DE202011110190U1 - Grinding roller with magnetic surface - Google Patents

Abstract

Grinding roller (1) consisting of a bandage (2) and a shaft (3), wherein the bandage (2) is shrunk onto the shaft (3), characterized in that the surface (4) of the bandage (2) is magnetized.

Description

The invention relates to a grinding roller of a high-pressure roller press with a magnetic surface for producing a uniform autogenous wear protection layer.

For the comminution of granular millbase, it is known to abandon the granular millbase on the nip of a high-pressure roller press. A high-pressure roller press consists of at least two equally large, rotatably mounted rollers which rotate in opposite directions at the same rotational speed and between which a predetermined nip pressure is maintained by a corresponding pressure device. In the high-pressure roller press, the material to be ground is crushed during compression only by the pressure maintained in the nip, ideally no shear forces occurring in the process. This means that the ground material to be crushed is only pressed, but not crushed. This method, by Schönert et. al is described as "high pressure crushing" is in the German patent application DE2708053A1 discloses and is particularly suitable for crushing brittle material such. As cement or mineral ores, such as magnetite (magnetic ironstone) or hematite (red iron stone).

Due to the high mechanical stress caused by the brittle regrind, high-pressure roller presses are subject to high wear. To counteract this wear, it is out of the EP0516952B1 known to equip the surface of the grinding rollers with hard bodies, which protrude like an igel from the surface of the grinding roller.

These hard bodies provide on the one hand for improved intake behavior of the ground material in the nip between the grinding rollers and serve on the other hand as anchor points to form an autogenous wear protection layer on the grinding roller. The autogenous wear protection layer is formed by the fact that during the pressing process, the grinding stock to be comminuted between these anchor points is so strong that it forms a continuous layer on the surface of the grinding roller and protects the grinding roller surface from mechanical wear. The pressing process and the bursting of the ground material thus takes place on the surface of the autogenous wear protection layer and not on the surface of the grinding roller itself.

The adhesion behavior of this autogenous wear protection layer on the grinding roller surface depends in addition to the properties of the ground material itself, such as. As the agglomeration behavior, also substantially from the pressure in the nip and the number of anchor points on the grinding roller. In the German patent DE4036040C2 For example, a method for forming such an autogenous wear-resistant layer on a grinding roll will be described.

However, the tendency to form an autogenous wear protection layer is heavily dependent on the fracture behavior of the ground material. Cement clinker forms fine fragments in the high pressure crushing with a tendency to maintain a mechanical connection with each other. Other regrinds, on the other hand, have a less pronounced tendency toward a cohesive layer of wear protection, but break apart to form dust and semolina. A regrind that forms a less coherent wear protection layer is magnetite (magnetic ironstone). Magnetite is an iron ore that is mined in iron ore mines in addition to the red iron stone (hematite). In order to separate the iron ore from the gait, it is first necessary to crush the ore before it is separated by sifting, floating or magnetic separation in ore and gait. The gangue is discarded in this workup to enrich the iron ore.

In order to reduce the wear of high pressure roll presses when used to comminute magnetite, it would be desirable to promote the propensity of forming a stable autogenous wear protection layer.

The object of the invention is achieved in that the surface of the grinding roller of a high-pressure roller press is magnetized. Further advantageous embodiments of the invention are specified in the subclaims.

The magnetization of the surface of the grinding roller magnetite has the advantage that the lower tendency to form a stable autogenous wear protection layer in magnetite (magnetite iron) is compensated by the magnetic surface that holds the magnetite orbit by the magnetization.

For the type of magnetic polarization of the surface of the grinding roller, however, it is important that this is radially polarized. An axial polarization of the grinding roller, such as a bar magnet, would result in the creation of a magnetically indifferent zone in the middle of the surface of the grinding roller, where the magnetic magnetite ore would not be attracted. The radial magnetization is known to be possible only with annular objects. Milling rollers for high-pressure roller presses are usually constructed in two parts and have a central shaft and a bandage, which forms the surface of the grinding roller. The bandage is hollow cylindrical and is shrunk onto the shaft.

Since the bandage for a high-pressure roller press thus has a hollow core, therefore, a radial polarization is feasible by the bandage is magnetized before shrinking onto the shaft. In the case of radial polarization, the entire round surface of the roller is either a magnetic south or north pole, and the inner round surface, which is seated on the shaft, is magnetically oppositely poled.

The uniformly magnetized surface supports the formation of a stable autogenous wear protection layer on the surface of the bandage by the magnetic attraction of the iron ore. The magnetization of the bandage, however, the shaft can form a magnetic pole of the entire grinding roller and thereby possibly pull ore bearings in the shaft bearings, which bearing damage would be expected. To prevent this, either a non-magnetizable metal can be used as the shaft or the magnetic flux of the bandage can be short-circuited at the edges of the roller in which a ring of easily magnetizable material surrounds the bandage.

The invention will be explained in more detail with reference to the following figures. It shows

1 a grinding roller according to the invention with a magnetized surface,

2 the grinding roller off 1 with device for magnetic short circuit

In 1 is a grinding roller according to the invention 1 pictured from a bandage 2 , and a wave 3 exists, with the bandage 2 on the wave 3 has shrunk. On the plan side of the grinding roller 1 on which the shaft 3 protrudes, is a magnetically indifferent zone 5 imaged at which the magnetic orientation of the magnetized with a first pole (for example, magnetic north pole) surface 4 the grinding roller 1 and the magnetized with a second pole (for example, magnetic south pole) inside 6 the bandage 2 cancel each other out. The entire, curved surface of the bandage 2 is thus uniformly magnetized. The surface of the bandage shown in this illustration 2 shows no hard body, which are usually introduced there to form an autogenous wear protection layer. In order to support the formation of the autogenous wear protection layer, however, it is provided to introduce such hard bodies into the magnetized surface as well.

Exemplary are magnetic field lines 7 drawn, which may be due to the geometry of the grinding roller, locally strong distortions. Because the magnetization of the bandage 2 the wave 3 magnetized, can thereby magnetic ore into the bearings for the shaft 3 be confiscated.

In 2 is the grinding roller off 1 with a device 7 which is a device 8th for generating a magnetic short circuit. This device consists of a metallic plate with particularly high magnetic conductivity around the field lines 7 ( 1 ) keep as possible in the area of the bandage, the magnetization of the shaft 2 can not be completely prevented, however, the magnetization can be greatly reduced.

LIST OF REFERENCE NUMBERS

1

grinding roll

2

bandage

3

wave

4

surface

5

magnetically indifferent zone

6

inside

7

magnetic field lines

8th

Device for generating a magnetic short circuit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2708053 A1 [0002]
• EP 0516952 B1 [0003]
• DE 4036040 C2 [0005]

Cited non-patent literature

• Schönert et. al [0002]

Claims (5)

Grinding roller ( 1 ) consisting of a bandage ( 2 ) and a wave ( 3 ), whereby the bandage ( 2 ) on the shaft ( 3 ) shrunk, characterized in that the surface ( 4 ) of the bandage ( 2 ) is magnetized. Grinding roller according to claim 1, characterized in that the bandage ( 2 ) is magnetically radially polarized. Grinding roller according to one of claims 1 to 2, characterized in that a device ( 8th ) on the plan side of the grinding roller ( 1 ) is provided, which generates a magnetic short circuit to the magnetization of the shaft ( 3 ) to minimize. Grinding roller according to one of claims 1 to 3, characterized in that the surface ( 4 ) of the bandage ( 2 ) is provided with hard bodies. Bandage for a grinding roller according to one of claims 1 to 4, characterized in that the bandage ( 2 ) is magnetized, preferably radially magnetized.

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