EP3322536A1

EP3322536A1 - Method and apparatus for the two-stage grinding of fresh stock

Info

Publication number: EP3322536A1
Application number: EP16736208.6A
Authority: EP
Inventors: Siegfried Strasser
Original assignee: KHD Humboldt Wedag AG
Current assignee: KHD Humboldt Wedag AG
Priority date: 2015-07-16
Filing date: 2016-07-08
Publication date: 2018-05-23
Also published as: US20180207646A1; CN107847943A; CA2992355A1; WO2017009240A1; DE102015009273B3

Abstract

The invention relates to a method for grinding fresh stock (1), having the steps of comminuting the fresh stock (1) in the roller gap (6) of a first roller press (4), to give ground grinding stock, dividing the ground grinding stock by means of adjustable dividing means (9, 31) of a dividing device (8) into a first part stream (12) and a second part stream (13) of ground grinding stock in a variably adjustable ratio and comminuting the ground grinding stock of the first part stream (12) in a second roller press (14). The invention also relates to a corresponding apparatus for grinding fresh stock (1). The invention provides for dividing the ground grinding stock issuing from the first roller press (4) by means of the dividing means (9, 31) into an intermediate stream (10) consisting of ground grinding stock issuing from an intermediate roller gap region (32), and into two peripheral streams (11a, 11b) each consisting of ground grinding stock issuing from one of the two roller gap peripheral regions (33a, 33b), wherein the two peripheral streams (11a, 11b) are combined to form the first part stream (12) and the intermediate stream (10) forms the second part stream (13), and conveying the second part stream (13) from the dividing device (8) into at least one bypass line (18), passing the second roller press (14).

Description

Method and device for two-stage grinding of fresh material

The invention relates to a method for grinding of fresh material, comprising the steps of crushing the fresh material in the nip between two rotatably mounted rollers of a first roller press ground millbase, dividing the ground millbase by means of adjustable dividing means of a dividing device in a first part-stream ground millbase and a second part-stream milled Grindings in a variably adjustable ratio and crushing of the ground material of the first part stream to be ground regrind in a second roller press. The invention further relates to a method corresponding to the method for grinding of fresh goods, comprising a first roller press for Gutbettzerkleinerung of the fresh material to ground regrind, wherein the first roller press has a nip between two rotatably mounted rollers, a splitter for dividing the ground grind by means of adjustable dividing means in a first partial stream ground millbase and a second partial stream ground millbase in a variably adjustable ratio and one of the splitter in the material flow direction downstream second roller press for crushing the ground millbase of the first partial flow to be ground millbase.

For the crushing of granular, brittle regrind such as cement clinker roller presses (high-pressure roller presses, high-quality roller mills) are used, in which two counter-rotating rollers form a nip between them. The millbase, which has been abandoned as a virgin material of the roller press, is fed to the nip, where it is comminuted under high pressure. At the same time, while largely avoiding shearing the particles of the granular regrind are interlinked. The compressive stress causes the material to be ground is pressed into flakes and thereby resulting structural cracks in the material a deagglomeration and thus allow winning small Mahlgutbestandteile in a subsequent process step, for example in static cascade classifiers allow. Frequently, therefore, roller presses are part of a Kreislaufmahlanlage in which by means of the use of static caution and dynamic Nachsichtern the desired fine material is discharged, while deposited coarse material kept in circulation and fed together with newly fed fresh material again the roller press for crushing.

Especially in Kreislaufmahlanlagen for cement production a finished product is sought, which has a particle size spectrum with the highest possible proportion of very fine particles. This usually leads to an economically and procedurally disadvantageous, high number of cycles for the millbase. A well-known way to increase the fines content while keeping the circulating transport as low as possible, is to follow the roller press in a two-stage process a second grinding device. Thus, in the unpublished patent application (reference 102015001404.8) of the Applicant taught in a Kreislaufmahlanlage for grinding of fresh goods, giving up fresh material for high-pressure crushing a first roller press and this nachzuschalten a second roller press.

A particular technical challenge is to adapt the operation of the two roller presses. Inasmuch as the first roller press is supplied with coarser material to be ground than the second roller press, into which already ground grinding material passes, the throughput in the first roller press is generally higher than in the second roller press. Assuming two equally sized roller presses, an adaptation by speed reduction, ie ultimately by reducing the performance of the first roller press would be made. Alternatively, as regards the Energy and cost disadvantageous to make an enlargement of the second roller press and / or their Bet ebsparameter.

In the Kreislaufmahlanlage the above-mentioned patent application (reference 102015001404.8) this problem is reduced in the adjustment of the operation of the two-stage cascaded roller presses characterized in that the flow of passing from the nip of the first roller press ground millbase in two streams (in a variably adjustable ratio to each other) is split. Since one of the two partial flows is led directly to a cautionary, only the other partial flow enters the crop feed of the second roller press. Insofar as this partial flow has a lower mass flow than the material flow which is fed to the first roller press, adjustment of the operation of the two roller presses does not necessarily require a noticeable speed or throughput / power reduction of the first roller press or a disadvantageously increased throughput , Service requirement for the second roller press. On the other hand, dividing the stream of ground millbase from the first roller press in this way, because of the bypass partial stream passing by the second roller press, causes the fines content in the total stream formed from both partial streams in the material flow direction behind the second roll press (actual or fictitious) is limited. In a Kreislaufmahlanlage this then leads to the disadvantage of not optimally reduced circulation number for a large Mahlgutanteil. Furthermore, in such a circuit used classifiers are at least economically disadvantageous to dimension the larger, the lower the amount of fines supplied.

The object of the invention is therefore to specify a method for the grinding of fresh material with a two-stage performed by connecting two roller presses crushing, in which the operation of the two roller presses can be suitably matched to each other and the proportion of fines in total velvet is increased. The object of the invention is also to provide a method corresponding to the device for grinding fresh food available.

The object of the invention is achieved by a method for grinding fresh food with the features of claim 1 and by a device for grinding fresh food with the features of claim 7. Further advantageous embodiments are specified in the subclaims to claim 1 and in the dependent claims to claim 7.

According to the invention, it is thus provided that the ground material leaving the nip of the first roller press is firstly divided into a medium flow milled material by means of the dividing means of the dividing device and is formed by ground milled material exiting from a central nip area (relative to the longitudinal direction of the nip) divided into two edge streams ground millbase, which are each formed from each one of the two, separated by the central nip area spaced Walzpaltrandbereiche ground millbase to divide. Thus, it is not so proceeded that the ground regrind continuously discharged over the entire length of the nip would first be merged into a stream of material, which would then be divided in a next step into two partial streams of ground millbase of the same nature. Rather, the finding is that, in particular as a result of the bulk cone, which arises above the nip with typically centrally performed Frischgutaufgabe roller presses, the intake behavior and the high pressure crushing in the nip over the entire length of the nip viewed not homogeneous. In the - relative to the longitudinal extent of the nip - middle region of the nip comparatively much feed material is drawn and there is a high pressure in the nip. In this central area, therefore, the highest degree of comminution is achieved with central fresh material feed. Toward the edges, ie along the nip to the two end faces of the roller press, the pressure decreases and with it the Zer- each degree of decrease. The exact location-dependent function of the pressure distribution along the nip depends primarily on the operating parameters (Walzenandruck, speed, etc.) of the roller press and the nature and quantity of the abandoned fresh material (and possibly the recirculated material) dependent. Typically, the pressure in a certain, symmetrically to the (in relation to the longitudinal extent) given center of the nip formed region is approximately constant or only slightly sloping outward, while the two edge regions by greater pressure drop each outward (ie in approximately mirror symmetry to each other) Marked are. In the center of the nip, therefore, finer crushed ground millbase results than at the edges.

According to the invention, therefore, the dividing device is arranged immediately below the nip, extended over its entire longitudinal extension, spatially even before it could come to a confluence of the along the nip downwardly exiting ground Mahlgutanteile to a stream. The dividing device includes dividing means, for example, in a special embodiment of the invention, two adjustable flaps, with which the ground mill material which is distributed over the nip can be divided into partial streams. According to the invention, the dividing means are arranged approximately symmetrically with respect to one another with respect to the longitudinal extent of the nip given center of the nip. As a result of their function, therefore, a middle stream of ground millbase and on both sides of this central region from the two edge regions of the nip each produce an edge stream. The ground millbase of the middle range has a higher degree of comminution, ie it consists of finer-grained (although normally still to be deagglomerated) material than the coarser ground millbase of the marginal streams, based on the particle size distribution spectrum.

The two border streams are then merged. In accordance with the invention, the partial stream, designated here for distinction as "first", is ground Ground material formed by the two merged edge streams. The middle stream of ground regrind forms the second partial stream of ground millbase. The percentage distribution of the total ground millbase of the first roller press in a ratio of the two partial flows to each other thus directly depends on the division performed, ie the respective setting of the dividing means from. The first partial flow with the comparatively coarsely present ground millbase of the first roller press (from the edge regions) is now fed to the second roller press for a further comminution process and fed into its nip. This coarser portion is thus over-ground in the second roller press to be ground millbase, wherein the term 'over-grinding' refers here to the additional comminution taking place in this second stage and does not mean erroneous operation of the grinding apparatus (in the sense of 'too much').

Furthermore, according to the invention, the second partial stream with the comparatively finer ground millbase (from the central area) is guided by means of the divider device into a bypass line. On the one hand, the bypass line communicates with the dividing device and, on the other hand, passes the second partial stream of ground millbase past the second roller press. Typically, in grinding cycles, the second partial stream from the bypass line will then be subsequently combined with the ground mill material of the second roller press to form a total stream, but it could also continue to be kept separate even if the cycle topography is appropriate. According to the invention, therefore, the ground regrind of the first roller press is not only divided purely quantitatively, but in a finer and a coarser proportion. The partial flow with the finer proportion is passed by the second roller press, the partial flow with the coarser fraction additionally over-mill. This not only has the advantage that the second roller press is relieved by supplying a flow of material that is less than that supplied to the first roller press and therefore advantageously adjusting the operation of the two roller presses in terms of throughput can be achieved to each other. Rather, the particle size distribution spectrum of the second partial flow (bypass) is shifted towards smaller particle sizes, so that when operating the two-stage grinding device within a Kreislaufmahlanlage to achieve a very fine-grained finished product advantageously less cycles are required than heretofore in the prior art (by Dividing into partial streams with approximately the same degree of comminution) is achieved. In the circulation, for example, in cement production typically existing classifier can be made smaller due to the supplied fine-grained material to be sighted.

In a preferred embodiment of the invention, both roller presses each have a Gutaufgabevorrichtung for the task of each material to be ground in the corresponding nip. In the case of the two-stage comminution process, the typical operating parameters such as rotational speed, contact pressure as well as the dimensioning of the two roller presses for normal operation can advantageously be matched to one another. However, in particular due to the varying nature of the fresh material and the ground regrind as well as variations in the crop feed in the first roll press during operation, fluctuations in the fill in the crop feeders and in the throughput in the roll presses are usually unforeseen. Also leads a induced, changed percentage distribution between the two sub-streams to changed operating conditions. For a controlled operation of the two-stage comminution device, a particularly advantageous embodiment of the invention therefore provides for regulating the fill level of the ground millbase of the first substream charged in the material dispensing device of the second web press as a control variable in a control loop. In this control loop, the setting position of the dividing means of the dividing device, that is about the angular and or distance adjustment of adjustable valves, as a manipulated variable, since the position of the dividing means sets the mass flow of the first partial flow (as well as the second partial flow), ie the per unit time by a transverse cut moving mass (mass flow), and thus the level in the crop feeding the second roller press. In order to determine the actual value of the controlled variable, a device is provided for measuring the fill level of the ground millbase of the first partial stream charged into the material feeding device of the second roller press. For this purpose, known per se measuring devices, for example. Pressure measuring or level sensors, can be used.

In a further embodiment of the invention it is further provided that, in particular for safety reasons, the crop delivery device of the second roller press has an overflow for discharging excess feedstock. This avoids that unforeseen fluctuations occurring in the material task in the short term lead to overfilling of the material feeding device of the second roller press. About the overflow derived material, ie ground millbase from the first partial flow is, in order to keep it in circulation, passed through a connecting line in the bypass line, which leads the second partial flow ground millbase.

In a further advantageous embodiment of the invention, it is provided that the first roller press has a crop delivery device for the task of Frischguts and that the level of discontinued in the crop delivery of the first roller press fresh material (including recirculated material) is controlled as a controlled variable in a control loop in which the mass flow of the fresh food to be dispensed is manipulated variable. In this way, a dosing of the discontinued fresh goods by speed change leading conveyor belts or per se known throttling and metering devices, such as using dosing weighers can be achieved in order to regulate an approximately constant - and suitable for the two-stage grinding process - level at the first roller press , In this case, the disturbance variable may in particular be a fluctuating quantity of recirculated material which, together with the fresh material, is given up for a further circulation of the first roller press. Furthermore, in a further refinement, the person skilled in the art can produce a coupling with the above-described control circuit for the filling level in the crop feeding device of the second roller press, for example by incorporating the filling level in the first roller press as a further actuating variable in this control loop.

Starting from the preferred embodiment of the method according to the invention or the device according to the invention, in which the fill level of the ground mill stock of the first part stream fed into the crop delivery device of the second roller press is regulated as a controlled variable in a control loop with the position of the dividing means as the manipulated variable, the further embodiment will be described the invention provided to limit the adjustment range of the manipulated variable suitable. Insofar as the setting of the adjusting means, for example of adjustable flaps, the percentage distribution of the mass flows of the first and the second partial flow is accompanied, this boundary condition can be formulated as a ratio of mass flows to each other. Extensive test runs at Kreislaufmahlanlagen for cement production have surprisingly revealed that for optimal coordination of the operation of the two roller presses on each other and for an efficient reduction of circulation numbers in the circuit as such a condition for the control of the level in the cropping device of the second roller press is to choose: The mass flow of the second partial stream of ground millbase should be at least 10% and at most 40%, preferably at least 15% and at most 30%, of the total mass flow, which is given as the sum of the mass flows of the first part stream and the second part stream of ground millbase.

In the case of the embodiment of the invention with an overflow at the crop feeding device of the second roller press and a feeding of excess feed material into the bypass line measurements during typical operation of the device according to the invention within a Kreislaufmahlanlage for cement production have shown that as an alternative embodiment of the invention for the boundary condition of the Setting range of the manipulated variable in the control loop advantageous The mass flow of that stream of material which is created by introducing the excess feed of the second roller press into the bypass section ground milled material should be at least 10% and at most 40%, preferably at least 15% and at most 35%, of the total mass flow , which is given as the sum of the mass flows of the first part stream and the second part stream ground millbase.

For the realization of the two alternative control circuits, each provided with the aforementioned boundary conditions, a first device for measuring the mass flow in the bypass line between the divider and, if present, the point of introduction of the excess feed material is provided in an embodiment of the device according to the invention. In addition or as an alternative to this, a second device is provided for measuring the mass flow of the material stream consisting of the ground material of the second partial stream and the excess feed, ie directly behind the point of introduction of the excess feed into the bypass line. Measuring devices which can be used are measuring devices known per se for the determination of mass flows in lines, for example on a radiometric basis. To obtain the percentage ratios, the values determined are based on the mass flow of the total flow. This can be determined by feeding the fresh material and recirculated Good composing task stream of the first roller press. Particularly suitable (especially in the case of an overflow on the first roller press) is also a determination of the mass flow of the ground grinding material which emerges from the second roller press, in the simplest case after its combination with the mass flow which passes from the bypass line. Since material transport on conveyor belts typically takes place here, a belt scale is suitable for this third mass flow measuring device, for example.

The proposed method according to the invention and the corresponding device according to the invention are not based on the embodiments explicitly presented here. limited. In particular, firstly, in principle, a three- or even higher-level process control can be achieved if further roller presses according to the principle presented, so as the second roller press, are followed. In addition, secondly, with corresponding dividing means or dividing means along the nip of the first roller press, a different division into partial flows can also be made, if required, than into a central and two merged edge streams of approximately equal size. The skilled person will be able to set this up easily if an asymmetric or otherwise different loading of the nip with regrind takes place. The specific division can be adjusted by appropriate means of adjusting then the given pressure distribution or comminution degree along the nip so that coarser Good is separated from finer Good and crushed a second time.

The invention will be explained in more detail with reference to the following figures. It shows

Fig. 1 is a schematic representation of the two-stage according to the invention

Process for grinding fresh food, and

Fig. 2 is a schematic representation in a lateral perspective of the division into

Partial flows after the first roller press.

FIG. 1 schematically shows an exemplary embodiment of the method according to the invention for grinding granular, brittle fresh material 1 with a corresponding device according to the invention. Fresh material 1 is optionally fed together with the recirculated in a (not completely shown) Kreislaufmahlanlage Good 2 in the crop feeding device 3 of the first roller press 4. In order to dose the feed quantity appropriately, the fill level 5 is controlled in the material feed device 3 and in a control loop with the mass flow meter. senstrom of the abandoned crop 1 regulated as a manipulated variable. In the nip 6 between the rollers 7a, 7b of the first roller press 4, the fresh material 1 (together with recirculated Good 2) crushed under high pressure to ground millbase and thereby pressed into slugs. Immediately below the entire nip 6 in its longitudinal extent a divider 8 is arranged. By means of the dividing means 8 arranged, adjustable dividing means 9 (not shown), the downwardly from the nip 6 in the normal case over its entire length continuously exiting ground millbase merged and thereby divided into a middle stream 10 ground millbase and two edge streams 1 1 a, 1 1 b ground millbase. In this case, it is assumed that the normal case of a material task (seen in the longitudinal extent) in the center over the nip 6 takes place by means of the material delivery device 3. Due to the pressure distribution along the nip 6, the middle stream 10 of more crushed, so on average feinkörnigerem material than the two edge streams 1 1 a, 1 1 b. The two boundary streams 1 1 a, 1 1 b are combined to form a first part stream 12 milled ground material, the middle stream 10 forms a second partial stream 13. The mass flow ratio of the two partial streams 12, 13 to each other by the divider 8 (by the position of the dividing means ) certainly.

According to the invention, the coarser ground millbase of the first partial stream 12 is fed to a second roller press 14 and comminuted into its mill slit 15 into ground mill 16 to be ground. Advantageously, the first roller press 4 is vertically above the second roller press 14 or above, but arranged laterally offset, so that the transport of the ground material of the first part of stream 12 is effected economically low gravity. In principle, however, a transport by means of a transport device is possible. In the exemplary embodiment illustrated, the comminuted material to be ground 16 is conveyed further by means of a conveyor belt 17, that is to say transported in particular to the classifiers of a Kreislaufmahlanlage (and thereby possibly first in a pneumatic Given promotion). Furthermore, according to the invention, the finer-grained ground grinding stock of the second partial flow 13 is not guided to the second roller press 14, but past it in a bypass line 18. The second roller press 14 can thereby operate at a lower throughput than the first roller press 4, so that a suitable adjustment of the operating parameters (in particular rotational speeds) of the two roller presses 4, 14 can be achieved without having to reduce the performance of the first roller press 4. The division into the partial streams 12 and 13 with their different particle size distributions has the advantage that the bypass is formed by the finer-grained ground millbase fraction. Within a Kreislaufmahlanlage this reduces the number of recirculations of non-selected material and increases the overall fine grain in the finished product.

The second roller press 14 also has a Gutaufgabevorrichtung 19. For security against unpredictable, short-term and as such difficult to avoid fluctuations in the mass flow of the first partial flow 12, an overflow 20 is provided on the excess feed 21 through a connecting line 22 at the discharge point 23rd is guided in the bypass line 18. The material flow 24 composed of the optionally present excess feed material 21 and the second part-stream ground material is released in the illustrated embodiment on the conveyor belt 17, where he together with the ground grinding material 16 the entire mass flow 25, that is, the sum of the mass flows of the first partial flow 12th and the second partial flow 13, forms.

The operation of the two series-connected roller presses 4, 14 can be optimally matched to each other when the level in the crop delivery device 19, in which the first partial flow 12 is abandoned, is regulated as a controlled variable in a control loop. As a control variable in the control loop, the setting position of the dividing means 9 is used in the divider 8, ie a controlled change in the proportional division between the first partial flow 12 and second partial flow 13 and the percentage of the bypass-like second partial flow 13 in the entire mass flow 25 brought about.

In addition to a continuous measurement of the level 26 in the crop delivery device 19 of the second roller press 14 are provided for carrying out the control: a first device 27 for measuring the mass flow of the second partial stream 13 ground millbase in the bypass line 18 between divider 8 and discharge point 23; and (/ or) a second device 28 for measuring the mass flow of the material stream 24 composed of the second partial flow 13 and the excess feed material downstream of the introduction point 23; and a third device 29 for measuring the mass flow of the entire mass flow 25, given in the illustrated embodiment by a belt scale 29. Using the measured values collected continuously or at regular discrete time intervals, the control circuit for the level 26 in the Gutaufgabevorrichung 19 of the second roller press 14 under Operate boundary conditions to the setting range of the manipulated variable (the position of the dividing means 9). For example, for operation within a typical Kreislaufmahlanlage for cement production proves a proportion of the mass flow of the branched off as a bypass second partial flow 13 of the total mass flow 25 of at least 10% and at most 40%, preferably at least 15% and at most 30%, for a sufficiently fine particle size distribution in the finished product, a suitable vote of the roller presses 4, 14 to each other and an economically favorable low circulation number in the circuit as advantageous.

FIG. 2 shows, in a schematic side view at the top, the supply of the fresh material 1, possibly together with material 2 recirculated in a grinding circuit, into the material delivery device 3 of the first roller press 4. Because of the lateral perspective, only one roller 7a of the first roller press 4 can be seen. The centrally placed product 1, 2 typically forms, above the nip 6 (hidden in the figure), a flattened pour cone 30 of greatest height in the middle and sloping towards the edges, depending on the longitudinal extent of the wale. zen 7a, 7b or of the nip 6. Directly below the nip, the divider 8 (not fully shown) with the dividing means 9 is arranged. In the illustrated embodiment, the division is done mechanically by adjustable flaps 31st The located in the below the entire nip 6 extending housing of the divider 8 flaps 31 are arranged mirror-symmetrically to the center of the nip longitudinal extension and movable, for example. By a motor. The flaps 9, 31 can be displaceable in opposite directions to each other below the nip 6, or, as in the illustrated embodiment, about an axis of rotation in its angular position (in opposite directions to each other) to be pivoted.

By the ever given position of the dividing means 9, 31, in the purely geometrically through the (free) ends of the flaps 9, a central nip area 32 (symbolically marked) of (in the figure) each one left and right located therefrom roll edge region 33a, 33b ( symbolically marked) is delimited along the nip 6, there is a division of down from the entire nip 6 passing ground millbase in a middle stream 10 of finer ground millbase and one edge stream 1 1 a, 1 1 b of coarser ground millbase. As described in connection with FIG. 1, the medium flow 10 is passed as a second partial flow 13 in the further bypass around the second roller press 14, while the edge currents 1 1 a, 1 1 b together form the first partial flow 12, which for over-grinding in the second roller press 14 is abandoned.

In the case of a possibly different pressure or comminution degree distribution along a nip 6, a suitably advantageous division into partial streams with mutually different particle size distribution can be carried out by a suitably adapted dividing device 8 by the person skilled in the art. LIST OF REFERENCE NUMBERS

Frischgut 18 Bypass line recirculated goods 19 Gutaufgabevorrichtung

(second roller press)

Gutaufgabevorrichtung (first

Roller press) 20 overflow

Roller press (first) 21 excess feed

Level (first roller press22 connecting line) 23 point of introduction

Nip (first rolls24 material flow

Press)

25 mass flow (total), 7b roller (first roller press)

26 level (second Rollen¬

Divider press)

Dividing agent 27 mass flow

Medium current measuring device (first) a, 11b Randstrom 28 Massenstrom-

Measuring device (second) first partial flow

29 mass flow second partial flow

Measuring device (third)

Roller press (second)

30 piles of material

Nip (second Rollen31 flap

Press)

32 medium nip area overground regrind

33a, 33b Walzenspaltrandbereich

conveyor belt

Claims

P A T E N T A N S P R E C H E

Process for grinding fresh food (1), comprising the steps

Comminution of the fresh material (1) in the nip (6) between two rotatably mounted rollers (7a, 7b) of a first roller press (4) to ground regrind,

Dividing the ground grind by means of adjustable dividing means (9, 31) of a dividing device (8) in a first part stream (12) ground millbase and a second part stream (13) ground millbase in a variably adjustable ratio, and

Crushing the ground regrind of the first part stream (12) to be ground grind (16) in a second roller press (14), characterized by

Splitting the ground material emerging from the nip (6) of the first roller press (4) by means of the dividing means (9, 31) of the dividing device (8) into a medium flow (10) ground from a (relative to the longitudinal direction of the nip (6)) medium-sized Zenspaltbereich (32) emergent ground millbase is formed, and in two edge streams (1 1 a, 1 1 b) ground mill, each of each one of the two, by the central nip area (32) spaced from each other Walzpaltrandbereiche (33 a, 33 b) formed ground grinding material are formed, wherein the merging of the two edge streams (1 1 a, 1 1 b) milled ground material forms the first part stream (12) ground millbase and the middle stream (10) ground millbase forms the second part stream (13) ground millbase, and through

Passing the second part stream (13) ground grinding material from the dividing device (8) in at least one bypass line (18) on the second roller press (14) over.

2. The method of claim 1, wherein the second roller press (14) has a crop feeder (19) for the task of ground regrind of the first part stream (12), and wherein the level (26) of the in the crop delivery device (19) of the second roller press (14) discontinued ground regrind of the first partial flow (12) is controlled as a control variable in a control loop in which the control position of the dividing means (9, 31) of the divider (8) is manipulated variable.

3. The method of claim 2, wherein the crop-feeding device (19) of the second roller press (14) has an overflow (20) for discharging excess Aufgabeguts (21), wherein the excess feed (21) in the second partial stream (13) milled ground material leading bypass line (18) is passed.

4. The method according to any one of claims 2 or 3, characterized by

Controlling the filling level (26) of the ground material of the first partial flow (12) fed into the material feeding device (19) of the second roller press (14) under the boundary condition to the setting range of the manipulated variable formed by the setting position of the dividing means (9, 31) Mass flow of the second partial stream (13) ground grinding material at least 10% and at most 40%, preferably at least 15% and a maximum of 30%, of the total mass flow (25), which is the sum of the mass flows of the first partial flow (12) and the second partial flow ( 13) ground millbase is given.

5. The method according to claim 3, characterized by

Controlling the filling level (26) of the ground material of the first part-stream (12) fed into the material-feeding device (19) of the second roller press (14) under the boundary condition to the setting range of the regulating variable formed by the setting position of the dividing means (9, 31), the mass flow of that material flow (24) which is formed by introducing the excess feed material (21) of the second roller press (14) into the bypass line (18) leading to the second partial flow (13) is at least 10% and at most 40% at least 15% and at most 35%, of the total mass flow (25), which is given as the sum of the mass flows of the first part stream (12) and the second part stream (13) ground millbase.

Method according to one of claims 1 to 5, wherein the first roller press (4) has a material feeding device (3) for the task of fresh food (1), and wherein the filling level (5) of the in the material feeding device (3) of the first roller press (4 ) checked fresh product (1) is controlled as a controlled variable in a control loop, in which the mass flow of the fresh food to be fed (1) is manipulated variable.

Apparatus for grinding fresh goods, comprising a first roller press (4) for comminution of the fresh material (1) to ground millbase, wherein the first roller press (4) has a nip (6) between two rotatably mounted rollers (7a, 7b), a divider (8) for dividing the ground regrind by means of adjustable dividing means (9, 31) in a first part stream (12) ground millbase and a second part stream (13) ground millbase in a variably adjustable ratio, and one of the dividing device (8) in the material flow direction downstream second roller press (14) for comminuting the ground material of the first part stream (12) to be ground millbase (16), characterized in that the dividing device (8) immediately below the nip (6) of the first Roller press (4) is arranged, wherein the dividing means (9, 31) to each other approximately symmetrically to the longitudinal extent of the roll gap (6) given center of the roll gap (6) are arranged for dividing the from the nip (6) emerging ground millbase in a medium flow (10) of ground material which is formed by a ground material leaving the center of the roll gap region (32) and in two edge streams (1 1 a, 11 b) of ground material which has been ground; each emerging from each one of the two, by the central nip area (32) spaced apart Walzpaltrandbereiche (33a, 33b) Milled material to be ground are formed, and wherein the first part stream (12) ground millbase is given as a combination of the two edge streams (1 1 a, 1 1 b) ground millbase and the second part stream (13) ground millbase as the middle stream (10) ground Mahlguts is given, and that at least one with the divider (8) in connection and the second part of the flow (13) ground grinding bypass passage (18) for bypassing the second roller press (14) is provided.

8. The device according to claim 7, characterized in that the second roller press (14) has a crop delivery device (19) for the task of ground regrind of the first partial flow (12), a device for measuring the level (26) of the in the Gutaufgabevorrichtung ( 19) of the second roller press (14) is provided ground millbase of the first partial flow (12) is provided, wherein the level (26) of the in the Gutaufgabevorrichtung (19) of the second roller press (14) abandoned ground millbase of the first partial flow (12) as a controlled variable is integrated in a control loop in which the setting position of the dividing means (9, 31) of the dividing device (8) manipulated variable.

9. Apparatus according to claim 8, characterized in that the crop delivery device (19) of the second roller press (14) has an overflow (20) for discharging excess Aufgabeguts (21), wherein a connecting line (22) is provided between the overflow (20) of the crop delivery device (19) of the second roller press (14) and the bypass line (18) for introducing the excess feed material (21) into the bypass line (18), and that one first device (27) for measuring the mass flow in the bypass line (18) between the divider (8) and the discharge point (23) of the excess feed material (21) is provided and / or a second device (28) for measuring the mass flow of the ground regrind of the second substream (13) and optionally the excess feed material (21) composing material flow (24) is provided, and that a third device (29) for measuring the mass flow of the stream of the ground grind (16) from the second roller press (14) is provided.

Device according to one of claims 7 to 9, characterized in that the dividing device (8) has two adjustable dividing means (9, 31), wherein the dividing means (9, 31) are designed as adjustable flaps (31).