MXPA98000019A - Ani cylinder mill - Google Patents

Abstract

The present invention relates to a method for grinding material in a ring roller mill which comprises at least one grinding ring, at least one roller fitted in the grinding ring and at least one unit fitted between the roller and the grinding ring, characterizing because the grinding operates at a subcritical speed and at a grinding pressure above 40 MPa, because the unit is placed in the path of compacted material after it has been released from the ring at a certain distance from a point P, which is the point on the ring where the material is released, so that the unit is hit by the agglomerates formed during the operation at an angle between 60 degrees and 120 degrees, where a is the angle between the surface of the unit and the direction of incidence of the material, after the last one is released from the grinding ring, and because the loose material is distributed over an aspiration area in front of the roller and on the knee

Description

RING CYLINDERS MILL DESCRIPTION OF THE INVENTION The present invention relates to a method for grinding material in a ring cylinder mill whose mill comprises at least one grinding ring, at least one roller fitted within the grinding ring and at least one unit fitted between the roller and the grinder ring. Such a mill can, for example, be used in connection with the manufacture of cement for the grinding of mineral slag materials, slag and similar materials. A ring cylinder mill is described in published European patent application No. 486371. In this mill the feed material is charged to a space before the grinding path where it is subjected to centrifugal action. Subsequently the material and air are carried axially through the mill. The grinding ring in this mill operates at grinding pressure between 10-40 MPa and a supercritical speed, which means that the material subjected to the grinding action is retained on the grinding ring along the entire turn. It is therefore possible and necessary to adjust the scrapers and the guide plates internally in the ring in order to release the material during the passage transversely to the grinding ring and to guide the material forward along the roller in the direction of flow. In a ring cylinder mill operated at a subcritical speed, the grinding material will only be retained on a part of the grinding ring. In an area above the grinding ring, depending on the rotating speed of the ring, the roughness of the ring surface and the characteristics of the processed material, the grinding material will be detached from the ring, continuing to fall along a downward path towards a tapered area in front of the roller. A uniform distribution of the material in the tapered area and in the grinding bed is of greater importance for the operation of the mill. Major variations in the thickness of the grinding bed will cause irregular operation or vibrations in the mill and substantial fluctuations in the torque of the impulse arrangement. Irregular loading of the roller can also cause wear of the segments that protect the surface of the grinding ring and the roller can be damaged. The intensity of the grinding pressure applied and the type of material being grinded are determining factors with respect to the shape that the compacted material will have after it passes under the roller in the mill. A high grinding pressure and / or a sticky material will lead to the formation of agglomerates that retain their shape after the material is discharged from the grinding ring, while a lower grinding pressure will result in the falling material being a material relatively loose, crumbly. Both the size and the hardness of the agglomerates will have an effect on the flattening of the bed of material deposited in the tapered zone and in the suitable grinding bed. A ring cylinder mill operating at a subcritical speed has a lower rotation rate than a ring cylinder mill operating at a supercritical speed. In order to increase production in a mill operating at a subcritical speed at the same level as a similar mill operating at a supercritical speed it is necessary to increase the grinding pressure. Normally the grinding pressure in a mill operated at a subcritical speed will be greater than 50 MPa. It is the object of the present invention to provide a method for grinding material in a ring cylinder mill where the agglomerates formed during operation are crushed and distributed along the tapered zone and the roller in such a way that they do not occur during operation undesirable vibrations or oblique roll placement. This is achieved according to the invention in a surprisingly simple way by mounting a unit at a certain distance from a point P on the ring. The unit is placed in the path where the compacted material falls out of the ring, descending towards the tapered zone in such a way that the unit is hit by the agglomerates formed during the operation at an angle between 60 ° and 120 °, where a is the angle between the surface of the unit and the direction of incidence of the material. During the grinding process the impact and distribution units will break the agglomerates, while distributing the loose material over the tapered area in a uniform layer. The maximum degree of impact is achieved when the material hits the surface of the unit at an angle between 70 ° and 110 °. The units do not need to have a solid surface, it can be an advantage that the units have a perforated surface or consist of a grid. If the material is fed symmetrically through the openings in both ends of the grinding ring, the agglomeration of material can occur mainly in the middle of the grinding ring and, therefore, the impact and distribution units can be properly configured in such way that break up the agglomerates, while diverting most of the material towards the sides of the grinding ring.

The invention will now be explained in more detail with reference to the drawings in which Figure 1 shows a cross-section through a ring cylinder mill, Figure 2A-D shows different configurations of the impact and distribution units, both from the side where the material hits the plate and from the cut through the length pathways of the beam 8. The mill in figure 1 has a ring 1 grinder and a roller 2. roller 2 and ring 1 grinder they rotate by means of a drive mechanism that is not shown and the roller 2 is pushed against the grinding ring 1 through a tension system. Between the roller 2 and the grinding ring 1, the partially ground material constitutes a grinding bed 4 and the space 4a in front of the roller, from which the fed material is retracted for compaction, is designated as the tapered area. In Figure 2B a unit configured as a flat plate 6 with end sections 5 is shown. The end sections ensure that the dispersion of the material hitting the unit has been restricted axially and that the material is directed downward towards the tapered zone. The axial extension of such a plate will typically correspond to the width of the roller.

Figures 2C and 2D show a unit configured with a raised area 7 which in Figure 2C has a shape that resembles that of a roof edge. In this configuration, the material is distributed from the middle of the grinding ring and out towards the sides, which is appropriate when there is a tendency for the material to be deposited in the middle of the grinding ring during the grinding process. The size of a unit, cf. Figure 2C or 2D, that is to say the axial extension, is a factor that contributes to determining how the curve of the final finished material will look, since the size will be significant with respect to the number of times that the material is recirculated in the mill. A small roof edge will thus result in a distribution curve of flat particles due to the same materials that are being subjected to various grindings, pass without intermediate separation, while a wider roof edge will result in a greater mixing and thus a more effective separation and a steeper particle size distribution curve. When the material is to be grinded in a ring roll mill as shown in Fig. 1 according to the invention, the material is fed to the mill through one or more inlet ducts through one or both stationary units which are installed at the end of the grinding ring 1 and directed to the tapered area where it is driven under the roller 2 and subjected to grinding action. Gradually as the amount of grinding material increases, the material is pushed over the edge of the grinding ring 1 where it is picked up and either circulated for grinding renewed in the mill or directed, for example while entertaining in a stream of air, outside through the stationary ends at the end of the mill grinder ring 1 for processing renewed elsewhere, if appropriate.

Claims (9)

R E I I N D C C O N E S

1. A method for grinding material in a ring cylinder mill whose mill comprising at least one grinding ring, at least one roller fitted within the grinding ring and at least one unit fitted between the roller and the grinding ring characterized because the mill operates at a subcritical speed and at a grinding pressure above 40 MPa, because the unit is placed in trajectory where the compacted material released from the ring at a certain distance from a point P, that the point on the ring where the Material is released, in such a way that the unit is hit by the agglomerates formed during the operation at an angle between 60 ° and 120 °, where a is the angle between the surface of the unit and the direction of material incidence, after the latter is released from the grinding ring, and because the loose material is distributed over the tapered area in front of the roller and on the roller.

2. The method according to claim 1, characterized in that the grinding pressure is between 60 MPa and 100 MPa. 3. The method according to claim 1 or 2, characterized in that the angle a is between 70 ° and 110 °.

3. The method according to claim 1 or 2, characterized in that the angle a is between 70 ° and 110 °.

4. The method according to claim 1, 2 or 3, characterized in that the distance between the point P and the unit is at least d / 4, where d is the internal diameter of the ring.

5. The method according to claim 1-4, characterized in that the unit is configured as one or more solid or perforated plates.

6. The method according to claim 5, characterized in that the unit consists of a plurality of vertically deflected plates.

7. The method according to claims 1-6, characterized in that at least one area on one or more of the units is raised in relation to the surface of a plate in such a way that most of the material striking the unit is directed towards the tapered area and the roller axially offset in relation to the point of impact of the material on the unit.

8. The method according to claim 7, characterized in that the raised area has a shape that resembles that of a roof edge or the like.

9. The method according to the claims 1 - . 1-8, characterized because the unit is equipped with end sections that are placed on the outermost part on the unit pointing in the direction of the stationary end walls.