WO2015156423A1

WO2015156423A1 - Liner for grinding mill

Info

Publication number: WO2015156423A1
Application number: PCT/KP2014/000032
Authority: WO
Inventors: Hyong Chol Kim; Chang Gil Rl
Original assignee: Hyong Chol Kim; Chang Gil Rl
Priority date: 2014-04-07
Filing date: 2014-04-28
Publication date: 2015-10-15

Abstract

A new type of liner for grinding mills consists of liner for cylindrical drum shell (1) with no fastening elements like bolt and liner for conical shell with small number of fastening devices. The liner can provide greater wear lifecycle for the grinding mills to be newly manufactured or present.

Description

UNER FOR GRINDING MILL

The present invention relates to an effective tool for grinding of ore minerals, rocks and other materials. Particularly, this invention relates to a liner to be used in the mill for grinding in course of mineral processing operations.

Background of the invention

Grinding mills are one form of apparatus used for processing materials as described above. Typical grinding mills are generally composed of a cylindrical drum shaped shell mounted for rotation about its central axis. The rotating drum continuously throws the rocks and the balls in a cataracting motion causing breakage of the bigger rocks primarily by impact. Solid material is fed into the drum, sometimes along with steel balls which are used for aiding the grinding process (e.g., SAG mills). In some processing operations, grinding rods are used instead of steel balls, but the grinding rods are added into the mill separately from the feed. As the drum rotates, the solid material id lifted up along the inside wall of the drum until the material reaches a point where gravity causes the solid material to fall downwardly to the lowest point of the drum. By this operation, the solid material, along with steel balls or rods when used, produce a crushing and grinding of the material.

The grinding mill drum or shell is lined with various elements that protect the inner wall of the shell and which are especially designed and positioned within the drum to provide optimal crushing or grinding of the solids. The particular liner elements employed in a grinding mill are specially determined by and selected in light of the type of solids being processed and the type of crushing or size of crushed material that is desired, as well as other factors such as the size of the mill and the size of the particular material being fed into the mill.

The significant impact forces generated during the operation of the grinding mills, due to continuous collision between the steel balls, ore and the inner shell liners of the rotating drum while comminuting the ore to finer particles also causing degradation of the grinding media and the liner of the drum. In view of the wear life cycle of the liner system being used, more the wear life cycle of the liners, better is the availability of the machine, which is desired. In order to ininimize the rate of wear and to prolong the life of the liners, various types of liners have been used. Normally, complete cast alloy steel liners, low metal & high rubber blended polymet liner system and only rubber liners are used in the AG / SAG Mills. Magnetic liner materials are also known to be used to retain in place the chips or flakes of the liners generated due to severe impact & abrasion on them in course of the grinding process. However, the above various liner materials have their individual limitations and do not provide very satisfactory results so far as the desired life of liner is concerned against aggressive operating conditions.

As is well-known in the art of grinding mills, the elements of the mill liner eventually crack and/or wear away over time due to the continuous impact of solids against the elements, and replacement of the elements is required. This necessitates that the mill be stopped for a period of time, which causes the cessation of the grinding of material, and may also necessitates the shutting down of other machinery in a plant that operates to further process the material produced by the mill.

In conventional grinding mill configurations that employ steel mill liner components, the process required for replacing broken steel elements is costly, not only because of the operating downtime necessary to replace the broken elements, but also because of the cost of the liner elements.

Most of existing mills have a lot of holes for fastening liner elements on the shells by bolts, which weaken rigidity of the shells. Increase of the thickness of the shell for compensation of rigidity requests increase of weight, that is, increase of driving system and electricity consumption. Many holes can also cause environmental pollution due to leakage during operation of the mills.

So, there has been a constant need of an improved liner for the inner shell of grinding mills which can overcome the above mentioned shortcomings.

Objects of the invention

Therefore, it is an object of the present invention to provide a liner, which can provide greater wear lifecycle for the grinding mills to be newly manufactured or present. It is another object of the invention to provide a new structure of liner for the grinding mills which makes it possible to reduce manufacture cost of the grinding mills markedly and give driving device the relief and reduce electricity consumption

It is another object of the invention to provide a liner for the grinding mills which can be introduced into all kinds of existing grinding mills

It is a further object of the invention to provide a liner for the grinding mills which makes it possible to minimize the additional facility requirement & down time and labor for the instaUation/dismantling, and maximize the utilization rate of equipment compared with the previous liners.

It is still another object to provide a liner for the grinding mills which makes it possible to reduce environmental pollution due to pulp leakage markedly.

The above objects of the invention will be apparent from the description of the exemplary embodiments of the invention described hereinafter. Of course, the present invention is not limited to such embodiments or to the drawings with the help of which the embodiments are described, purely for explaining the invention, by way of example.

Summary of the Invention

The present invention provides a liner system consisting of liner for cylindrical shell with no fastening devices and liner for conical shell with a small number of fastening devices to achieve the above purposes.

The liner elements for cylindrical shell are not separated from the shell due to the gravity or another external action during stop or operation of the mill because liner elements of which cross sections are sectoral, constitute a circumference in dense contact with each other. Therefore, there is no use of fastening element like bolt for shell liner.

There are holes uniformly-arranged on contact surface with ore and there is empty space except border on contact surface with the cylindrical shell.

Liner for the conic shell consists of liner elements for the conic shell with no fastening components and with relatively severe abrasion rate, and fastening covers with small number of fastening components and with little abrasion rate. The sectoral liner elements for the conic shell have holes arranged uniformly on their contact surfaces with ore and have certain depth of uniform space except border on their contact surfaces with the conic shell, and the parts become thicker gradually toward the cylindrical shell.

Since there is no hole on the cylindrical shell and there are a few holes on the conical shell, in case of manufacturing a new mill, it is possible to reduce the thicknesses of both the cylindrical shell and the conical shell in view of rigidity increase, which makes it possible to reduce total weight and moment of inertia of mill, resulting in reducing electric energy consumption and increasing lifetime of driving device.

Because of small number of bolt holes, there is little environmental pollution due to leakage and assembling and disassembling is simple and the time for it is short.

Brief Description of Drawings

Figure 1 depicts an exemplary mill equipped with liner of the present invention. Figure 2 depicts an exemplary liner for cylindrical shell according to the present invention.

Figure 3 depicts an exemplary liner element for cylindrical shell according to the present invention.

Figure 4 depicts an exemplary liner for conical shell according to the present invention.

Figure 5 depicts an exemplary liner element for conical shell according to the present invention.

Figure 6 depicts an exemplary fastening cover for conical shell according to the present invention.

Detailed description of the Invention

Figure 1 depicts the inside of mill with liner elements according to the present invention.

According to Figure 2, the whole inside surface (2) of the cylindrical shell (1) is covered with one kind of liner elements.

Figure 3 depicts the liner element for cylindrical shell. In case that the same fan-shaped liner elements consist of circumstance in dense contact with each other, they can be fastened on inside face of the shell without fasteners like bolt & nut.

This is possible based on mechanical phenomenon that fan-shaped liner parts are not separated from the shell by reaction toward the shell in case the gravity or other external action toward center is exerted on them during stop or operation of the mill if they form a circle in dense contact by contact surfaces (8) since the length of outside arc of liner part is longer than the one of the inside arc of it.

The bigger the difference between the length of outside arc (3) and the length of inside arc (4) is, the bigger the effect is.

La: length of outside arc

L_: length of inside arc

Ra: radius of outside arc

Ri: radius of inside arc

φ : central angle of arc

Namely, the bigger the difference between the radius of outside arc and the radius of inside arc (Ra -Ri) is and the bigger the central angle of arc , that is, the more the number of parts forming a circle, the bigger this effect gets.

However, there is limitation to the difference between the radius of outside arc and the radius of inside arc (Ra -Ri) and there is also to limitation to reducing the number of parts forming the circle.

According to the invention, considering enough reaction effect on the gravity or other external actions and effective handling, the number of parts forming the circle can be 3~2θ, that is, the arc central angle of the part can be 2π/3 ~ π/10 depending on the size of mills, preferably the number of parts can be 4~i6, that is, central angle can be π/2 ~ π/8.

In this case, liner parts for cylindrical shell can be fastened to the shell without the help of fastening devices like bolts & nuts.

Thus, there are not holes for fastening liner elements to the shell and this can increase the rigidity of the shell and decreases the thickness and the weight of the shell. In the view of the moment of inertia, this means the decrease of the moment of inertia by mass as much as weight decreases in the same size of mills.

As figure 3 indicates, there are not any holes for fastening on liner element for cylindrical shell and there are 6-12 holes (7) uniformly-arranged on their contact surface with the feed accounting for 30-40% of whole contact surface with ore. In case that there are rise and fall by balls or feed brashes which are filled up in this space and get dense each other during operation, total real contact surface with ore gets bigger than the case there are not holes, so that milling effect increases.

Since liner elements for cylindrical shell are fastened by themselves but not by bolts & nuts, to decrease final remaining weight of elements on dismantling after lifetime, liner elements have a certain depth of uniform empty space (6) except border (5) on its contact surface with cylindrical shell and its depth is io-3omm.

As result, holes (7) and space (6) except border (5) toward the shell make it possible to manufacture thicker liner part with same weight of material, thereby increasing wear lifetime cycle of liner part by about 1.5 times.

According to the invention, liner system for conical shell consists of two kinds of liner parts, that is, a liner part for conical shell and a fastening cover.

Figure 5 and figure 6 depict liner part for conical shell and fastening cover.

The liner element for the conical shell have a certain depth of uniform empty space

(15) except border (14) on its contact surface with the conical shell and the contact surface (13) is fastened by the contact surface (17) of fastening cover, and contact surface (16) is fastened by liner for the cylindrical shell.

Fastening cover is fastened by 2 bolts through holes (12).

Liner element for the conical shell has different velocities and wear rates on different positions of radius direction. That is, wear becomes big toward the shell and there is little wear toward the center:

According to the present invention, there are liner elements with no fastening bolt on the shell side which has severe wear and there are fastening covers fastened by 2 bolts per cover on the center side which has little wear.

Fan-shaped liner element for the conical shell is fastened by liner for the cylindrical shell and the conical shell on one side, and by fastening cover on the other side, therefore there is no need of holes for fastening devices. Considering the increase of wear rate toward the cylindrical shell, liner part for the conical shell gets thicker toward the cylindrical shell.

As in the liner elements for the cylindrical shell, liner elements for the conical shell come into contact with the shell by border and have 10-30 mm depth of uniform space on the shell side.

liner elements for the conical shell have certain depth of space except two edges shaded by liner elements for the cylindrical shell.

Therefore, the moment of inertia becomes small since the distribution of mass gets different in case that the same weight of liner parts are manufactured considering the above condition.

Considering the space on the conical shell side and the space on cylindrical shell side, it is possible to increase the wear lifetime cycle by manufacturing thicker liner element with the same weight of liner material.

Since there are no holes on the cylindrical shell and there are little holes on the conical shell compared with the previous shell, resultant increase of rigidity makes it possible to reduce the thickness and the weight of the shell, that is, manufacturing cost and the moment of inertia of the shell.

The number of liner elements for the conical shell is 16-32 and the number of fastening covers is 2-4. Each fastening cover is fastened by 2 bolts.

It is to be understood that the inventive concept has been described with the help of non-limiting exemplary embodiments. The scope of the invention is to be construed, as defined in the appended claims. Various alterations, modifications and improvements may be made without departing from the scope and spirit of the invention.

Claims

1. Liner system consisting of liner for the cylindrical shell with no fastening devices and liner for the conical shell with small number of fastening elements.

2. Liner system claimed in claim l, wherein liner for the cylindrical shell consists of liner elements with sectoral cross section which form circle in dense contact each other so that they may not be separated from the shell by the gravity or another external action with no fastening elements.

3. Liner element claimed in claim 2, wherein the number of parts consisting of circumstance is 3-20, preferably 4-16.

4. Liner element claimed in claim 2, which has 6-12 holes uniformly arranged on its contact surface with ore and the total surface of the holes accounts for 30-40% of the contact surface with ore.

5. Liner element claimed in claim 2, which has a certain depth of uniform empty space except the border on its contact surface with the cylindrical shell and its depth is io-3omm.

6. Liner system claimed in claim 1, wherein liner for the conical shell consists of liner elements for the conical shell with no fastening devices and fastening covers with small number of fastening devices.

7. Liner element for conical shell claimed in claim 6, of which contact surface with ore is sectoral, and which is fastened by liner for the cylindrical shell and cylindrical shell on one side and, by fastening cover on the other side.

8. The number of liner elements for the conical shell claimed in claim 6 is 16-32.

9. The number of fastening covers for the conical shell claimed in claim 6 is 2-4 and each cover is fastened by 2 bolts.

10. Liner element claimed in claim 6, which has 10-30 mm depth of uniform empty space except the border on its contact surface with conical shell.

11. Liner element claimed in claim 6, which has uniform space shaded by liner for the cylindrical shell except two edges on contact part with liner for the cylindrical shell and cylindrical shell.

12. Liner element for the conical shell claimed in claim 6, which gets thicker toward cylindrical shell.