WO2016124627A1

WO2016124627A1 - Closed-circuit grinding plant comprising two grinding devices and method for operating the closed-circuit grinding plant

Info

Publication number: WO2016124627A1
Application number: PCT/EP2016/052245
Authority: WO
Inventors: Jörg BINNER
Original assignee: Khd Humboldt Wedag Gmbh
Priority date: 2015-02-04
Filing date: 2016-02-03
Publication date: 2016-08-11
Also published as: DE102015001404B3

Abstract

The invention relates to a method for operating a closed circuit grinding plant for grinding fresh material (1), comprising the steps of: crushing the fresh material (1) to form ground material (5) in a first grinding device (3) realised as a roller press; dividing the ground material (5) into a first and second sub-stream (7, 8) in a variably adjustable ratio; pre-sifting the first sub-stream (7) in a static sifting device (10) arranged under the first grinding device (3), wherein sifted-out material (13) and separated coarse material (15) are discharged; pneumatic transporting of the sifted-out material (13) to a dynamic sifting device (18) arranged above the first grinding device (3); post-sifting of the sifted-out material (13), wherein grit (20) and finished material (9) are discharged; and recirculating of the grit (20) to the first grinding device (3). The invention also relates to a corresponding closed-circuit grinding plant. According to the invention, the separated coarse material (15) is recirculated to the first grinding device (3), the ground material of the second sub-stream (8) is crushed in a second grinding device (25) to form reground material (27) and the reground material (27) is pre-sifted in the static sifter (10).

Description

Kreislaufmahlanlage with two grinders and method for

Operation of the Kreislaufmahlanlage

The invention relates to a method for operating a Kreislaufmahlanlage for grinding of fresh material, comprising the steps of crushing the fresh material to ground millbase in a first, designed as a roller mill grinding device, dividing the ground millbase ground millbase ground mill and a second partial stream ground millbase in one variably adjustable ratio, precalculations of the first part-stream ground millbase in at least one arranged below the first grinding static sifter, wherein Sichtbare Sichtgut and separated coarse material separated from the at least one static classifier are discharged, pneumatic transport of the suspended in a classifying air flow, exposed Sichtguts by a Rising to at least one above the first grinding device arranged dynamic classifier, indulgence of the exposed Sichtguts in the at least one dynamic classifier, wherein ge separating grits and a stream of classified finished product and classifying air from the at least one dynamic sifter, and recirculating the greens to the first grinder. The invention further relates to a corresponding to the process Kreislaufmahlanlage for grinding of fresh goods, comprising a first, designed as a roller press grinding bed for comminution of fresh material to ground regrind, a first dividing device for dividing the ground millbase in a first part-stream ground millbase and a second part-stream ground Grindings in a variably adjustable ratio, at least one below the first grinder disposed static sifter for pre-sighting of the first part-stream milled ground material with at least one entry port for the ground material, a Sichtgutaustrag for the discharge of sifted Sichtgut and at least one discharge opening for the discharge of separated coarse material and at least one above the first grinding device arranged dynamic classifier for the protection of the visible material, which is exposed by the at least one static classifier, with a visible material inlet for the entry of a stream of classifying air and the sighted material, a coarse material discharge device for the discharge of semolina and with a fine material discharge device for the discharge of a stream of selected finished goods and classifying air, wherein the Sichtgutaustrag the static classifier with the Sichtguteintritt the at least one dynamic classifier by a riser for pneumatic transport of suspensie in a classifying air stream and the coarse material discharge device of the dynamic classifier is in communication with a crop delivery device of the first grinding device for recirculating the cereal.

From brittle fresh material can be obtained by milling a granular fines. An important application is given in cement production, where cement and / or cement raw meal is to be obtained by grinding from cement clinker and possibly additives. In particular, roller presses (high-pressure roller presses, good-bed roller mills) are used as the grinding device, in which the material is comminuted in a good bed by pressure in the gap between two counter-rotating rollers. The material emerging from the nip after the stress consists of a finer-grained fraction and a coarse-grained fraction of material which is only slightly comminuted and / or jammed into slugs. In order to obtain the fine material, the ground material is ground in a visual process, which is often carried out for efficiency and wear reasons advantageous in two steps. Typically, a prospect in a dynamic air sifter, eg a dynamic rod sifter ter, which is preceded by a static, often also disagglomerierend acting caution material flow side. For the quality of the discharged from the dynamic Nachsichter finished good in particular its particle size distribution, ie the statistical composition of different sized particles, is essential. In cement production, high cement quality is often achieved when avoiding a steep distribution with a narrow distribution to a narrow range of grain sizes (in the case of RRSB distribution) and instead realizing a flat grain size distribution with a correspondingly wide grain band. It has been shown that in this case, the particularly fine-grained fraction is important. For each cement qualities intended, the exact grain size distribution setting suitable for this purpose, given the starting material properties given, is a problem that is theoretically very difficult to obtain. Rather, in practice, a predominantly empirical approach is important, which often also depends on variations in the adjustment of the grain size spectrum in a given system.

Compared to systems in which a Frischgutmahlvorrichtung (roller press) a static, disagglomerating acting cautery and a dynamic Nachsichter are linearly connected one behind the other, it can be regarded as a first step to achieve finer grain sizes, separated coarse material or grits from the classifiers in a grinding circuit for to re-supply a renewed compressive stress of the grinding device, as proposed in DE 102 21 739 A1. However, if in addition to the fresh good a comparatively large amount of a small and medium granular Good, which is discharged from the static classifier, enters the roller press, it may lead to Entlüftungsund material pressing difficulties in the nip of the roller press, which the operation of the roller press or May affect the grinding result (also with regard to the particle size distribution on the side of small particle sizes).

The grain size in the finished product can be further refined by two-stage grinding processes, if, for example, as taught in DE 34 07 535 A1, a finely ground the grinding device (eg ball mill) for pre-shredding a good bed roller mill is connected upstream. Procedural improvements can then be achieved by dividing into two partial cycles. Thus, according to the still unpublished German patent application DE 10 2013 020 888.2 between the fresh material crushing roller press and a finely milled ball mill the static caution is switched so that only the cautious discharged coarse material of the ball mill is fed (and after grinding from there into the dynamic Classifier passes), while the sighted material there is passed directly to the dynamic classifier. The use of economically intensive ball mills is according to the teaching of the still unpublished German patent application DE 10 2014 010 065.0 thereby advantageously avoided that the coarse material discharged from the cautery is fed instead a running as a roller press second grinding device. After further grinding, it is then recirculated to the precautionary, until it is there classified and fed to the dynamic classifier. A disadvantage of this system - as well as in the aforementioned systems and systems with two initially completely separate circulation systems in which only the finished goods are brought together (see, for example, the unpublished German patent application DE 10 2013 019 840.2) - is that not with simple and rapidly executable, reproducible measures (for example during ongoing operation) influence on the particle size distribution (slope / width) of the finished goods can be taken. A change in the particle size distribution can here in addition to changes in the Frischgutzufuhr essentially and only within narrow limits regularly only by changing operating parameters of the grinding devices used (speed, contact pressure, etc.) and classifier (air flow, etc.) can be achieved.

The object of the invention is therefore to specify a method for operating a Kreislaufmahlanlage for grinding of fresh material, through which a flat particle size distribution can be achieved with a high fine-grained fraction in the finished product and in which by simple means in a relatively short time the grain Size distribution can be selectively varied. The object of the invention is also to provide a corresponding to the process Kreislaufmahlanlage for grinding fresh food available.

The object of the invention is achieved by a method for operating a Kreislaufmahlanlage for grinding fresh food with the features of claim 1 and by a Kreislaufmahlanlage for grinding fresh food with the features of claim 8. Further advantageous embodiments are specified in the subclaims to claim 1 and in the dependent claims to claim 8.

According to the invention, it is therefore provided that, in the method, the coarse material separated in the at least one static classifier is recirculated to the first grinding device. For this purpose, the at least one discharge opening of the at least one static classifier is connected to the material delivery device of the roller press. The transport can be done mechanically, for example by a bucket elevator, or - energetically cheaper and thus economically cheaper - pneumatically. In the two-stage screening process, the coarse material separated off in the static classifier does not claim the dynamic classifier, but is sent to a further comminution and kept in circulation in the grinding circuit until a sufficiently small particle size allows a view in the static classifier. The sighted visual material is then passed through a riser, suspended in the classifying air stream, to the dynamic classifier for the sake of indulgence. According to the invention, grinding of the ground grind of the second partial stream of ground grind is further provided. For this purpose, a second grinding device is connected downstream of the first dividing device, wherein the second grinding device is connected to the at least one entry opening of the at least one static classifier. At the first divider device, therefore, a partial flow ('second partial flow') is branched off from the flow of the ground regrind and fed into a separate partial circuit. In the second grinding device, preferably as a roller press. leads, the grinding material already ground in the first roller press is now over-ground, the expression of the "Übermahlens" refers here to the further comminution and not about a faulty operation of the grinding device means (in the sense of 'too much'). On the contrary, according to the invention such further comminution of the agglomerated slugs (of the second partial flow) is currently provided. The second grinding device, designed as a roller press, may be lower in performance than the first, since it has a lower throughput due to the partial flow formation than the first roller press. Furthermore, they already give pre-shredded good in them, while the Frischgutaufgabe takes place only in the first grinding device. If the second grinding device is also a roller press, it can therefore be operated on average at a lower speed than the first roller press.

The ground grinding material discharged from the second grinding device is, preferably gravity-fed, directed to the static classifier, where, like the first part-stream ground grinding material, it is placed in the entry opening for precaution. The advantage according to the invention therefore firstly lies in the fact that the visual material to be classified in the static classifier consists of several constituents which differ with respect to the particle size. Parts thereof are at least simply (in the first roller press) ground millbase, other components are ground in the first roller press (at least) once and additionally (at least) over-ground in the second mill. Together, this leads to a flatter particle size distribution, wherein in the case of cement production, the cement quality is improved by the fact that an increased fines content is given with smaller grain sizes. In addition, the second advantage is that the particle size distribution in the finished product can be influenced by very easy-to-use means, namely by controlling the first dividing device, for example as a splitter gate. The division of the ground grind on the described subcircuits, so in particular the amount that is supplied to a grinding, can be made variable and in the ongoing betheb be changed. This allows the skilled person, who strives for a high cement quality, to rapidly adjust both the Kreislaufmahlanlage to changing Frischgutbeschaffenheiten by varying the partial flow ratio at the first divider, as well as by varying the division ratios on an empirical basis to make experiments under which quantitative conditions the best cement qualities arise in finished goods. In addition there is the advantage that due to the multiple comminution in the circulations in the partial circuits, the first roller press does not already have to realize a particularly fine grinding. Thus, the speed and thus also the regrind throughput can regularly turn out to be slightly higher than in a comparable cycle grinding plant without a second grinding device.

In an advantageous embodiment of the invention, the at least one static classifier is given as a cascade classifier. Such a cascade classifier typically has a substantially V-shaped and shaft-shaped housing in which two Sichtzonenbegrenzungswände between them form a viewing zone. The walls have cascaded baffles. This has the advantage, over and above the actual visual process caused by the blown-in view air, that material deposited for sifting hits the baffles from above. The material emerging from roller presses in cement production is partly comminuted in the good bed, but partly also agglomerated, i. compressed into rags. Fall and impact of the slugs in the Cascade classifier have a disagglomerating effect. A predominantly fine- and medium-grained fraction is classified as Sichtgut and discharged with Sichtsichtluft this static caution from the Sichtgutaustrag. The coarse material falling against the air stream due to its gravity is discharged through a corresponding discharge opening and, according to the invention, recirculated to the first grinding device.

In a further advantageous embodiment of the invention, the at least one dynamic classifier is given as a dynamic rod basket sifter. Generic dy- Namely rod basket sifters have a satisfactory sighting efficiency and have proven themselves in operation. The stream of sifting air and the material to be sifted therein, the material to be sifted by the static custodian, is introduced via at least one visible material inlet into a generally spiral-shaped feeding device in which it is guided to a rotating rod basket. Its arranged over the circumference of the rod basket rods act as turbo elements that accelerate the Sichtluftstrom and therein Sichtgut. In the complex interaction of centrifugal forces and frictional forces in the air flow, the fines pass into the interior of the bar basket and are discharged as finished goods together with the classifying air (as exhaust air) through a fine material discharge opening. The fraction of the heavier grains is conveyed to the edge of the classifier zone and, for example, by gravitational action down as grits discharged through the Grobgutaustragsvornchtung and recirculated in the grinding circuit to the first grinding device, so abandoned in the crop delivery of this roller press.

A particularly advantageous embodiment of the invention provides that, between the second grinding device and the at least one static classifier, a second dividing device for dividing the millbase ground in the second mill into a millbase ground mill and a second partial stream of ground millbase in a variably adjustable millbase Ratio is arranged. The divider arrangement arranged here is provided, for example, as a splitter gate, by means of which the volumetric ratio between the two mutually separated substreams can be adjusted in a targeted manner and varied in tests by the skilled person, as proves to be advantageous for the desired particle size distribution in the finished product. The first part-stream of ground millbase is then fed to the at least one static classifier for precaution, that is, for example gravity-induced, in the usual way through the connecting line existing between the second mill and the static cautery. The second partial stream of ground millbase is recirculated as a bypass stream directly to the first mill. This provides a further possibility to influence the particle size distribution of the product in favor of a flatter distribution. A certain portion of the ground material to be quantitatively determined by the skilled person in experiments is passed here as a bypass past the static precautionary agent and instead returned directly to the first grinding device designed as a roller press. This can be done in suitable union with the coarse material stream coming from the static sifter. By this bypass passes once over-grinding material in the first grinding device, where it is crushed and is then proportionately redirected by splitting at the first divider to the second grinding device. Here, therefore, takes place a second oversize. This process is iterated by further loop runs, although, in the usual case, with the number of revolutions, the proportion of mill grinds ground several times rapidly reduces to negligibly small quantities. Nevertheless, it has surprisingly been found that the proportionately double and multiple overmilling caused by the bypass has a favorable influence on the particle size distribution of the finished product.

In order to exploit the gravitational effect economically and constructively simply for material transport in the circuit, in one embodiment of the invention the second grinding device is arranged below the first grinding device and above the static classifier, ie below the nip between the rollers of the first grinding device and above the entry opening static sifter, designed as a V-shaped cascade sifter. The second grinding device may be given as a ball mill or as an impact hammer mill. In a preferred embodiment of the invention, however, it is provided that the second grinding device is designed as a roller press. The use of roller presses with their high-pressure comminution is usually by comparatively lower energy and thus cost, characterized by less susceptibility to interference, thus less need for repair and maintenance, as well as a higher material throughput. The roller press has a speed-controlled drive. The roller press can be dimensioned smaller in the grinding circuit according to the invention in accordance with the respective typical proportion of the material flow to be comminuted by it than the roller press of the first grinding device. With regard to the advantages of the method according to the invention, it can be stated that a flat particle size distribution or a wide grain band can also be achieved with exclusive use of roller presses in the Kreislaufmahlanlage, although on the one hand, while economically favorable and comparatively low maintenance roller presses on the other hand often rather narrow Produce grain belts.

When loading the first grinding device, it may in particular due to changes in the amount of recirculated Gutanteils to

Fluctuations in the application of regrind come directly to changes in the level height in the shaft-like crop delivery device above the nip, takes place in the generic roller presses between the rollers or rolls the Gutbettzerkleinerung. The actual value of the filling level can be measured in its time course in various previously known ways, for example with pressure cans. For a suitable operation of the roller press, however, the amount of ground material fed there per unit time should not exceed specific upper and lower limits. If the feed quantity is too low, the crushing effect of the roller press comes to a standstill due to insufficient pressure. Too large an amount of feed leads to backwater and overflow in the cropping device. For the continuous realization of a suitable target value, an embodiment of the invention therefore provides for the level of the material to be ground fed into the material feeding device of the first grinding device (consisting of the fresh product, the semolina, the separated coarse material and, in the case of the existence of the described bypass in material flow direction behind the second grinding device - to control from the over-ground regrind of the bypass stream in a control loop with the mass flow of the abandoned fresh material as a manipulated variable. Changes in the amount of fresh food supplied lead both directly to task in the Gutaufgabeschacht the first grinding device to a change in the local level and with a corresponding time delay by the resulting change in the amount of recirculated in the circulation to her material. The amount / mass of the fresh material fed per unit time of the first grinding device can be adjusted by the speed of the conveyor belts used, but in particular by pre-switching corresponding per se known throttling or metering devices, such as a feeder belt.

In the preferred case, the second grinding device is given in the grinding circuit as a roller press. As with the first roller press is also for a trouble-free, effective operation of the second roller press the actual value of the level of the supplied grind, ie the ground grind of the second, coming from the first grinder ago partial flow in Gutaufgabeschacht above the nip within specific upper - And lower limits, ie in sufficiently small difference to a suitable setpoint, to lead. An advantageous embodiment of the invention therefore provides to regulate the level of the given in the cropping device of the second grinding device, ground millbase of the second part stream ground millbase in a control loop with the speed of the roller press as a manipulated variable. The amount of material supplied per unit time of the second grinding device in a given mode of operation depends on the amount of fresh material fed into the grinding cycle, but in particular on the distribution ratio of the ground material to be ground by the dividing device after the first grinding device. The setting of this ratio is thereby carried out by the person skilled in the art from the point of view of achieving a desired particle size distribution curve in the finished product. well done. As a result of correspondingly brought about variations, in particular at the dividing device, fluctuations in the crop feed quantity of the second roller press therefore have to be compensated for their operation. The level in the material feed chute, measured for example by pressure cans, is dependent on the throughput in the nip, and the flow rate can be influenced by the rotational speed of the rollers, ie by the speed of the roller drive.

In the case that the second grinding device is not as a roller press, but, for example. As a ball mill or impact hammer mill, given analog control loops are provided which dose the feed quantity to the second grinding device in a suitable manner.

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

Fig. 1 shows a Kreislaufmahlanlage invention in a schematic representation in the embodiment with second roller press and bypass.

In Figure 1, the Kreislaufmahlanlage invention and the corresponding method for their operation in one embodiment are shown schematically. Fresh material 1 is fed into the multi-part grinding cycle by feeding it to the material-feeding device 2 of the first grinding device 3, which is designed as a roller press (high-pressure roller press, good-bed roller mill). In the material dispensing device 2 is formed by the supplied fresh material 1 and in the grinding circuit recirculated material a level 4, which can be determined, for example, by pressure boxes or other known for this purpose measuring devices at any time. In a preferred embodiment, the level 4 is controlled in a control loop so that it is suitable for the operation of the roller press 3, ie for the comminution in the nip. As a manipulated variable here is the supplied mass flow of the fresh material 1 by suitable Dosiermaßnah- For example, with the aid of an upstream weighfeeder (not shown), adjusted accordingly. Down comes out of the nip between the counter-rotating rollers of the roller press 3 ground millbase 5. In the case of cement production, the ground regrind 5 is partly in the form of agglomerated flakes. In the dividing device 6, the stream of ground millbase 5 is divided into a first part-stream ground millbase 7 and a second part-stream ground millbase 8. The ratio The amount-related distribution between the two partial streams ground grinding material 7, 8 is controlled by the expert by a setting on the first divider 6 so that ultimately sets the finished grain size 9 the desired particle size distribution. The variable adjustment also offers both ways to adapt the Kreislaufmahlanlage to different textures of the fresh material 1, as well as to bring about variations in the particle size distribution of the finished good 9 in a test operation of the plant. In the usual case, the first partial stream of ground grind 7 will be stronger than the second partial stream of ground grind 8.

The first part-stream milled ground material 7 is guided in the manner known by already existing Kreislaufmahlanlagen to a static classifier 10, which is arranged for a lower, because gravity-assisted material transport height related below the first grinding device 3 and first divider 6. The static classifier 10 is given in the case of execution as a V-shaped cascade classifier and fulfills the function of a precaution in the grinding circuit. The material to be sighted of the first part-stream ground material 7 enters through an entry port 1 1 in the static classifier 10, there is at least partially disagglomerated and emerging from the Sichgutaustrag 12, predominantly fine and medium-grained fraction of Sichtgutem Sichtgut 13 and in a from the discharge opening 14 downwardly emerging coarse-grained fraction of separated coarse 15 separated.

The sighted material 13 discharged from the static sifter 10 together with the classifying air 16 is pneumatically, i. Suspended in the flow of the classifying air 16, passed through a riser 17 to the Nachsichtvorgang to the dynamic classifier 18. This transport path can also be done mechanically, for example by a bucket elevator, but this is generally unfavorable in terms of energy and maintenance. The stream of classifying air 16 and classified Sichtgut 13 enters via a Sichtguteintritt 19 in the typically designed as Stabkorbsichter dynamic classifier 18 a. As a result of the screening process, a still coarser fraction, the meal 20, leaves the coarse material discharge device 21 downwards out of the dynamic classifier 18. The meal 20 is recirculated in the grinding circuit to the material feeding device 2 of the first grinding device 3. In order to make this transport route economically favorable, the dynamic classifier 18 is arranged in height above the first grinding device 3. Furthermore, the fine-grained finished product 9, which is still being suspended in the flow of classifying air 16, is discharged from the dynamic classifier 18 by the fine-material discharge device 22. For a recovery of the desired fine finished good 9 of the classifying air 16-finished 9-stream is passed into a cyclone 23, where the finished good 9 is separated according to the principle of a centrifugal separator of the classifying air 16. This is discharged as exhaust air 24 either in the surrounding atmosphere (in compliance with environmental guidelines) or it can, for example, with fan help, advantageously returned to the static classifier 10, where it is injected after suitable compression as a classifying air (not shown here).

The separated coarse material 15 emerging from the static separator 10 is recirculated mechanically or preferably also pneumatically for a further comminution process to the first grinding device 3, whereby a second partial circuit is formed in the Kreislaufmahlanlage. The separated coarse good is given up together with the fresh material 1 in the crop delivery device 2 of the roller press 3.

According to the method according to the invention, a second grinding device 25 is integrated into the cycle grinding plant, which is preferably also present in the illustrated embodiment as a roller press. This can be kept smaller than the first roller press 3 because of the lower material throughput. The second partial stream ground millbase 8 branched off at the first dividing device 6 is guided into the crop delivery device 26 of the second grinding device 25. Advantageously, the second grinding device 25 is arranged vertically below the nip of the first roller press 3. In the second grinding device 25, there is a further comminution (here: comminuted comminution) of the slugs of the second substream of ground millbase 8, the so-called over-grinding. From the nip of the second grinding device 25 now further comminuted, so oversized grinding material 27 exits. This millbase 27 consisting of smaller particles than millbase ground in the first part-stream 7 is now passed to the static classifier 10 for precaution, where it is fed into the entry opening 11 together with the first part-stream ground millbase 7. This completes a further partial loop in the Kreislaufmahlanlage. In order to enable gravity-induced transport of the ground meal 27, the second grinding device 25 (with its nip) height above the entry opening 1 1 of the static separator 10 is arranged.

The quantity of ground material 8 ground in the second part-stream, which is supplied to the second grinding device 25, is set by the person skilled in the art in terms of an optimum particle size distribution in the finished product 9 and will suitably vary under particular circumstances. In order to continuously adjust a level 28 suitable for the operation of the second grinding device 25, which is given as a roller press, in its material delivery device 26, the level 28 of the second grinding device 25 is continuously fed by suitable measuring means, eg pressure cans. determined and integrated into a control loop. The manipulated variable here is the speed of the roller press 25. If the rollers of the roller press 25 are driven, for example, at a higher speed, their increased rotational speed increases the entry into the nip and the material throughput and thus reduces the level 28 in the material delivery device 26.

In the illustrated embodiment of the method according to the invention, a further measure for increasing the adjustment possibilities of the particle size distribution in the finished product 9, in particular in favor of a flatter particle size distribution, is provided. In material flow direction after the second grinding device 25, a second dividing device 29 is arranged, which divides the ground millbase 27 in a first partial flow ground mill 30 and a second partial flow of ground mill 31 in a quantitative ratio to each other, the expert in terms of the particle size distribution in the finished product. 9 can be set variably at the example. As splitter gate running second divider 29. While the first partial flow of ground meal 30, as heretofore described for the basic form of the process, is passed to the static classifier 10 for caution, the second partial flow of ground meal 31 passes as a bypass past the static classifier 10 and directly for further comminution to the first milling device 3 led. He can, if this allows the geometry of Kreislaufmahlanlage advantageous, on the transport path with the stream of separated in the static separator 10 coarse material 15 are combined. In this way, portions of the bypass 31 can even be over-milled two times (or even multiply in a strongly decreasing proportion iteratively), which overall contributes to a flattening of the particle size distribution spectrum.

The means used in the Kreislaufmahlanlage, so primarily the settings of the two divider devices 6, 29, allow a simple as well as variable and fast influencing or optimizing the quality of the finished good 9, which is particularly advantageous in cement production. LIST OF REFERENCE NUMBERS

Fresh goods 16 Classifying air

Gutaufgabevorrichtung (first 17 riser

grinder)

18 dynamic sifter first grinding device / Rol¬

19 visible goods entry

lenpresse

20 grotes

Level (first Mahlvorrich¬

21 coarse material discharge device)

22 fine material discharge device ground regrind

23 cyclone

first divider

24 exhaust air

first part stream (ground

Regrind) 25 second grinding device second partial flow (gemahle26 crop feed device nes regrind) (second grinding device)

Finished good 27 Overground regrind static sifter 28 Level (second grinder)

entry opening

29 second divider

Sichtgutaustrag

30 first partial flow (übermahle¬

Visual goods (selected)

regrind)

discharge

31 second partial flow / bypass

Coarse material (ground regrind)

Claims

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

Method for operating a Kreislaufmahlanlage for grinding fresh food (1),

having the steps

Comminuting the fresh material (1) to ground millbase (5) in a first grinding device (3) designed as a roller press,

Dividing the ground millbase (5) into a first part-stream ground millbase (7) and a second part-stream ground millbase (8) in a variably adjustable ratio,

Precaution of the first part stream ground millbase (7) in at least one arranged below the first grinding device (3) static separator (10), wherein selected Sichtgut (13) and separated coarse material (15) separated from the at least one static separator (10) discharged be, pneumatic transporting of in a classifying air flow (16) sus- pensierten, exposed Sichtguts (13) by a riser (17) to at least one above the first grinding device (3) arranged dynamic classifier (18),

Indulgence of the exposed Sichtguts (13) in the at least one dynamic sifter (18), wherein separated from one another Grieße (20) and a stream of sifted Fertiggut (9) and Sichtluft (16) from the at least one dynamic classifier (18) are discharged and

Recirculating the meal (20) to the first grinding device (3), characterized by

Recirculating the coarse material (15) separated in the at least one static separator (10) to the first grinding device (3),

Crushing the ground material to be ground of the second part-stream ground millbase (8) in a second grinding device (25) to be ground millbase (27), and

Precaution of the ground meal (27) in the at least one static classifier (10).

2. The method of claim 1, wherein the at least one static classifier (10) is designed as a cascade classifier (10), and wherein the at least one dynamic classifier (18) is designed as a dynamic rod basket classifier (18).

3. The method according to one of claims 1 or 2, characterized by

Dividing the millbase (27) ground in the second grinding device (25) into a first partial flow of ground material (30) and a second partial flow of ground millbase (31) in a variably adjustable ratio, wherein the first partial flow passes over ground millbase (30) for precaution the at least one static classifier (10) is guided, and the second partial stream of ground millbase (31) is recirculated as bypass stream (31) directly to the first grinding device (3).

4. The method according to any one of claims 1 to 3, wherein the running as a roller press first grinding device (3) has a crop delivery device (2) above a provided for the comminution crushing roller gap, and wherein the level (4) of the in the crop delivery device (2) of first grinding device (3) given, to be ground Guts (consisting of the fresh material (1), the grits (20), the separated coarse material (15) and possibly from the milled ground material of the bypass stream (31)) in a control loop with the mass flow of the abandoned fresh material (1) is regulated as a manipulated variable.

5. The method according to any one of claims 1 to 4, wherein the second grinding device (25) as a roller press (25) which is arranged below the first grinding device (3) and above the static separator (10) is executed.

6. The method according to any one of claims 1 to 4, wherein the second grinding device (25) is a ball mill or an impact hammer mill.

7. The method according to any one of claims 1 to 5, wherein the roller press as a (25) executed second grinding device

(25) a variable speed drive and a crop delivery device

(26) above a rolling gap provided for the comminution grinding, and wherein the level (28) of the in the Gutaufgabevorrichtung (26) of the second grinding device (25) abandoned, ground millbase of the second part stream ground grinding material (8) in a control loop at the speed the roller press (25) is regulated as a manipulated variable.

8. Kreislaufmahlanlage for grinding fresh food (1), comprising a first, designed as a roller press grinding device (3) for Gutbettzerkleinerung of the fresh material (1) to be ground millbase (5), a first dividing device (6) for dividing the ground millbase (5) into a first part-stream ground millbase (7) and a second part-stream ground millbase (8) in a variably adjustable ratio, at least one static classifier below the first miller (3) (10) for the preparation of the first part-stream milled ground material (7) with at least one entry opening (1 1) for the ground material (7), a Sichtgutaustrag (12) for the discharge of sifted Sichtgut (13) and with at least one discharge opening (14) for the discharge of separated coarse material (15), and at least one above the first grinding device (3) arranged dynamic classifier (18) for the indentation of the at least one static classifier (18) exposed Sichtguts (13) with a Sichtguteintritt ( 19) for the entry of a stream of classifying air (16) and the exposed Sichtgut (13), a Grobgutaustragsvor- direction (21) for the Discharge of meal (20) and with a fine material discharge device (22) for the discharge of a stream of selected finished goods (9) and classifying air (16), wherein the Sichtgutaustrag (12) of the static classifier (10) with the Sichtguteintritt (19) the at least one dynamic sifter (18) is connected by a riser (17) for the pneumatic transport of the sighted material (13) suspended in a classifying air stream (16), and wherein the coarse material discharge device (21) of the dynamic classifier (18) is provided with a crop delivery device (2) the first grinding device (3) for the recirculation of the cereals (20) is in communication, characterized in that the at least one discharge opening (14) of the at least one static classifier (10) is in communication with the crop delivery device (2) of the first grinding device (3) for recirculation of the separated coarse material (15), and the first dividing device (6) a second grinding device (25) for comminuting the ground millbase of the second part stream of ground millbase (8) to be ground millbase (27) is downstream, wherein the second grinding device (25) with the at least one entry opening (1 1) of the at least one static classifier ( 10) for the preparation of the milled ground material (27) is in communication.

9. Kreislaufmahlanlage according to claim 8, characterized in that between the second grinding device (25) and the at least one static separator (10), a second divider (29) for dividing the grinding in the second grinding device (25) ground material (27) in a first Partial flow of ground grind (30) and a second partial flow of ground grind (31) is arranged in a variably adjustable ratio, wherein a guiding of the first partial flow of ground grind (30) is provided to the at least one static separator (10) for precaution, and a recirculation of the second partial flow of ground mill material (31) is provided as a bypass flow (31) directly to the first grinding device (3) for comminuted comminution.

Kreislaufmahlanlage according to any one of claims 8 or 9, characterized in that the second grinding device (25) below the first grinding device (3) and above the static classifier (10) is arranged, wherein the second grinding device (25) as a ball mill or as impact hammer mill or is preferably designed as a roller press.