2022-06-02 16:26:37

The inner surface of the ball mill cylinder is generally equipped with lining plates of various shapes. The lining plate is the main wearing part of the ball mill, and its use cost is about 2%-3% of the product price. The performance and service life of the lining plates are the issues that users are very concerned about. The choice of the lining plate will directly affect the performance of the ball mill.

In the following part, we introduce the function, classification and installation requirements of lining plates in ball mill.

Functions of lining plates

There are two kinds of materials for making linings: metal materials (manganese steel, chrome steel, etc.) and rubber. At present, metal material lining plates are used more in China, and rubber lining plates are also widely used in mines. The lining plate mainly has the following functions:

Protect the cylinder and enhance the rigidity of the cylinder

The cylinder is an important part of the ball mill, and the price is relatively expensive. After the lining plates are installed in the cylinder, the cylinder will not directly withstand the impact and grinding of the grinding media and the material to be ground, thus protecting the cylinder and prolonging the service life of the cylinder and the equipment. The lining plate and the cylinder body are closely combined, and also play a role in enhancing the rigidity of the cylinder body.

Transfer energy

During the rotation of the cylinder, with the help of the special shape and frictional force of the surface of the lining plate, the grinding balls are lifted to a certain height, giving them a certain potential energy and throwing kinetic energy, so that they can produce a "circular arc- parabolic" motion trajectory that meets the requirements of the grinding process and then impacts and grinds materials.

Grade the grinding balls automatically

Automatic grading lining plate such as angle spiral lining plate, conical grading lining plate, etc., can make the grinding body (grinding balls) of different gradations in the cylinder, along the axial direction of the ball mill, according to the change of grinding particle size reasonable forward grading, so that the grinding body (grinding balls) of different diameters in the process of grinding the corresponding particle size material, play the maximum function. In other words, the automatic grading lining plate can make the larger steel balls in the same milling bin gather at the feeding end of the bin to crush the larger size material, and at the same time make the smaller steel balls gather at the discharging end of the bin to crush the smaller size material.

Classification of lining plates

The shape of the ball mill lining plate can be divided into 9 shapes according to different requirements, namely wedge shape, wave shape, plano-convex shape, flat shape, stepped shape, long shape, rudder shape, K-shaped rubber lining and B-shaped rubber lining board (as shown in the figure below).

1. The flat lining plate is used for the fine grinding chamber, and the rising height of the grinding balls depends on the static friction coefficient with the lining plate.

2. The bead lining plate is used in the first grinding chamber, which can make the grinding balls rise higher and have greater impact energy.

3. The convex lining plate is similar to the bead lining plate.

4. The wave-shape lining plate is suitable mill rod mill.

5. The stepped shape lining plate is suitable for the grinding bin and is widely used. It has the following three advantages:

a) The lifting height of the same layer of grinding balls is uniform and consistent.

b) Uniform wear on the surface of the plate.

c) The restraining ability of the lining plate acts on the grinding bodies of other layers, which reduces the sliding wear between the lining plate and the outermost grinding body, and also prevents the sliding and wear between the grinding bodies of different layers.

6. Hemispherical lining plate is suitable for crushing bin.

7. The wave shape lining plate is suitable for the boltless lining board laid in the fine grinding bin, and its crest and tightness are very small.

8. The grading lining plate can automatically grade the steel balls.

The shape of the cylinder lining plate has a great influence on the work of ball mill. When dealing with coarse-grained materials, undulating (such as corrugated, convex, overlapping and stepped) lining plates should be installed on the cylinder of the ball mill. This kind of lining plate can lift the grinding medium to a higher height, thereby enhancing the impact ability of the medium and improving the production capacity of ball mill.

Fine grinding (often refers to the second stage grinding) is mainly based on grinding and peeling. The smooth-shaped lining plate is easy to roll the steel balls and the grinding and peeling effect is strong, so the smooth-shaped lining plate is mostly used for the cylinder of the fine grinding ball mill.

Installation requirements of lining plate

1. The space between the lining plate at the rear end of the liner installation and the end cover of the cylinder should be filled with cement mortar with a compressive strength grade of 43.5MPa.

2. The bolts of the fixed end lining plate shall not be filled with cement mortar, and shall be able to rotate or enter and exit.

3. The lining plate is generally directional, and care must be taken when installing it, so as not to reverse it.

4. The arc length of all circumferential gaps should not exceed 310mm, and the areas exceeding them should be wedged with steel plates to cut them off.

5. The gap between adjacent lining plates is not more than 3~9mm.

6. A partition should be laid between the lining plate and the inner surface of the cylinder body according to the design requirements. If there is no requirement, cement mortar with compressive strength of 42.5MPa can be filled between the two, and the excess part can be squeezed out through the bolts of the solid lining plate, and the bolts of the lining plate shall be tightened again after cement mortar is solidified.

7. When installing the lining plate with rubber pad, open the rolled rubber plate 3 to 4 weeks before installation to allow it to stretch freely; when using the rubber plate, the long side of the rubber plate should follow the cylinder body. Axial, the short side follows the circumference of the cylinder body.

8. Carefully check the geometric shape of the lining plate bolt holes and the lining plate bolts and carefully clean the lining plate bolt holes and flashes, burrs, and protrusions on the lining plate bolts, so that the bolts can freely penetrate to the required position.

9. The complete set of lining bolts should be composed of dazzling bolts, dust-proof washers, flat washers, spring washers and nuts; in order to prevent dust leakage, do not forget to use dust-proof washers during use.

10. When tightening the lining plate bolts, a torque wrench should be used. Lining plate bolts of different specifications should be tightened according to the corresponding tightening torque requirements.

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