DE102015001404B3 - Kreislaufmahlanlage with two grinders and method for operating the Kreislaufmahlanlage - Google Patents

Abstract

The invention relates to a method for operating a Kreislaufmahlanlage for grinding of fresh material (1), comprising the steps of crushing the fresh material (1) to ground millbase (5) in a first, designed as a roller press grinding device (3), dividing the ground millbase (5 into a first and second partial flow (7, 8) in a variably adjustable ratio, precautions of the first partial flow (7) in a static sifter (10) arranged below the first grinding device (3), with sighted material (13) being separated and separated coarse material (15), pneumatic transport of the exposed Sichtguts (13) to a above the first grinding device (3) arranged dynamic classifier (18), indulgence of the exposed Sichtguts (13), wherein cereal (20) and finished product (9) are discharged , and recirculating the meal (20) to the first grinding device (3). The invention further relates to a corresponding Kreislaufmahlanlage. According to the invention, a recirculation of the separated coarse material (15) to the first grinding device (3), comminution of the ground product of the second part stream (8) in a second grinding device (25) to be ground mill (27) and a pre-grinding of the ground material (27 ) in the static separator (10).

Description

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, with selected Sichtgut and separated coarse material separated from the at least one static classifier, pneumatically transporting 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 method Kreislaufmahlanlage for grinding of fresh goods, comprising a first, designed as a roller press grinding bed for comminuting the fresh material to ground regrind, a first dividing device for dividing the ground millbase ground millbase ground mill and a second part stream Grindings in a variably adjustable ratio, at least one arranged below the first grinding static sifters for the preparation of the first part flow milled grind with at least one entry opening 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 arranged above the first grinding device dynamic classifier for the protection of the sight of the at least one static classifier Sichtgut with a Sichtguteintritt for the entry of a stream of Sichtluft and the exposed Sichtgut, a Grobgutaustragsvorrichtung for the discharge of grits and with a fines discharge device for discharging a stream of selected finished goods and classifying air, wherein the Sichtgutaustrag the static classifier with the Sichtguteintritt the at least one dynamic classifier is connected by a riser for pneumatic transport of the sighted material suspended in a classifying air stream, and wherein the coarse material discharging device of the dynamic classifier is in communication with a crop feeding device of the first grinder recirculating grinding device.

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 emerging from the nip after the stress material consists of a finer-grained fraction and a coarse material fraction only slightly crushed and / or crushed to slugs material. 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 classifier, e.g. B. a dynamic rod basket sifter, which is preceded by a static, often also disagglomerating 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 reintroduce a renewed compressive stress of the grinding device, as in DE 102 21 739 A1 proposed. However, if in addition to the fresh produce a comparatively large amount of a small and Medium grained Good, which is discharged from the static classifier, enters the roller press, it may lead to ventilation and material pressing difficulties in the nip of the roller press, which may affect the operation of the roller press or the grinding result (also in terms of 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, such as, as in the DE 34 07 535 A1 It is taught that a fine bed roller mill is preceded by a pulverizing grinding device (eg ball mill) for pre-shredding. Procedural improvements can then be achieved by dividing into two partial cycles. Thus, according to the post-published German patent application DE 10 2013 020 888 A1 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 is fed to the ball mill (and passes from there into the dynamic classifier after grinding), while the there sighted Sichtgut directly to the dynamic classifier is directed. The use of economically intensive ball mills is according to the teaching of the post-published German patent DE 10 2014 010 065 B3 thereby advantageously avoided that the coarse material discharged from the caution is fed to a second grinding device instead designed as a roller press. 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 post-published German patent application DE 10 2013 019 840 A1 ) - is that it is not possible to influence the particle size distribution (steepness / width) of the finished product with simple and quickly executable, reproducible measures (eg during operation). 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.

In the German translation DE 689 12 012 T2 the European patent specification EP 0 352 192 B1 is a method for operating a Kreislaufmahlanlage for grinding of fresh goods is known in which the fresh material is ground in a first, designed as a roller press grinder. In this case, the ground millbase is divided into a first partial flow and a second partial flow in a variable ratio. The first partial stream is predisposed in a static separator arranged below the first grinding device. The sighted material to be separated and the separated coarse material are discharged separately from the static classifier and the sighted material to be classified is passed via a riser to a dynamic classifier arranged above the first grinding device. Finally, the sighted visual material is re-sized in the dynamic sifter, wherein separately from each other grits and a stream of sifted finished goods and classifying air are discharged from the dynamic sifter. The grits are recirculated to the first grinding device, wherein the coarse material separated in the static separator is recirculated in the first grinding device, and the ground material to be ground of the second part stream is ground in a second grinding device to be ground grind.

The object of the invention is therefore to provide 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 particle 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 mechanical, z. B. by a bucket elevator, or - energetically cheaper and thus economically cheaper - done 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 classified Sichtgut is then suspended by a riser in the classifying air stream, directed 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 ground millbase and guided into a separate partial circuit. In the second grinding device, preferably embodied as a roller press, the ground material already ground in the first roller press is now ground, the expression of the "overmilling" here referring to the further comminution and not an incorrect operation of the grinding device (in the sense of one, too much ') means. 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. Added to this is the second advantage that the particle size distribution in the finished product by very easy-to-use means, namely by controlling the first divider, z. B. given as Splittergate, can be influenced. 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 also changed during operation. 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 during cement production is partly comminuted in the good bed, but partly also agglomerated, d. H. compressed into scabs. 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 flow by its gravity is discharged through a corresponding discharge opening and recirculated according to the invention 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 dynamic rod cage sifters have satisfactory screening efficiency and have proven themselves in operation. The stream of sifting air and the material to be sifted therein, the exposed material of the static guardian, 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 enter the interior of the Bar basket and is 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, discharged by gravitational action down as grits through the Grobgutaustragsvorrichtung and recirculated in the grinding circuit to the first grinding device, so abandoned in the Gutaufgabevorrichtung 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 ground material ground in the second grinding device into a first partial flow ground millbase and a second partial flow of ground millbase arranged in a variably adjustable ratio is. 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 of the static classifier, executed as a V-shaped cascade classifier. 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 characterized by comparatively lower energy and thus cost, by lower susceptibility to interference, thus less need for repair and maintenance and by 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 fluctuations in the application of regrind come directly to changes in filling level in the shaft-like crop delivery above the nip, in the generic roller presses between the rollers or Rolling the Gutbettzerkleinerung takes place leads. 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 filling level of the charge agent fed to the material-feeding device of the first grinding device grinding stock (consisting of the fresh material, the grits, the separated coarse material and - in the case of passing the described bypass in the material flow direction behind the second grinding device - from the overground millbase of the bypass stream) in a control loop with the mass flow of the abandoned fresh material to be controlled 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, d. H. in a 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 made by the skilled person from the point of view of achieving a desired grain size distribution curve in the finished product. 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:

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

In 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 the crop feeder 2 the first, as roller press (high-pressure roller press, high-bed roller mill) running grinding device 3 is supplied. In the goods handler 2 forms through the supplied fresh goods 1 and in the grinding circuit recirculated material a level 4 For example, which can be determined at any time by pressure cans or other measuring devices known for this purpose. In a preferred embodiment, the level is in a control loop 4 so regulated that he for the operation of the roller press 3 , ie for the Gutbettzerkleinerung in the nip, is suitable. The manipulated variable here is the supplied mass flow of the fresh material 1 by appropriate dosing, eg. With the aid of an upstream dosing belt weigher (not shown), adapted accordingly. Down comes out of the nip between the counter-rotating rollers of the roller press 3 ground regrind 5 out. The ground regrind 5 in the case of cement production is partly in the form of agglomerated slugs. In gravity-induced transport, the stream passes through ground grinding stock 5 first a z. B. executed as splitter gate, first divider 6 , In the divider 6 the stream becomes ground regrind 5 divided into a first part-stream ground millbase 7 and a second partial stream of ground meal 8th , The ratio of the volume-related distribution between the two partial streams of ground material 7 . 8th by the expert by a setting on the first divider 6 so controlled that ultimately in finished goods 9 sets the desired particle size distribution. The variable adjustment also offers both possibilities, the Kreislaufmahlanlage different textures of the fresh material 1 as well as variations in the particle size distribution of the finished product 9 in a test operation of the plant cause. In the usual case, the first partial stream of ground millbase 7 stronger than the second partial stream of ground regrind 8th ,

The first partial stream of ground meal 7 becomes a static sifter in the manner already known by existing Kreislaufmahlanlagen 10 led, for a more favorable, because gravity-assisted material transport height related below the first grinding device 3 and first divider 6 is arranged. The static sifter 10 is given in the case of execution as a V-shaped cascade classifier and fulfills the function of a precaution in the grinding cycle. The goods to be sighted of the first partial flow of ground material 7 enters through an entry port 11 in the static classifier 10 a, is there at least partially disagglomerated and in one of the Sichgutaustrag 12 emerging, predominantly fine and medium-grained fraction of sifted Sichtgut 13 and in one of the discharge opening 14 Downstream emerging coarse fraction of separated coarse material 15 separated.

That along with the classifying air 16 from the static sifter 10 discharged, oriented Sichtgut 13 becomes pneumatic, ie suspended in the stream of the classifying air 16 through a riser 17 to the forbearance process to the dynamic classifier 18 directed. 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 sighted air 16 and sighted visual goods 13 occurs via a Sichtguteintritt 19 in the typically as Stabkorbsichter running dynamic classifier 18 one. As a result of the sighting process occurs a still coarser fraction, the Greeße 20 , from the coarse material discharge device 21 down from the dynamic classifier 18 out. The grits 20 becomes a cropping device in the grinding cycle 2 the first grinding device 3 recirculated. To make this transport economical way, the dynamic classifier 18 heightwise above the first grinding device 3 arranged. Further, by the fines discharge device 22 the fine-grained finished product, which was selected during the process of hindrance 9 , still suspended in the stream of classifying air 16 , from the dynamic classifier 18 discharged. For obtaining the desired fine finished good 9 the classifying air is 16-finished 9-stream into a cyclone 23 led where the finished product 9 on the principle of a centrifugal separator of the classifying air 16 is disconnected. This is called exhaust air 24 either in the surrounding atmosphere (in compliance with environmental guidelines) delivered or they can, for example with fan help, advantageous for static sifter 10 be returned where it is injected after suitable compression as a classifying air (not shown here).

That from the static sifter 10 emerging, separated coarse material 15 is mechanically or preferably also pneumatically for a further crushing operation to the first grinding device 3 recirculates, whereby a second partial circuit is formed in the Kreislaufmahlanlage. The separated coarse material is combined with the fresh product 1 into the material handler 2 the roller press 3 given up.

According to the method according to the invention is in the Kreislaufmahlanlage a second grinding device 25 integrated, which is preferred and also given in the illustrated embodiment as a roller press. This can be kept smaller than the first roller press because of the lower material throughput 3 , Into the cropping device 26 the second grinding device 25 becomes the at the first divider 6 branched, second partial flow ground regrind 8th guided. Advantageous for this is the second grinding device 25 heightwise below the nip of the first roller press 3 arranged. In the second grinding device 25 finds another crushing (here: Gutbettzerkleinerung) of the slugs of the second part stream ground millbase 8th instead, the so-called over-grinding. From the nip of the second grinding device 25 Now continue to crushed, so over-ground regrind 27 out. This from smaller particles than in the first part of the ground grinded meal 7 existing, ground millbase 27 now becomes the precautionary to the static classifier 10 where it is ground together with the first part of the ground grind 7 in the entry opening 11 is abandoned. This completes a further partial loop in the Kreislaufmahlanlage. To a gravity-induced transport of the ground meal 27 to enable is the second grinding device 25 (with their nip) height above the entry opening 11 of the static classifier 10 arranged.

The amount of milled in the second partial flow regrind 8th , that of the second grinding device 25 is supplied to the expert in terms of an optimal particle size distribution in the finished product 9 and will vary these under appropriate circumstances suitable. To a given for the operation of the roller press, second grinding device 25 suitable level 28 in their Gutaufgabevorrichtung 26 continuously adjust, the level is 28 the second grinding device 25 continuously by suitable measuring means, for. B. pressure cans determined and integrated into a control loop. The manipulated variable here is the rotational speed of the roller press 25 on. Be the rollers of the roller press 25 z. B. driven at a higher speed, so are increased by the increased rotational speed of the indentation in the nip and the material flow rate and thus the level 28 in the material handler 26 reduced.

In the illustrated embodiment of the method according to the invention is a further measure to increase the adjustment possibilities of the particle size distribution in the finished product 9 , in particular in favor of a flatter particle size distribution provided. In material flow direction after the second grinding device 25 is a second divider 29 arranged, which is the ground millbase 27 in a first partial flow of ground grind 30 and a second partial flow of ground millbase 31 in a quantitative ratio to each other, the expert in terms of the particle size distribution in the finished product 9 at the example. As Splittergate executed second divider 29 can be set variably. During the first partial flow of ground meal 30 as previously described for the basic form of the method, for a precautionary to the static classifier 10 is guided, the second partial flow is ground grinding material 31 as a bypass on the static separator 10 over and directly to the recent comminution to the first grinding device 3 guided. He can, if this allows the geometry of Kreislaufmahlanlage advantageous, on the transport path with the current of the static separator 10 separated coarse material 15 to be united. Shares of the bypass 31 In this way, it is even possible to grind twice (or in multiply decreasing proportion iteratively several times), which as a whole 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 optimization possibility of the quality of the finished goods 9 , which is particularly advantageous in cement production.

LIST OF REFERENCE NUMBERS

1

fresh material

2

Gutaufgabevorrichtung (first grinding device)

3

first grinding device / roller press

4

Level (first grinding device)

5

ground regrind

6

first divider

7

first partial flow (ground regrind)

8th

second partial flow (ground regrind)

9

finished product

10

static sifter

11

entry opening

12

Sichtgutaustrag

13

Visual goods (selected)

14

discharge

15

oversize

16

classifying air

17

riser

18

dynamic sifter

19

Sichtguteintritt

20

tailings

21

Grobgutaustragsvorrichtung

22

Feingutaustragvorrichtung

23

cyclone

24

exhaust

25

second grinding device

26

Gutaufgabevorrichtung (second grinding device)

27

ground regrind

28

Level (second grinding device)

29

second divider

30

first partial flow (overground regrind)

31

second partial flow / bypass (ground regrind)

Claims (10)

Method for operating a Kreislaufmahlanlage for grinding fresh food ( 1 ), comprising the steps - chopping the fresh product ( 1 ) to ground regrind ( 5 ) in a first grinding device designed as a roller press ( 3 ), - splitting of the ground material ( 5 ) in a first partial flow milled ground material ( 7 ) and a second partial stream of ground millbase ( 8th ) in a variably adjustable ratio, - precalculations of the first part-stream ground millbase ( 7 ) in at least one below the first grinding device ( 3 ) arranged static classifier ( 10 ), whereby sighted visual material ( 13 ) and separated coarse material ( 15 ) separated from each other from the at least one static classifier ( 10 ), - pneumatic transport of the in a classifying air stream ( 16 ) suspended, 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 sight ( 13 ) in the at least one dynamic classifier ( 18 ), where separately ( 20 ) and a stream of classified finished goods ( 9 ) and classifying air ( 16 ) from the at least one dynamic classifier ( 18 ), and - Recirculating the greek ( 20 ) to the first grinding device ( 3 ), characterized by - recirculating in the at least one static separator ( 10 ) separated coarse material ( 15 ) to the first grinding device ( 3 ), - crushing of the ground regrind of the second partial stream of ground millbase ( 8th ) in a second grinding device ( 25 ) to be ground ( 27 ), and - precautions of the ground material ( 27 ) in the at least one static separator ( 10 ). Method according to claim 1, - wherein the at least one static separator ( 10 ) as cascade classifier ( 10 ), and - wherein the at least one dynamic classifier ( 18 ) as a dynamic rod cage sifter ( 18 ) is executed. Method according to one of claims 1 or 2, characterized by dividing the in the second grinding device ( 25 ) ground millbase ( 27 ) in 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 of ground millbase ( 30 ) for precaution to the at least one static classifier ( 10 ), and - the second partial flow of ground millbase ( 31 ) as a bypass current ( 31 ) directly to the first grinding device ( 3 ) is recirculated. Method according to one of claims 1 to 3, - wherein the first grinding device designed as a roller press ( 3 ) a material delivery device ( 2 ) above a rolling gap provided for the comminution, and - wherein the level ( 4 ) of the material delivery device ( 2 ) of the first grinding device ( 3 ) abandoned, to be grounded Guts (consisting of the fresh goods ( 1 ), the Greek ( 20 ), the separated coarse material ( 15 ) and possibly from the oversized regrind 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. Method according to one of claims 1 to 4, wherein the second grinding device ( 25 ) as a roller press ( 25 ), which are below the first grinding device ( 3 ) and above the static classifier ( 10 ) is arranged is executed. Method according to one of claims 1 to 4, wherein the second grinding device ( 25 ) is a ball mill or an impact hammer mill. Method according to one of claims 1 to 5, - wherein the roller press ( 25 ) carried out second grinding device ( 25 ) a variable-speed drive and a crop delivery device ( 26 ) above a rolling gap provided for the comminution, and - wherein the level ( 28 ) of the material delivery device ( 26 ) of the second grinding device ( 25 ) abandoned, ground regrind of the second part stream ground millbase ( 8th ) in a control loop at the speed of the roller press ( 25 ) is regulated as a manipulated variable. Kreislaufmahlanlage for grinding fresh food ( 1 ), comprising - a first grinding device designed as a roller press ( 3 ) for Gutbettzerkleinerung of Frischguts ( 1 ) to ground regrind ( 5 ), - a first splitter device ( 6 ) for the division of the ground regrind ( 5 ) in a first partial flow milled ground material ( 7 ) and a second partial stream of ground millbase ( 8th ) in a variably adjustable ratio, - at least one below the first grinding device ( 3 ) arranged static classifier ( 10 ) for the preparation of the first part-stream ground millbase ( 7 ) with at least one entry opening ( 11 ) for the ground regrind ( 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 protection of the at least one static separator ( 18 ) exposed Sichtguts ( 13 ) with a Sichtguteintritt ( 19 ) for the entry of a stream of classifying air ( 16 ) and the exposed Sichtgut ( 13 ), a coarse material discharge device ( 21 ) for the export of grits ( 20 ) and with a fines discharge device ( 22 ) for the discharge of a stream of classified finished goods ( 9 ) and classifying air ( 16 ), whereby - the Sichtgutaustrag ( 12 ) of the static classifier ( 10 ) with the visible goods entry ( 19 ) of the at least one dynamic classifier ( 18 ) by a riser ( 17 ) for the pneumatic transport of the in a classifying air stream ( 16 ) suspended, exposed Sichtguts ( 13 ), and wherein - the coarse material discharge device ( 21 ) of the dynamic classifier ( 18 ) with a material delivery device ( 2 ) of the first grinding device ( 3 ) for the recirculation of the grits ( 20 ), characterized in that - the at least one discharge opening ( 14 ) of the at least one static classifier ( 10 ) with the material delivery device ( 2 ) of the first grinding device ( 3 ) for the recirculation of the separated coarse material ( 15 ), and - the first division ( 6 ) a second grinding device ( 25 ) for comminuting the ground regrind of the second substream of ground millbase ( 8th ) to be ground ( 27 ), wherein the second grinding device ( 25 ) with the at least one entry opening ( 11 ) of the at least one static classifier ( 10 ) for the preparation of the ground material ( 27 ). 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 device ( 29 ) for splitting the in the second grinding device ( 25 ) overpowered Grist ( 27 ) in a first partial flow of ground material ( 30 ) and a second partial flow of ground millbase ( 31 ) is arranged in a variably adjustable ratio, wherein - a guiding of the first partial flow of ground millbase ( 30 ) to the at least one static classifier ( 10 ) is provided for precaution, and - a recirculation of the second partial flow of ground millbase ( 31 ) as a bypass current ( 31 ) directly to the first grinding device ( 3 ) is provided for Gutbettzerkleinerung. 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 ), wherein the second grinding device ( 25 ) is designed as a ball mill or as an impact hammer mill or preferably as a roller press.

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