), and individual particles of the second partial amount of the bulk material (6) containing coarser material to be milled (7) are in contact with the first roller (10) and the second roller (11) of the high-pressure roller mill (9); - creating a material bed in the feed area between the rollers from an oversupply of material by means of a filled material chute or hopper (31), so that the first and second rollers (10, 11) can draw the material from the feed area into the milling gap (d); - milling the bulk material (6) by exerting a pressure on the first and second rollers (10, 11) in the direction of the milling gap (d) of the high-pressure roller mill (9) to produce the milled product (17), so that particles of the finer material to be milled (5) are milled by means of a packed particle bed in the milling gap (d), while particles of the coarser material to be milled (7) are comminuted in the milling gap (d) by direct contact with the rollers (10, 11); and - discharging the ground product (17) through the outlet opening (16), wherein, following the grinding of the bulk material (2), the milling product (17) is conveyed into a separation stage (14) for separation into finer milling product (12) and coarser milling product (13), and wherein milling product (12; 13) is subsequently conveyed back into the feed opening (15).

2. Method according to claim 1, characterized in that the first roller (10) and the second roller (11) rotate at different speeds, preferably at a speed ratio of greater than 1.1 : 1, particularly preferably of greater than 2 : 1.

3. Method according to one of the preceding claims, characterized in that a further high-pressure roller mill (9) is provided downstream of the separation stage (14) for further milling of the finer grinding product (12).

4. A high-pressure roller mill (9) for producing flour (2) and / or semolina (3) from material, in particular cereals (1), cocoa, sunflower seeds and rice or any combinations thereof, comprising a feed opening (15), an outlet opening (16), a first roller (10) and a second roller (11), at least one of the two rollers (10, 11) being mounted movably in a direction (s) substantially perpendicular to the direction of rotation of one of the two rollers (10, 11) in order to set a milling gap (d) between the two rollers (10, 11), characterized in that the rollers (10, 11) can be locked relative to one another in such a way that, during intended use, essentially no oscillations of the rollers (10, 11) relative to one another are possible, the high-pressure roller mill (9) further comprising a material shaft or hopper (31) for producing a material bed in the feed region between the rollers (10, 11), and the outelt opening (16) being connected to the feed opening (15) via a separation stage (14) by means of a return arrangement (23).

5. High-pressure roller mill (9) according to claim 4, characterized in that the high-pressure roller mill (9) has no damping device for damping with respect to a deflection in the direction (s) of the roller.

6. High-pressure roller mill (9) according to one of claims 4 to 5, characterized in that at least one of the two rollers (10, 11) is designed as a profiled roller with at least one sectional depression (18) in the roller surface (19), in particular essentially parallel to the longitudinal axis of the profiled roller, and in that the sectional depression (18) is self-cleaning at least when the profiled roller rotates.

7. High-pressure roller mill (9) according to one of claims 5 to 6, characterized in that the at least one sectional depression (18) has an average width (b) in the range from 0.5 mm to 20 mm, preferably from 2 mm to 10 mm and particularly preferably from 4 mm to 6 mm in the circumferential direction of the profiled roller.

8. High-pressure roller mill (9) according to one of claims 4 to 7, characterized in that the at least one sectional depression (18) of the profiled roller has an average depth (t) in the radial direction in the range from 0.3 mm to 10 mm, preferably from 0.5 mm to 5 mm and particularly preferably from 0.7 mm to 1.8 mm.

9. High-pressure roller mill (9) according to one of claims 4 to 8, characterized in that the roller surface (19) with the at least one sectional depression (18) of the profiled roller along an intersection between the roller surface and the area of the depression intersecting the roller surface encloses on average an internal angle (a) of 100° to 170°, preferably of 120° to 150° and particularly preferably of 130° to 140°.

10. High-pressure roller mill (9) according to any one of claims 4 to 9, characterized in that the profiled roller has at least two recesses (18) spaced apart from each other in the circumferential direction and having an average spacing (k) in the circumferential direction in the range from 0.15 mm to 10 mm, preferably from 0.15 mm to 5 mm and particularly preferably from 0.15 mm to 0.5 mm.

11. High-pressure roller mill (9) according to any one of claims 4 to 10, characterized in that the sectional depression (18) of the profiled roller has a flat surface section (27), in particular substantially perpendicular to the radius of the profiled roller.

12. High-pressure roller mill (9) according to any one of claims 4 to 11, characterized in that the first roller (10) and / or the second roller (11) have a diameter (w) in the range from 400 mm to 1000 mm and preferably from 600 mm to 800 mm.

13. High-pressure roller mill (9) according to one of claims 4 to 11, characterized in that at least one of the two rollers (10, 11, 32) comprises a roller body (42) and at least one surface segment (33) which is substantially annular in particular in cross-section; the at least one surface segment (33) is for forming a particularly profiled roller surface (19) of the at least one roller (10, 11, 32) and covers an angular range (m) of 22° to 90°, preferably of 30° to 45° and particularly preferably of 32° to 40° in the circumferential direction of the roller body (42); the at least one surface segment (33) is detachably fastened to the roller body (42) by means of a fastening means (35); the roller (32) comprises a torque transmission device (34) for transmitting torque from the roller body (42) to the surface segment (33); and the roller body (42) comprises a balancing device (36), wherein the balancing device (36) is designed in particular as a recess, in particular a bore, arranged at least in sections in the roller body (42), wherein the recess is arranged substantially parallel to the longitudinal axis (21) of the roller body (42), and wherein at least one balancing weight can be inserted into the recess.