WO2024160679A1

WO2024160679A1 - Lifting liner for a rotary tube mill

Info

Publication number: WO2024160679A1
Application number: PCT/EP2024/051936
Authority: WO
Inventors: Xavier Prignon
Original assignee: Magotteaux International S.A.
Priority date: 2023-02-03
Filing date: 2024-01-26
Publication date: 2024-08-08
Also published as: CN118785977A; EP4410430A1

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

Lifter shield for rotary tubular crusher

Subject of the invention

[0001] The present invention discloses a lifting shield for the first chamber of a rotary tubular crusher with a horizontal axis comprising a cylindrical shell intended to contain the material to be crushed and a load of grinding machines (balls, cylpeps, boulpeps). The shielding has 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 raise the grinding bodies. The lifting capacity of the elements with deflectors can be adapted depending on the material to be crushed.

State of the art

[0002] Rotary crushers with a horizontal axis are well known from the state of the art in the field of mining and more particularly in cement works. These crushers are equipped with lifting shields for wet and dry grinding. They rotate around a horizontal axis, and generally contain steel balls of varying dimensions. The material to be crushed is introduced into one side of the crusher and, as it progresses towards the outlet, it is crushed and crushed between the grinding machines which are raised by the deflecting elements of the shielding during the rotation of the crusher .

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

[0004] A conventional rotary mill with a horizontal axis 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 includes a classifying shield containing grinding balls with a diameter generally between 15 mm and 60 mm.

The shielding according to the present invention is a lifting shield intended for the first chamber of a crusher. Its performance is mainly measured 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 produce a lifting shield having great flexibility of use due to its numerous possible configurations by decoupling the wear of the base plate of the armor from that of the deflector. The heavily worn baffle can optionally be replaced individually without having to replace the entire shield when it is configured in two parts with a base and a detachably mounted baffle.

[0007] The lifting effect is obtained by a continuous ring of deflectors creating lifting corridors. The deflectors are arranged in a “zigzag” fashion, parallel or not. This arrangement allows, with a more or less accentuated “zigzag” and a studied distance between two deflector rings, to meet a large number 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 coating of the interior wall of the shell of a rotary crusher containing a load of grinding machines, said shield comprising an exterior cylindrical face matching the interior surface of the ferrule 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 ferrule characterized in that said deflector elements form a continuous ring in the shape of a zigzag characterized by an angle alpha > 0°, relative to a plane perpendicular to the generator of the crusher.

[0009] The preferred embodiments of the invention comprise at least one, or any suitable combination of the following characteristics: the alpha angle varies between 5 and 25°, preferably between 10 and 25° and in a particularly preferred manner between 10 and 21.8°; the shield elements having baffles have two parts, a base and a baffle 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 grinding machines; the distance between the continuous zigzag rings is constant thanks 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 represents between 1 and 2 times its width.

Definition

In the present invention, by “continuous” ring it must be understood 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 solely to illustrate the present invention and have no limiting nature.

The alpha angle (10; 15; 21.8°) is the angle formed by the deflector with a plane perpendicular to a generator of the crusher. The higher the alpha angle, the higher the lifting capacity of the deflector, all other things being equal;

The “position” (parallel; opposite) describes the arrangement of the continuous zigzag rings relative to each other, for example parallel or not or even 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 armour plates without deflectors.

[0011] Figure 12 describes a system for fixing the removable deflector on its base plate. The screw fixes the deflector on its base plate which is itself fixed on the shroud of the horizontal axis crusher.

Detailed description of the invention

[0012] The energy required to crush an ore depends on its particle size and its crushability and when a significant crushing energy is necessary, a significant lifting of the load is required, it is therefore necessary to accentuate the lifting profile. When the crusher rotates, this causes a projection of a greater part of the grinding balls which fall back into rain and become relatively ineffective for crushing.

[0013] A conventional lifting shield equipped with lifting plates comprising projecting radial noses wears on average at a speed of 1 mm per 1000 hours of grinding for applications in cement plants. For some minerals this can represent much more. This wear is however not uniform, it is around 1.8 mm/1000 h of operation on the protruding noses, while it is only around 0.4 mm/1000 h of operation in the hollow of the plate. This is the reason why the lifting and therefore crushing performance decreases significantly at the end of its life, which requires the replacement of the entire shielding while this shielding still has approximately 40% of its initial weight and the "weight used” of the shielding therefore represented only 60%.

[0014] Based on this observation, the objective of the present invention was therefore to dissociate the lifting functions from those of protecting the shell. The wear of the armor elements not provided with deflectors has no impact on the lifting capacities, their sole function is to protect the shell. We therefore thought of combining elements without deflectors with elements equipped with deflectors. This makes it possible to considerably increase the used weight of the armor before replacement up to 75% of its initial weight and therefore, as a corollary, to increase the lifespan of the armor. [0015] For armor elements configured in two parts which comprise a base and a deflector mounted in a removable manner, only the deflector which affects the lifting capacity can be replaced in certain cases, even when its base has already been the subject 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 from 60 to 100 mm in 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 spaced apart from each other and presenting a more or less accentuated “zigzag” configuration and described by an alpha angle 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)

The parameters mainly influencing the lifting capacities of the armor according to the invention are: the distance between the continuous rings of deflectors arranged in a zigzag and therefore ultimately the number of armor plates equipped with deflectors;

The accentuation of the zigzag by an alpha angle of 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 the continuous rings in zigzag in relation to each other, for example parallel or not or even in “opposition”;

The height of the deflector in direct relation to the diameter of the grinding balls used. For 100 mm grinding balls the height of the deflector 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).

The shielding according to the present invention presents a wide variety of possible configurations and therefore great flexibility of use. Certain ores will require large lifting capacities with many deflector elements, a significant height and with a high alpha angle unlike others where we will work in gentler 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 deflectors must be related 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.

Baffle heights generally vary from 40 to 200mm, preferably between 60 and 160mm and width from 50 to 90mm. The distance between two continuous zigzag rings may 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 armor plates can be variable, that of 314 mm illustrated in the examples corresponds to a DI N standard (DI N 24111) to take into account their fixing system. [0021] The shrouds 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 grinder manufacturer. So far, only the DI N standard has established itself 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 manufacturers and the size of the grinders.

[0022] When the deflector and the base plate are manufactured in a single piece, the system according to the invention makes it possible to replace only the plates with deflector 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 lifespan. This removable attachment allows the replacement of the deflector alone because it ensures lifting while the wear of the base or of the shielding elements without deflectors has little impact on the grinding performance, as long as the shroud of the crusher is protected.

[0023] Advantages of shielding according to the invention

To the extent that 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 load, 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 deflectors and therefore separately replaceable, it is possible to increase the thickness of the base plates of the shielding which makes it possible to increase the useful part to resist wear and therefore the duration of overall life. This also makes it possible to reduce the weight fraction of shielding lost when the shielding is at the end of its life. In In this case, the deflectors can be replaced one or more times before the base plates are worn.

The shielding according to the invention also has 2 additional major advantages:

• With a base plate and a 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 good crushing of the majority of products processed in ball mills in cement plants, ( see table above)

Examples

Crushing from fine and soft products (e.g. crushed limestone < 4 mm, with configuration 157314/parallel/750) to the coarsest and hardest product (e.g. molten clinker >100 mm in configuration 157628/opposite/500), with average lifting of Portland clinker (<40 mm in configuration 157628/parallel/500). By increasing the alpha angle of the deflectors, for example to 21.8°, an equivalent lift 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 plant materials but can of course be extrapolated to other materials and particularly in the mining field, for example for iron ore, lead or zinc ores, etc.). This flexibility drastically reduces costs associated with manufacturing and managing shield designs and standardizes shield 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 large, heavier particles which are mainly found at the periphery of the charge. These large particles will therefore stay longer in the first chamber of the crusher and will be more likely to be crushed correctly before progressing towards the exit of the crusher.

Claims

1. Lifting shield intended to form part of the covering of the interior wall of the shell of a rotary crusher containing a load of grinding machines, said shield comprising an exterior cylindrical face matching the interior surface of the shell and rows comprising elements deflectors and rows without deflector elements, the deflector elements having a projecting radial profile oriented inwardly perpendicular to the surface of the shell characterized in that said deflector elements form a continuous ring in the shape of a zigzag characterized by an angle alpha > 0°, relative to a plane perpendicular to the generator of the mill.

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

3. Lifting armor according to any one of claims 1 or 2 in which the armor 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 grinding 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 a position of opposition to each other.

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