Lifting lining for a rotary tube mill

Abstract

The present invention relates to a lifting lining intended to form part of the covering of the inner wall of the shell of a rotating mill, the shell of the rotating mill containing a load of grinding tools, said lining comprising a cylindrical outer 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 directed inwards perpendicular to the surface of the shell, characterized in that the deflector elements form a continuous ring in a zigzag shape at an angle α, the angle α of the deflector elements with respect to a plane perpendicular to the generatrix of the mill being >0.

Description

Technical Field

[0001] The present invention discloses a lifting lining for a first chamber of a horizontal axis rotary tube mill, the first chamber of the horizontal axis rotary tube mill comprising a cylindrical shell intended to contain the material to be ground and a load of grinding tools (balls, cylindrical pebbles, spherical pebbles). The lining comprises rows of elements with deflectors and rows of elements without deflectors, and 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 can be adjusted according to the material to be ground. Background Art

[0002] Horizontal axis rotary mills are well known in the prior art in the mining industry and more particularly in cement production. These mills are equipped with lifting linings for wet grinding and dry grinding. They rotate about a horizontal axis and generally contain steel balls of different sizes. The material to be ground is introduced on one side of the mill and, as it advances towards the outlet, it is broken and ground between the grinding tools, which are lifted by the deflector elements of the lining when the mill rotates.

[0003] Such mills equipped with their linings are specifically described in the documents EP0998353A1, BE1011286A3, BE09301481, WO0197975A, US3869091A, US6951315 B2.

[0004] Conventional horizontal axis rotary mills are generally divided into two or three successive chambers in the axial direction by means of diameter dividing walls. The first chamber (in which the coarse crushing of the material takes place) contains grinding balls with a diameter generally between 60 mm and 100 mm. The second chamber (in which the fine grinding takes place) generally includes a classification lining which contains grinding balls with a diameter generally between 15 mm and 60 mm.

[0005] The lining according to the present invention is a lifting lining intended for the first chamber of the mill. Its performance is mainly measured according to its lifting capacity while minimizing the wear rate, which is generally expressed in millimeters measured per 1000 hours of operation. Summary of the Invention

[0006] The object of the present invention is to produce a lifting lining which, due to its many possible configurations, has great flexibility in use and the wear of the base plate of the lining is independent of the wear of the deflectors. When the lining is constructed in two parts, with a base and a removably mounted deflector, the deflectors which are significantly worn can optionally be replaced individually without having to replace the entire lining.

[0007] The lifting effect is obtained through a continuous ring of deflectors, which creates a lifting corridor. The deflectors are arranged in a "zigzag" pattern, either parallel or non-parallel. This arrangement makes it possible to meet a wide variety of requirements with a single modular element by carefully selecting the "zigzag" pattern, which is more or less emphasized, and the distance between the two rings of deflectors.

[0008] The present invention relates to a lifting lining intended to form part of the covering of the inner wall of the casing of a rotary mill, the casing of the rotary mill containing a load of grinding tools, said lining comprising a cylindrical outer face matching the inner surface of the casing, and rows of deflector elements and rows without deflector elements, the deflector elements having a protruding radial profile directed inwards perpendicular to the inner surface of the casing, characterized in that the deflector elements form a continuous ring in a zigzag shape at an angle α, and the angle α of the deflector elements with respect to a plane perpendicular to the generatrix of the mill is > 0°.

[0009] Preferred embodiments of the present invention include at least one or any suitable combination of the following features:

[0010] - The angle α ranges between 5° and 25°, preferably between 10° and 25°, and particularly preferably between 10° and 21.8°;

[0011] - The lining element including the deflector has two parts, namely a base and a deflector removably attached to its base;

[0012] - The height of the deflector is between 0.5 times and 4 times the diameter of the grinding tool, preferably between 1 time and 2 times;

[0013] - Due to the parallel arrangement of the rings relative to each other, the distance between the continuous rings in a zigzag shape is constant;

[0014] - The distance between the continuous rings in a zigzag shape is variable, and preferably the continuous rings in a zigzag shape are in opposite positions to each other;

[0015] - The height of the deflector is between 1 time and 2 times its width.

[0016] Definition

[0017] In the present invention, a "continuous" ring means that the deflectors are positioned one after another to form a line in a continuous zigzag shape but consisting of separate parts. Thus, the deflectors do not directly contact each other at the joints between the two base plates of the lining, but are usually spaced apart by a few millimeters, and this small space depends on the tolerance, which is always necessary in an ironworks. Description of the Drawings

[0018] The following Tables 1 and 2 summarize Figures 1 to 11The information in Figures 1 to 11 shows examples of possible configurations. These examples are only intended to illustrate the invention and are in no way limiting.

[0019] - The angle α (10°; 15°; 21.8°) is the angle formed by the deflector with the plane perpendicular to the generatrix of the mill. All other conditions being equal, the greater the angle α, the greater the lifting capacity of the deflector.

[0020] - "Position" (parallel; opposite) describes the arrangement of the successive loops in a zigzag relative to each other, e.g., parallel or non - parallel, or alternatively "opposite".

[0021] - The length of the pitch of the deflector (314 mm and 628 mm); see the figure below.

[0022] - The distance between the rows (500 and 750) of the deflector is the distance between successive loops of the deflector arranged in a zigzag; the rows including the plates of the deflector are in each case separated by one or two rows of lining plates not including the deflector.

[0023]

[0024]

[0025] Figure 12 Describes a system for attaching a removable deflector to its base plate. Screws attach the deflector to its base plate, which in turn is attached to the housing of a horizontal - axis mill. Detailed Description

[0026] The energy required to grind ore depends on its particle size and its breakability, and when significant crushing energy is required, the load must be significantly lifted, and thus the lift profile must be emphasized. When the mill rotates, this causes most of the grinding balls to be thrown up and thus they fall like rain and become relatively inefficient for the purpose of crushing.

[0027] For applications in cement production, conventional lifting linings equipped with lifting plates including radial protrusions wear at an average rate of 1 mm of grinding per 1000 hours. In the case of certain ores, this rate may be much higher. However, this wear is uneven, about 1.8 mm / 1000 hours of operation on the protrusions and about 0.4 mm / 1000 hours of operation in the depressions of the plates. This is why at the end of the service life, the performance in terms of lifting and thus grinding drops significantly and the entire lining needs to be replaced, even though the lining is still about 40% of its initial weight, and thus the "used weight" of the lining is only 60%.

[0028] In view of the above, the object of the present invention is therefore to separate the lifting function from the function of protecting the shell. The wear of the lining elements without deflectors has no effect on the lifting capacity, and their function is purely to protect the shell. Thus, the idea is to combine the elements without deflectors with the elements equipped with deflectors. This makes it possible to increase the service weight of the lining significantly before replacement to up to 75% of its initial weight and thus correspondingly extend the service life of the lining.

[0029] For a lining element consisting of two parts (which include a base and a removably mounted deflector), in some cases, even if its base has suffered considerable wear, it is possible to replace only the deflector that affects the lifting capacity.

[0030] Thus, the lining according to the invention comprises a combination between plates that are generally flat and smooth and intended to protect the shell against wear and plates equipped with deflectors that form a continuous ring and ensure the lifting of the grinding bodies, which are generally steel balls measured to have a diameter between 60 mm and 100 mm. (See for example Figure 5 and Figure 7 , which show grinding balls of 100 mm.)

[0031] The lining plates including deflectors are arranged such that they form a plurality of continuous rings with a greater or lesser distance between these rings and have a "zigzag" configuration, which is more or less emphasized and is described by the angle α formed between the deflector and the plane perpendicular to the generatrix of the mill. (See for example Figure 1 , Figure 9 and Figure 10 , which illustrate three different angles.)

[0032] The parameters that mainly affect the lifting capacity of the lining according to the invention are:

[0033] - The distance between the continuous rings of deflectors arranged in a zigzag and thus ultimately the number of lining plates equipped with deflectors.

[0034] - The zigzag with the angle α emphasized between 5° and 25°, preferably between 10° and 25°; this angle is measured with respect to the plane perpendicular to the generatrix of the mill.

[0035] - The continuous rings in a zigzag are arranged relative to each other, for example parallel or non - parallel or alternatively "opposite".

[0036] - The height of the deflector is directly related to the diameter of the grinding balls used. For grinding balls measured to be 100 mm, the height of the deflector generally ranges from 80 mm to 200 mm (generally between 0.5 times and 4 times the maximum diameter of the grinding balls, preferably between 0.8 times and 2 times).

[0037] The lining according to the invention has a variety of possible configurations and thus great flexibility in use. Some ores require a considerable lifting capacity, using a large number of deflector elements with a large height and a large angle α. In contrast to other ores, for other ores, the working conditions require less, using fewer rows of plates equipped with deflectors and a smaller angle α.

[0038] In the new state, the diameter of the grinding balls used generally ranges from 50 mm to 125 mm, preferably 60 mm to 90 mm, and the height of the deflector must be proportional to the diameter of the balls used and must be between 0.5 times and 4 times the maximum diameter of the grinding balls used, preferably between 0.8 times and 2 times.

[0039] The height of the deflector generally ranges from 40 mm to 200 mm, preferably between 60 mm and 160 mm, and the width is from 50 mm to 90 mm. The distance between two consecutive rings in a zigzag shape can range between 200 mm and 800 mm, preferably between 500 mm and 750 mm, and will be adjusted according to the length of the first chamber of the mill. The length of the lining plate can vary, and the length of 314 mm shown in the example corresponds to the DIN standard (DIN 24111) in order to take into account their attachment system.

[0040] Therefore, the housing of the mill is drilled with a certain number of holes to allow bolts to pass through for attaching the lining plate. The configuration and diameter of the drilling vary from mill manufacturer to mill manufacturer. So far, DIN is the only standard implemented in Western Europe, and it is characterized by a longitudinal distance of 250 mm between the holes and a circumferential distance of 314.16 mm in the circular arc. The diameter of the holes ranges from 30 mm to 42 mm, depending on the manufacturer and the size of the mill.

[0041] When the deflector and the base plate are made as a single piece, the system according to the invention makes it possible to replace only the plate with the deflector when the deflector wears. However, depending on the desired service life, the deflector can also be removably attached to its base, which generally has a thickness ranging between 30 mm and 80 mm. This removable attachment allows the deflector to be replaced separately, because it is the deflector that ensures the lifting, and the wear of the base without the deflector or the lining element has little effect on the grinding performance, while the housing of the mill is protected.

[0042] Advantages of the lining according to the present invention ,

[0043] Since the lifting of the grinding bodies is generated by friction on the lateral surface of the continuous rings in a zigzag shape rather than by radial protrusions, the advantages of the lining according to the invention are as follows:

[0044] · Wear on the rings basically does not modify the angle α of the ring section, which makes it possible to maintain the same load-lifting level and constant performance over time;

[0045] · The continuous zigzag rings do not throw the balls towards the load feet and are therefore more efficient in grinding, with less impact between the grinding balls and the lining plates;

[0046] · In a two-part construction with a deflector that is removable and thus individually replaceable, the thickness of the base plate of the lining can be increased, which makes it possible to increase its useful part for resisting wear and thus extend the overall service life. This also makes it possible to reduce a small part of the lining weight loss when the lining reaches the end of its service life. In this case, the deflector can be replaced one or more times before the base plate is worn out.

[0047] The lining according to the invention also offers two additional major advantages:

[0048] · Using the base plate and one type of lifter, there are possibly more than eight different lining configurations, which makes it possible to cover almost all the lifting variants required for the good crushing of most of the products currently processed in ball mills used for cement production (see the table above).

[0049] Example

[0050] The product crushing ranges from fine and soft (e.g., crushed limestone <4 mm, configuration 15° / 314 / parallel / 750) to the coarsest and hardest (e.g., molten clinker >100 mm, configuration 15 / 628 / opposite / 500), with an average lifting of Portland clinker (<40 mm, configuration 15° / 628 / parallel / 500). By increasing the angle α of the deflector, for example, increasing it to 21.8°, as long as the space between the rings is increased, or by reducing the pitch of the deflector, equivalent lifting can be achieved.

[0051] Conversely, if the angle α of the deflector is reduced, equivalent lifting is achieved by reducing the space between the rings or increasing the pitch of the deflector.

[0052] The examples given relate to cement production materials, but of course can be extrapolated to other materials, especially in the mining industry, such as iron ore, gold ore, lead ore or zinc ore, etc.). This flexibility makes it possible to significantly reduce the costs associated with the manufacture and management of lining models and standardize the lining plates for customers using different ball mills.

[0053] ·According to the present invention, arranging the deflector in a continuous ring on the lining has the effect of preferentially retaining the largest and heaviest particles, which are found mainly at the periphery of the load. Thus, these large particles will remain in the first chamber of the mill for a longer time and will be more likely to be properly broken before moving to the outlet of the mill.

Claims

1. A lifting lining intended to form part of a covering of the inner wall of the housing of a rotary mill, the housing of the rotary mill containing a load of grinding tools, the lifting lining comprising a cylindrical outer surface matching the inner surface of the housing and rows with deflector elements and rows without deflector elements, the deflector elements having a projecting radial profile directed inwards perpendicular to the inner surface of the housing, characterized in that, The deflector element forms a continuous loop in a zigzag shape at an angle α, where the angle α of the deflector element with respect to a plane perpendicular to the generatrix of the mill is > 0°.

2. The lifting lining according to claim 1, wherein, The angle α ranges between 5° and 25°.

3. The lifting lining according to any one of claims 1 and 2, wherein, The lifting lining having the deflector element has two parts, namely a base and a deflector removably attached to its base.

4. The lifting lining according to any one of claims 1 and 2, wherein The height of the deflector is between 0.5 times and 4 times the diameter of the grinding tool.

5. The lifting lining according to any one of claims 1 and 2, wherein, The distance between the continuous loops in a zigzag shape is constant due to the parallel arrangement of the continuous loops relative to each other.

6. The lifting lining according to any one of claims 1 and 2, wherein, The distance between the continuous loops in a zigzag shape is variable.

7. The lifting lining according to any one of claims 1 and 2, wherein The height of the deflector is between 1 time and 2 times its width.

8. The lifting lining according to claim 1, wherein, The angle α ranges between 10° and 25°.

9. The lifting lining according to claim 1, wherein The angle α ranges between 10° and 21.8°.

10. The lifting lining according to any one of claims 1 and 2, wherein, The height of the deflector is between 1 time and 2 times the diameter of the grinding tool.

11. The lift lining according to claim 6, wherein, The continuous loops in a zigzag shape are in opposite positions to each other.

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