EP2785472B2 - Device for classifying grainy products - Google Patents

Description

• wobei der statische Sichter in einem Sichtergehäuse mit zumindest einem ersten Materialeintritt, zumindest einem Sichtgaseinlass und zumindest einem Grobgutaustritt mehrere treppenartig untereinander angeordnete Prall- und Leiteinbauten aufweist,
• wobei der dynamische Sichter als Stabkorbsichter mit rotierendem Stabkorb ausgebildet ist und ein zweites Sichtergehäuse mit zumindest einem Mittelgutaustritt und einem Feingutaustritt aufweist.

The invention relates to a device for classifying granular material into at least three fractions, with at least one static classifier forming a first classifying stage and at least one dynamic classifier forming a second classifying stage,

• wherein the static classifier has a plurality of impact and guide elements arranged in a staircase-like manner in a classifier housing with at least one first material inlet, at least one classifying gas inlet and at least one coarse material outlet,
• wherein the dynamic sifter is designed as a rod basket sifter with a rotating rod basket and has a second sifter housing with at least one medium material outlet and one fine material outlet.

The granular material to be sifted can be, for example, cement, cement-containing materials, cement raw material, limestone or slag, but also ores or the like. In practice, roller presses or material bed roller mills are used in particular to crush such granular materials. In this high-pressure crushing of the granular material to be ground, it is crushed in the gap between two press rollers (material bed crushing). During the crushing process, agglomerates are formed, which are referred to as flakes. Material bed roller mills of this type can be operated in a closed circuit with a static and/or dynamic sifter. The material bed roller mill is then positioned below a sifter, for example, so that the coarse material fraction emerging from the sifter is (re)fed to the roller mill. The material emerging from the roller mill is in turn fed to the material inlet of the classifying device, which is a multi-stage device consisting of a static classifier and a dynamic classifier. In the static classifier, the slugs are deagglomerated via the impact and guide elements, and at the same time the coarse material fraction is separated and fed to the roller press. The "finer" material enters the dynamic classifier with the classifying gases, where it is subjected to fine classification. The fine material classified from this classifier is discharged together with the classifying gas and collected as finished product in the following cyclones and/or filters. The middle fraction classified from the dynamic classifier can, for example, also be fed back to the roller press or to another grinding stage. Such measures are known from the state of the art (see, for example, DE 43 37 215 A1 ).

A generic viewing device of the type described above is known, for example, from the DE 42 23 762 B4 This sifting device has a rotating rod basket in a housing with turbo elements distributed around the circumference of the rotor and with inlets and outlets for sifting air, sifting material, fines, medium material and coarse material. A shaft-shaped screening chamber is arranged at the same height on the side in front of the horizontally arranged rod basket, which has an inlet opening for the sifting material at the top that is separate from the sifting air, an opening for the sifting air arranged opposite the rod basket at the side, a discharge opening for a sifted coarse grain fraction at the bottom and two opposing shaft boundary walls that form a screening zone between them and are permeable to the sifting air. These shaft boundary walls of the screening chamber that are permeable to the sifting air have blind-like guide plates that are inclined diagonally downwards in the direction of the discharge opening for the sifted coarse material fraction, which act as impact and guide fittings and also ensure deagglomeration of the slugs.

Also typical of the JP-6-106 135 A , where the sieve basket of the dynamic sifter rotates around a vertical axis.

Furthermore, it has been proposed to provide roof-shaped installations for wind sifters, which are arranged in a cascade shape in such a way that the ridge edge of each installation is approximately vertically below the discharge edge of the surface of the installation arranged above it that faces the wind flow (cf. EN 1 002 600 ).

From the WO 03/097241 A1 A generic screening device is also known, whereby the dynamic screen - as in DE 42 23 762 B4 - is equipped with a rod basket rotating around a horizontal axis. In order to minimize the problems of mechanical transport of the ground material in the circuit, this prior art proposes arranging the static cascade sifter below the roller gap of the roller press and arranging the secondary sifter above this roller press, which should be designed in particular as a dynamic rod basket sifter. The disadvantage of this design is the considerable height. The connecting line between the two sifters increases the investment and operating costs.

An alternative embodiment of a multi-stage classifier with a compact design is shown in the US 7 854 406 B2 The sifting device consists of several concentric housings, with a rod basket rotating around a vertical axis serving as the secondary sifting stage. The secondary sifting stage is formed by a simple cyclone, with the sifting material and the sifting gas being fed in via a common feed line that is connected in a spiral to the sifter housing. Deagglomeration of the slugs is only possible to a limited extent in the static sifting stage.

From the EN 10 2004 027 128 A1 A device is known for classifying granular material into at least three grain fractions with a static classifier and a dynamic classifier, which are arranged rotationally symmetrically about a common axis in a common housing.

Finally, the EN 10 2006 039 775 A1 a special design sifter with static Cascade sifter and a further sifter known as a post-sifter, wherein the cascade sifter has two packages of cone rings arranged spaced apart one above the other and concentrically to one another.

Furthermore, the DD253771A1 an air classifier for classifying fine-grained bulk materials in particular into at least two fractions, consisting of a cylindrical upper housing section, which is followed at the bottom by a semolina cone with semolina discharge. The rod basket rotates around a vertical axis. The aim is to improve the distribution of the material in the classifying chamber of classifiers with rod baskets so that the separation accuracy is increased and the energy consumption, related to the end product, is reduced, regardless of the speed and shape of a spreading plate. For this purpose, a ring container with a fluidizing bottom is provided as a dispersing device, which is arranged above the classifying gas inlet nozzle in the area of the rod basket inside or outside the classifier housing and is connected to the classifying chamber via an annular gap and/or an annular channel.

The known sifters of the type described have basically proven themselves in practice, but they have potential for further development, particularly with regard to their sifting efficiency.

The invention is therefore based on the object of creating a device for classifying granular material into at least three fractions of the type described at the beginning, which is characterized not only by a particularly compact structure, but also in particular by low investment and operating costs and higher classifying efficiency. In particular, such a classifying device should enable economical operation of a grinding plant with at least one roller press with high classifying efficiency.

To solve this problem, the invention provides a device for sifting granular material into at least three fractions, which has the features of claim 1.

The invention is based first of all on the fundamentally known finding that it is advantageous to combine a static sifter and a dynamic sifter in the form of a rod basket sifter, since a first coarse material fraction can be sifted out via the static sifter, so that the dynamic sifter with the relatively sensitive rotating components is not unnecessarily burdened with coarse material. According to the invention, the static and dynamic sifters are combined in a particularly efficient and compact design by using a rod basket with a vertical axis of rotation and by connecting the static sifter directly to the side of the dynamic sifter, with the static sifter fulfilling both the task of slug deagglomeration and a first coarse separation in terms of process technology. The static sifter and dynamic sifter are therefore brought spatially close together so that both sifters work particularly efficiently in terms of energy, and the static sifter can simultaneously fulfill the task of slug deagglomeration.

In combination with the inventive connection of the static sifter to the dynamic sifter, the use of the rod basket sifter rotating around a vertical axis is of particular importance. This design with a "vertical" rod basket sifter is characterized by a uniform flow of air to the rod basket or rotor and thus by improved sifting efficiency. The problems that occur in the prior art with "horizontally" arranged rod basket axes are avoided within the scope of the invention, so that an overall improved sifting efficiency is achieved.

According to the invention, the sifter housing of the static sifter opens into the sifter housing of the dynamic sifter in a tangential or spiral orientation. In any case, the sifter housing of the static sifter is always compactly connected laterally to the sifter housing of the dynamic sifter, so that the static sifter housing merges into the dynamic sifter housing. The sifter according to the invention therefore has housing areas which can be assigned to both the static sifter and the dynamic sifter as a transition between the static sifter and the dynamic sifter. It is further provided that the sifter housing of the dynamic sifter has an upper housing section in which the rotating rod basket is arranged, and a lower housing section in which a discharge funnel for the middle material is arranged, the static sifter being connected with its housing to the lower housing section of the dynamic sifter and merging into this lower housing section. This lower housing section of the dynamic sifter therefore forms the transition area between the static sifter and the dynamic sifter. The housing of the dynamic classifier is cylindrical, so that the upper housing section and the lower housing section are cylindrical. The lower housing section of the dynamic classifier then also functions as a cyclone, which can influence both the function of the static classifier and the function of the dynamic classifier. This cyclone formed by the lower housing section can influence the effect of the static classifying stage. At the same time, however, this cyclone can also be viewed as part of the dynamic classifier, since it forms an inflow channel for the vertical impact on the rod basket and since the discharge funnel of the dynamic classifier can also be arranged within this housing section or cyclone. This also makes it clear that, according to the invention, the static classifier and the dynamic classifier are closely connected spatially and functionally.

As described, the static classifier is preferably attached to the lower housing section of the dynamic The static sifter is then usually positioned below the rod basket (in a side view). Alternatively, however, it is within the scope of the invention to arrange the static sifter or static sifters at the same height or at least in some areas at the same height as the rotating rod basket.

Within the static separator, not only is there an initial separation of coarse and medium material, but a deagglomeration of the slugs can also take place. The deagglomeration of the slugs is achieved with the help of the impact and guide elements integrated into the static separator. The impact and guide elements can be formed in a known manner by impact plates or guide plates inclined against each other. In a preferred embodiment, these plates or plates can be adjusted in their inclination, e.g. pivoted or rotated about a horizontal axis. Since the functioning of the static separator during operation - in contrast to a dynamic separator - can only be influenced to a limited extent, such an adjustment option is useful. The desired conditions of the static separator can be set so that the flow conditions in particular can be optimized. Alternatively, the impact and guide elements can also be formed by roof-like installations, such as those from the EN 1 002 600 are known. The roof-like fittings can optionally be moved horizontally. The static sifter always combines the task of slug deagglomeration on the one hand and an initial coarse material separation on the other.

While the (second) sifter housing of the dynamic sifter is usually cylindrical or at least partially cylindrical, the static sifter has a shaft-like or box-like housing that is preferably aligned at an angle to the vertical, so that the impact and guide fittings arranged inside are also arranged along a slope. The shaft-like housing has the material inlet or inlets for the material to be sifted and at least one sifting gas inlet, via which air is supplied, for example. For this purpose, the shaft-like housing can have a (lower) shaft wall that is oriented at a predetermined angle α between 10° and 80°, e.g. 40° to 60°. The housing can therefore be arranged (in side view) overall at an angle to the vertical. The same applies to the impact and guide fittings arranged one below the other in a staircase-like manner within the housing. Between these, the viewing zone of the first viewing stage is formed, which is oriented at a predetermined angle β between 20° and 70°, e.g. 20° to 40° relative to the vertical. However, the invention also includes a shaft-like housing which is not oriented at an angle to the vertical, but parallel to the vertical.

The sifting gas inlet can be formed, for example, by at least one inlet opening arranged diagonally above the internals. Alternatively or additionally, it is possible for the sifting gas inlet to be formed by one or more openings arranged in the shaft wall. These openings can be closed, for example, by flaps, so that the sifting gas supply can be varied by opening and closing. It is therefore within the scope of the invention that either an (upper) inlet opening of the type described is provided or that openings are provided in the shaft wall. Preferably, however, a combination of these measures is implemented, so that at least one inlet opening arranged diagonally above the internals and one or more openings arranged in the shaft wall are provided, whereby these openings can optionally be closed, for example, by flaps. It is then possible to work with "variable" air supply and consequently air volume control. It is expedient if the individual flaps can be opened and closed individually, in groups and/or together, whereby variable and targeted adjustment is particularly preferably possible by adjusting the openings. In the context of the invention, flaps generally mean means for opening and closing the openings and in particular for adjusting the amount of air passing through. By regulating the air volume appropriately, it is possible to further increase the visibility efficiency.

There is also the option, or additional option, for the classifying gas inlet to be formed by an area of the classifier housing that is free of shaft walls. In this embodiment, the shaft wall is not required, so that the system can then operate with an open flow.

Of particular importance within the scope of the invention is the combination of the first separator housing, which is connected laterally, e.g. tangentially or spirally, with the rod basket arranged in a vertical orientation. The direction of rotation of the rod basket can be oriented with or against the tangential or spiral-like connection direction of the static separator housing.

The dynamic classifier is particularly preferably provided with one or more additional material inlets in the upper part, e.g. in the upper housing section. This is particularly useful if the classifier is integrated into a multi-stage grinding system, because the ground material can then be fed to a second stage for classifying via this (second) material inlet. This can, for example, be the discharge material from a second comminution device, e.g. a ball mill. The integration of the classifier device into a single- or multi-stage grinding system is explained in more detail below.

It is fundamentally within the scope of the invention that a single static separator in the inventive, e.g. tangential or spiral, type is connected to the dynamic separator. Preferably However, especially in large units, two or more static sifters, each with a sifter housing, are connected to the dynamic sifter. The sifting for sifting a coarse material fraction and for deagglomerating the slugs can therefore be carried out in parallel in several sifting stages, with the individual sifting stages then acting in parallel on one and the same dynamic sifter. The connection of the several static sifters is preferably symmetrical (in plan view). It is therefore within the scope of the invention that the several static sifters are arranged "symmetrically" and thus equidistantly around the circumference. The offset is 360°/n in relation to the circumference, where "n" means the number of static sifters. If two static sifters are used, they are preferably connected to the dynamic sifter offset by an angle of 180° in plan view. If three static classifiers are used, they are preferably arranged offset by an angle of approximately 120°, and if four static classifiers are used, they are preferably arranged offset by an angle of 90° from each other, etc.

In addition to the impact and guide fittings already provided in the static classifier, it can be useful to also provide impact fittings in the area of the dynamic classifier, e.g. inside the classifier housing of the dynamic classifier, preferably in its lower housing section, which can take on the function of a cyclone for the reasons explained. Impact fittings can be connected to the inside of the housing wall of this cyclone, which can function as "tripping edges" or "peeling edges". They are intended to counteract the cyclone effect of this part of the classifier and consequently reduce this cyclone effect. With the help of these fittings arranged on the wall, the material collecting in the wall area can be brought back towards the center or axis, so that the screening function is optimized.

According to another proposal, it is optionally provided that the sifter housing of the dynamic sifter is provided with one or more additional air inlets that take on the function of an air bypass. Not only is the air supplied via the air inlet of the static sifter, but additional air can also be supplied via the dynamic sifter. This then leads to the air supply in the area of the static sifter being reduced, so that an optimized adjustment of the air flow can be achieved in this way. This additional air supply can be implemented, for example, in the upper housing section of the sifter housing of the dynamic sifter.

Finally, it is within the scope of the invention to optionally provide additional air distribution devices, e.g. perforated plates or the like, in the area of the static classifier. These can be arranged in the classifier housing of the static classifier in the direction of flow in front of the impact and guide fittings. They lead to better air distribution over the entire height of the static classifier.

The sifting device according to the invention can be used for sifting a wide variety of granular materials, in particular for sifting cement, cement raw materials, limestone and similar materials. Alternatively, the invention also covers the sifting of ores or the like. The natural reserves of such raw materials have been largely exhausted, so that extraction is shifting to regions that are difficult to access and do not have sufficient water supplies. The sifter according to the invention can be used particularly efficiently there.

• zumindest einer ersten Zerkleinerungsvorrichtung und
• zumindest einer Sichtereinrichtung der beschriebenen Art,

wobei das aus der ersten Zerkleinerungsvorrichtung austretende Material über den ersten Materialeintritt in die Sichtvorrichtung eintritt und wobei das aus dem Grobgutaustritt der Sichtvorrichtung (bzw. dem statischen Sichter) austretende Grobgut der ersten Zerkleinerungsvorrichtung zugeführt wird, wobei das aus der Sichtvorrichtung (bzw. dem dynamischen Sichter) austretende Mittelgut bzw. die mittlere Fraktion ebenfalls der ersten Zerkleinerungsvorrichtung oder alternativ auch einer zweiten Zerkleinerungsvorrichtung zugeführt wird. Besonders bevorzugt ist ergänzend zu der ersten Zerkleinerungsvorrichtung folglich auch eine zweite Zerkleinerungsvorrichtung vorgesehen, so dass dann eine zumindest zweistufige Mahlanlage realisiert ist. Bei der ersten Zerkleinerungsvorrichtung kann es sich bevorzugt um eine Gutbettwalzenmühle und folglich eine Walzenpresse handeln. Bei der zweiten Zerkleinerungsvorrichtung kann es sich z. B. um eine Kugelmühle handeln. Das aus der Sichtvorrichtung (nämlich der zweiten Sichtstufe) ausgesichtete Mittelgut kann folglich dieser zweiten Zerkleinerungsvorrichtung, z. B. der Kugelmühle, zugeführt werden, wobei dieses Gut mit der zweiten Zerkleinerungsvorrichtung zerkleinert und dann über den zweiten Materialeintritt wiederum der zweiten Sichtstufe, nämlich dem dynamischen Sichter, zugeführt werden kann. Das in der ersten Sichtstufe ausgesichtete Grobgut wird folglich der Walzenpresse zugeführt, während das Mittelgut ("Grieße") zur Kugelmühle geführt wird, wobei das Austragsmaterial der Kugelmühle zum dynamischen Sichter und das ausgetragene Material der Walzenpresse zur statischen Sichtstufe geführt werden. Damit gelingt insgesamt eine energetisch besonders günstige Zerkleinerung des Materials, und zwar unter Verwendung des beschriebenen mehrstufigen Sichters, ohne dass die zweite Zerkleinerungsstufe einen eigenen Sichter benötigt.The invention also relates to a single-stage (circulation grinding plant) or multi-stage grinding plant for the comminution of granular material with

• at least one first crushing device and
• at least one screening device of the type described,

wherein the material emerging from the first comminution device enters the sifting device via the first material inlet, and wherein the coarse material emerging from the coarse material outlet of the sifting device (or the static sifter) is fed to the first comminution device, wherein the medium material or the middle fraction emerging from the sifting device (or the dynamic sifter) is also fed to the first comminution device or, alternatively, to a second comminution device. Particularly preferably, a second comminution device is therefore also provided in addition to the first comminution device, so that at least a two-stage grinding system is then realized. The first comminution device can preferably be a material bed roller mill and consequently a roller press. The second comminution device can be, for example, a ball mill. The medium material sifted out of the sifting device (namely the second sifting stage) can therefore be fed to this second comminution device, e.g. B. the ball mill, whereby this material can be crushed with the second crushing device and then fed via the second material inlet to the second sifting stage, namely the dynamic sifter. The coarse material sifted in the first sifting stage is then fed to the roller press, while the medium material ("semolina") is fed to the ball mill, whereby the discharge material from the ball mill is fed to the dynamic sifter and the discharge material from the roller press is fed to the static sifting stage. This makes it possible to crush the material in a particularly energy-efficient manner, using the described multi-stage sifter, without the second shredding stage requiring its own sifter.

Alternatively, however, a multi-stage, e.g. two-stage grinding system can be implemented, in which a further, separate sifter is provided in addition to the sifter according to the invention. The middle fraction of the first sifter according to the invention described is in turn fed to a second comminution device, e.g. a ball mill. The discharge material from this ball mill is then not - as previously described - fed to the first sifter, but to the second, separate sifter, whereby the coarse material emerging from this second sifter is fed to the ball mill again, while the fine material emerging from the second sifter can in turn be discharged as product.

Finally, the invention also includes single-stage grinding systems in which both the coarse material emerging from the screening device according to the invention and the medium material are fed to a first (single) comminution device, e.g. a roller press, and the material emerging from this comminution device in turn enters the screening device according to the invention via the material inlet. This creates a single-stage circulating grinding system.

Fig. 1

einen teilweisen Vertikalschnitt durch eine erfindungsgemäße Sichtereinrichtung in vereinfachter Darstellung,

Fig. 2

eine Draufsicht auf den unteren Teil des Gegenstandes nach Fig. 1 in einer ersten Ausführungsform,

Fig. 3

eine Draufsicht auf den unteren Teil des Gegenstandes nach Fig. 1 in einer zweiten Ausführungsform,

Fig. 4

eine abgewandelte Ausführungsform des Gegenstandes nach Fig. 1 (Ausschnitt im Bereich des Unterteils),

Fig. 5

eine Draufsicht auf den unteren Teil des Gegenstandes nach Fig. 4 und

Fig. 6

schematisch eine zweistufige Mahlanlage mit einer erfindungsgemäßen Sichtereinrichtung.

It is within the scope of the invention that the first comminution device, e.g. roller press, is arranged above the sifting device. However, the roller press is particularly preferably positioned below the sifting device. The invention is explained in more detail below using a drawing that represents only one exemplary embodiment. They show:

Fig.1

a partial vertical section through a sifting device according to the invention in a simplified representation,

Fig. 2

a plan view of the lower part of the object after Fig.1 in a first embodiment,

Fig.3

a plan view of the lower part of the object after Fig.1 in a second embodiment,

Fig.4

a modified embodiment of the article according to Fig.1 (cutout in the lower part area),

Fig.5

a plan view of the lower part of the object after Fig.4 and

Fig.6

schematically shows a two-stage grinding plant with a classifying device according to the invention.

The Fig. 1 to 5 The sifting device 1 shown serves to sift granular material, e.g. cement, into at least three fractions. The device 1 is composed of a static sifter 2 and a dynamic sifter 3, which are combined with one another in a particularly compact manner. The static sifter 2 forms a first sifting stage, and the dynamic sifter 3, which is arranged downstream of the static sifter 2 in the direction of the sifting medium flow, forms a second sifting stage.

The static classifier 2 has a classifier housing 4 with a first material inlet 5, classifying gas inlet 6 and coarse material outlet 7. Within the classifier housing 4, several impact and guide elements 8, 9 are arranged one below the other in a staircase-like manner. In the exemplary embodiment, these elements are designed as impact plates 8, 9, which also take on the function of guide plates for the static classifier. In Fig.1 It can be seen that there are two groups of impact plates 8, 9 inclined towards each other, whereby these impact plates 8, 9 are adjustable about pivot axes 10 so that the inclination of the impact plates 8, 9 is adjustable.

The second classifying stage is formed by the dynamic classifier 3, which has a classifier housing 11. This cylindrical classifier housing 11 has an upper cylindrical section 11a and a lower cylindrical section 11b. In the upper part 11a of this classifier housing 11, a rotating rod basket 12 is arranged, which is surrounded by a set of guide vanes 13. These are stationary guide vanes that are arranged at a fixed or adjustable angle of attack to the axis of rotation of the rod basket. The rod basket 12 rotates about a vertical axis 14. For this purpose, a drive 15 is connected to the rod basket 12. Below the rod basket 12, within the second classifier housing 11, a discharge cone 16 is connected, which in turn is connected to the medium material outlet 17. The fine material outlet 18 is connected to the upper part 11a of the classifier housing 11, through which the gas-fine material mixture is discharged. Furthermore, further material inlets 19 are connected to the upper part 11a of the housing.

The starting material to be sifted is fed to the sifting device 1 via the first material inlet 5. The material to be sifted then enters the first sifting stage and subsequently the static sifter 2 via this. The sifting gas, e.g. air, is fed in through the gas inlet 3. This can also be hot drying gases, for example. The material to be sifted now falls onto the system of impact and guide plates 8, 9, which in particular leads to the deagglomeration of the flakes and agglomerates created during grinding in a roller press. The sifting medium flows through the material and can dry it at the same time. The static sifter works as a cross-flow air sifter, so that the coarse material falls through the housing 2 into the lower discharge cone 20 and is discharged from there via the coarse material discharge 7. This discharge cone 20 is structurally connected to the lower part 11b of the separator housing 11 of the dynamic separator 3.

The static classifier and the dynamic classifier are connected to one another in a very compact manner, so that the static classifier 2 merges into the dynamic classifier 3. The static classifier is connected with its classifier housing 4 laterally to the classifier housing 11 of the dynamic classifier. In the exemplary embodiment, it can be seen that the classifier housing 4 of the static classifier 2 merges into the lower housing section 11b of the classifier housing 11, so that the housing section 11b of the classifier housing 11 can be functionally assigned to the static classifier on the one hand and the dynamic classifier on the other. It establishes the connection between the static classifier and the dynamic classifier, with the cylindrical lower housing section 11b also fulfilling the function of a cyclone.

In any case, the fraction separated from the static classifier 2 enters the dynamic classifier 3 together with the separating gas, namely into the upper area 11a of the classifier housing 11 and there into the area of the rod basket 12. The desired fine separation takes place between this rotating rod basket 12 and the conductor blades 13. The "coarser" or medium-sized parts pass through the inner discharge funnel or discharge cone 16 to the discharge pipe and consequently the medium-sized material outlet 17 ("semolina discharge pipe"). This medium-sized fraction is also referred to as "semolina". The fine material is discharged from the classifier together with the gases through the fine material and gas outlet 18. Additional material can be fed directly to the second separation stage via the additional material inlets 19. This can, for example, be material that is fed from an additional crushing device, e.g. a ball mill. This will be discussed in connection with the Fig.6 discussed in more detail.

The Fig. 2 and 3 now show that the static classifier 2 according to the invention is connected directly to the second classifier housing 11 of the dynamic classifier 3 with a shaft-like first classifier housing 4 arranged obliquely to the vertical, in the embodiment in tangential or spiral orientation. Fig. 2 shows an embodiment with a spiral connection, while Fig.3 shows an embodiment with tangential connection.

It can be seen in the two exemplary embodiments that two static classifiers 2 with two classifier housings 4 are connected to the classifier housing 11 of the dynamic classifier 3. The dynamic classifier 3 is therefore acted upon in parallel by two static classifiers 2. For this purpose, the two static classifiers 2 are positioned offset by 180° in the exemplary embodiment. The direction of rotation of the rod basket can correspond to the connection direction of the tangential or spiral connection or can be designed in the opposite direction.

The Fig. 4 and 5 The embodiment shown corresponds essentially to the embodiment according to Fig.1 and 3 . It differs geometrically in particular in the arrangement and design of the discharge funnel 16 of the dynamic classifier, which in the embodiment according to the Fig. 4 and 5 over the entire height of the lower section 11 b of the sifter housing 11 and also over the entire height of the sifter housing 4 of the static sifter 2. Apart from that, the embodiments differ according to Fig. 1 to 3 on the one hand and 4 and 5 on the other hand in their geometric design, especially in the area of the static separator and its guide fittings. The basic structure and functionality are identical.

The shaft-like first sifter housing, which is connected to the second sifter housing in a tangential or spiral orientation, is of particular importance. The figures show that this shaft-like first housing 4 or its (lower) shaft wall 21 is oriented at a predetermined angle α obliquely to the vertical. In the exemplary embodiment, this angle α is approximately 40° to 60°, e.g. approximately 50°. It can also be seen that the viewing zone of the static sifter, formed between the impact plates 8, 9 arranged one below the other in a step-like manner, is also oriented at a certain angle β obliquely to the vertical. In the exemplary embodiment, this angle β is approximately 20° to 40°, e.g. 25°. This overall obliquely oriented housing 4 is connected according to the invention in a spiral or tangential manner to the housing of the dynamic sifter.

The figures show an embodiment in which the static sifter is connected to the side of the dynamic sifter, but is positioned spatially below the rotating rod basket. However, embodiments can also be implemented optionally in which the static sifter is arranged (at least in some areas) at the same height as the rotating rod basket. The same applies to embodiments with several static sifters.

Furthermore, in the embodiments shown, the air supply takes place in particular via the illustrated sifting gas inlet 6. Alternatively or additionally, additional sifting gas inlets can be provided, which are formed in particular by openings arranged in the shaft wall 21. This is not shown in the figures. Such openings can be opened and closed by suitable means, e.g. flaps, slides or the like, whereby variable adjustment and thus air quantity control is possible in particular by adjustable means.

The arrangement of the impact plates 8, 9 is shown in the figures only as an example. It is indicated that the articulation points of the impact plates 8, 9 do not have to lie on a common straight line, but can be arranged at a distance from each other. This is particularly evident in Fig.4 However, it is also within the scope of the invention that the articulation points of the baffle or guide plates are arranged (for example) on a straight line or are toothed and thus designed to mesh with one another. However, they can also be designed - as shown in the figures - with a distance between the articulation points, whereby this distance is Fig.4 is significantly larger than Fig.1 The vertical distance between the individual plates does not have to be the same, but can vary from plate to plate. The plates can also be set at different angles.

The multi-stage classifier 1 according to the invention can be particularly preferably integrated into a single-stage or multi-stage grinding plant, as is shown for example in Fig.6 is shown. A cement grinding plant is shown as an example. In the center of the figure, the multi-stage classifier 1 can be seen, which is made up of a static classifier 2 and a dynamic classifier 3. Below the classifier 1, a first crushing device 22 is shown in the embodiment as a roller press and thus a material bed roller mill 22. Furthermore, a second crushing device 23 is shown in the embodiment as a ball mill 23.

The two-stage grinding system shown works as follows:
The starting material to be shredded is fed from one or more bunkers 24, e.g. via the transport devices 25, 26, which open into the sifting device 1 via the material inlet 5. There, the material is sifted into three fractions in the manner already described. The coarse material sifted out from the coarse material outlet 7 is fed again to the roller press 22. From there, it reaches the sifting device 1 again via the transport devices 27 and 25, 26. The medium material sifted out from the second sifting stage, i.e. the middle fraction, is fed to the ball mill 23 via the medium material outlet 17 and the transport device 28. The grinding system therefore has the roller press 22 for pre-grinding the material and the ball mill 23 for regrinding the material. The ball mill 23 is e.g. B. equipped with a material discharge 29, a dust removal filter 30 and a mill fan 31. The material emerging from the ball mill 23 is then fed via the transport devices 29, 32, 33, with which it is brought to the dynamic classifier 3. There it again reaches the second classifying stage via the material inlets 19.

The finest fraction is removed from the sifting device, namely from the dynamic sifter 3, together with the gases through the fines outlet 18 into the following separation cyclones 34. Here, it is separated as a finished product from the gases, which are removed with the fan 35 and partly fed back into the sifting device 1 and partly or completely fed to a dust removal system.

The two-stage grinding system shown can be modified in an alternative design. For example, the roller press 22 can be placed above the sifting device 1, in contrast to the arrangement shown. In this case, the fresh material to be ground is first fed into the roller press, from which the pre-ground material is fed to the sifting device according to the invention. There, the material is again classified into three fractions in the manner described. This embodiment is not shown.

Alternatively, it is also possible to integrate a second, separate screening device into the two-stage grinding system, so that the discharge material from the ball mill is then fed not to the first screening device shown in the figures, but to a separate second screening device (not shown). Alternatively, only a single comminution device, e.g. the roller press shown, can be used, so that the additional ball mill is then dispensed with. The final grinding then takes place in the roller press, with the screening device according to the invention and the roller press then forming a "simple", "single-stage" circulating grinding system. This is also not shown in the figures. However, the multi-stage screen according to the invention can be used equally for the various types of grinding systems.

Claims (19)

1. A device (1) for purposes of separating granular material into at least three fractions, with

   at least one static separator (2) forming a first separation stage, and

   at least one dynamic separator (3) forming a second separation stage, wherein

   the static separator (2) is designed as a cross-flow separator, and, in a separator housing (4) with at least one first material entry port (5), at least one separator gas inlet (6) and at least one coarse grade material exit port (7), has a plurality of baffle and guide fittings (8, 9) arranged under one another in the form of a staircase, wherein

   the dynamic separator (3) is designed as a rod basket separator with a rotating rod basket (12), and has, at least in some regions, a cylindrical separator housing (11) with at least one medium grade material exit port (17) and one fine grade material exit port (18), characterised in that,

   the static separator (2) with its separator housing (4) is connected directly onto the side of the separator housing (11) of the dynamic separator (3) and merges into the latter with a tangential or spiral-form orientation, and

   the rod basket (12) of the dynamic separator (3) rotates about a vertical axis (14), and

   the separator housing (11) of the dynamic separator (3) has an upper cylindrical housing section (11a), in which the rotating rod basket is arranged, and has a lower cylindrical housing (11b), wherein

   the static separator (2) with its housing (4) is connected onto the lower housing section (11b) and merges into the latter,

   wherein in the lower housing section (11b) a discharge hopper (16) for the medium grade material is arranged.
2. The device in accordance with claim 1, characterised in that, the baffle and/or guide fittings are formed from baffle plates and/or guide vanes (8, 9) that are inclined relative to one another.
3. The device in accordance with claim 2, characterised in that, the inclination of the baffle plates and/or guide vanes (8, 9) can be adjusted.
4. The device in accordance with claim 1, characterised in that, the baffle and/or guide fittings (8, 9) are formed from roof-type fittings.
5. The device in accordance with claim 4, characterised in that, the roof-type fittings can be moved in the horizontal direction.
6. The device in accordance with one of the claims 1 to 5, characterised in that, the shaft-type housing (4), or at least one shaft wall (21) of the said housing of the static separator (2) is oriented at an angle to the vertical, for example, at a prescribed angle (a) of between 10° and 70° relative to the vertical.
7. The device in accordance with one of the claims 1 to 6, characterised in that, the separation zone of the static separator (2), formed between the baffle and/or guide fittings (8, 9) arranged under one another in the form of a staircase, is oriented at a prescribed angle (β) of between 10° and 70° relative to the vertical.
8. The device in accordance with one of the claims 1 to 7, characterised in that, the separator gas entry port (6) is formed by at least one entry port opening arranged at an angle above the fittings (8, 9).
9. The device in accordance with one of the claims 1 to 8, characterised in that, the separator gas entry port (6) is alternatively or additionally formed from a plurality of openings arranged in the shaft wall (21) of the separator housing (4) of the static separator (2), and adjustable as required, or from a region of the said housing without a shaft wall.
10. The device in accordance with one of the claims 1 to 9, characterised in that, air distribution devices, for example, perforated plates, are arranged in the separator housing (3) of the static separator (2) upstream of the baffle and/or guide fittings (8, 9) in the flow direction.
11. The device in accordance with one of the claims 1 to 10, characterised in that, the tangential or spiral connection is oriented in the direction of rotation, or against the direction of rotation, of the rod basket (12).
12. The device in accordance with one of the claims 1 to 11, characterised in that, the separator housing (11) of the dynamic separator (3) has at least one second material entry port (19).
13. The device in accordance with one of the claims 1 to 12, characterised in that, two or a plurality of static separators (2), in each case with a separator housing (4), are connected onto the side of the dynamic separator (3).
14. The device in accordance with claim 13, characterised in that, the plurality of static separators (2) are arranged over the periphery with an angular displacement of 360°/n, wherein n corresponds to the number of static separators.
15. The device in accordance with one of the claims 1 to 14, characterised in that, additional baffle fittings are arranged in the separator housing (11) of the dynamic separator (3), for example, in its lower housing section (11b); these are preferably arranged on the inner face of the housing wall.
16. The device in accordance with one of the claims 1 to 15, characterised in that, the separator housing (11) of the dynamic separator (3) is provided with one or a plurality of additional air supplies as a bypass, for example in its upper housing section (11a).
17. A grinding facility, in particular a circulatory grinding facility, or a multi-stage grinding facility, for the grade reduction of granular material, with at least one first grade reduction device (22), and with at least one separation device (1), in accordance with one of the claims 1 to 16, wherein

    the material exiting from the first grade reduction device (22) enters via the first material entry port (5) into the separation device, wherein

    the coarse grade material exiting from the coarse grade material exit port (7) of the static separator (2) is supplied to the first grade reduction device (22), and wherein

    the medium grade material exiting from the dynamic separator (3) is supplied to the first grade reduction device (22), or to an additional second grade reduction device (23).
18. The facility in accordance with claim 17, with a second grade reduction device (23), wherein the medium grade material exiting from the dynamic separator (3) is completely or partially supplied to the second grade reduction device (23), and wherein
    the material exiting from the second grade reduction device (23) is supplied via the second material entry port (19) to the dynamic separator (3), or to a separate second separator device.
19. The facility in accordance with claim 17 or 18, characterised in that, the first grade reduction device (22) is designed as a roller press, and/or the second grade reduction device (23) is designed as a ball mill.

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