EP3209423B1 - Grinding plant for comminution of material and method of comminution of material - Google Patents

Description

The invention relates to a grinding plant for comminuting regrind and a method for comminuting regrind.

State of the art

It is known to comminute ground material, such as limestone, dolomite, ores, clinker, slag or fly ash, in a grinding plant which has at least one grinding device and a classifier.

From the DE 102011055762 A1 a grinding plant for comminuting ground material is known, which has a classifier with a static and a dynamic classifier and at least one grinding device.

The grist is usually fed into the classifier or the grinding device. In the classifier, the ground material is separated into a fine and a coarse grain fraction, the coarse grain fraction being fed to the grinding device for comminution. Following the comminution, the ground material is sifted again in the classifier, with the coarse ground material being fed back to the grinding device. In the operation of the grinding plant, irregular process fluctuations often occur, which are, for example, natural fluctuations in the nature of the ground material, such as grain size or density. Such process fluctuations lead to an overload of the grinding device, with sufficient comminution of the ground material in the grinding device no longer being achieved. This leads, on the one hand, to greater wear and tear on the grinding device and, on the other hand, to the fact that the inadequately comminuted material to be ground is fed back to the grinding device and the grinding process is considerably extended.

Disclosure of the invention

On this basis, it is the object of the present invention to provide a grinding system which overcomes the disadvantages described above and prevents overloading of the grinding device and enables efficient comminution of the material to be ground.

According to the invention, this object is achieved by a grinding plant with the features of the independent device claim 1 and by a method with the features of the independent method claim 8. Advantageous further developments result from the dependent claims.

A grinding plant for comminuting ground material comprises a grinding device and a classifier connected to the at least one grinding device for classifying the ground material with a static classifier and a dynamic classifier, the static classifier being arranged such that it at least partially encloses the dynamic classifier. The sifting device has at least one coarse material outlet for discharging coarse material having a coarse grain fraction, at least one semolina outlet for discharging grit having a medium grain fraction and at least one finished material outlet for discharging finished material having a fine grain fraction. Coarse material is preferably to be understood as a regrind with a grain size of about 10-100mm, grit a regrind with a grain size of approximately 1-10mm and finished material a regrind with a grain size of approximately 30-300 µm. Furthermore, the grinding system comprises a control / regulating device for controlling / regulating at least a part of the grinding material flow to the at least one grinding device.

With the control / regulating device for controlling / regulating at least a part of the grinding material flow, overloading of the at least one grinding device is reliably avoided. The grinding device is overloaded when the flow of ground material into the grinding device exceeds the optimum operating point of the grinding device of for example 250-350 t / h, in particular about 300 t / h.

Controlling the regrind flow is understood to mean that a maximum regrind flow value, such as 300 t / h, is set and, if the actual value of the regrind flow is exceeded, it is changed so that it reaches or falls below the maximum regrind flow value. Controlling the grinding material flow is understood to mean the directional influencing of the grinding material flow to the at least one grinding device without feedback.

The grist is preferably brittle materials such as limestone, dolomite or ore material. In particular, the ground material in cement production includes clinker, slag, cement, cement raw material, cement-containing substances and / or fly ash.

The grinding device comprises, for example, a roller press or a ball mill in which the ground material is comminuted.

The viewing device comprises a static classifier and a dynamic classifier. The viewing device preferably comprises a first inlet for admitting a first material flow, for example from a roller mill and / or a fresh material feed, into the viewing device and at least one second inlet for admitting a second material flow, for example from a ball mill, into the separating device. The classifier also has, for example, a distributor device which is designed such that it feeds the material flow of the first inlet to the static classifier and feeds the material flow of the second inlet to the dynamic classifier, the static classifier and the dynamic classifier being connected in such a way that one Regrind flow from the static sifter is made possible in the dynamic sifter.

The grist stream enters the first inlet of the classifier via a fresh feeder and is fed to the static classifier via a distributor device. A static sifter comprises a plurality of flow devices, for example guide blades, which serve to deagglomerate the material flow flowing through the static sifter. The static sifter is designed in particular in such a way that it forms a cylindrical-ring-shaped sifting zone between the flow devices and the dynamic sifter is arranged within the static sifter. The static sifter is fed via a sifting air duct, for example by means of a fan, sifting air, which is directed via the plurality of guide vanes of the flow device against the material flow flowing through the static sifter.

The coarser grain fraction, the coarse material, of the material flow flowing into the classifier through the first inlet leaves the static classifier through the coarse material outlet, with the finer grain fraction of the ground material being pneumatically fed to the dynamic classifier through the classifying air.

A dynamic sifter comprises a moving viewing zone, for example a rotating rod basket, into which a material flow with a small grain size, in particular up to about 10 mm, enters. The dynamic sifter is arranged, for example, coaxially to the static sifter and rotationally symmetrical to the drive axis of the moving viewing zone. The material flow of medium grain size, the grit, is rejected by the dynamic classifier and emerges from the classifier through the grit outlet. The grist stream that passes through the dynamic classifier has a grain size of up to about 300 µm and emerges from the classifier through the finished material outlet.

The ground material emerging from the coarse material outlet and the grist outlet is fed to at least one grinding device for comminution. For example, the coarse material is fed to a roller mill and the grit is fed to a ball mill, or the coarse material and the grit are brought together and fed to a single grinding device, for example a roller mill or a ball mill.

Following the comminution, the ground material is fed to the classifier and enters the second inlet of the classifier. The material flow entering the classifier through the second inlet is fed to the dynamic classifier via a distributor device, whereby the material rejected by the dynamic classifier leaves the classifier through the coarse material outlet and the material that has entered the moving field of view of the dynamic classifier leaves the classifier through the finished material outlet exit.

The control / regulating device regulates / controls the ground material flow to the at least one grinding device, this being for example the ground material flow between the grist outlet of the classifying device and the inlet of the grinding device, the ground material flow between the coarse material outlet and the inlet of the grinding device or the ground material flow between the coarse material outlet, the Comprises semolina outlet and the inlet of the grinding device.

According to the invention, the control / regulating device comprises a metering device arranged between the semolina outlet and the at least one grinding device, which is designed such that it limits at least part of the grinding material flow to the at least one grinding device. A metering device is to be understood as a device which continuously conveys a specific, adjustable amount of ground material. Such a metering device is, for example, a conveyor belt with a height limiter that is withdrawn from a bunker, or a rotary valve or a screw conveyor that is designed in such a way that it can be operated at a constant speed and conveys a maximum grist flow of around 300-400 t / h, in particular around 300 t / h. A metering device that limits the flow of ground material reliably prevents a very large flow of ground material, as occurs when process fluctuations suddenly occur, from flowing into the grinding device and from exceeding its maximum capacity. The metering device thus enables optimal operation of the grinding device. The arrangement of the metering device between the semolina outlet and the inlet of the at least one grinding device offers the advantage that the supply of the semolina of medium grain size to the at least one grinding device is metered and does not, for example, exceed a certain maximum value. This prevents an excessive amount of grit in the grinder. In particular, the grit, which has a smaller grain size than the coarse material, ensures that the grinding device runs unevenly. A small amount of grist makes it possible to operate the grinding device more efficiently with a larger amount of grist, since a large proportion of grind in the grist, for example, causes the grist to float in the grinder during the grinding process and thus causes inefficient grinding.

According to a further embodiment, the control / regulating device comprises at least one measuring device for determining a flow of ground material to the at least one grinding device. Such a measuring device is, for example, an electromagnetic measuring sensor, an inductive flow meter or a mechanical flow meter such as a baffle plate or a belt scale. The control / regulating device comprises, for example, two measuring devices, one measuring device determining the ground material flow from the coarse material outlet and another measuring device determining the ground material flow from the grist outlet.

Such a measuring device for measuring the flow of ground material to the grinding device enables the flow of ground material to be regulated as a function of the measured grist flow. If the ground material flow exceeds a certain value, which corresponds, for example, to the maximum capacity of the grinding device, the fresh material flow fed into the grinding system is reduced, for example.

According to a further embodiment, the measuring device is arranged between the metering device and the at least one grinding device. This arrangement enables the flow of ground material to be regulated before the maximum delivery rate of the metering device is reached. If the flow of regrind increases sharply due to the process, this is registered by the measuring device and, for example, from a certain value that is below the maximum delivery rate of the dosing device, the amount of fresh material fed into the grinding system is reduced. When the amount of fresh material is reduced, the flow of material to be ground to the grinding device is usually reduced with a time delay. The metering device, however, prevents the flow of material to be ground from increasing beyond the optimum operating point of the grinding device.

According to a further embodiment, the grinding system has a fresh material feed for admitting fresh material into the grinding system, the control / regulating device being connected to the fresh material feed and being designed in such a way that it leaves the semolina outlet when a threshold value of the grinding material flow determined by the measuring device is reached to the at least one grinding device, the fresh material flow entering the grinding system via the fresh material feed is reduced.

According to a further embodiment, a buffer store is arranged between the semolina outlet and the at least one grinding device. The buffer store is preferably arranged upstream of the dosing device, so that in the case of a grinding stock flow that is greater than the maximum grinding stock flow that can be conveyed by the dosing device, the grinding stock is stored in the buffer store. The buffer store comprises, for example, an outlet cone the classifier, which is connected to the semolina outlet of the ground material classified in the static classifier. The arrangement of the buffer store between the semolina outlet and the at least one grinding device enables the semolina to be buffered, which corresponds only to a partial flow of the entire flow of grist. This enables the targeted buffering of a partial flow, with the buffer store being, for example, small in size. The buffer store also offers the possibility of intermediate storage of the semolina while the fresh material flow is reduced via the fresh material feed in response to the maximum ground material flow being exceeded.

According to a further embodiment, the grinding system has a first grinding device, in particular a roller press, and a second grinding device, in particular a ball mill, wherein the semolina outlet is in connection with an inlet of the second grinding device and wherein the buffer store is in connection with the first grinding device Has overflow. Such an overflow preferably comprises an overflow line which conveys grinding stock out of the buffer store. The overflow limits an increase in the grist in the buffer storage. This enables the use of a small buffer store and prevents the grist from rising, for example up to the dynamic classifier.

According to a further embodiment, the overflow has a measuring device for measuring the mass flow flowing through the overflow. This enables the grinding stock flow flowing from the buffer store to the first grinding device to be monitored. According to a first aspect, a method for comminuting regrind has at least the following steps:
Crushing the ground material in at least one grinding device, sifting the ground material in a classifier into coarse material, grits and fine material, the classifier having a static classifier and a dynamic classifier having, wherein the static sifter is arranged in such a way that it at least partially encloses the dynamic sifter, and wherein the ground material flow to the at least one grinding device is controlled / regulated by means of a control / regulating device and wherein the control / regulating device comprises a metering device which limits the supply of the meal to the at least one grinding device.

The advantages described above with reference to the grinding plant apply in a procedural equivalent to the method for comminuting ground material.

Preferred embodiments of the invention

Fig. 1

zeigt eine schematische Darstellung einer Mahlanlage mit einer Sichteinrichtung und zwei Mahlvorrichtungen gemäß einem Ausführungsbeispiel.

Fig. 2

zeigt eine schematische Darstellung einer Mahlanlage mit einer Sichteinrichtung und einer Walzenpresse gemäß einem weiteren Ausführungsbeispiel.

Fig. 3

zeigt eine schematische Darstellung einer Mahlanlage mit einer Sichteinrichtung und einer Kugelmühle gemäß einem Ausführungsbeispiel.

Fig. 4

zeigt eine schematische Darstellung einer Sichteinrichtung gemäß Fig. 1 bis 3.

The invention is explained in more detail below using several exemplary embodiments with reference to the accompanying figures. The information such as "above" and "below" or "left" and "right" serve to better explain the schematic representation of the exemplary embodiments of the invention shown in the figures, without restricting the invention to the exemplary embodiments shown or a specific installation position.

Fig. 1

shows a schematic representation of a grinding plant with a viewing device and two grinding devices according to an embodiment.

Fig. 2

shows a schematic representation of a grinding plant with a classifier and a roller press according to a further embodiment.

Fig. 3

shows a schematic representation of a grinding plant with a viewing device and a ball mill according to an embodiment.

Fig. 4

shows a schematic representation of a viewing device according to Figs. 1 to 3 .

Fig. 1 shows a grinding plant 10 for comminuting brittle grist such as limestone, clinker, dolomite or ore material. The grinding system 10 has a first grinding device 12, a viewing device 14 and a second grinding device 16.

The first grinding device 12 is in the in Fig. 1 illustrated embodiment, a roller press with two counter-rotating grinding rollers 18a, 18b, which via a in Fig. 1 A pressing device (not shown) can be subjected to grinding pressures of up to 250 MPa, a grinding gap being maintained between the grinding rollers 18a, 18b. The roller press also has a feed chute 20 which is arranged above the grinding rollers 18a and 18b. The feed chute 20 has a tubular upper section and a funnel-shaped lower section for guiding grinding stock into the grinding gap between the grinding rollers 18a and 18b. Furthermore, the roller press 12 has an outlet opening 38 for discharging material to be ground by the grinding rollers 18a, 18b.

The classifier 14 has a static classifier and a dynamic classifier and is arranged below the first grinding device 12. Furthermore, the classifier 14 comprises a first inlet 32 and a second inlet 34 for admitting a material flow, as well as three outlets, wherein a coarse material outlet 24 for discharging coarse material sifted out by the static sifter, a semolina outlet 26 for discharging grit sifted out by the dynamic sifter and a finished goods outlet 28 is provided for discharging finished goods that have at least passed the dynamic classifier. The coarse material usually has a grain size of 10-100 mm, the grit a grain size of about 1-10 mm and the fine material a grain size of about 30-300 µm. The detailed structure of the viewing device 14 is with reference to FIG Fig. 4 explained in more detail.

The first inlet 32 of the sifting device 14 is connected to the outlet 38 of the first grinding device 12, so that the material to be ground is guided from the outlet 38 into the sifting device by means of gravity. The connection between the first inlet 32 of the viewing device and the outlet 38 of the first grinding device 12 is realized, for example, via a chute.

The second inlet 34 of the classifying device is connected to the outlet of the second grinding device 16 via a further conveying device 36 which conveys the ground material ground in the ball mill to the second inlet 34 of the classifying device.

The classifying device 14 also has a classifying air inlet 40 for admitting a classifying air flow into the static classifier.

A conveyor device 30, which is shown schematically as a pipeline, connects to the coarse material outlet 24 of the viewing device 14. Such a conveying device 30 comprises, for example, a conveyor belt or a bucket elevator for conveying ground material from the coarse material outlet 24 of the classifying device 14 to the feed chute 20.

A metering device 42 connects to the semolina outlet 26 of the viewing device 14. Such a metering device 42 is, for example, a speed-controllable ballast or rotary valve which, via rotating vane cells, guides a predetermined maximum amount of ground material from the grit outlet 26 of the classifying device 14 to the second grinding device 16.

The semolina outlet 26 of the classifying device 14 for discharging semolina is connected to the inlet of the second grinding device 16. The connection is, for example, an in Fig. 1 Conveyor device not shown, such as a conveyor belt or a chute.

A measuring device for measuring a mass flow from the viewing device 14 to the second grinding device 16 is arranged between the metering device 42 and the inlet of the second grinding device 16.

The second grinding device 16 is arranged below the viewing device 14 and in the in Fig. 1 illustrated embodiment a ball mill which has a tubular base body, within which a plurality of grinding bodies are arranged, which grind the grinding stock located inside the ball mill, for example by rotating the base body about the longitudinal axis.

The grinding system 10 also has a fresh material feed 22, which is shown schematically between the viewing device 14 and the first grinding device 12. The fresh goods task 22 comprises, for example, conveyor belts and is arranged such that fresh goods are fed to an inlet of the classifying device 14.

The grinding plant 10 also has two separators 46, 48 for separating the air flow from the grinding stock. A first separator 46 is connected to the finished goods outlet 28 of the classifying device. The fine material / air mixture exiting from the finished material outlet 28 is separated at the separator 46 into fine material and air flow 50. A second separator 48 is connected to the outlet of the ball mill 16 for separating the grinding stock exiting from the ball mill from the air stream 52.

During operation of the grinding system 10, fresh material is fed into the first inlet 32 of the classifying device 14 via the fresh material feed 22. The fresh material is, for example, coarse-grained ground material.

The ground material flows through the first inlet 32 into the static classifier, in which it is classified into coarse material and grits. The coarse material leaves the classifying device through the coarse material outlet 24 and flows via the conveying device 30 to the feed shaft 20 of the roller press 12 and then into the grinding gap between the grinding rollers 18a and 18b, in which it is ground. The ground material ground in the roller press 12 enters the first inlet 32 of the classifier 14 and then into the static classifier of the classifier 14, where it is classified into coarse material and grits.

The semolina leaves the sifting device through the semolina outlet 26. The metering device 42 connected to the semolina outlet 26 conveys a certain maximum amount of grist to the inlet of the ball mill 16, for example via a gravel sluice. h, especially 350 t / h. The grinding plant is usually operated in such a way that the amount of ground material is around 250-350 t / h, in particular 300 t / h. The metering device 42 reliably prevents the material flow of grist from the grit outlet 26 to the inlet of the ball mill 16 from exceeding an adjustable maximum value, thereby achieving optimum grinding in the ball mill 16 and preventing overload on the ball mill 16.

If the amount of ground material exceeds the maximum delivery amount of the dosing device 42, the ground material collects above the dosing device 42 in the semolina outlet 26 of the classifying device. In order to prevent the grist from backing up in the classifier 14, in particular in the dynamic classifier, an in Fig. 1 The return line shown in dashed lines is arranged between the grit outlet 26 and the coarse material outlet 24. The return of grist collecting in the semolina outlet 26 is implemented, for example, via an overflow (not shown) in the area of the semolina outlet 26. In addition, a semolina cone, in particular a buffer storage, is arranged above the semolina outlet 26, in which semolina accumulates. If the material in the area of the semolina outlet 26, in particular in the buffer store, exceeds a certain height, it is guided via the overflow into the return line 54 to the conveying device 30.

Following the metering device 42, the mass flow of the ground material is measured in the measuring device 44. The grinding system 10 also has a control / regulating device (not shown) which comprises, for example, the metering device 42 and / or the measuring device 44. The mass flow detected by the measuring device 44 is transmitted, for example, to the control / regulating device which, if the mass flow exceeds a predetermined value, reduces the amount of fresh food via the fresh food feed 22 and thus reduces the amount of semolina emerging from the semolina outlet 26.

Such a metering device 42 offers the advantage that process fluctuations in the grinding system are compensated for and overloading, i.e. too large a quantity of ground material in the ball mill, is prevented. The control / regulating device can be used to control / regulate the supply of fresh material as a function of the amount of grit entering the ball mill. In the event of an overload situation, in which the proportion of grits in the fresh product is very high, the amount of fresh product can be reduced via the fresh product feed 22 before the maximum delivery rate of the dosing device 42 is reached, and thus the operation of the dosing device 42 with the maximum delivery rate limited to a short period of time or the maximum delivery rate can be prevented.

The grinding stock emerging from the semolina outlet 26 of the classifying device 14 enters the ball mill 16 and is ground in it. Following the ball mill 16, the ground material is fed either via the separator 48 or directly to the conveying device 36, which conveys the ground material to the second inlet 34 of the classifying device 14.

The ground material enters the dynamic classifier via the second inlet 34 and is classified into grit and finished material. The grits leave the classifier 14 through the grit outlet 26 and the finished product leaves the classifier through the finished product outlet 28. Following the finished product outlet 28, the grist-air mixture is separated into finished product and air flow 50 via the separator 46.

Fig. 2 shows a grinding system 56 with a roller mill 12 and a viewing device 14, which essentially corresponds to the grinding system 10 of FIG Fig. 1 are arranged. In contrast to the grinding system 10 of the Fig. 1 comprises the grinding plant 56 of the Fig. 2 no ball mill 16.

Fresh product is fed into the first inlet 32 of the viewing device 14 via the fresh product feed 22. The coarse material leaving the classifying device 14 through the coarse material outlet 24 and the grit leaving the classifying device 14 through the grit outlet 26 are brought together and then fed via the conveyor device 30 to the feed shaft 20 of the roller mill. A metering device 42 and a measuring device 44 for measuring the mass flow of grist from the grist outlet 26 are arranged between the conveying device 30 and the semolina outlet 26 of the viewing device 14. The metering device 42 limits the amount of meal that is conveyed to the roller mill 12 via the conveyor device 30 to a maximum value and thus prevents an overload case in which an excessive amount of ground material, in particular meal, is conveyed to the roller mill 12. A further measuring device 45 is arranged between the coarse material outlet 24 and the conveying device 30 for determining the coarse material mass flow to the roller mill 12. The measuring devices 44 and 45 determine the amount of grit and gob material and transmit this value, for example, to a control / regulating device, not shown, which From a certain maximum value, for example 250-350 t / h, in particular 300 t / h, the amount of fresh material entering the grinding system 56 is reduced via the fresh material feed 22.

Fig. 3 shows a grinding plant 58 with a ball mill 16 and a viewing device 14, which essentially corresponds to the grinding plant 10 of FIG Fig. 1 arranged are. In contrast to the grinding system 10 of the Fig. 1 comprises the grinding plant 58 of the Fig. 3 no roller mill 12.

The coarse material leaving the classifying device 14 through the coarse material outlet 24 and the grit leaving the classifying device 14 through the grit outlet 26 are brought together and fed to the ball mill 16. A metering device 42 and a measuring device 44 for measuring the mass flow of ground material from the semolina outlet 26 are arranged between the semolina outlet 26 of the classifying device 14 and the inlet of the ball mill 16. The metering device 42 limits the amount of meal that is conveyed to the ball mill 16 to a maximum value and thus prevents an overload situation. A further measuring device 45 is arranged between the coarse material outlet 24 and the inlet of the ball mill 16 for determining the coarse material mass flow to the ball mill 16. The measuring devices 44 and 45 determine the amount of material to be ground to the ball mill 16 and transmit this value, for example to a control system (not shown). / Control device which, from a certain maximum value, reduces the amount of fresh material entering the grinding system 56 via the fresh material feed 22.

Fig. 4 shows a viewing device 14 according to Figs. 1 to 3 with a static sifter 60 and a dynamic sifter 62. The static sifter 60 is arranged around the dynamic sifter 62 and has a cylindrical shape. Furthermore, the static sifter comprises an outer cylindrical wall and a first, outer static flow device 64 and a second, inner static flow device 66 arranged radially inwards for this purpose. The first and second flow devices 64, 66 each have parallel guide vanes, the guide vanes of the first flow device 64 are employed in a radially sloping manner. The guide vanes of the second flow device 66 are positioned in the opposite direction to the guide vanes of the first flow device 64. Between the first and the second Flow device 64, 66, a cylindrical static viewing zone 68 is formed.

Within the static sifter 60, the dynamic sifter 62 is arranged radially inward of the second flow device 66. The dynamic classifier 62 comprises a rod basket 70 with rods running in the axial direction. The rod cage 70 is driven in rotation via a drive shaft 72 attached to the upper end of the rod cage. The dynamic sifter 62 is arranged coaxially to the static sifter 60 and rotationally symmetrical to the drive axis 72. The dynamic viewing zone 74 is formed between the viewing basket and the second flow device 66. Furthermore, vertical, rod-shaped guide elements (not shown) that adjoin the flow device 64 can be arranged in the dynamic viewing zone 74.

A distributor device 76 is arranged at the upper end of the rod basket 70 and has a first disk 78 and a parallel second disk 80. The second disk 80 has the same diameter as the rod basket 70, is firmly connected to it and forms a cover of the cylindrical rod basket 70. The first disk 78 is arranged parallel to the second disk 80 above the latter and is annular, with a recess in trained in the middle. A passage is formed between the first disk 78 and the second disk 80. The first disk 78 and the second disk 80 are connected to one another in a manner not shown, so that a rotation of the second disk 80 firmly connected to the rod cage 70 causes a rotation of the first disk 78.

A first inlet 32 and a second inlet 34 for admitting a material flow into the viewing device are arranged above the distributor device 76. The inlets 32, 34 have concentric openings which are arranged around the drive shaft 72 and which include the inlets shown in tubular form, the inlet opening of the first inlet 32 being above the inlet opening of the second Inlet 34 is arranged. The drive shaft 72 of the dynamic classifier 62 extends centrally, in the axial direction, through the second inlet 32.

A classifying air duct 82 is arranged around the static classifier 60. The classifying air duct 82 is shown schematically on the side, on the left side of the static classifier 60. The classifying air duct 82 is in fluid connection with the static classifier, so that classifying air can flow from the outer wall of the static classifier 60 through the outer static flow device 64 into the classifying zone 68 of the static classifier 60. The direction of flow of the classifying air is shown by the direction of the arrow in the classifying air duct 82.

Fig. 4 also shows three outlets 24, 26, 28 for discharging the sighted material flow from the sifting device 14. The coarse material outlet 24 comprises a channel which is arranged below the static viewing zone 68 in such a way that the material rejected in the static viewing zone falls into the channel and through Coarse material outlet 24 emerges from the viewing device 14. The semolina outlet 26 comprises a channel which is arranged below the dynamic classifying zone 74 in such a way that the material rejected by the dynamic classifier falls into the channel and exits the classifying device 14 through the grit outlet 26. The finished goods outlet 28 has a channel which is arranged below the rod cage 70 and through which the material passed through the static and dynamic sifting stages 68, 74 emerges from the sifting device 14 together with the sifting air inside the rod cage 70.

During operation of the viewing device 14, a coarse stream of material flows in the direction of arrow 84 through the first inlet 32 onto the first disk 78, which is driven to rotate via the drive shaft 72. The rotation of the first disk 78 moves the material on the disk 78 radially outward and enters the static viewing zone 68 of the static sifter 60 from above. The impact of the material flow on the disk 78 and the rotation of the disk 78 also ensure a Deagglomeration of the material.

From the outer wall of the static classifier 60, classifying air enters the static classifier 60 and flows through the outer flow device 64 against the material flow flowing through the static classifying zone 68. In the static classifying zone 68, the material flow is deflected radially inward towards the inner flow device 66 by the entering classifying air. The coarse material flows through the static classifying stage following gravity and falls down to the coarse material outlet 24. The finer material is pneumatically conveyed by the classifying air through the inner flow device 66 into the dynamic classifying zone 74, in which it is again divided into a coarse and a fine one Material is separated. The coarse material is rejected by the bars of the rod basket 70 and falls down to the semolina outlet 26. The fine material passes through the rods of the rod basket 70 into the interior of the rod basket and is discharged with the sifting air in the direction of the finished goods outlet 28.

The viewing device 14 has three outlets 24, 26, 28 for three different grain fractions of the material flow. The stream of material flowing into the separator 14 through the first inlet 32 is classified into three different grain fractions, which leave the separator 14 through three different outlets 24, 26, 28.

The stream of material entering the viewing device 14 through the second inlet 34 passes through the viewing device 14 in the direction of arrow 86 and initially flows onto the second disk 80, which is driven to rotate by the drive axle. The material is moved radially outward by the rotation of the disk 80 and enters the dynamic classifying zone 74, which adjoins the second disk 80, in the dynamic classifier 62. As already described with reference to the material flow flowing into the classifying device 14 through the first inlet 32, the coarser material falls through the dynamic classifying zone down to the grit outlet 26.

The finer material enters the rod basket 70 and is discharged downwards together with the classifying air in the direction of the finished goods outlet 28.

The material entering the sifting device through the second inlet 34 is sifted into two grain sizes, the finer ground material, in particular finished material, being discharged from the sifting device 14 through the finished material outlet 28 and the coarser ground material, in particular semolina, through the semolina outlet 26.

The classifier 14 enables two material streams of different grain sizes to be fed into the classifier, the first material stream being fed to both the static classifier 60 and the dynamic classifier 62 and the second material stream being fed exclusively to the dynamic classifier 62. This enables an inlet of a coarse material flow through the first inlet 32 and an inlet of a finer material flow through the second inlet 34 into the viewing device 14.

The ones related to the Figs. 1 to 3 grinding device described in which the with reference to Fig. 4 The viewing device 14 described is arranged, enables a considerable saving of space, since a viewing device is used for two material flows and an additional separator can be dispensed with. Furthermore, the grinding system described enables additional line elements between a static and a dynamic viewing device to be dispensed with. The grinding system also ensures that the grinding devices are operated at their optimal operating point, thus enabling efficient comminution of the material to be ground.

List of reference symbols

10

Grinding plant

12

first grinding device, roller press

14th

Viewing device

16

second grinding device, ball mill

18a

Grinding roller

18b

Grinding roller

20th

Feed chute

22nd

Fresh goods feed

24

Coarse material outlet

26th

Semolina outlet

28

Finished goods outlet, fine goods outlet

30th

Conveyor

32

first inlet of the viewing device

34

second inlet of the viewing device

36

Conveyor

38

Outlet opening of the first grinding device

40

Sight air inlet

42

Dosing device

44

Measuring device for measuring the mass flow

45

Measuring device for measuring the mass flow

46

Separator

48

Separator

50

Airflow

52

Airflow

54

Return line

56

Grinding plant

58

Grinding plant

60

static sifter

62

dynamic sifter

64

external static flow device

66

internal static flow device

68

static viewing zone

70

Rod basket

72

drive shaft

74

dynamic viewing zone

76

Distribution device

78

first slice

80

second disc

82

Air duct

Claims (11)

1. A grinding installation (10) for comminuting material for grinding, comprising at least one grinding apparatus (12, 16), and
   a classifying device (14) which is connected to the at least one grinding apparatus (12, 16) and which serves for classifying the material for grinding and which comprises a static classifier and a dynamic classifier, wherein the static classifier is arranged so as to at least partially surround the dynamic classifier,
   wherein the classifying device (14) comprises at least one coarse material outlet (24) for the discharge of coarse material which comprises a coarse grain fraction,
   at least one grit outlet (26) for the discharge of grit which comprises a medium grain fraction, and
   at least one finished material outlet (28) for the discharge of finished material which comprises a fine grain fraction,
   characterized in that the grinding installation comprises an open-loop/closed-loop control device for open-loop/closed-loop control of at least a part of a stream of material for grinding to the at least one grinding apparatus (12, 16),
   wherein the open-loop/closed-loop control device comprises a dosing device (42) which is arranged between the grit outlet (26) and the at least one grinding apparatus (12, 16) and which is designed so as to limit at least a part of the stream of material for grinding to the at least one grinding apparatus (12, 16).
2. The grinding installation (10) as claimed in claim 1, wherein the open-loop/closed-loop control device comprises at least one measurement device (44, 45) for determining at least a part of the stream of material for grinding to the at least one grinding apparatus (12, 16).
3. The grinding installation (10) as claimed in claim 2, wherein the measurement device (44) is arranged between the dosing device (42) and the at least one grinding apparatus (12, 16).
4. The grinding installation (10) as claimed in claim 2 or 3, wherein the grinding installation (10) comprises a fresh material feed (22) for the admission of fresh material into the grinding installation (10), and wherein the open-loop/closed-loop control device is connected to the fresh material feed (22), and designed, such that, when the stream of material for grinding, determined by means of the measurement device (44), from the grit outlet (26) to the at least one grinding apparatus (12, 16) reaches a threshold value, said open-loop/closed-loop control device reduces the fresh material stream entering the grinding installation (10) via the fresh material feed (22).
5. The grinding installation (10) as claimed in one of the preceding claims,
   wherein a buffer store is arranged between the grit outlet (26) and the at least one grinding apparatus (12, 16).
6. The grinding installation (10) as claimed in claim 5, wherein the grinding installation (10) comprises a first grinding apparatus (12), in particular a roller press, and a second grinding apparatus (16), in particular a ball mill, wherein the grit outlet (26) is connected to an inlet of the second grinding apparatus (16), and wherein the buffer store comprises an overflow which is connected to the first grinding apparatus (12).
7. The grinding installation (10) as claimed in claim 6, wherein the overflow comprises a measurement device for determining the stream of material for grinding flowing through the overflow.
8. A method for comminuting material for grinding, having at least the steps:

   comminuting the material for grinding in at least one grinding apparatus (12, 16),

   classifying the material for grinding in a classifying device (14) into coarse material, grit and finished material, wherein the classifying device (14) comprises a static classifier and a dynamic classifier, wherein the static classifier is arranged so as to at least partially surround the dynamic classifier, and

   characterized in that

   at least a part of the stream of material for grinding to the at least one grinding apparatus (12, 16) is controlled in open-loop/closed-loop fashion by means of an open-loop/closed-loop control device and wherein the open-loop/closed-loop control device comprises a dosing device (42) limiting the stream of grit material to the at least one grinding apparatus (12, 16).
9. The method as claimed in claim 8, wherein the method comprises the steps:

   determining at least a part of the stream of material for grinding to the at least one grinding apparatus (12, 16) by means of a measurement device (44, 45), and

   open-loop/closed-loop control of at least a part of the stream of material for grinding to the at least one grinding apparatus (12, 16) in a manner dependent on the stream of material for grinding determined by means of the measurement device (42).
10. The method as claimed in one of claims 8 or 9, wherein
    fresh material is admitted into the grinding installation (10) by means of a fresh material feed (22), and the flow rate of fresh material is controlled in open-loop/closed-loop fashion in a manner dependent on the determined stream of material for grinding to the at least one grinding apparatus (12, 16).
11. The method as claimed in one of claims 8 to 10, wherein the method comprises the steps:

    comminuting the material for grinding in a first grinding apparatus (12), in particular in a roller mill,

    comminuting the material for grinding in a second grinding apparatus (16), in particular in a ball mill,

    conducting the coarse material to the first grinding apparatus (12),

    conducting the grit to the second grinding apparatus (16), and

    determining the stream of material for grinding to the second grinding apparatus (16) by means of a measurement device (44).

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