WO1999042217A1

WO1999042217A1 - Wet process grinder equipped with baffle and outlet baffle for said grinder

Info

Publication number: WO1999042217A1
Application number: PCT/BE1999/000024
Authority: WO
Inventors: Robert Schneider
Original assignee: Magotteaux International S.A.
Priority date: 1998-02-20
Filing date: 1999-02-18
Publication date: 1999-08-26
Also published as: EP0937503A1; CA2320796A1; ZA991316B; AU2504999A

Abstract

The invention concerns a wet process autogenous or semi-autogenous or discharge grate-type grinder, comprising an outlet baffle between the grinding chamber and the outlet trunnion, said baffle consisting of an upstream wall and a downstream wall forming a section internal to the baffle called discharge chamber. The invention is characterised in that the baffle central part is provided with means integral with said baffle enabling part of the ground material to pass in the section central zone, the remainder of the material being evacuated towards the outlet trunnion (2). The invention also concerns the baffle for said grinder.

Description

SHREDDER WORKING IN A WET ROUTE PROVIDED WITH A PARTITION AND OUTLET PARTITION FOR THE SHREDDER

Subject of the invention

The present invention relates to shredders working in the wet, either of the autogenous type, also called FAG shredders (Full Autogenous Grinding), or of the semi-autogenic type, also called SAG shredders

(Semi Autogenous Grinding), but also to ball mills operating by grid discharge.

The present invention relates more particularly to an outlet partition disposed in such grinders.

Technological background

Two large families of shredders coexist, on the one hand the shredders working in the wet process and on the other hand the shredders working in the dry process. In general, the solutions developed for shredders working in the dry process cannot be directly transposed to shredders working in the wet process.

The different types of shredder are fitted with an outlet partition which allows the ground material to be discharged to an outlet pin. Possibly, in some cases, the shredders are fitted with partitions 2

intermediaries separating two successive grinding chambers.

Discharge grinders by grid include a partition usually consisting of a frame, the upstream face of which is covered by grids pierced with a plurality of openings, thus letting through the sufficiently crushed material while retaining the insufficiently crushed material and the bodies. grinding. The upstream face is spaced from the downstream face, which is preferably full except for a central discharge opening.

Within the partition is thus delimited a small compartment in which the material which passes through the lights penetrates. This material is able to circulate diametrically within the compartment. Lifting elements or lifters are provided in this partition in order to lift the material above the axis of the crusher by rotation of the crusher, from where it falls, possibly on a deflector, to move towards the opening discharge center. In the case of shredders operating with overflow discharge, the shredders tend to keep the material within the grinding chambers for too long, which produces undesirable superfins, the retention time being too long and the overfilled mill, causing some load slippage and reducing the mill throughput.

For this type of shredder, no deflector member is present, and the crushed materials are discharged directly by overflowing via the central discharge opening towards the outlet pin.

For grinders operating at 100% grid discharge, we observe the presence of an organ 3

deflector which forces the material to follow a preferred path towards the outlet pin.

For this type of grinders, it is observed that these are often insufficiently filled because they discharge the material more and sometimes too quickly and therefore have a higher flow rate. However, since too little material is retained within the grinding chamber, the mill does not operate optimally. In addition, in the particular case of ball mills, there is significant wear of the grinding bodies due to an increase in the direct impact (without interposition of material) metal / metal, either grinding bodies between them, or grinding bodies with the shielding. It is also necessary to take into account the loss of energy without grinding effect caused by these shocks and especially by the lack of material to be ground.

To control the level of the material within the grinding chamber, and therefore the retention time, several methods of adjusting the passage of the material through the plurality of openings in the upstream wall of the partition have been proposed.

Document US-A-1787897 describes a partition intended to be placed between two successive grinding compartments and the chassis of which consists of several segments assembled together, each segment comprising two arms and a part corresponding to a portion of circumference intended to marry the shielding of the shell, the two arms being connected to the opposite end of the circumference portion by an essentially conical portion so as to create, when the different segments of the chassis are secured, a conical deflector element. The upstream face of the wall covering the 4

partition frame conventionally has openings (or openings) so as to allow the entry of sufficiently ground material into the partition, while the rear face has no openings except for an annular discharge passage placed at the periphery of the conical element so as to evacuate the crushed materials out of the partition.

The publication FR-A-2126051 describes a method and a device which make it possible to regulate the quantity of material mixed with the grinding bodies in a grinding compartment of a ball mill tube for example, and in which the grinding can also be carried out both dry and wet. In this document, there is described a partition intended to separate two successive grinding chambers or to be used as an outlet partition, which comprises means for adjusting the level of material within the grinding chamber, consisting of vanes pivoting around of a longitudinal axis so as to be able to adjust the useful volume or comprising a telescopic part making it possible to also adjust this useful volume.

Document DE-477135 describes a deflector member in the form of a movable cone secured to the crusher, which makes it possible to partially or completely return the material originating from the lifting elements (or lifting elements), in this case blades, towards the compartment upstream of the partition, in order to regrind the insufficiently ground particles which have entered the partition. By this system, the material again passes through a grid, which in theory could allow a control of the retention time within the mill. However, as this cone is an integral part of the mill, an important part of the regulating mechanism operates inside the grinder. This device is actually particularly vulnerable due to wear and seizure by grains and steel waste.

Various devices have also been proposed making it possible to return part of the ground material to the grinding chamber.

Document FR-2261812 describes a very simple system for returning insufficiently ground materials (also called "pebbles") associated with already worn grinding bodies to the grinding chamber, which essentially comprises in the central area of the end wall a discharge tube which is associated with a two-way valve, so as to conduct the insufficiently ground materials again towards the grinding chamber while the sufficiently ground material leaves this grinding chamber.

Document GB-A-2064364 describes a drum crusher intended for a wet process of the autogenous or semi-autogenous type, and which has a partition adjacent to the outlet partition itself provided with a material discharge pin separated from the outlet partition by a space, said upstream wall comprising on the one hand a first group of relatively small openings through which the finely ground material which leaves the mill can penetrate and go towards the outlet pin and a second group of relatively larger openings through which a material comprising both fine particles and coarse particles can leave the mill. This second group of openings communicates with an outlet of the material by deflection means which prevent this mixture from leaving the mill. In this case, the deflection elements act only 6

on a part of the material, that is to say the part which comes from relatively large openings, and not on all the material coming from all the openings. This means that it will be impossible to properly control the material retention time within the mill.

Document US Pat. in a controllable way. This means that the mill described in this document does not have a grid or a discharge chamber. In addition, maintaining the fall conditions in a grinding chamber for an autogenous mill is relatively problematic. This becomes impossible in the case of a semi-autogenous mill or in the case of a ball mill.

Document O86 / 04526 describes a device for adjusting the retention time of a material in the mill which can be an autogenous, semi-autogenic or ball mill, and which comprises a reservoir chamber upstream of the outlet bottom. This mill is characterized by the fact that it comprises a discharge duct more commonly called a "spoon", substantially coaxial with the mill, separated from the latter and movable longitudinally. This spoon enters the reservoir chamber through the outlet bottom of the mill and is provided at its upstream end with a first opening made in its upper part. This spoon can advance to near the upstream face of the reservoir chamber. It should be noted that this device called "spoon" is fixed by 7

compared to the rotation of the mill, and will not allow it to resist the moving mass if it is used for large mills. In addition, since it is a fixed element, it is necessary to provide a particularly large clearance between said spoon and the grinder.

It should be noted that most of the methods for regulating aim to propose either means making it possible to reinject into the grinding chamber, if necessary, the insufficiently ground material, or propose devices for partially closing the discharge zone in order to '' increase the retention time and / or the level of material within the grinding chamber.

However, the latest devices proposed are adjustable and mobile devices, which can only be envisaged for small size shredders. The present invention is particularly interested in shredders of large and very large dimensions, the diameter of which can reach 12 meters and beyond. Document US-A-2344162 describes a device which makes it possible to divert the ground material towards the outlet pin and to return the crushed material and the spent balls into the grinding chamber while the objective of the system according to the invention is also to deflect the ground material towards the outlet pin but to eliminate these same crushed and worn balls towards the outside of the crusher so that they do not enter the grinding chamber because they reduce the efficiency thereof.

Document DE-A-549694 describes a mill working in the dry process in which an intermediate partition between two successive grinding chambers is shown. At no time, we only observe a setting 8

level will be performed. Only a stream of air is used to separate the fines from the material to be ground. In addition, the intermediate partition described does not have a grid.

Document US-A-2815176 describes again a mill working only in the dry process and intended for an application for which it is sought to produce a mixture of fine and coarse materials according to a percentage determined for graphite electrodes. Again, an air stream is used to remove the fines. Finally, this device does not include a grid, will not be able to achieve separation of the pebbles and no adjustment of the level of grinding in said grinder is provided.

Document DE-A-2848343 describes a device comprising an intermediate partition between two successive grinding chambers. It will be observed that an axis or rod passes through the different grinding chambers. The fact of presenting such an axis will not allow use in large size shredders, since this axis is unable to support the large masses displaced in this case. Finally, we observe that all matter without distinction is likely to pass from one room to another.

AIMS OF THE INVENTION The present invention relates to a mill working in the wet, either of the autogenous type or of the semi-autogenic type, or else operating essentially by grid discharge but which combines both the advantages of a mill discharge by grid and by overflow.

More specifically, the present invention aims to propose new means present in the partition which 9

make it possible to act on the level of material within the grinding chamber by preventing too rapid or too great an exit of this material.

The present invention aims to propose a solution which is particularly simple from a mechanical point of view, and which should not require the placement of a mobile element, which would be unacceptable for certain applications and in particular for large or very large dimension. In addition, the present invention aims to propose a solution which also makes it possible to avoid blocking of the discharge chamber by the insufficiently ground material ("pebbles") and by the grinding bodies already worn.

Main characteristic elements of the present invention

The present invention relates to a mill working in the wet, autogenous, semi-autogenic or even ball type, operating by grid discharge, comprising an outlet partition between the grinding chamber and the outlet pin. Said partition comprises two walls, the volume between the upstream wall and the downstream wall forming a compartment into which the material penetrates. This material can circulate diametrically in said compartment, called "discharge chamber".

The upstream wall is a wall essentially covered with perforated grids comprising a plurality of openings which allow the sufficiently crushed material to pass through said compartment inside the partition. 10

The downstream wall, which is spaced from the upstream wall, is preferably full with the exception of the central part which remains open and which is directed towards the discharge pin. The present invention is characterized in that said partition comprises means integral with this partition making it possible to ensure (partial) passage of part of the material in the central zone of the compartment provided between the upstream wall and the downstream wall of the partition and therefore towards the grinding chamber upstream of said partition, the rest of the material being discharged towards the outlet pin. This therefore allows mixed operation of the mill by discharge / overflow. The fact that the means are integral with the partition means that these will be subjected to the rotation of the mill and can therefore be used even in very large mills.

According to a first preferred embodiment of the present invention, the means allowing a partial passage through the central zone of the partition are constituted by deflectors in the form of sheets connecting the upstream wall to the downstream wall in the central compartment area. If all the deflectors are placed, one obtains a cone or a pyramid of discharge and a 100% operation by discharge.

In order to obtain a modulated operation of the evacuation of the material out of the partition between 0 and 100% by overflow (overflow), only a certain number of these deflectors will be available, the others being removed. 11

Placing deflectors without opening in a certain number of sectors of the partition makes it possible to deflect a part of the ground material towards the outlet pin, the rest falling back into the discharge chamber so as to maintain a new, almost constant in the grinder.

According to a second embodiment of the present invention, the means allowing a partial passage through the central zone of the partition are constituted by the placement of a truncated cone in this zone. In order to obtain a modulated operation of the evacuation of the material out of the partition between 0 and 100% by overflow (overflow), again a truncated cone is used which does not cover the entire width of the discharge chamber. In this case, an annular passage will be provided on the upstream side of the cone, which allows a partial fall of the material in the discharge chamber.

The fact of placing a more or less complete truncated cone in the internal compartment of the partition makes it possible to determine the quantity of material which is directed towards the outlet pin and the quantity of material which falls in the discharge chamber, so as to maintain almost constant level in the mill.

In a particularly advantageous manner, deflector grids have also been placed in the compartment inside the partition in the most diametrical part of the latter, that is to say towards the periphery. These grids allow the direct evacuation to the outlet pin of the material or of the grinding machines worn or broken without allowing them to be returned to the discharge chamber. 12

Optionally, provision may be made on these deflecting grids for lights which allow the passage of the finer material with possibly a return to the grinding chamber. It is also provided, to allow the evacuation of the material out of the partition, that the downstream wall has an annular opening arranged around the attachment zone of the deflectors or of the cone.

Brief description of the figures

Figure 1 shows a longitudinal sectional view of a ball mill having a single grinding chamber and equipped with an outlet partition usually used. FIG. 2 represents a view in longitudinal section shown in FIG. 1, and corresponding to a first embodiment of a partition equipped with means for regulating the level of the material within the grinding chamber. Figures 3 show several views in cross section along the axis XX 'of the partition shown in Figure 2 seen from the pin according to various load situations of the crusher. Figures 4 show several views in longitudinal section along section AA according to a second embodiment of a partition equipped with means for regulating the level of material within the grinding chamber according to various load conditions of the grinder. 13

Figure 5 shows a cross-sectional view along the axis XX 'of the partition of figure

4d view from the journal according to various load situations of the mill. FIG. 6 represents a detailed view of a grid used in a partition as described in FIG. 5.

Figures 7 show the possibilities of the adjustment means used in the second embodiment.

Description of several preferred embodiments of the invention

In the figures, identical references relate to identical or analogous elements.

The crusher of Figure 1 is a crusher that operates in the wet process and which is formed of a ferrule 1 carried by two conical bottoms 2 and 3. The conical outlet bottom 3 is secured to an outlet partition 15 with which outlet pin 4 forms a body. On the entry side, a pin 5 is also integral with the bottom 2. The pins are carried by bearings (not shown) in Figure 1. The crusher is driven by a crown and a pinion (not shown). To protect the shredder from wear and tear, the ferrule 1 and the inlet and outlet bottoms 2 and 3 are fitted with shielding 8 and 9. In addition, the ferrule 1 is provided with a manhole 7 the cover of which is formed by a shielding element fixed by stirrups 10 and bolts 11. The crusher shown in FIG. 1 comprises only one grinding chamber 6, which is partially filled with grinding bodies 17, which are in 14

the present case of metal balls, and materials to be ground.

Particular examples of partitions are shown in more detail in Figures 2, 3, 4, 5 and 7. Usually, the partitions consist essentially of a frame, itself comprising a certain number of sectors. In the various exemplary embodiments shown in the figures, twelve steel sectors are joined together to create a partition. In the case of an outlet partition, these sectors directly follow the bottom 3 of the mill and are bolted to it by bolts (not shown in the figures).

The partitions shown in the various embodiments have an upstream face and a downstream face which delimit a volume 12 called the discharge chamber. Usually, the upstream face of the various assembled sectors is covered by grids also made of steel 14 which come to bear on the corresponding sectors.

These various grids, an example of which is shown in more detail in FIG. 6, are pierced with a plurality of openings or openings 20 which allow the passage of the sufficiently ground material. Wider openings 21, called "pebbles ports" and located at various places in these grids, make it possible to avoid the accumulation of very difficult to grind materials and of used grinding machines in the grinding chamber, which would reduce the effectiveness of it. The openings 20 of the grid widen from their entry to the upstream face of the grid towards their exit to the downstream face of the grid, so that the 15

particles entering it are easily released. Optionally, on the side of the upstream face, the grids 9 can be provided with ribs (not shown in the figures). The center of the upstream wall of the partition is in the form of an opening closed by a sheet metal covered with rubber on its two faces and fixed to the frame so as to force the ground material to pass through the grids. The downstream wall of the chassis has a central opening according to the embodiment shown in the various figures, which communicates directly with the outlet pin.

Usually, the central part of the partition is equipped with a deflector or discharge cone, the top of which is directed towards the outlet of the mill. This discharge cone is generally in the form of a frustoconical central part in order to direct the material present in the compartment of the partition towards the outlet pin. To do this, the base of this frustoconical part is directed upstream while its top is directed towards the downstream wall in order to slide the material directly towards the outlet pin.

In addition, this partition is equipped with elements called "deflecting grids" 18 which aim to separate coarse or insufficiently ground parts as well as the worn balls from the fine. These deflecting grids 18 also make it possible to directly selectively direct the insufficiently ground materials (pebbles) towards the outlet pin so as to eliminate them. 16

The present invention aims to provide means which make it possible to regulate the level of material in the compartment 12 of the partition and consequently in the grinding chamber 6 which communicates with the compartment 12 via the grids 9, thanks to the deflection of a quantity of more or less material towards the outlet pin, while the non-deflected material falls back into the compartment 12.

According to the embodiment shown in FIGS. 2 and 3, it suffices not to install deflectors 19 on a certain number of sectors of the partition, thus not forcing part of the material contained in this sector to go towards the output pin.

This embodiment is shown in detail in Figures 3a, 3b, 3c and 3d. In the case of FIG. 3a, all the deflectors 19 are placed, which forces all the material to go towards the outlet pin and thereby prevents operation by overflowing of the mill. Figure 3d shows an arrangement in which none of the deflectors 19 is provided, which allows the crusher to operate at 100% by overflow (100% overflow). Figures 3b and 3c represent intermediate situations between the 100% grid (0% overflow) and 100% overflow (100% overflow), namely 50% and 75% overflow.

According to the embodiment shown in Figures 4, the frustoconical part is made using a cone.

According to the present invention, the cone is a truncated cone at the base, that is to say that it makes it possible to open a passage at the base of the cone on the upstream side of the partition. This allows a partial passage of part of the material 17

towards the outlet pin, the other part falling back into compartment 12.

More particularly, FIG. 4a represents a cone which does not allow operation by overflow (0% overflow) and occupies the entire central zone of compartment 12. FIG. 4d represents the conditions under which no cone is arranged, allowing overflow operation (100% overflow). Figures 4b and 4c show intermediate situations.

FIG. 7 represents a partition in which the second embodiment was used. As already mentioned, it can be seen that the upstream face is covered at the periphery with grids having openings, while the central part is covered by a disk 16 made of sheet metal. The downstream face is formed at the periphery by the shielding or by a solid wall in the case of an intermediate chamber, while the central part is free. The two walls define a compartment, the central part of which is provided with radial elements which are arranged so as to hold in place either the cones or the deflectors.

In Figures 7b and 7c, there is shown an exploded view of the various elements constituting the central area of the wall, in which different heights of cones have been proposed. The partial fixing of the cones is provided by means known per se, of the bolt, nut, etc. type. The choice of a type of cone is governed by the type of material to be ground and the fineness of the material desired 18

in order to obtain a correct level of material to be ground in the upstream grinding chamber.

Claims

19 CLAIMS

1. Grinder working in the wet, autogenic type, semi-autogenic type or ball mill operating by grid discharge, comprising an outlet partition between the grinding chamber and the outlet pin, said partition consisting of an upstream wall and a downstream wall constituting an internal compartment in the partition called the discharge chamber, characterized in that the central part of the partition is provided with means integral with this partition making it possible to pass a portion of the ground material in the central zone of the compartment (12) and therefore towards the discharge chamber of said partition, the rest of the material being discharged towards the outlet pin (2).

2. Crusher according to claim 1, characterized in that the means integral with the partition and ensuring the passage towards the discharge chamber of part of the crushed material consist of deflectors in the form of sheets connecting the wall upstream to the downstream wall of the discharge chamber, and in that only part of said deflectors are placed, the others being removed.

3. Crusher according to claim 1, characterized in that the means making it possible to pass a portion of the ground material into the central zone of the partition are constituted by the placement of a truncated cone leaving a passage on the side of the upstream wall of the central zone of the compartment.

4. Crusher according to any one of the preceding claims, characterized in that there are deflecting grids in each sector of the partition. 20

5. Partition for grinder working in the wet, autogenic type, semi-autogenic type or even ball mill operating by grid discharge, comprising an outlet partition between the grinding chamber and the outlet pin or an intermediate partition between two successive grinding chambers, characterized in that said partition consists of a chassis comprising on the upstream face at the periphery of the grids provided with openings and on the downstream face a solid partition, possibly constituted by the shielding of the crusher, the central part of the partition being provided with means allowing partial operation of the mill by overflow discharge.

6. Partition according to claim 5, characterized in that the means allow a partial opening of the central space of the partition between the periphery and the center and thus allow a passage of the material by return to the discharge chamber.

7. Partition according to claim 5 or 6, characterized in that the means consist in proposing the partial placement of deflectors thus not covering the whole of the central space of the partition.

8. Partition according to claim 5 or 6, characterized in that the means consist in proposing the placement of a cone which does not cover the entire space of the central part and thus allowing the passage of part of the material towards the discharge chamber.