Rotor and its use, manufacturing method and agitator mill

Abstract

The invention relates to a rotor for a stirred mill, the rotor having a substantially cylindrical rotor body, an outer wall of which defines an inner surface of a grinding chamber through which feed material to be processed flows during operation of the stirred mill. A ceramic ring is arranged at a rotor end of the rotor body, which rotor end is arranged opposite a product inlet of the stirred mill. The invention further relates to a stirred mill comprising a rotor according to the invention, to the use of a rotor according to the invention in a stirred mill for producing a dispersion, and to a method for producing a rotor.

Description

Technical Field

[0001] This invention relates to a rotor for a stirring mill, and more particularly to a wear-resistant, dimensionally stable plastic rotor. Background Technology

[0002] Stirring mills have wide applications in grinding and dispersing solids in liquids. They are used, for example, in the production of adhesives, printing inks, cosmetics, pharmaceuticals, or as raw materials for battery slurries (especially silicon). Typically, in a vertical stirring mill, a grinding chamber is formed by a stator and a rotor rotating about a vertically oriented central longitudinal axis, in which, where applicable, auxiliary grinding media (e.g., ceramic balls) are used to produce dispersions. For this purpose, grinding tools in the form of pins, for example, can be attached to the rotor and / or stator. The feed material is guided into the grinding chamber through a product inlet, ground in the grinding chamber, and discharged through a product outlet. Such stirring mills are known, for example, from EP 1 992 412 A1.

[0003] Especially in the production of raw materials for battery slurries, a fineness of 100nm to 200nm (x50) must be achieved, requiring long grinding times. Due to the abrasion resistance of the solids being processed, significant wear is expected in the processing zone within the grinding chamber. Furthermore, metal contamination in the final product should be avoided; therefore, metal-free rotors are preferred over conventional steel rotors in agitated grinding mills.

[0004] The use of ceramic and plastic rotors is known in the prior art. However, the production of ceramic rotors is very expensive and complex in terms of design. For example, SSiC or SiSiC are highly wear-resistant due to their hardness, but are therefore also sensitive to breakage. Both ceramics also have very good thermal conductivity, significantly higher than steel. However, the production of large components presents significant challenges.

[0005] Using plastic rotors can also avoid metal contamination. However, depending on the feed material, this type of rotor can be subject to rapid mechanical wear. Plastic materials are particularly affected in areas of grinding media compression (high energy density areas). Furthermore, it is always essential to check the compatibility of the plastic used for the rotor with the feed material to ensure its chemical resistance. The generally poor thermal conductivity of plastics is also a significant disadvantage. Summary of the Invention

[0006] One object of the present invention is to provide a cost-effective rotor for a stirred mill that is dimensionally stable and particularly resistant to common solvents and is especially suitable for the production of battery slurries. The wet grinding of abrasive solids should be able to achieve non-destructive wear in the final product.

[0007] The basic idea of ​​this invention is to use a rotor body for a stirred mill rotor that has wear elements made of ceramic in high energy density regions, particularly in the lower region of the processing zone, i.e., at the lower end of the rotor. Specifically, in the case of a stirred mill arranged vertically at the bottom of the processing zone, i.e., in the lower region of the rotor, the combination of the gravity and deflection of the product solids and the grinding media on the grinding media, along with high rotor speed, results in high wear on the rotor. Typically, the highest wear in a stirred mill occurs at the rotor end, i.e., at the point opposite the product inlet.

[0008] Therefore, according to the present invention, a rotor is provided having a substantially cylindrical rotor body, the outer wall of which defines the inner surface of a grinding chamber through which the feed material to be processed flows during operation of a stirred mill. A ceramic ring is arranged in a region of the rotor having a high energy input. This region is the rotor side opposite the inlet where the product enters the stirred mill. In a vertical stirred mill, this is the lower portion of the rotor body. The surface of the ceramic ring specifically forms a portion of the outer wall of the rotor, which forms the inner surface of the grinding chamber. This portion preferably extends to a grinding tool arranged on the outer wall of the rotor. Thus, the grinding tool can secure the ceramic ring against twisting and / or detachment.

[0009] The ceramic ring is preferably connected to the rotor body, particularly by threaded connection, adhesive bonding, or interlocking connection via a profile fit. According to a preferred embodiment, if the rotor body is made of plastic, the ceramic ring can also be cast into the rotor body.

[0010] The ceramic ring may have a substantially L-shaped cross-section, wherein the longer side of the L-shaped ceramic ring, i.e. its leg, is arranged on the outer surface of the rotor. Alternatively, the ceramic ring may have a substantially U-shaped cross-section, with its legs arranged on both the outer and inner surfaces of the rotor.

[0011] Preferably, the ratio of the length L of the portion of the rotor's outer wall formed by the ceramic ring to the rotor's outer diameter D, L / D, is between 0.05 and 0.5. The ratio of the thickness S1 of the portion of the ceramic ring forming the rotor's outer wall to the total rotor wall thickness S2, S1 / S2, is preferably between 0.1 and 0.9.

[0012] The plastic rotor may contain at least one of the following materials: PA, PET, PEEK, PVDF, and POM. The ceramic ring may contain at least one of the following materials: ZrO2, SSiC, SiSiC, and Si3N4.

[0013] The present invention also provides a stirred mill having a rotor according to the invention. According to a known mill, the stirred mill according to the invention further includes a stator having an inner stator wall, wherein the rotor is arranged within the stator. Furthermore, a product inlet and a product outlet are provided, and a grinding chamber is formed between the inner stator wall and the outer rotor wall. Feed material can be guided into the grinding chamber via the product inlet and out of the grinding chamber via the product outlet.

[0014] The ratio of the rotor's outer diameter D to the stator's inner diameter D2 is preferably 0.6 ≤ D / D2 ≤ 0.95. Furthermore, the stirring mill may have an inner stator arranged within a portion of the rotor, wherein a product outlet is formed between the outer walls of the rotor and the inner stator. The ratio of the inner stator's outer diameter d22 to the rotor's inner diameter d1 is preferably 0.8 ≤ d22 / d1 ≤ 0.98.

[0015] The present invention also relates to the use of the rotor according to the invention in a stirring and grinding mill for producing dispersions, particularly battery slurries, and a method for producing the rotor. The method includes the step of joining a ceramic ring to the rotor body, particularly by adhesive bonding, threaded connection, or profile-fit interlocking connection. Attached Figure Description

[0016] The invention will now be described in more detail with reference to the accompanying drawings, in which:

[0017] Figure 1 This is a cross-sectional view of a conventional vertical mixing and grinding mill.

[0018] Figures 2A to 2C This is a cross-sectional view of the rotor of a vertical stirring mill according to an embodiment of the present invention, and

[0019] Figures 3A to 3C This is a cross-sectional view of a rotor for a vertical stirring mill according to another embodiment of the present invention. Detailed Implementation

[0020] Figure 1 Details of a vertically arranged stirring mill according to the prior art are shown as an example. Figure 1 The stirred mill shown conventionally has a mill container or stator 2 with an internal grinding chamber 8. The grinding chamber 8 is at least partially filled with grinding elements 43. The stirred mill also includes an inner stator 22 and a rotor 35 rotatable about a central longitudinal axis 19. Grinding tools 38 extending into the grinding chamber 8 are attached to the rotor 35. A second tool 74 extending into the grinding chamber 8 is attached to the inner wall 9 of the container or stator. The processed feed material is guided through the gap between the rotor 35 and the inner stator 22 to form a protective screen 30, which accommodates the grinding elements 43 and flows out via a discharge line 31.

[0021] Figures 2A to 2C It shows how to use such Figure 1 The diagram shows a cross-sectional view of the rotor of a vertical stirring mill. The rotor according to the illustrated embodiment of the invention has a generally cylindrical rotor body 351 with an outer diameter 32. The rotor body 351, having an outer diameter D, can be made of plastic or steel, with plastic being preferred. The rotor and... Figure 1 The stators shown together form a grinding chamber during the operation of the stirred mill, through which the feed material to be processed flows.

[0022] The greatest wear on the rotor of a vertical stirred mill typically occurs in the lower region of the rotor, a region of high energy density resulting from the combination of gravity, the deflection of the feed material against the grinding media, and the high rotor speed. Generally, in both vertical and horizontal stirred mills, the region causing the greatest wear is the area opposite the product inlet during operation. According to the invention, an annular wear ring is provided precisely in this region, made of a hard and therefore highly wear-resistant ceramic material. In this case, for example, the material is ZrO2, SSiC, SiSiC, and Si3N4. Thus, the rotor 35 can be largely manufactured from a cost-effective rotor matrix, however, the easily worn portions are replaced by a wear-resistant ceramic material.

[0023] like Figure 2A and Figure 2C As shown in the detailed view indicated by Y and further enlarged, the ceramic ring 352 may have a substantially L-shaped profile, wherein the shorter side of L forms the underside and the longer side (i.e., the leg of L) forms the lower portion of the outer side 32, where the greatest wear occurs. The lower portion of the length L of the outer side 32 and the underside of the rotor having a total wall thickness S2 are thus formed by the ceramic ring 352.

[0024] The ceramic ring 352 is connected to the rotor body, for example, by threaded connection, adhesive bonding, or, in the case of a plastic rotor body, by casting into the plastic. On the outer side 32 of the rotor, the ceramic ring 352 preferably extends upwards to the bottom row of the grinding tools 38, such as... Figure 2A and Figure 2B As shown in the cross-section indicated by X. Therefore, the ceramic ring 352 can be additionally secured by the grinding tool 38, in particular to prevent twisting or falling off.

[0025] The ratio of the ceramic ring wall thickness S1 to the rotor total wall thickness S2 is preferably 0.1. <S1 / S2<0.9。

[0026] Figures 3A to 3C A cross-sectional view of a rotor according to another embodiment of the present invention is shown. Figures 2A to 2C As shown, a wear element made of ceramic is attached to the lower part of the rotor body 351. According to... Figures 3A to 3CThe implementation shown is also achieved in the form of a ceramic ring 352, which is consistent with... Figures 2A to 2C Unlike other rotors, this one has a substantially U-shaped profile, such that, in addition to a portion of the lower and outer sides 32, a portion of the inner surface of the rotor (i.e., a portion of the product outlet) is also reinforced by wear elements via the second leg of the U. This again... Figure 3A and Figure 3C The details, indicated by Y, are shown more precisely. On the outer side 32, the ceramic ring 352 can extend upwards at least to the bottom row of the grinding tool 38, as shown in... Figure 3A and Figure 3B The cross section represented by X is shown.

[0027] The present invention also provides a stirring and grinding mill using a rotor according to the invention. For this purpose, only as... Figure 1 The rotor 35 shown in the exemplary embodiment is based on the invention as follows: Figures 2A to 2C or Figures 3A to 3C The rotor is shown as an example in the diagram. For the ratio of the outer diameter of the rotor 35 to the inner diameter of the stator 2, a typical extension of this stirring mill produces a value between 0.6 and 0.95. The ratio of the outer diameter of the inner stator 22 to the inner diameter of the rotor 35 is, for example, 0.8 to 0.98.

[0028] The rotor according to the invention can be manufactured, in particular, by joining a ceramic ring 352 to a rotor body 351. This can be achieved, in particular, by gluing, threaded connection, or profile-fit interlocking connection. If the rotor body 351 is made of plastic, the ceramic ring 352 can also be cast into the plastic rotor body 351.

[0029] The rotor according to the invention and the stirring mill using the rotor are particularly suitable for producing dispersions requiring high fineness (e.g., x50 = 100 nm to 200 nm), which results in long grinding times, during which these dispersions must remain as free of metal contaminants as possible. This is, for example, the production of raw materials for battery slurries.

Claims

1. A rotor (35) for a stirred mill, comprising: The rotor body (351) is basically cylindrical, and the outer wall (32) of the rotor body defines the inner surface of the grinding chamber through which the feed material to be processed flows during the operation of the stirred mill; A ceramic ring (352) is disposed at the rotor end of the rotor body (351), wherein the rotor end is arranged opposite the product inlet of the mixing and grinding mill. The rotor body (351) is made of plastic; The surface of the ceramic ring (352) forms part of the outer wall (32) of the rotor; The portion extends to a grinding tool (38) disposed on the outer wall (32) of the rotor, and the ceramic ring (352) is secured by the grinding tool (38) to prevent twisting and / or detachment.

2. The rotor (35) according to claim 1, wherein the rotor (35) is configured for use in a vertical stirring mill.

3. The rotor (35) according to claim 1 or 2, wherein the ceramic ring (352) is connected to the rotor body (351).

4. The rotor (35) according to claim 1 or 2, wherein the ceramic ring (352) has a substantially L-shaped cross-section, and wherein the legs of the L-shaped ceramic ring (352) are arranged on the outer wall (32) of the rotor (35).

5. The rotor (35) according to claim 1 or 2, wherein, The ceramic ring (352) has a substantially U-shaped cross-section, and the legs of the U-shaped ceramic ring (352) are arranged on the outer wall (32) and inner surface of the rotor (35).

6. The rotor (35) according to claim 1, wherein the ratio L / D of the length L of the portion of the outer wall (32) of the rotor (35) formed by the ceramic ring (352) to the outer diameter D of the rotor (35) is between 0.05 and 0.

5.

7. The rotor (35) according to claim 1, wherein the ratio of the thickness S1 of the portion of the ceramic ring (352) forming the outer wall (32) of the rotor (35) to the total wall thickness S2 of the rotor is between 0.1 and 0.

9.

8. The rotor (35) according to claim 1 or 2, wherein the rotor body (351) has at least one of the following materials: PA, PET, PEEK, PVDF and POM.

9. The rotor (35) according to claim 1 or 2, wherein the ceramic ring (352) has at least one of the following materials: ZrO2, SSiC, SiSiC and Si3N4.

10. The rotor (35) according to claim 3, wherein the ceramic ring (352) is threadedly connected to the rotor body (351) or interlocked with the surface of the rotor.

11. A stirring grinder, comprising: The rotor (35) according to any one of claims 1 to 10; A stator (2) having a stator inner wall (9), wherein the rotor (35) is arranged within the stator (2); Product entry point; and Product discharge outlet A grinding chamber (8) is formed between the inner wall (9) of the stator and the outer wall (32) of the rotor (35), wherein the feed material can be guided into the grinding chamber (8) via the product inlet and out of the grinding chamber (8) via the product outlet.

12. Use of a rotor (35) according to any one of claims 1 to 10 in a stirred mill for producing dispersions.

13. The use according to claim 12, wherein the dispersion is a battery slurry.

14. A method for manufacturing a rotor (35) according to any one of claims 1 to 10, characterized by the following steps: - Connect the ceramic ring (352) to the rotor body (351).

15. The method of claim 14, wherein the ceramic ring (352) is connected to the rotor body (351) by adhesive bonding, threaded connection or profile-fit interlocking connection.

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