EP2540396A1 - Method and device for producing flour and/or semolina - Google Patents

Abstract

The method involves movably mounting rollers (10, 11) e.g. profile rollers, for adjusting a grinding gap (d) between the rollers. The grinding gap and/or attenuation are adjusted such that a subset of a fine ground product (5) forms a packed particle bulk material (6) in the grinding gap. Particles of a subset of a coarse ground product (7) are in contact with the rollers of a product bed roller mill (9). The bulk material is ground into a ground product (17) in the product bed roller mill. The ground product is discharged through a discharge aperture. The attenuation is hydraulic and/or pneumatic attenuation.

Description

The present invention relates to a process for the production of flour and / or semolina and to a high-bed roller mill and the use thereof according to the preambles of the independent claims.

Methods and apparatus for making flour and / or semolina are known per se. For example, is from the EP 0 335 925 B1 a method and an apparatus for producing milled cereal products such. As flour, semolina or haze known on the principle of high milling. The millbase is often roll-milled and repeatedly sieved. In this case, a material to be ground is passed over double-roller grinding stages, wherein the material to be ground is guided over at least two such milling stages and is performed without screening between the individual stages and is then sighted at the Doppelvermahlung respectively.

However, such devices have the disadvantage that the expenditure on equipment is very great due to the necessity of several grinding stages, which is costly. In addition, the use of multiple grinders makes large buildings necessary for the mill, further increasing the cost of constructing a mill.

From the WO 2010/000811 A1 For example, there is known a method of making flour and / or semolina using a variable bed, soft bed roller mill. The nip sets depending on the amount and the type of grain to be ground and the set pressure exerted on the rollers in the direction of the nip, a.

However, this known method and the corresponding device have the disadvantage that larger particles are not reliably ground in the material to be ground and it may come to vibrations of the rollers due to the processed material to be processed, which often also includes particles in the size of the nip. In addition, heat is hardly added to the material to be ground in such high-bed roller mills, which is desirable in the production of certain types of flour, however.

It is therefore an object of the present invention to avoid the disadvantages of the known, in particular to provide a method and an apparatus with which flour from a regrind containing finer and coarser millbase can be reliably produced. A further object of the present invention is also to provide a device and a method by which flour from Good can be produced inexpensively and energetically favorable, wherein in particular also sufficient heat is supplied into the flour during grinding.

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

The inventive method for producing flour and / or semolina from good, in particular cereals, cocoa, sunflower seeds and rice or any combination thereof, thereby comprises the following steps: Good is fed from a bed in a feed opening of a bed of high-quality rollers. The good bed roller mill comprises a first roller and a second roller, wherein at least one of the two rollers is movably supported in a direction substantially perpendicular to the direction of rotation of one of the two rollers for setting a grinding gap between the two rollers. In addition, a damping is adjustable with respect to a deflection in the direction in which the roller is movably mounted is, and / or the grinding gap is fixed. The bed consists of particles with a size distribution and comprises in particular one of the following types or mixtures thereof: good, semolina, shell parts. In a further step, which can also be carried out before the above step, the grinding gap is set in particular fixed and / or the damping is adjusted so that a first subset of the bed containing finer millbase forms a packed particle bed in the grinding gap. In addition, the adjustment is made such that individual particles of a second subset of the bed containing coarser millbase are in contact with the first roller and the second roller of the good bed roller mill. Subsequently, a grinding of the bulk material in the good bed roller mill in ground product. After grinding, the milling product is discharged through a discharge opening.

For the purposes of the present application, cereals, cocoa, sunflower seeds and rice or any combination thereof are understood to be good.

Bread wheat, durum wheat, corn and buckwheat or any combinations thereof are preferably used as cereals in the process according to the invention.

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.

For the purposes of the present application, a good-bed roller mill is understood to mean such a roller mill, in which a crop bed is formed in the catchment area between the rollers, when the good-bed roller mill consists of an oversupply of good, e.g. B. by means of a filled material shaft or funnel, this feed can. The comminution is based for the finer millbase on a packed particle bed in the grinding gap. In the sense of the present application, a direction of rotation is understood to be the vector perpendicular to the plane of rotation in the mathematical sense.

Under an attenuation with respect to a deflection in the direction in which the roller is movably mounted, in the sense of the present Annunciation an attenuation for the suppression of vibrations understood, as is possible for example with shock absorbers or controllable hydraulic and / or pneumatic damping, preferably hydraulic dampers are used.

The use of such an adjustable damping with respect to the deflection is particularly advantageous when a force-controlled roller mill is used in which, for example, mechanically biased springs or hydraulically coupled gas pressure accumulators are used to generate force and a pressure is exerted on the rollers in the direction of the refining gap. In such an embodiment, yes, a grinding gap between these rollers forms depending on the amount and type of material to be ground in the grinding gap and the set pressure. Due to variations in the composition of the ground material or by a certain proportion of coarser material to be ground, which is in contact with both rolls, the good bed roller mill can be vibrated, for example. These vibrations can now be reduced or even completely suppressed with the adjustable damping.

When using a fixed grinding gap is preferably dispensed with a damping, since here the rollers to each other locked and thus can not be vibrated.

For the purposes of the present application, a size distribution of particles, in particular regrind, is understood to mean the distribution of the largest dimension of the particles of the millbase.

For the purposes of the present application, a grinding gap is understood to mean the gap between the two rolls and, in particular, the smallest roll spacing during operation of the good-bed roll mill, whereby only the area of the rolls is taken into account which, during normal use, is in contact with the ground material during operation.

The method according to the invention now has the advantage that the finer millbase is ground in a good bed situation and, moreover, the coarser millbase is likewise comminuted and, in particular, highly stressed, so that the coarser millbase is already heavily comminuted by means of a pass. As a result, the use of multiple grinding stages is largely avoided, in particular, the highest possible energy efficiency of the grinding is achieved.

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.

This has the advantage that the ground material is ground more efficiently, since in particular larger shear forces occur in the ground material when operating at different speeds.

Another advantage is that the setting quantity of the speed ratio, i. the speed ratio, the rollers is an additional parameter to optimize the milling process for producing flour and thus the process can be better optimized. In addition, a smaller pressure in the grinding gap can be used, since the grinding is supported by the particular greater shear forces due to the different speeds of the rollers. This leads to smaller pressures and thus to better solubility for further separation of the meal product after milling.

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.

Particularly preferably, at least one of the two rollers is designed as a profile roller. The profiled roller in particular has a section-wise depression in the roller surface, in particular substantially parallel to the longitudinal axis of the respective roller.

For the purposes of the present application, the surface of the roll is understood to mean the surface which is located radially furthest apart from the longitudinal axis, whereby only the part in contact with the material to be ground in use is taken into account when used as intended.

This has the advantage that a small grinding gap is adjustable for reliable grinding of the coarser ground material, which is thereby more stressed and therefore more ground. At least in the section-wise recesses forms between the rollers a Gutbetttsituation, in which the smaller Particles are reliably ground in a packed particle bed.

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

By "self-cleaning" in the sense of the present application is meant that at least during the rotation, i. H. In the operation of the rollers regrind does not remain in the section-wise depressions, but reliably falls out of these and can be further processed in the downstream devices.

This self-cleaning embodiment of the recesses in sections has the advantage that the collection of ground material in the bed of high-quality roller can be done permanently reliable in operation, which is often not the case with non-self-cleaning sections.

The self-cleaning configuration of the section-wise depressions can be achieved by selecting the geometry of the section-wise depressions and / or by selecting the corresponding surface roughness.

Preferably, after the grinding of the ground material, the ground product is conveyed to a separation stage for separation into finer ground product and coarser ground product. In particular, the coarser ground product is conveyed back into the feed opening.

Such separation stages such as zig-zag sifter, Griessputzmaschinen, Plansichter, turbo-heaters, hopper separators or Querstromsichter are from the prior art known, such as in the WO 2010/000811 A2 described.

For example, zig-zag separators separate the product into a finer product and a coarser product due to the different specific gravity and / or the size of the particles in the product.

For example, plansifters separate product to be separated into finer product and coarser product by sieving, essentially due to the size of the particles in the product.

This separation of the ground product into finer and coarser ground product has the advantage that the respective fractions can be fed to different uses. The return of the coarser millbase into the feed opening of the good bed roller mill has the advantage that the system can be operated in circulation operation and thus the number of good bed roller mills or other grinding stages can be reduced, resulting in cost savings and energy savings.

Particularly preferably, the separation stage is followed by another good-bed roller mill for further grinding of the finer meal product.

This has the advantage that the further good-bed roller mill can have other process parameters such as, for example, the speed of the rollers or of the grinding gap for optimal grinding of the finer grinding product.

Another aspect of the present invention is directed to a good bed roller mill, particularly for performing a method as described above. This good bed roller mill includes a first roller and a second roller, wherein at least one of the two rollers is formed as a profile roller with at least one section-wise depression in the roller surface. This section-wise recess 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.

As already explained above, the self-cleaning property of the section-wise depression is achieved by the geometric design and / or by the surface properties of the section-wise depression.

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

Preferably, the section-wise depression extends at least over the entire length of the profile roller, which is in contact with the material to be ground in the intended use. In other words, the section-wise depression in the circumferential direction is formed as a section-wise depression.

During operation, at least one of the two rollers is preferably movably mounted in a direction essentially perpendicular to the direction of rotation of one of the two rollers in order to set a grinding gap between the two rollers. An attenuation with respect to a deflection in the direction in which the roller is movably mounted, is adjustable and / or the grinding gap is fixed.

For the purposes of the present application, a fixed setting of the grinding gap means an infinite damping, as at fixed set Mahlspalt when used as intended substantially no vibrations of the rolls are possible to each other.

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

In the context of the present application, the mean of the width is the mean value of the width along the longitudinal direction, i. H. the longest extent of the sectional depression, understood.

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

For the purposes of the present application, the mean of a depth of the section-wise depression is understood to be the mean value of the lowest point along the greatest extent of the sectional depression.

Preferably, the roller surface with the at least one section-wise depression of the profiled roller in a section between the roller surface and the surface of the recess which intersects the roller surface has on average an internal angle of 100 ° to 170 °. The roll surface with the at least one section-wise depression preferably encloses an angle of 120 ° to 150 ° and particularly preferably of 130 ° to 140 °.

For the purposes of the present application, an internal angle means an angle on the inside of the roller surface facing the longitudinal axis of the profiled roller, in a sectional plane perpendicular to the longitudinal axis.

For the purposes of the present application, an average of an internal angle means an average value along a section between the roller surface and the section-wise depression.

This embodiment as described above with regard to one of the parameters width, depth and internal angle or combinations thereof has the advantage that the sectional recess at least during rotation of the profile roller is self-cleaning, whereby the operation can be done in the long term reliable and also expensive cleaning devices that are costly , not needed.

Particularly preferably, the profile roller on at least two circumferentially spaced apart, partially depressions. These section-wise recesses spaced apart in the circumferential direction have a mean distance 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.

The average distance between the section-wise depressions means the average distance along the longest extension of the section-wise depression, the distance between the two mutually facing sides of the section-wise depressions being determined.

This embodiment with at least two sections-wise depressions has the advantage that the grinding of the coarser Grindings reliably done on the roll surface and a Gutbetttsituation in the wells may arise for grinding the finer meal.

Most preferably, the section-wise depression of the profile roller on a flat surface portion. Preferably, this surface portion is arranged substantially perpendicular to the radius of the profile roller.

For the purposes of the present application, a plane surface section does not mean curved or curved surface sections, but such a surface section with a usual surface roughness and / or damage usually occurring during operation, such as scratches, is also considered to be flat.

This has the advantage of further improving the self-cleaning of the section-wise depression.

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

This large diameter, in contrast to conventional roll mills, has the advantage that the product feed is improved.

A further aspect of the present invention is directed to the use of a high bed roller mill as described above for the production of flours and / or semolina from cereals, cocoa, sunflower seeds and rice or any combination thereof, in particular according to the method described above.

This use has the advantages described above.

An additional aspect of the present invention is directed to a good bed roller mill having a first roller and a second roller, at least one of the two rollers being movably supported 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, and wherein an attenuation with respect to a deflection in the direction in which the roller is movably mounted, is adjustable and / or the grinding gap is fixedly adjustable.

The alternative good bed roller mill can in particular be combined with the embodiments disclosed for this good bed roller mill.

Figur 1:

Schematische Seitenansicht einer erfindungsgemässen Gutbettwalzenmühle mit Schüttgut;

Figur 2:

schematische Draufsicht auf eine alternative erfin-dungsgemässe Gutbettwalzenmühle mit Schüttgut;

Figur 3:

schematische Darstellung eines erfindungsgemässen Profils einer Profilwalze;

Figur 4:

alternatives Profil einer erfindungsgemässen Profil-walze in schematischer Darstellung;

Figur 5:

schematische Darstellung einer erfindungsgemässen Gutbettwalzenmühle mit einer Trennstufe und Produkt-zuführung;

Figur 6:

alternative Anordnung einer erfindungsgemässen Gut-bettwalzenmühle mit Auflöser, Trennstufe sowie Pro-duktrückführung;

Figur 7:

Flussdiagramm eines erfindungsgemässen Verfahrens un-ter Verwendung von zwei Gutbettwalzenmühlen;

Figur 8:

schematische Darstellung eines vergrösserten Aus-schnitts einer erfindungsgemässen Gutbettwalzenmühle mit zwei Profilwalzen und Schüttgut;

Figur 9:

schematische Seitenansicht einer alternativen erfin-dungsgemässen Gutbettwalzenmühle mit Niveausensor im Zufuhrtrichter;

Figur 10:

Anordnung einer erfindungsgemässen Gutbettwalzenmühle mit mehreren Trennstufen.

Further features and advantages of the invention will be explained in more detail below with reference to exemplary embodiments for better understanding, without the invention being restricted to the exemplary embodiments. Show it:

FIG. 1:

Schematic side view of a good bed roller mill according to the invention with bulk material;

FIG. 2:

schematic plan view of an alternative according to the invention good bed roller mill with bulk material;

FIG. 3:

schematic representation of an inventive profile of a profile roller;

FIG. 4:

alternative profile of a profile roller according to the invention in a schematic representation;

FIG. 5:

schematic representation of a novel Gutbettwalzenmühle with a separation stage and product feed;

FIG. 6:

alternative arrangement of a good bed roller mill according to the invention with dissolver, separation stage and product return;

FIG. 7:

Flowchart of a method according to the invention using two high-bed roller mills;

FIG. 8:

schematic representation of an enlarged Aus-section of a novel Gutbettwalzenmühle with two profiled rollers and bulk material;

FIG. 9:

schematic side view of an alternative according to the invention Gutbettwalzenmühle with level sensor in the feed hopper;

FIG. 10:

Arrangement of a good-bed roller mill according to the invention with a plurality of separation stages.

In FIG. 1 is shown in a schematic side view of a Goodbettwalzenmühle 9. A bed 6 comprises finer material to be ground 5 and coarser material to be ground 7, which is drawn by the rotation in the direction r of the two rollers 10 and 11 in the grinding gap d.

The roller 10 is movably mounted in the direction s, ie perpendicular to the direction of rotation, whereby a grinding gap d is adjustable. The rollers 10 and 11 both have a diameter w of 600 mm and are supported for rotation in direction r by means of the bearings 20. The rollers have a smooth roller surface 19 on. The bearing 20 has to avoid vibrations to a damping device 26, which is designed as pneumatic damping.

The grinding gap d is variable in the present case depending on the retracted bulk material 6, wherein a pressure acting in the direction of the grinding gap d by the rollers 10 and 11 is set so that the finer material to be ground 5 is ground by means of a packed particle bed in the grinding gap d and the coarser material to be ground 7 is comminuted in the grinding gap d by direct contact with the rollers 10 and 11. In this case, the good-bed roller mill 9 has the damping device 26 known to the person skilled in the art in order to prevent the occurrence of vibrations of the rollers relative to one another.

The roller 10 has a peripheral speed of 1 m / s and the roller 11 has a peripheral speed of 1.5 m / s. The speed ratio between the rollers 10 and 11 is therefore 1.5: 1.

In operation, by rotating the rollers in the direction of bulk material 6, finer material to be ground 5 and coarser material to be ground 7 are now drawn into the machine bed roller mill 9. Between the two rolls in the grinding gap d, which is set here to a value of 1 mm, forms a packed particle bed with respect to the finer millbase, whereby the finer millbase is ground.

The coarser material to be ground 7 contacts, at least in the region of the grinding gap d, the first roller 10 and the second roller 11, so that this coarser material to be ground is strongly comminuted.

After milling, the ground product 17, which may be, for example, flour, is now removed from the high-pressure bed mill.

In FIG. 2 is a schematic representation of a plan view of a Goodbettwalzenmühle 9 substantially according to FIG. 1 shown.

From here on and below, like reference characters denote like components throughout the figures.

In contrast to the good bed roller mill 9 according to FIG. 1 Here are both rollers movably mounted in the direction s. In operation for grinding, the rollers are rotatable about the longitudinal axis 21 by means of the bearings, not shown here, both of which comprise a damper designed as a shock absorber, not shown here.

In contrast to FIG. 1 here is the grinding gap d fixed in operation to a value of 1 mm. In the present case, grain 1 is ground as a coarser ground material and semolina 3 as a finer ground material.

The roller 10 in the present case has a peripheral speed of 0.8 m / s and the roller 11 has a peripheral speed of 2.4 m / s. Thus, there is a speed ratio of 3: 1.

Another difference to FIG. 1 is that the roller 10 is formed in the present case as a profile roller with a profile, not shown here.

In FIG. 3 a section of a profile of a roller is shown in a schematic representation.

The profile has two completely illustrated, section-wise depressions 18 with a mean depth t of 1.2 mm, wherein the section-wise depressions 18 have a flat surface section 27 perpendicular to the radius of the profile roller. The flat surface portion 27 thus includes an angle p = 90 ° with the indicated as a dashed line radius of the roller. A width b of the recess 18 is 4.3 mm and a distance k between the sectional depressions on the roller surface 19 is 0.2 mm. The interior angle a is 135 °.

On both sides of the section-wise depressions 18 based on FIG. 3 has the roller not shown here more sections depressions.

In FIG. 4 an alternative profile of a profile roller is shown as a detail. The profile roller has a recess 18 with a width b of 7 mm and a depth t of 1.8 mm. The sectional recess 18 is in contrast to FIG. 3 not symmetrical and has on the one side in the circumferential direction an angle a of 120 ° and on the other side in the circumferential direction an angle a 'of 140 °.

In FIG. 5 schematically a plant 24 comprising a high-pressure roller mill 9 with two rollers 10 and 11 is shown. The rollers 10 and 11, both as profile rollers with a profile according to FIG. 3 are configured, are set to a fixed grinding gap d of 0.1 mm. The good bed 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 by means of a conveyor assembly 25 in a separation stage 14, the here designed as a zigzag sifter, promoted. In a zig-zag sifter, the ground product 17 is separated into finer ground product 12 and coarser ground product 13. This separation is essentially due to the physical properties of the particles, such as size, levitation 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 good bed roller mill 9. Finer ground product 12 is removed from the assembly 24 here as flour.

In FIG. 6 a further arrangement according to the invention 24 is shown, which has a plan sifter as separation stage 14 and in addition between Gutbettwalzenmühle 9 and separation stage 14, a resolver 22. The resolver 22 is designed as impact dissolver, as it is the expert, for example from the WO 2010/000811 A1 is known. As bulk material 6 cocoa is used here.

In FIG. 7 a flow chart of a method according to the invention is shown. Bulk material 6, here sunflower seeds, is fed to a fine bed roller mill 9 and ground in this. The ground product is fed to a separation stage 14 in which the ground product is separated into finer ground product 12 and coarser ground product 13. The coarser ground product 13 is fed back into the bed of good rolling mill 9.

The finer ground product 12 is fed in the present case another Gutbettwalzenmühle 9, wherein this further Gutbettwalzenmühle another separation stage 14 is connected downstream. In this, the ground product from the further good-bed roller mill 9 is again separated into finer ground product 12 and coarser ground product 13, wherein the coarser ground product 13 back into the another good bed roller mill 9 is fed back. The finer ground product 12 can now be further processed as flour.

In FIG. 8 is a schematic representation of a detail part of a Goodbettwalzenmühle 9 shown. The first roller 10 and the second roller 11 are each according to profiles FIG. 3 educated. The rollers rotate in the direction of rotation r, wherein the roller 10 has a peripheral speed of 3 m / s and the roller 11 has a circumferential speed of 0.5 m / s, ie the rollers have a speed ratio of 6: 1.

A grinding gap d is fixed to a value of 0.8 mm, with no damping device is provided. The distance k is 0.3 mm.

The bulk material 6 comprises semolina as a finer ground material and shell parts 4 and not shown here grain as coarser millbase, which as to FIG. 1 is ground described.

In FIG. 9 is a Gutbettwalzenmühle 9 according to FIG. 1 shown. In a feed hopper 31 is regrind 8, which forms a bed. A supply of regrind 8 in the feed hopper 31 is not shown here.

The feed hopper 31 comprises a level sensor 30 for measuring the level of ground material 8 in the feed hopper 31. Due to the measured level of ground 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.

If the level of regrind 8 falls below a predetermined value, for example, then by reducing the peripheral speed of at least one of the rolls 10 or 11, the level of regrind can be reduced 8 be increased in the feed hopper 31, since through this measure the throughput is reduced by the Goodbettwalzenmühle 9, while regrind 8 is further supplied to the feed hopper 31.

By increasing the peripheral speed of at least one of the rollers 10 or 11, the level of material to be ground 8 in the feed hopper 31 can be reduced because through this measure the throughput is increased by the Goodbettwalzenmühle 9, while material to be ground 8 is further supplied to the feed hopper 31.

It is also possible, on the basis of the measurement with the level sensor 30, to control the supply of ground 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 good bed roller mill 9.

A difference to FIG. 1 is that the rollers 10 and 11 are formed as profile rollers with a profile, not shown here.

In FIG. 10 a further alternative arrangement 24 according to the invention is shown, which has a plan sifter and a zig-zag sifter as separating steps 14.

About a Good bed roller mill 9 is a bed 6, here a mixture of rice and cereals, from regrind. The material to be ground is ground in the product bed roller mill 9 into ground product, which is subsequently conveyed into the plan sifter.

In the plansifter, the ground product is separated into a finer ground product 12, medium ground product 29 and coarser ground product 13. In addition, another fraction from the plansifter as flour 2 is discharged. The middle ground product 29 is in a promoted further separation stage 14, which is designed here as a zig-zag sifter. The middle ground product 29 is separated in the zigzag sifter into finer ground product and coarser ground product 13, the zigzag sifter being adjusted so that the finer ground product substantially contains bran 28. The mass fraction of bran 28 on the ground material 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 millbase.

The finer ground product 12 and the coarser ground product 13 from the plan sifter and the coarser ground product 13 from the zig-zag sifter are conveyed back into the good bed roller mill 9 by means of the return arrangement 23.

Claims (15)

Method for producing flour (2) and / or semolina (3) from good, in particular grain (1), cocoa, sunflower seeds and rice or any combination thereof, comprising the following steps: - Feeding of material from a bed (6) in a feed opening (15) of a good bed roller mill (9) comprising a first roller (10) and a second roller (11), wherein for setting a grinding gap (d) between the two rollers (10 , 11) at least one of the two rollers (10, 11) is movably mounted in a direction (s) substantially perpendicular to the direction of rotation of one of the two rollers (10, 11), and wherein a damping with respect to a deflection in the direction (s) of Roller is adjustable and / or the grinding gap (d) is fixed, wherein the bed (6) consists of particles having a size distribution and in particular at least millbase one of the following types or mixtures thereof contains: Good, semolina (3), shell parts (4 ); marked by Adjusting the particular fixed grinding gap (d) and / or the damping, such that a first subset of the bed (6) containing finer millbase (5) forms a packed particle bed in the grinding gap (d) and individual particles of a second subset of the bed ( 6) containing coarser millbase (7) in contact with the first roll (10) and the second roll (11) of the good bed roll mill (9) are; - grinding the bulk material (6) in the high-bed roller mill (9) into ground product (17); - Removal of the meal product (17) through a discharge opening (16). A method according to claim 1, characterized in that the first roller (10) and the second roller (11) rotate at different speeds, preferably in a speed ratio of greater than 1.1 _: 1, more preferably of greater 2: 1. Method according to one of claims 1 to 2, characterized in that at least one of the two rollers (10; 11) is formed as a profile roller, in particular with at least one section-wise recess (18) in the roller surface (19), wherein the section-wise recess (18 ) is formed in particular substantially parallel to the longitudinal axis of the profile roller. A method according to claim 3, characterized in that the profile of the profile roller is formed substantially self-cleaning, in particular at least during rotation of the profile roller. Method according to one of claims 1 to 4, characterized in that subsequent to the grinding of the bulk material (2) the ground product (17) is conveyed into a separation stage (14) for separation into finer ground product (12) and coarser ground product (13), wherein in particular the coarser ground product (13) is fed back into the feed opening (15). A method according to claim 5, characterized in that the separation stage (14) is followed by a further good-bed roller mill (9) for further grinding the finer meal product (12). Good bed roller mill (9), in particular for carrying out a method according to one of the preceding claims, comprising a first roller (10) and a second roller (11), wherein at least one of the two rollers (10; 11) is formed as a profile roller with at least one section Recess (18) in the roll surface (19), in particular substantially parallel to the longitudinal axis of the profile roller, characterized in that the section-wise recess (18) is self-cleaning at least during rotation of the profile roller. A good-bed roller mill (9) according to claim 7, characterized in that at least one of the two rollers (10; 11) is movably mounted in one direction (s) substantially perpendicular to the direction of rotation of one of the two rollers (10; 11) for setting a grinding gap ( d) between the two rollers (10, 11), wherein an attenuation by means of a damping device (26) with respect to a deflection in the direction (s) of the roller is adjustable and / or the grinding gap (d) is fixedly adjustable. Good bed roller mill (9) according to one of claims 7 to 8, characterized in that the at least one section recess (18) in the circumferential direction of the roll profile on average a width (b) in the range of 0.5 mm to 20 mm, preferably 2 mm to 10 mm and more preferably from 4 mm to 6 mm. Good bed roller mill (9) according to one of claims 7 to 9, characterized in that the at least one section recess (18) of the profile roller in the radial direction on average a depth (t) in the range of 0.3 mm to 10 mm, preferably from 0.5 mm to 5 mm and more preferably from 0.7 mm to 1.8 mm. A good bed roller mill (9) according to any one of claims 7 to 10, characterized in that the roller surface (19) with the at least one sectional recess (18) of the profile roller along a section between the roller surface and the surface of the recess which intersects the roller surface in the middle an internal angle (a) of 100 ° to 170 °, preferably from 120 ° to 150 ° and particularly preferably from 130 ° to 140 ° includes. A good-bed roller mill (9) according to any one of claims 7 to 11, characterized in that the profiled roller has at least two circumferentially spaced, partially recesses (18) having a mean distance (k) in the circumferential direction in the range of 0.15 mm to 10 mm, preferably from 0.15 mm to 5 mm and more preferably from 0.15 mm to 0.5 mm. Good-bed roller mill (9) according to one of claims 7 to 12, characterized in that the section-wise depression (18) of the profiled roller has a flat surface section (27), in particular substantially perpendicular to the radius of the profiled roller. A good bed roller mill (9) according to any one of claims 7 to 13, characterized in that the first roller (10) and / or the second roller (11) has a diameter (w) in the range of 400 mm to 1000 mm and preferably from 600 mm 800 mm. Use of a good bed roller mill (9) according to any one of claims 7 to 14 for the preparation of flours and / or semolina from cereals, cocoa, sunflower seeds and rice or any combination thereof, in particular according to a method according to one of claims 1 to 6.

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