EP0998353B1 - Tube mill - Google Patents

Abstract

The mill comprises a cylindrical shell (16) lined with an interior lining and intended to contain material to be ground and a charge of grinding implements, in which the lining, which is made up of rings of juxtaposed individual lining plates, has interior longitudinal lifting profiles to encourage the lifting of the charge and of the material to be ground as the mill rotates. In order to adapt the lifting profile to the parameters and conditions in which the mill operates, each plate has, on the rear face, when viewed in the direction in which the mill rotates, a step (10b, 12b, 14b) of a radial height that is taller than the front face, and each ring of plates comprises several different types of plate (10, 12, 14) which differ at least in terms of the radial height of their step (10b, 12b, 14b) and which follow on from one another, in the circumferential direction, in a determined order.

Description

The present invention relates to a rotary mill comprising a cylindrical shell fitted with an inner shielding and intended for contain material to be ground and a load of grinding media, in which the shielding, which consists of rings of shielding plates individual juxtaposed, has longitudinal undulations interior to favor the lifting of the load and the material to grind during rotation of the grinder.

The invention relates more particularly to the shredders used in cement plant and in the mining industry. These shredders are made up of a metallic cylindrical ferrule rotating around its axis longitudinal and containing a grinding load made up of machines grinders, usually balls, but can also be made up of cylpeps, boulpeps, etc. of variable dimensions. The material to be ground is introduced on one side of the mill and, as and when measure of its progress towards the exit, on the opposite side, it is crushed and crushed between the crushing machines.

During the rotation of the mill, the material to be ground and the load are raised by the shielding and, from a moment given, slide, again, down. It follows that the burden of grinder is mainly concentrated in the fourth quarter trigonometric if the mill rotates counterclockwise and in the third quarter if the grinder turns clockwise of a watch, and occupies in it, in a radial plane, an area in the form of "bean" as shown in FIG. 4A of the patent application Belgian 09301481. Grinding is carried out by shear forces and friction during the movement of the mass. To get a efficient shredding and avoid breakage of armor and gear shredding, the shielding must have a profile such that it picks up the load up to a level such that it remains compact because a lift too important causes the projection of balls beyond the foot of the charge, that is, the balls directly hit the shield, without interposition of material to be ground. On the other hand, the load must be raised enough so that there is good mixing of the mass. It goes without saying that the filling coefficient plays a role determining in the grinding efficiency and that the shaped area bean occupied by the load must have a shape, a position and well-defined dimensions for efficient grinding and optimal.

To favor the lifting of the material and the load, it is known to provide on the plates forming the inner shielding of the longitudinal corrugator which is suitable for operating conditions and parameters of the mill. The problem is, however, that if the corrugations or profiles of the plates of grinding are suitable for a specific grinder, this may not be no longer the case if conditions change. You should know, in fact, that the load and material lifting depends on many factors like, for example, the size of the mill, its speed of rotation, the size of the grinding machines, etc.

In addition, the armor plates are subject to wear intense so that even if the lifting conditions are optimal at the start, they can deteriorate quickly due to change of the profile of the plates caused by wear.

Known armor plates also have the handicap to be quite heavy, of the order of 40 to 50 kg, so that their manipulations are painful and dangerous. Reforms of labor laws tend to prohibit the handling of objects weighing more than 25 kg.

Another constraint is that of replacing the plates worn and their attachment to the shell, especially when they are bolted. You should know that the ferrules have, in view the fixing of the armor plates, the holes which are arranged following generally standard standards but that these standards may vary from manufacturer to manufacturer. Any plate model that does not meet these standard holes would result in the need to drill the mill again, which cannot be envisaged because it is a very expensive operation which has for consequence of a deformation of the shell and a risk of leakage of increased ground material.

Document DE 1126709 describes a crusher whose plates of shield form steps in the direction of rotation. different plates of different radial depths follow one another in a determined order. The side with the greatest radial depth is found at the front, seen in the direction of rotation. This presents the disadvantage that the grinding machines are projected, which reduces grinding efficiency and increases the risk of plate rupture. In addition, the steps of a ring are offset from the terraces of an adjacent ring, i.e. the terraces are not axially aligned. This causes shear forces which increase the speed of wear of the plates on the edges.

Document WO 86/04267 also describes a grinder, the armor plates are arranged in steps to form lifting ramps. In this grinder, there is, in fact, only one type bleachers. In addition, the plates are bolted to the ferrule of so that the arrangement of the plates is limited to the configuration of the holes in the shell.

In shredders with stepped shielding, it is necessary to increase the inclination of the ramps when the diameter of the mill increases. In known mills, this requires an increase in thickness of all the plates, which increases the total weight of the shield.

The object of the present invention is to provide a new type shielding which alleviates the disadvantages described above and, more particularly, a grinder whose shield is formed of armor plates which allow the lifting profile to be adapted to parameters and operating conditions of the mill and which changes less quickly due to wear.

To achieve this objective, the invention proposes shielding the genre described in the preamble which is characterized in that each plate has, on the rear face, seen in the direction of rotation, a step with a higher radial height than the front face, in this that each plate ring has several types of plates which differ, at least, by the radial height of their tier and by the nature of their material and which follow one another in the circumferential direction, according to a determined order. A certain number of one of the types of plates are bolted mounting plates at the ferrule, all the other plates not necessarily fixed to the ferrule by bolts but being held in place by simple arch effect.

Since there are several types of plates different form, we can, by a judicious choice, based on tests, combine the different types of plates to form a profile of well-defined lifting that allows optimal lifting adapted to operating conditions of the mill.

According to another aspect of the invention, the different types of plates also differ in the nature of their material. We can therefore combine different types of plates depending on their risk of wear. It thus becomes possible to produce a profile of lift which is less vulnerable to wear, i.e. to keep longer the initial lift profile. It is also possible to combine the plates optimally to have both good wear resistance and good impact resistance.

Armor plates, with the exception of fixing plates, preferably have, on their radial faces, at least one longitudinal rib, respectively a longitudinal groove corresponding or vice versa to interlock with each other and be held in place by the fixing plates.

Since most of the armor plates are not bolted to the ferrule but are held simply by mutual interlocking, there is, during the installation of such shielding, less stress due to the arrangement of the drill holes in the ferrule.

Each of the plates is preferably sized to so as not to exceed a weight of 25 kg. This reduced weight facilitates handling of the plates and is within the limits imposed by new legislation. In addition, smaller, chunky plates allow the use of less resilient steels or cast iron, which allows to choose better compromises wear / impact resistance than with conventional shields.

• la figure 1 montre une vue en perspective d'un assemblage de trois types de plaques de blindage ;
• la figure 2 montre une vue latérale des plaques de la figure 1 ;
• la figure 3 montre une partie d'une couronne de plaques de blindage constituée d'une combinaison de deux types de plaques choisies parmi les trois types de la figure 1 ;
• la figure 4 montre une vue latérale de la combinaison de la figure 3 ;
• la figure 5 montre une vue analogue à celle de la figure 3 avec une autre combinaison de deux types de plaques ;
• la figure 6 montre une vue latérale de la combinaison de la figure 5 ;
• la figure 7 montre une partie d'un anneau de plaques de blindage constituée d'une combinaison des trois types de plaques de la figure 1 et
• la figure 8 monte une vue latérale de la combinaison de la figure 7.

Other particularities and characteristics will emerge from the description of some advantageous embodiments presented below, by way of illustration, with reference to the appended drawings in which:

• Figure 1 shows a perspective view of an assembly of three types of armor plates;
• Figure 2 shows a side view of the plates of Figure 1;
• FIG. 3 shows part of a crown of armor plates made up of a combination of two types of plates chosen from the three types of FIG. 1;
• Figure 4 shows a side view of the combination of Figure 3;
• Figure 5 shows a view similar to that of Figure 3 with another combination of two types of plates;
• Figure 6 shows a side view of the combination of Figure 5;
• FIG. 7 shows part of a ring of armor plates made up of a combination of the three types of plates of FIG. 1 and
• FIG. 8 shows a side view of the combination of FIG. 7.

Figures 1 and 2 show different types of plates shield 10, 10a, 12 and 14 having a slightly outer surface curve to match the inside of the cylindrical shell of the grinder indicated schematically by the reference 16. Seen in the direction of rotation of the mill, represented by arrow A, every plates have a front face whose height is less than that of the rear face so as to define a step on the side rear of each plate, step which has a rounded 10b, 12b, 14b, so that the juxtaposition of the plates creates a wavy profile.

The different types of plates are distinguished at least by the height of their rear face, that is to say the height of their step 10b, 12b and 14b. This is how the step 14b of the plates 14 is more marked as the step 12b of the plates 12 which, in turn, is more marked as the step 10b of the plates 10 or 10a. From the point of view of contribution to the shape of the interior profile, plates 10 and 10a are identical since they have the same tier. The plaques 10 and 10a can therefore be considered of the same type, so that Figures 1 and 2 show three different types of plates.

However, unlike plates 10, plates 10a are fixing plates and have, for this purpose, an opening central 18 to be bolted to the shell 16 through a hole of the ferrule 16.

All plates other than plates 10a are not fixed directly to ferrule 16 but are simply held in place by arch effect and mutual interlocking. For this purpose, each plate has, on the rear face, over the entire length, a groove 20 and on the front face, a corresponding rib 22 which can be engaged in the groove 20 of the previous plate. The grooves 20 and the ribs 22 can, of course, be reversed.

The fixing plates 10a have neither rib nor groove. The front and rear faces are smooth and re-entrant, converging thus towards the ferrule 16. The timing is achieved by means of corners 24 and 26 of triangular section which are inserted between the plates of fixing and neighboring plates. These corners 24 and 26 have inclined inner faces complementary to the inclined faces of the mounting plate 10a. The outer faces of the corners 24 and 26 are straight and provided with a groove 20, respectively with a rib 22 to fit into the rib 22, respectively in the groove 20 of the adjacent plates. Thus, the tightening of the fixing plate 10a at the ferrule 16 generates a tangential spreading force which is transmits to adjacent plates and securely holds their mutual sockets. Using corners of varying thickness, one can determine the amplitude of tightening, in particular to be able catch up with play during operation.

The different types of plates 10, 12 and 14 can be differentiate, in addition to the height of their step, by the nature of their material or alloy. Thus, the plates most exposed to wear, in particular the plates 12 and 14 with the most marked step, can be made of cast iron with good wear resistance and plates 10 which are less exposed may be made of steel. We see thus to a more regular wear which maintains the profile longer initial reliever.

The overall dimensions of the different plates are preferably such that their weight does not exceed 25 kg. To alleviate plates, it is notably possible that their outer side ferrule side has indentations as shown schematically in lines interrupted 28.

By making a judicious choice between the different types plates available and alternating them according to a combination determined, we can adapt the profile of the plates lifters with parameters and operating conditions of the crusher so that the lifting of the material and the load is sufficient without projection of grinding devices, that is to say that the mass occupies the ideal bean shape, favorable for grinding optimal.

This possibility of choosing between different types of plates allows a substantial reduction in the weight of the shielding. Thus, a shield with the combination of plates according to FIG. 5 in a shredder with a diameter of 5.2 m a weight / m ² of 525 kg while a conventional shield using plates identical to each other has a weight of 668 kg / m ² for a shredder of the same diameter and for a comparable lifting effect.

If the operating conditions of the mill change for one reason or the other, it is possible, at any time, to change type of plate and / or combination to restore a profile ideal ripple.

Figures 3 and 4 show a first example of arrangement plates according to which only two types of plates are used 10 and 12 and according to which, on each plate of a type 10 or 12, are juxtaposed two plates of the other type 12 or 10.

Figures 5 and 6 illustrate an arrangement similar to previous but here, we alternate the type 10 plates with those of type 14.

Figures 7 and 8 illustrate an example of arrangement with a double alternation of the three types of plates 10, 12 and 14. The chosen combination is: 10-12-10-14-10-12 ..., that is to say that there is twice as many type 10 plates as type 12 plates and type 14 plates.

It is of course possible to provide other combinations than those cited above as examples. Likewise, it is possible to provide more than three different types of plates.

In addition, it may be that, in the same mill, the conditions are different depending on which one is on the side of entrance or exit side, especially as a result of grinding progressive and changing grain size of the material to be ground. To adapt the profile of the lifting plates to these different conditions, we could provide, in the same grinder, at the entrance, types of plates and / or combinations different from those at the outlet.

The invention therefore provides for a new crusher with shielding perfectly modular and adaptable to conditions and parameters variables.

Claims (7)

1. Rotary mill consisting of a cylindrical drum (16) equipped with interior armour plating and intended to contain material to be crushed and a charge of grinding medium in which the plating, which consists of rings of individual adjacent armour plate, has interior longitudinal raising profiles to help raise the charge and the material to be crushed when the mill rotates, distinguished by the fact that every plate has, on its back face, seen in the direction of rotation of the mill, a step (10b, 12b, 14b) of a radial height greater than the front face, by the fact that each ring of plates consists of several different types of plate (10, 12, 14) that are distinguished at least by the radial height of their steps (10b, 12b, 14b), which follow each other, in the direction of the circumference, according to a fixed sequence, and which are aligned axially and in which a certain number of one of the types of plate (10) are fixing plates (10a) bolted to the drum (16), none of the other plates being fixed to the drum (16) by bolts but being held in place by a simple arching effect.
2. Mill as in Claim 1, distinguished by the fact that the different types of plate (10, 12, 14) are also distinguished by the nature of their materials.
3. Mill as in Claim 1, distinguished by the fact that the plates with the most prominent steps are of cast iron and the plates with the least prominent steps are of steel.
4. Mill as in any of Claims 1 to 3, distinguished by the fact that all the armour plates, except for the fixing plates (10a) have on their front faces and their back faces at least one longitudinal rib (22) and one longitudinal matching groove (20) respectively or vice versa so as to fit into each other and to be held in place between the fixing plates (10a).
5. Mill as in Claim 4, distinguished by the fact that the back and front faces of the fixing plates (10a) converge towards the drum (16) and are separated from the armour plates by wedges (24,26) which have, on their external faces, a groove (20) or a rib (22) respectively which fits into the rib (22) or the groove (20) respectively of each adjacent plate.
6. Mill as in Claim 5, distinguished by the fact that the wedges (24, 26) have variable thicknesses.
7. Mill as in any of Claims 1 to 6, distinguished by the fact that each type of plate weighs less than 25 kg.

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