Lifting liner for a rotary tube mill

Abstract

The present invention relates to a lifting liner intended to form part of the lining of the inner wall of the shell of a rotary mill containing material to be ground, the liner comprising a cylindrical outer face conforming to the inner surface of the shell and rows with deflector elements and rows without deflector elements, the deflector elements having a projecting radial profile oriented inward perpendicular to the surface of the shell, characterised in that the deflector elements form a zigzag-shaped continuous ring characterised by an angle alpha > 0° with respect to a plane perpendicular to the generatrix of the mill.

Description

DP.MAGO.0165 / PC 1 Lifting shield for rotary tubular crusher Subject of the invention

[0001] The present invention discloses a lifting shield for the first chamber of a horizontal-axis rotary tubular mill comprising a cylindrical shell intended to contain material to be ground and a load of grinding media (balls, cylpeps, boulpeps). The shield comprises rows of elements with deflectors and elements without deflectors, the elements without deflectors are only intended to protect the shell and the elements with deflectors are intended to lift the grinding bodies. The lifting capacity of the elements with deflectors is adaptable depending on the material to be ground. State of the art

[0002] Horizontal shaft rotary mills are well known in the state of the art in the mining field and more particularly in cement works. These mills are equipped with lifting liners for wet and dry grinding. They rotate around a horizontal axis, and generally contain steel balls of varying dimensions. The material to be ground is introduced on one side of the mill and, as it progresses towards the outlet, it is crushed and ground between the grinding media which are lifted by the deflecting elements of the liner as the mill rotates.

[0003] Such crushers equipped with their shields are described in particular in the documents EP0998353A1; BE1011286A3; BE09301481; WO0197975A; US3869091A; US6.951315 B2.

[0004] A conventional horizontal axis rotary mill is generally divided into two or three successive chambers, in the axial direction, by means of a diametrical separation partition. The first chamber, in which the coarse crushing of the material takes place, contains grinding balls generally having a diameter between 60 mm and 100 mm. The second chamber, in which the fine grinding takes place, generally has a classifying lining containing grinding balls generally having a diameter between 15 mm and 60 mm.

[0005] The shielding according to the present invention is a lifting shield intended for the first chamber of a crusher. Its performance is measured mainly by its lifting capacities while minimizing the wear rate generally measured in mm per 1000 hours of operation. Purpose of the invention

[0006] The objective of the present invention is to provide a lifting shield with great flexibility of use due to its numerous possible configurations by decoupling the wear of the base plate of the shield from that of the deflector. The deflector, which is highly subject to wear, can optionally be replaced individually without having to replace the entire shield when the latter is configured in two parts with a base and a detachably mounted deflector.

[0007] The lifting effect is achieved by a continuous ring of deflectors creating lifting corridors. The deflectors are arranged in a "zigzag" pattern, either parallel or not. This arrangement allows, with a more or less pronounced "zigzag" and a studied distance between two deflector rings, to meet a wide range of needs with unique modular elements. Summary of the invention

[0008] The present invention relates to a lifting shield intended to form part of the lining of the inner wall of the shell of a rotary crusher containing a load of grinding media, said shield comprising an outer cylindrical face matching the inner surface of the shell and rows comprising deflector elements and rows without deflector elements, the deflector elements having a projecting radial profile oriented inwards perpendicular to the surface of the shell, characterized in that said deflector elements form a continuous zigzag-shaped ring characterized by an angle alpha > 0°, relative to a plane perpendicular to the generator of the crusher.

[0009] Preferred embodiments of the invention comprise at least one, or any suitable combination of the following features: the angle alpha varies between 5 and 25°, preferably between 10 and 25° and particularly preferably between 10 and 21.8°; the shielding elements comprising deflectors comprise two parts, a base and a deflector removably attached to its base; the height of the deflectors represents between 0.5 and 4 times, preferably between 1 and 2 times the diameter of the crushing machines; the distance between the continuous zigzag rings is constant due to a parallel arrangement of the rings relative to each other; the distance between the continuous zigzag rings is variable and preferably where the continuous zigzag rings are in opposition to each other; the height of the deflector is between 1 and 2 times its width. Definition In the present invention, by "continuous" ring it is meant that the deflectors are positioned one after the other to form a continuous zigzag line but made up of separate pieces. The deflectors are therefore not in direct contact with each other at the junction between two base plates of the shielding but are generally spaced a few millimeters apart, this small space is conditioned by the tolerances which are always necessary in foundry. Brief description of the figures

[0010] Tables 1 and 2 below summarize the information in Figures 1 to 11 which give examples of possible configurations. These examples are intended only to illustrate the present invention and are not limiting in nature. The angle alpha (10; 15; 21.8°) is the angle formed by the deflector with a plane perpendicular to a generator of the crusher. The higher the angle alpha, the higher the lifting capacity of the deflector, all other things being equal; The "position" (parallel; opposite) describes the arrangement of the continuous rings in a zigzag pattern relative to each other, for example, parallel or not, or in "opposition"; The length of the deflector pitch (314 mm and 628 mm - pitch in English) see figure below. The distance between rows of deflectors (500 and 750) is the distance between the continuous rings of deflectors arranged in a zigzag pattern; The plates with deflectors are each separated by one or two rows of armor plates without deflectors.

[0011] Figure 12 describes a system for fixing the removable deflector to its base plate. The screw fixes the deflector to its base plate which is itself fixed to the shell of the horizontal shaft crusher. Detailed description of the invention

[0012] The energy required to crush an ore depends on its granulometry and crushability and when significant crushing energy is required, significant lifting of the load is required, so the lifting profile must be accentuated. When the crusher rotates, this causes a projection of a larger portion of the grinding balls which fall back as rain and become relatively ineffective for crushing.

[0013] A conventional lifting liner equipped with lifting plates with projecting radial noses wears on average at a rate of 1 mm per 1000 hours of grinding for cement applications. For some ores this can be much higher. This wear is however not uniform, it is approximately 1.8 mm / 1000 hours of operation on the projecting noses, while it is only approximately 0.4 mm / 1000 hours of operation in the hollow of the plate. This is the reason why the lifting performance and therefore the grinding performance decreases significantly at the end of its life, which requires the replacement of the entire liner while this liner still contains approximately 40% of its initial weight and the "used weight" of the liner therefore only represented 60%.

[0014] Based on this observation, the objective of the present invention was therefore to dissociate the lifting functions from that of protecting the shell. The wear of the shielding elements not provided with deflectors has no impact on the lifting capacities, their sole function is to protect the shell. It was therefore considered to associate elements without deflectors with elements equipped with deflectors. This makes it possible to considerably increase the weight used of the shielding before replacement up to 75% of its initial weight and therefore, as a corollary, to increase the service life of the shielding.

[0015] For two-part configured shield elements that have a base and a removably mounted deflector, only the deflector that affects the lifting capacity may be replaced in some cases, even when its base has already been subject to significant wear.

[0016] The shielding according to the present invention therefore comprises an association between plates, generally flat and smooth, intended to protect the shell against wear and plates equipped with deflectors which form a continuous ring and ensure the lifting of the grinding bodies, generally steel balls of 60 to 100 mm diameter. (See for example figures 5 and 7 illustrated with 100 mm grinding balls).

[0017] The shielding plates comprising the deflectors are arranged in such a way that they form a plurality of continuous rings more or less distant from each other and having a more or less accentuated “zigzag” configuration and described by an angle alpha formed between the deflector and the plane perpendicular to a generator of the crusher, (see figures 1, 9 and 10 for example which illustrate 3 different angles)

[0018] The parameters mainly influencing the lifting capacities of the armour according to the invention are: the distance between the continuous rings of deflectors arranged in a zigzag pattern and therefore ultimately the number of armour plates equipped with deflectors; The accentuation of the zigzag by an angle alpha between 5 and 25°, preferably between 10 and 25°; the angle is measured relative to a plane perpendicular to a generator of the crusher. The arrangement of continuous rings in a zigzag pattern relative to each other, for example parallel or not or even in “opposition”; The height of the baffle is directly related to the diameter of the grinding balls used. For 100 mm grinding balls the height of the baffle generally varies from 80 mm to 200 mm. (generally between 0.5 and 4 times, preferably between 0.8 and 2 times the maximum diameter of the grinding ball).

[0019] The shielding according to the present invention presents a wide variety of possible configurations and therefore great flexibility of use. Some ores will require large lifting capacities with many deflector elements, of a significant height and with a high alpha angle unlike others where one will work in milder conditions with fewer rows of plates equipped with deflectors and a lower alpha angle.

[0020] The diameter of the grinding balls used, when new, generally varies from 50 to 125 mm, preferably 60 to 90 mm and the height of the baffles must be in relation to the diameter of the balls used and it must represent between 0.5 and 4 times, preferably between 0.8 and 2 times the maximum diameter of the grinding balls used. The heights of the baffles generally vary from 40 to 200 mm, preferably between 60 and 160 mm and the width from 50 to 90 mm. The distance between two continuous zigzag rings can vary between 200 and 800 mm, preferably between 500 and 750 mm and will be adapted according to the length of the first chamber of the crusher. The length of the shielding plates can be variable, the 314 mm length illustrated in the examples corresponds to a DI N standard (DI N 24111) to take into account their fixing system.

[0021] The shells of the crushers are thus pierced with a certain number of holes allowing the passage of the bolts for fixing the armor plates. Both the configuration of the holes and their diameter vary depending on the crusher manufacturer. Until now, only the DI N standard has been imposed in Western Europe and is characterized by a longitudinal hole distance of 250 mm and a circumferential distance of 314.16 mm arc. The diameter of the holes varies from 30 to 42 mm depending on the manufacturer and the size of the crushers.

[0022] When the deflector and the base plate are manufactured in a single piece, the system according to the invention allows only the plates with deflector to be replaced when they are worn. The deflector can however also be removably attached to its base which generally has a thickness varying between 30 and 80 mm, depending on the desired service life. This removable attachment allows the replacement of the deflector alone because it ensures lifting while the wear of the base or even of the shielding elements without deflectors has little impact on the grinding performance, as long as the mill shell is protected.

[0023] Advantages of the shielding according to the invention Since the lifting of the grinding bodies is created by friction on the lateral faces of the continuous zigzag-shaped rings and not by projecting radial noses, the advantages of the shielding according to the invention are as follows: • wear on the rings does not significantly modify the alpha angle of the ring segments, which makes it possible to maintain the same level of load lifting and constant performance over time; • the continuous zigzag rings do not project the balls towards the foot of the charge, the grinding efficiency is then better and there are fewer impacts between the grinding balls and the armor plates; • in the two-part configuration with removable and therefore separately replaceable deflectors, it is possible to increase the thickness of the base plates of the armour, which makes it possible to increase the useful part to resist wear and therefore the overall service life. This also makes it possible to reduce the weight fraction of armour lost when the armour is at the end of its life. In In this case, the deflectors can be replaced one or more times before the base plates become worn.

[0024] The shielding according to the invention also has two additional major advantages: • With one base plate and one type of lifter it is possible to cover more than 8 different shielding configurations making it possible to cover practically all the common lifts necessary for the proper crushing of the majority of products processed in ball mills in cement plants, (see table above) Examples Crushing of fine and soft products (e.g. crushed limestone < 4 mm, with a 157314 / parallel / 750 configuration) to the coarsest and hardest product (e.g. fused clinker >100 mm in a 157628 / opposite / 500 configuration), with Portland clinker as average lifting (<40 mm in a 157628 / parallel / 500 configuration). By increasing the alpha angle of the deflectors, for example to 21.8°, equivalent lifting can be obtained provided that the space between the rings is increased, or by reducing the pitch of the deflectors. Conversely, if we reduce the alpha angle of the deflectors we obtain an equivalent lift by reducing the space between rings or by increasing the pitch of the deflectors. The examples are given for cement materials but can of course be extrapolated to other materials and in particular in the mining sector, for example for iron, gold, lead or zinc ores, etc.). This flexibility makes it possible to drastically reduce the costs linked to the manufacture and management of shielding models and to standardize the shielding plates for customers using different ball mills. • The arrangement of the deflectors in continuous rings on the shielding according to the invention has the effect of preferentially retaining the larger, heavier particles which are mainly found at the periphery of the load. These larger particles will therefore remain longer in the first chamber of the crusher and will have a greater probability of being crushed correctly before progressing towards the crusher outlet.

Claims

CLAIMS 1. Lifting shield intended to form part of the lining of the inner wall of the shell of a rotary crusher containing a load of grinding media, said shield comprising an outer cylindrical face matching the inner surface of the shell and rows comprising deflector elements and rows without deflector elements, the deflector elements having a projecting radial profile oriented inwards perpendicular to the surface of the shell, characterized in that said deflector elements form a continuous zigzag-shaped ring characterized by an angle alpha > 0°, relative to a plane perpendicular to the generator of the crusher.

2. Lifting shield according to claim 1 in which the angle alpha varies between 5 and 25°, preferably between 10 and 25° and particularly preferably between 10 and 21.8°.

3. Lifting shield according to any one of claims 1 or 2 in which the shielding elements with deflectors comprise two parts, a base and a deflector removably fixed to its base.

4. Lifting shield according to any one of the preceding claims in which the height of the deflectors represents between 0.5 and 4 times, preferably between 1 and 2 times the diameter of the crushing machines.

5. Lifting shield according to any one of the preceding claims, in which the distance between the continuous zigzag rings is constant thanks to a parallel arrangement of the rings relative to each other.

6. Lifting shield according to any one of the preceding claims in which the distance between the continuous zigzag rings is variable and preferably where the continuous zigzag rings are in opposing positions relative to each other.

7. Lifting shield according to any one of the preceding claims in which the height of the deflector represents between 1 and 2 times its width.

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