WO2021013926A1

WO2021013926A1 - Grinding device and method for operating a grinding device

Info

Publication number: WO2021013926A1
Application number: PCT/EP2020/070802
Authority: WO
Inventors: Michael Wilczek; Thomas Rüther
Original assignee: Thyssenkrupp Industrial Solutions Ag; Thyssenkrupp Ag
Priority date: 2019-07-25
Filing date: 2020-07-23
Publication date: 2021-01-28
Also published as: DE102019211059A1

Abstract

The present invention relates to a grinding device (10), in particular an agitator mill, which has a grinding chamber (12) with a plurality of grinding media and a material inlet (18) for admitting in particular dry grinding stock into the grinding chamber (12) and an agitator (14), the grinding device (10) having a plurality of water inlets (42) for admitting water into the grinding chamber (12). The invention also relates to a method for operating a grinding device (10) with a grinding chamber (12) having a plurality of grinding media and an agitator (14), said method comprising the steps of: - admitting grinding stock into the grinding chamber (12) and - admitting water into the grinding chamber (12) via a plurality of water inlets.

Description

Grinding device and method for operating a grinding device

The invention relates to a grinding device, in particular an agitator mill, with a plurality of water inlets for admitting water into the grinding chamber. The invention also relates to a method for operating such a grinding device.

Agitator mills, for example, are used for processing raw materials, in particular mineral crushed / ground materials such as limestone, oil sand, coal and ores such as iron ore and nickel ore. An agitator ball mill has, for example, a horizontally or vertically standing grinding chamber in which a substantially horizontally or vertically extending agitator is arranged.

Agitator mills are usually operated with a mixture of water and ground material (slurry), as the high fineness of the material results in more efficient size reduction and easier transport of the material through the grinding chamber. The high thermal load due to the high energy density within an agitator mill is reduced on the one hand by the water and on the other hand by a cooling jacket. The addition of surfactants, for example, also reduces the clumping of the material. When crushing cement clinker, the above-described operation of the agitator mill is not possible due to the hydraulic activity of the material. Cement clinker is usually dry-ground, whereby the high temperatures and the high mechanical stress cause static charging of the material, which can lead to agglomeration of the material. An agitator mill is known, for example, from EP 3 06 0 345 B1.

Proceeding from the prior art, it is the object of the present invention to provide an agitator mill which prevents agglomeration of the ground material and overheating of the agitator mill components. This object is achieved according to the invention by an agitator mill with the features of the independent device claim 1 and by a method according to the independent method claim 12. Advantageous further developments result from the dependent claims.

According to a first aspect, a grinding device, in particular an agitator mill, comprises a grinding chamber with a plurality of grinding bodies and a material inlet for admitting, in particular, dry ground material into the grinding chamber. The grinder also includes an agitator and a plurality of water inlets for admitting water into the grinding chamber.

Such a grinding device is used, for example, for comminuting cement clinker or raw materials, in particular mineral crushed / ground materials such as limestone, oil sand, coal and ores such as iron ore and nickel ore.

The grinding chamber of the grinding device is preferably designed as a hollow cylinder, the agitator being arranged in particular completely within the grinding chamber. The grinding chamber is also at least partially filled with a plurality of very wear-resistant grinding bodies which are, for example, spherical or cylindrical and are freely movable within the grinding chamber. The agitator of the grinding device serves to mix the ground material and the grinding media within the grinding chamber, whereby the grinding material is comminuted by the grinding media. The agitator preferably extends axially through the grinding chamber and is preferably driven to rotate about the central axis of the grinding device and relative to the grinding chamber and has a drive shaft on which a plurality of stirring elements are attached which protrude into the grinding chamber and are, for example, rod-shaped or helical are and in particular wind spirally around the drive shaft. The stirring elements preferably extend in the radial direction of the drive shaft and are firmly connected to it, for example welded or formed in one piece with it. The stirring elements are for example evenly spaced from one another, preferably arranged over the entire length of the grinding chamber.

The drive shaft of the agitator extends in particular in the horizontal direction through the grinding chamber and preferably protrudes from the grinding chamber at the end of the grinding chamber on the material inlet side. The drive shaft is driven in particular by a drive motor outside the grinding chamber. The agitator is designed in such a way that when it rotates around the drive shaft, it transports a thorough mixing of the material and at the same time the material from the end of the grinding chamber on the material inlet side to the opposite end, at which a material outlet is arranged.

The water inlets allow water to be fed into the grinding chamber separately from the bulk material to be ground, which is fed into the grinding chamber via the material inlet. Preferably, only dry ground material is fed into the grinding chamber via the material inlet and only water is fed into the grinding chamber via the water inlets. It is conceivable that more water inlets are arranged at the end of the grinding chamber on the material outlet side than at the end of the grinding chamber on the material inlet side. The water inside the grinding chamber ensures that the grinding device and the material are cooled, so that both the components of the grinding device and the material to be ground are protected from damage due to overheating. The water inlets are preferably evenly distributed over the extension of the grinding chamber, so that a uniform supply of water into the grinding chamber is possible. In particular, exactly as much water per unit of time is fed into the grinding chamber of the grinding device as it evaporates during the grinding process, so that a reaction of the ground material with the water is minimized or avoided. By adding a small amount of water to the grinding chamber, especially in agitator mills, on the one hand the temperature in the grinding chamber is lowered and on the other hand the static charge on the particles of the grist is reduced, which reduces the tendency to agglomerate. According to a first embodiment, the water inlets are arranged, for example exclusively, in the agitator. The water inlets are preferably arranged in the drive shaft and / or the agitating elements of the agitator. For example, the water inlets are designed in the shape of a nozzle, so that a finely dosed inlet of the water into the grinding chamber is made possible. The water inlets are preferably arranged, for example, evenly distributed over the entire agitator. According to a further embodiment, the water inlets are arranged essentially uniformly spaced from one another over the extent of the grinding chamber.

According to a further embodiment, the agitator comprises a conduit for conducting water which extends axially through the agitator and is connected to the plurality of water inlets. According to a further embodiment, the line extends preferably coaxially through the drive shaft, which is in particular designed as a hollow shaft. The line preferably extends coaxially to the agitator through the entire agitator and in particular at least one end of the agitator out of the grinding chamber. The line is preferably connected to the water inlets arranged in the agitator, so that water flows from the line to the water inlets and into the grinding chamber. A line arranged in the agitator for conducting the water offers a particularly space-saving solution.

According to a further embodiment, the agitator has a drive shaft and a plurality of agitating elements arranged thereon, the water inlets being arranged in the agitating elements and / or the drive shaft. For example, each of the stirring elements has at least one water inlet. In particular, the water inlets are arranged at the end of the stirring elements pointing radially outward. The water inlets are designed, for example, as channels extending radially outward from the line for guiding water, which open into the grinding chamber. According to a further embodiment, the grinding device has a housing which at least partially encloses the grinding chamber, the water inlets being arranged in the housing. For example, the agitator and the housing each have a plurality of water inlets. It is also conceivable that the water inlets are formed exclusively in the housing and not in the agitator. The housing is designed in particular as a hollow cylinder. In particular, the housing is arranged stationary relative to the agitator, so that it does not rotate during the grinding process. The agitator is mounted within the grinding chamber and rotatable relative to the housing.

According to a further embodiment, the housing is double-walled with an outer wall and an inner wall and a cavity is formed between the outer wall and the inner wall which is connected to the line and / or at least one water inlet for letting water into the cavity. According to a further embodiment, the water inlets are formed in the inner wall, so that the water flowing through the water inlet into the cavity passes through the water inlets in the inner wall into the grinding chamber. The water inlet preferably extends through the outer wall.

According to a further embodiment, the housing comprises two housing sections which are arranged fluidly separated from one another and each have a water inlet. For example, the first housing section comprises the material inlet and the second housing section the material outlet, so that the housing sections are preferably arranged one behind the other in the direction of flow of the material to be ground. Each housing section has an outer wall and an inner wall with a plurality of water inlets for admitting water into the grinding chamber. Two separate housing sections enable a targeted supply of water to different areas of the grinding chamber.

According to a further embodiment, the grinding device has a metering device which is connected to the water inlets, the Dosing device designed and set up in such a way that a water-solids ratio of about 1:50 to 1: 150, in particular 1: 100, is set in the grinding chamber. The metering device comprises, for example, a pump and / or a diaphragm in the line or the water inlets and preferably a control device connected to this. The regulating device is preferably designed to regulate the amount of water flowing through the water inlets into the grinding chamber per unit of time. The regulating device is designed in particular in such a way that the amount of water flowing through the water inlets into the grinding chamber over a certain time unit corresponds to the amount of water evaporating over the same time unit during the grinding process.

For example, the grinding device additionally comprises a temperature measuring device connected to the regulating device within the grinding chamber for determining the temperature of the ground material or the gas phase within the grinding chamber. The regulating device is preferably designed in such a way that it increases or decreases the amount of water in the grinding chamber as a function of the determined temperature. For example, the amount of water is increased when the temperature exceeds a predetermined limit value. The amount of water is reduced, for example, when the temperature falls below a predetermined limit value. The temperature limit is, for example, 80 ° C to 140 ° C, in particular 100 ° C to 120 ° C

The invention also comprises a method for operating a grinding device with a grinding chamber with a plurality of grinding bodies and an agitator, comprising the steps:

- Letting ground material into the grinding chamber and

- Let water in the grinding chamber via a plurality of water inlets.

The embodiments and advantages described above with reference to the grinding device also apply in procedural correspondence to the method for operating a grinding device. According to one embodiment, the admission of water takes place separately from the admission of the ground stock. According to a further embodiment, a water / solids ratio of about 1:50 to 1: 150, in particular 1: 100, is set within the grinding chamber.

The amount of water admitted into the grinding chamber via the water inlets over a unit of time preferably corresponds to the amount of water evaporating over the same unit of time during operation of the grinding plant.

Description of the drawings

The invention is explained in more detail below using several exemplary embodiments with reference to the accompanying figures.

Fig. 1 shows a schematic representation of a grinding device in a sectional view according to an embodiment.

2 shows a schematic representation of a grinding device in a sectional view according to a further exemplary embodiment.

In Fig. 1, a grinding device 10 is shown. The grinding device 10 is an agitator mill which has an essentially hollow cylindrical grinding chamber 12 in which an agitator 14 is arranged. The cylindrical grinding chamber 12 is arranged horizontally by way of example, with a material inlet 18 being provided at one end of the grinding chamber 12 for admitting, in particular, dry material to be ground. At the opposite end of the grinding chamber 12, a material outlet 20 for discharging ground material from the grinding chamber 12 is arranged. The agitator 14 extends coaxially to the grinding chamber 12 within this and comprises a drive shaft 16. The agitator 16 comprises the drive shaft 16 and a plurality of agitating elements 22 which are attached to the drive shaft 16 and extend in the radial direction to the drive shaft 16. The stirring elements 22 are, for example, projections that extend radially to the drive shaft 16, such as rods, drivers or arms. For example, the stirring elements 22 are helical, in particular helical or in the form of a cylindrical spiral, and wind around the drive shaft 16. The helical stirring elements 22 have, for example, a constant slope. The stirring elements 22 are, for example, attached to the drive shaft 16 offset uniformly from one another. By way of example, the stirring elements 22 in FIG. 2 have approximately the same distance from one another over the extent of the drive shaft 16. In particular, the stirring elements 22 and the drive shaft are made of steel, preferably sheet metal made of a ductile and weldable steel. The stirring elements 22 are preferably firmly connected to the drive shaft 16, for example welded or formed in one piece with it. A wear protection 24 is attached to the drive shaft 16, for example. The wear protection is, for example, a coating made of a flart metal or a metal matrix composite material.

A drive motor 26 is attached to the drive shaft 16, which drives the drive shaft 16 in rotation so that the agitator 14 rotates about the longitudinal axis when the grinding device 10 is in operation. The drive motor 26 is at least partially surrounded by a motor housing 28 and is connected to the drive shaft 16, for example, via a drive element not shown in FIG. In the grinding chamber 12, freely movable grinding bodies, for example grinding balls, which are not shown in FIG. 1, are arranged, which are used to comminute the material. The rotation of the agitator 14 transports the grinding media together with the material to be ground along the agitator 14. The grinding bodies are preferably moved both in the horizontal direction and also radially outward with respect to the grinding chamber 12. The material leaves the grinding device 10 through the material outlet 20 at the end of the grinding chamber 12.

The grinding device 10 furthermore has a separation device 30, which is located at the end region of the grinding device 10 on the material outlet side within the Grinding chamber 12 is arranged. The separation device 30 serves to separate the ground material from the grinding media in front of the material outlet 20, so that the grinding media remain within the grinding chamber 12. The separation device 30 is, for example, a rotor basket that is attached coaxially to and on the drive shaft 16 so that it rotates with the agitator 14. The rotor basket has a plurality of parallel rods or holes, the rods being spaced apart from one another or the holes having a diameter that is smaller than the diameter of the grinding media so that they do not get into the interior of the rotor basket. The interior of the rotor basket is connected to the material outlet 20, so that the material that has entered the rotor basket leaves the grinding chamber through the material outlet 20.

The grinder 10 also has a housing 32 that is stationary relative to the agitator 14 so that it is not driven by the drive shaft 16 and does not rotate. The housing 32 is, for example, double-walled so that a cavity 34 is formed between two parallel walls of the housing 32. The housing 32 preferably comprises an outer wall 36 and an inner wall 38 which delimits the grinding chamber 12. It is also conceivable that the housing 32 only has one wall. The housing 32 encloses the grinding chamber 12 at least partially or completely. The drive shaft 16 extends through the housing 32 at the turn of the grinding chamber 12 on the material inlet side. The drive shaft 16 is designed as a hollow shaft, with a conduit 40 coaxial to this being formed within the drive shaft 16 for conducting water. The line 40 preferably extends into at least one, a plurality or all of the stirring elements 22.

The grinding chamber 12 has a plurality of water inlets 42 for admitting water into the grinding chamber. For example, the agitator 14 has a plurality of water inlets 42 which are preferably attached to the agitating elements 22 and / or in the drive shaft 16 and are connected to the line 40 such that water flows through the line 40 to the water inlets 42 and into the ok

Grinding chamber 12 arrives. One or a plurality of water inlets 42 are preferably arranged in each case on the radially outer regions of the stirring elements 22.

The grinding device 10 also has a water inlet 44 which is arranged on the end of the drive shaft 16 protruding from the housing 32 and is connected to the line 40.

For example, the inner wall 38 of the housing 32 has a plurality of water inlets 42, the line 40 preferably being connected to the cavity 34 between the outer wall 36 and the inner wall 38, so that water flows into the cavity 34 and via the water inlets 42 in the inner wall 38 enters the grinding chamber 12. It is conceivable that water inlets 42 are in the inner wall 38 of the housing 32 and / or in the agitator 14.

When the grinding device 10 is in operation, the material to be ground is passed through the material inlet 18 into the grinding chamber and moved there in the direction of the material outlet 20 by means of the rotating agitator 14. The grinding media arranged inside the grinding chamber work together with the circulation to crush the material. During the grinding process, water is let into the grinding chamber 12 via the water inlets 42, so that the ground material and the grinding device 10 are cooled. Preferably, the amount of water admitted into the grinding chamber 12 per unit of time corresponds to the amount of water evaporating within the grinding chamber in the same unit of time, so that the material inside the grinding chamber 12 is exclusively cooled by the water and not mixed with it to form a mixture of water and grist becomes. The amount of water is preferably so small that only a very small, preferably negligible, proportion of the ground material reacts with the water and, for example, hardens if the ground material is, for example, cement clinker.

The grinding device 10 preferably has a metering device (not shown in the drawings) for adding water to the grinding chamber 12. The metering device comprises, for example, a pump or a diaphragm and one with it connected control device. The control device is preferably connected to a temperature measuring device within the grinding chamber 12, so that the temperature within the grinding chamber 12 is transmitted to the control device. The control device is connected, for example, to the pump or the diaphragm for adding water to the grinding chamber 12, the control device being designed such that it varies, in particular increases or decreases, the amount of water to be added to the grinding chamber 12 as a function of the transmitted temperature. For example, the amount of water in grinding chamber 12 is increased when the temperature inside grinding chamber 12 exceeds a certain value and vice versa.

Fig. 2 shows a further embodiment of a grinding device 10, wherein the same elements are provided with the same reference numerals. The grinding device 10 in FIG. 2, in contrast to the grinding device in FIG. 1, has a first and a second housing section 46, 48, each of which has an inner wall 38 and an outer wall 36 with a respective flea space 50, 52. The first and second flea spaces 50, 52 are arranged separately from one another, so that they are not fluidly connected to one another. Each housing section 46, 48 has a water inlet 54, 56 which are connected to the respective flea space 50, 52, so that water flows from the respective water inlet 54, 56 into the flea space 50, 52 connected to it. For example, the line 40 within the drive shaft 16 designed as a flea shaft is not connected to the flea spaces 50, 52.

List of reference symbols

10 grinding device 12 grinding chamber

14 agitator

16 drive shaft

18 Material inlet 20 Material outlet 22 Stirring element

24 Wear protection 26 Drive motor

28 motor housing

30 separation device 32 housing

34 cavity

36 outer wall

38 inner wall

40 line

42 water inlet

44 Water inlet

46 Housing Section

48 housing section 50 first cavity 52 second cavity 54 first water inlet 56 second water inlet

Claims

1. Grinding device (10), in particular an agitator mill, having

a grinding chamber (12) with a plurality of grinding media and one

Material inlet (18) for admitting particularly dry grist into the

Grinding chamber (12) and

an agitator (14),

characterized in that

the grinding device (10) has a plurality of water inlets (42) for admitting water into the grinding chamber (12).

2. Grinding device (10) according to claim 1, wherein the water inlets (42) are arranged in the agitator (14).

3. Grinding device (10) according to one of the preceding claims, wherein the agitator (14) comprises a conduit (40) for conducting water which extends axially through the agitator (14) and is connected to the plurality of water inlets (42) .

4. Grinding device (10) according to one of the preceding claims, wherein the agitator (14) has a drive shaft (16) and a plurality of agitating elements (22) arranged thereon and wherein the water inlets (42) in the agitating elements (22) and / or the drive shaft (16) are arranged.

5. Grinding device (10) according to claim 4, wherein the conduit (40) extends through the drive shaft (16).

6. Grinding device (10) according to one of the preceding claims, wherein the grinding device (10) has a housing (32) at least partially enclosing the grinding chamber (12) and wherein the water inlets (42) are arranged in the housing (32).

7. grinding device (10) according to claim 6, wherein the housing is double-walled with an outer wall (36) and an inner wall (38) and wherein a cavity (34) is formed between the outer wall (36) and the inner wall (38), which is connected to the line (40) and / or at least one water inlet (54, 56) for letting water into the cavity (34).

8. grinding device (10) according to claim 7, wherein the water inlets (42) are formed in the inner wall (38).

9. Grinding device (10) according to one of claims 6 to 8, wherein the housing (32) comprises two housing sections (46, 48) which are arranged fluidly separated from one another and each have a water inlet (54, 56).

10. grinding device (10) according to claim 1, wherein the water inlets (42) are arranged over the extension of the grinding chamber (12) substantially evenly spaced from one another.

11. Grinding device (10) according to one of the preceding claims, wherein a metering device is provided which is in communication with the water inlets (42) and wherein the metering device is designed and set up such that in the grinding chamber (12) a water-solids ratio of about 1:50 to 1: 150, in particular 1: 100 is set.

12. A method for operating a grinding device (10) with a grinding chamber (12) with a plurality of grinding bodies and an agitator (14), comprising the steps:

- Letting ground material into the grinding chamber (12) and

- Admitting water into the grinding chamber (12) via a plurality of water inlets (42).

13. The method according to claim 9, wherein the admission of water takes place separately from the admission of the grist.

14. The method according to claim 9 or 10, wherein a water-solids ratio of about 1:50 to 1: 150, in particular 1: 100, is set within the grinding chamber (12).