EP4065281B1 - Wear-resistant element for a comminution device - Google Patents

Description

The invention relates to a wear protection element for partial insertion into a recess on the surface of a wear surface of a shredding device and a shredding device with such a wear protection element.

In comminution devices, such as grinding rollers or crushers, which are used in particular when comminuting hard ore, for example, there is a high level of wear on the surface of a wear surface, such as the grinding roller surface, during operation of the comminution device. To counteract this wear, it is made, for example, from the DE 2006 010 042 A1 known to apply additional wear protection elements to the surface of the grinding roller. At a certain level of wear, it is necessary to replace or renew the wear protection elements of the grinding roller, for example, in order to guarantee efficient grinding. Such a replacement is very costly due to the frequency and number of wear protection elements. The above-mentioned problem is also known from other technical areas, such as the storage of abrasive materials in a silo or bunker.

From the WO 2016/008967 A1 Ceramic grains and processes for their production are known.

It is therefore the object of the present invention to provide a wear protection element that has high wear resistance and at the same time can be produced inexpensively.

This task is achieved by a wear protection element with the features of independent device claim 1. Advantageous further training results from the dependent requirements.

According to a first aspect, the invention comprises a wear protection element for attachment to a shredding device or a silo, the wear protection element being formed entirely from a ceramic comprising yttrium-stabilized, tetragonal polycrystalline zirconium oxide (TPZ), the TPZ has a volume fraction of at least 60%, preferably at least 80%, in particular 95% to 100% of the ceramic.

The wear protection element is, for example, cylindrical or has a polygonal cross section. In particular, one end of the wear protection element is designed such that it can be fastened to the surface of the wear surface, in particular in a recess in the surface of the wear surface.

The comminution device is, for example, a roller mill, a roller crusher, a hammer mill or a vertical roller mill, the wear surface being in particular the surface of a grinding roller which is exposed to high levels of wear during operation of the comminution device, the hammer tools and the surface of the grinding track of a hammer mill or the surface of the Rollers and the grinding plate of a vertical roller mill. It is also conceivable that the wear protection element is, for example, plate-shaped and is attached to the inner wall of a warehouse, in particular a silo for mineral rocks.

The wear protection element is made entirely of ceramic. It is also conceivable that only a part of the wear protection element, such as the area protruding from the surface of the shredding device, is made of ceramic. For example, the wear protection element has a fastening area that is partially or completely attached in the recess in the surface of the shredding device and a wear area that is completely or partially formed from the ceramic.

A wear protection element made of yttrium-stabilized, tetragonal polycrystalline zirconium oxide (TPZ) has very favorable wear behavior together with high toughness. This is particularly advantageous when using such wear protection elements in shredding devices.

According to a first embodiment, the ceramic has a porosity of less than 5%, preferably less than 4%, in particular less than 3%. The ceramic preferably has a porosity of at least 1%.

A porosity of less than 5%, preferably less than 4%, in particular less than 3% leads to improved wear behavior. The aforementioned porosity information is preferably the total porosity, which corresponds to an average value of the pore sizes of the material. Preferably, the pores are substantially evenly distributed throughout the ceramic material.

For example, the ceramic has a density of 1.5 to 5 g/cm ³ , preferably 2 to 4 g/cm ³ , in particular 2.7 to 3 g/cm ³ . For example, the ceramic has an Al2O3 (corundum) content of 10%. This leads to improved wear resistance with a small reduction in the toughness of the ceramic.

According to a further embodiment, the ceramic has a ratio of monoclinic to tetragonal zirconium oxide of less than 40%, in particular less than 30%, preferably less than 20%. The ratio of monoclinic to tetragonal zirconium oxide is preferably at least 2%. For example, the zirconium oxide contained in the ceramic has less than 40%, in particular less than 30%, preferably less than 20% monoclinic zirconium oxide, the remaining zirconium oxide being tetragonal zirconium oxide. The ratio of monoclinic to tetragonal zirconium oxide is determined, for example, using X-ray diffraction in accordance with ISO 13356. At a ratio of more than 40%, preferably more than 30%, in particular more than 20% monoclinic to tetragonal and / or cubic zirconium oxide, negative effects occur, such as too rapid a conversion of metastable zirconium oxide into the stable monoclinic phase, whereby a Volume increase occurs. If the transformation occurs too quickly, surface tensions arise, which, for example, cause local cracks.

According to a further embodiment, the yttrium-stabilized zirconium oxide of the ceramic has a grain size D50 of less than 1.5 μm, preferably less than 1µm, in particular less than 0.8µm. The D50 grain size of the ceramic is preferably at least 0.2 µm. The D50 value refers to the grain size of 50% of the ceramic grains. In the exemplary D50 grain size value, 50% of the grains of the yttrium-stabilized zirconium oxide have a grain size diameter of less than 1.5 μm, preferably less than 1 μm, in particular less than 0.8 μm.

The D90 value of the grain size is preferably less than 3µm, in particular less than 2µm, preferably less than 1.5µm. Wear protection elements of a shredding device are exposed to local stresses. Therefore, a wide grain size distribution should be avoided in order to prevent the formation of cracks or breakouts.

According to a further embodiment, the ceramic has an yttrium content of 2-4 mol% Y2O3. The advantages of such an yttrium content are better sintering behavior at an even lower sintering temperature, as well as a finer crystalline structure, which in turn leads to higher fatigue resistance and improved fracture toughness. Furthermore, the ceramic has, for example, Ce-TZP with a content of 10 - 12 mol% of CeO2. In particular, the ceramic has a content of 8-10 mol% of Mg-PSZ. It is also conceivable that the ceramic has a content of 5-10 mol% of MgO as a stabilizer.

According to a further embodiment, the ceramic has a number of pores with a size of more than 200 μm of less than 0.1 per mm ² . The number of pores per surface also provides an indication of wear resistance. A small number of pores of a relatively large size, such as more than 200µm, ensures high wear resistance as local breakouts from the ceramic material are avoided.

The ceramic preferably has a number of pores with a size of more than 150 μm of less than 0.4 per mm ² . In particular, the ceramic has a number of pores with a size of more than 100 μm of less than 2 per mm ² . Such a number of pores significantly increases the service life of the wear protection element.

The invention also includes a shredding device with a wear surface and a wear protection element as described above, the wear protection element being at least partially mounted in a recess in the surface of the wear surface. According to one embodiment, the wear protection element is materially connected to the wear surface, in particular welded, glued or soldered.

The advantages described with reference to the wear protection element also apply to the shredding device with such a wear protection element.

Description of the drawings

Fig. 1

zeigt eine schematische Darstellung einer Zerkleinerungseinrichtung in einer Frontansicht gemäß einem Ausführungsbeispiel.

Fig. 2

zeigt eine schematische Darstellung einer Mahlwalze der Zerkleinerungseinrichtung gemäß Fig. 1.

Fig. 3

zeigt schematische Darstellungen eines Ausführungsbeispiels des Verschleißschutzelements in einer Schnittansicht.

Fig. 4

zeigt schematische Darstellungen eines nicht erfindungsgemäßen Ausführungsbeispiels eines Verschleißschutzelements in einer Schnittansicht.

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 shredding device in a front view according to an exemplary embodiment.

Fig. 2

shows a schematic representation of a grinding roller of the shredding device Fig. 1 .

Fig. 3

shows schematic representations of an exemplary embodiment of the wear protection element in a sectional view.

Fig. 4

shows schematic representations of an embodiment of a wear protection element not according to the invention in a sectional view.

In Fig. 1 a comminution device 10, in particular a roller mill, is shown schematically. The comminution device 10 comprises two grinding rollers, shown schematically as circles, with wear surfaces 12, 14, which have the same diameter and are arranged next to one another. A grinding gap is formed between the wear surfaces 12, 14 of the grinding rollers, the size of which can be adjusted, for example.

During operation of the comminution device 10, the grinding rollers rotate in opposite directions to one another in the direction of rotation shown by the arrows, with material to be ground passing through the grinding gap in the direction of fall and being ground.

Fig.2 shows an end region of a grinding roller which has a wear surface 12 on which wear protection elements 16 are attached. The wear protection elements 16 are mounted in the outer periphery of the surface of the grinding roller. By way of example, the wear protection elements 16 which are spaced apart from one another and arranged next to one another Fig. 2 a circular cross section. It is also conceivable that the wear protection elements 16 vary across the surface of the grinding roller in size, number, cross-sectional shape and arrangement relative to one another in order, for example, to compensate for local differences in wear during operation of the comminution device 10.

Furthermore, the grinding roller has wear protection corner elements 17 attached to its end, which, for example, have a rectangular cross section and are arranged next to one another in a row in such a way that they form a ring over the circumference of the grinding roller. Other cross-sectional shapes of the wear protection corner elements 17 are also conceivable, which differ from those in Fig. 2 Cross-sectional shape shown may vary. An arrangement of the wear protection corner elements 17 at a distance from one another is also possible. In Fig. 2 For example, only the left end of the grinding roller with the wear surface 12 is shown, the right end, not shown, advantageously being identical in structure.

Fig. 3 shows a wear protection element 16 in a sectional view. The wear protection element is, for example, cylindrical and made entirely of ceramic. The ceramic is the yttrium-stabilized, tetragonal polycrystalline zirconium oxide (TPZ), the TPZ having a volume fraction of at least 60%, preferably at least 80%, in particular 95% to 100% of the ceramic. The ceramic material offers the advantage of particularly high wear resistance while being relatively inexpensive to produce.

Fig. 4 shows an exemplary embodiment which does not correspond to the invention, wherein the wear protection element 16 has a jacket 18 and a core 20 which is at least partially radially surrounded by the jacket 18. The core 20 extends axially along the central axis of the essentially cylindrical wear protection element 16 to the upper end face of the wear protection element 16. The core 20 is, for example, cylindrical and is preferably firmly connected to the jacket 18. It is also conceivable that a plurality of cores 20, for example two, four or six cores 20, extend through the wear protection element 16, preferably parallel to one another. The diameter of the core 20 is, for example, approximately 10 to 30% of the diameter of the wear protection element 16.

Fig. 4 shows a sectional view of the wear protection element 16 not according to the invention. The wear protection element 16 has a fastening area 24 and a wear area 22, the fastening area 24 being arranged in the recess 26 on the surface of the wear surface 12 of the grinding roller and being connected to the wear surface 12 of the grinding roller. For example, the wear protection element 16 is cohesively connected to the fastening area 24 with the recess 26 in the surface of the wear surface 12 of the grinding roller, in particular welded, soldered or glued or positively connected, in particular screwed or wedged. The wear area 22 of the wear protection element 16 is at least partially or completely arranged outside the recess 26 in the wear surface 12, so that it protrudes from the surface of the wear surface 12 in the radial direction of the grinding roller, not shown. In the exemplary embodiment shown, the fastening area 24 comprises approximately a third of the entire wear protection element 16, with the wear area 22 approximately comprising the further two thirds. The fastening area 24 is made of a metal, such as steel.

The wear area 22 of the wear protection element 16 has the jacket 18 and the core 20, the jacket 18 preferably made of a ceramic material, such as tungsten carbide, titanium carbide, titanium carbonitride, vanadium carbide, chromium carbide, tantalum carbide, boron carbide, niobium carbide, molybdenum carbide, aluminum oxide, zirconium oxide, and / or silicon carbide or a combination of the materials mentioned. The ceramics include Yttrium-stabilized tetragonal polycrystalline zirconia (TPZ). Furthermore, particles made of industrial diamonds, for example high-strength ceramics, can also be embedded in a ceramic or metallic matrix in the jacket 18. For example, the jacket 18 has a matrix material in which a plurality of particles are arranged. The particles are in particular a highly wear-resistant material, which includes, for example, diamond, ceramic or titanium. The matrix material includes, for example, tungsten carbide. The particles are in particular bonded to the matrix material, for example by sintering.

During operation of the shredding device 10, the wear protection elements 16 are exposed to a high level of wear, with the wear area 22 of the wear protection elements 16 protruding from the surface of the wear surfaces 12, 14 of the grinding rollers in particular wearing out. The wear-resistant material of the wear area 22 significantly reduces the wear of the wear protection elements 16. Furthermore, the fastening area, which is exposed to little or no wear, is not made from the more expensive, wear-resistant material. The metal core makes it possible to remove the wear protection element from the recess 26 in the roller surface, even if the wear area 22 is already heavily worn, by pulling out the wear protection element 16 on the metal core 20 using an appropriate tool.

The fastening area 24 is made entirely of metal and is firmly connected to the core 20. For example, the fastening area 24 is glued, soldered or welded to the core 20 or formed in one piece with it.

Reference symbol list

10

Shredding device/roller mill

12

Wear surface / grinding roller

14

Wear surface / grinding roller

16

Wear protection element

17

Wear protection corner element

18

Coat

20

core

22

Wear area

24

Fastening area

26

recess

Claims (8)

1. Wear-resistant element (16) for attaching to a comminution device or to a silo, characterised in that the
   wear-resistant element (16) is formed fully from a ceramic which comprises yttrium-stabilised, tetragonal polycrystalline zirconia (TPZ), wherein the TPZ has a volume fraction of at least 60%, preferably at least 80%, and in particular 95% to 100% in the ceramic.
2. Wear-resistant element (16) according to claim 1, wherein the ceramic has a porosity of less than 5%, preferably less than 4%, in particular less than 3%.
3. Wear-resistant element (16) according to one of the preceding claims, wherein the ceramic has a ratio of monoclinic to tetragonal zirconia of from 10% to 40%, in particular less than 30%, preferably less than 20%.
4. Wear-resistant element (16) according to one of the preceding claims, wherein the yttrium-stabilised zirconia of the ceramic has a grain size D50 of less than 1.5 µm, preferably less than 1 µm, in particular less than 0.8 µm.
5. Wear-resistant element (16) according to one of the preceding claims, wherein the ceramic has a content of yttrium of from 2 to 4 mol % Y2O3.
6. Wear-resistant element (16) according to one of the preceding claims, wherein the ceramic has a pore number with a size of more than 200 µm of less than 0.1 per mm2.
7. Comminution device (10) having a wear area (12, 14) and a wear-resistant element (16) according to one of claims 1 to 6,
   wherein the wear-resistant element (16) is mounted at least partially in a recess (26) in the surface of the wear area (12, 14).
8. Comminution device (10) according to claim 7, wherein the wear-resistant element (16) is connected in an integrally bonded manner, in particular is welded, glued or soldered, to the wear area (12, 14).

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