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Function and Wear Analysis of Ball Mill liner, how to reduce

Date:2019-07-10 17:16     writer:cement editor     Views:

Ball mill is an important equipment for the preparation of various powder materials in metallurgy, mineral processing, building materials, chemical industry, power generation, ceramics and other industrial departments. The inner surface of the ball mill cylinder is generally equipped with various shapes of liner. Liner is the main vulnerable part of ball mill, and its use cost is about 2% ≤ 3% of the product price. The performance and service life of liner are of great concern to users. Today, we will take a look at the factors that affect the service life of liner and how to reduce wear and prolong its service life.

Function of liner

 

1. Protect the stiffness of the cylinder and the stiffness of the reinforced cylinder


The cylinder is an important part of the ball mill, and the price is more expensive. After the liner is installed in the cylinder, the cylinder will not directly bear the impact and grinding of the grinding medium and the ground material, thus protecting the cylinder and prolonging the service life of the cylinder and the whole equipment. The liner and the cylinder are closely combined, and also play the role of strengthening the stiffness of the cylinder.

Different shapes of liner

 

2. Transfer energy


In the process of cylinder rotation, with the help of the special shape and friction force of the liner surface, the sphere is raised to a certain height, and the sphere is given a certain potential energy and drop kinetic energy, so that they can produce a "circular arc parabola" trajectory that meets the requirements of grinding process, impact and grind the material.

3, automatic grading sphere


Automatic grading liner, such as angular spiral liner, conical graded liner, etc., can make the grinding bodies of different grades in the cylinder be classified rationally along the axial direction of the mill according to the change of grinding particle size, so that the grinding bodies of different diameters can play the greatest role in the process of crushing the corresponding particle size materials. In other words, the automatic grading liner can make the larger steel ball in the same grinding bin be assembled at the feed end of the silo in order to crush the larger material block, and at the same time, the smaller steel ball can be assembled at the discharge end of the bin in order to crush the smaller material block.

Cause Analysis of liner Wear

 

1. Wear and tear between liner and steel ball


The working principle of the ball mill is to use the cylinder to rotate, and according to the actual needs of the operation, the steel ball is raised to a certain height and then dropped by parabola to impact the material in the cylinder, so that the material and the liner can be fully rubbed. Therefore, under continuous work, the steel ball and liner will appear serious wear phenomenon, which is directly related to the hardness of the material.

2. The material and heat treatment process of the liner is unreasonable.


The material and heat treatment process of the liner directly determine the mechanical properties of the liner, which will have an important impact on the wear of the liner. If the material of liner is not selected improperly and the heat treatment process is unreasonable, the anti-fatigue strength and service life of liner will be greatly reduced, which will not meet the requirements of grinding operation of ball mill, and even the problem of plastic change drum will occur.

Heat treatment of liner is an important way to reduce the wear of liner of ball mill, so the appropriate heat treatment process should be selected according to the material of liner. However, in the actual work, the relevant staff lack of understanding of the material of the liner, so in the work of heat treatment, the processing of the liner is insufficient, not only does not play a strengthening role, but makes the strength of the liner lower, when hit by the steel ball and material, there will be plastic deformation. The unreasonable heat treatment process will also affect the yield strength of the liner and make the bolt of the ball mill break under the action of great shear force.

3. Impact of ball mill operation.


Once the ball mill is in an abnormal operation state, it will also bring adverse effects to the use of liner. Generally speaking, the steel ball in the ball mill is mixed with the material, so when the steel ball hits the liner in a parabola state, the material will play a certain buffering role and gradually grind the material. When the equipment runs at low load, the steel ball will directly impact the liner, resulting in serious wear and tear of the liner and even fracture.

How to reduce the wear of liner?

 

1. Reasonable selection of steel balls and liners


Reasonable selection of steel ball and liner is an important way to reduce the wear of liner. Therefore, it is necessary to fundamentally reduce the loss of liner during the operation of ball mill by starting with the size and quantity of rigid ball and the hardness ratio between ball mill liner and steel ball. Generally speaking, the hardness ratio of ball mill liner to steel ball should be controlled at about 1 ≤ 0.8; secondly, it is necessary to control the ratio of mineral powder to steel ball in the ball mill. Generally speaking, the mineral powder is about twice as much as the steel ball. Once this proportion is misaligned, it is easy to cause the ball mill to run at low load, which leads to the direct impact of the steel ball on the liner and the fracture of the liner. In addition, attention should be paid to the material and hardness of the liner. Reasonable selection of heat treatment process of liner.

2. The liner adopts new material.


The basic requirements of liner material selection can be summarized as follows: high wear resistance under certain impact load. It includes the following three aspects:

The overall hardness, composition and structure of the liner are uniform.

It has high impact fatigue durability and can resist the impact of a certain strength.

It has a low wear rate, which is not deformed or broken during use.

With the development of technology, the new material liner has also begun to be used in ball mill, such as the composite liner composed of rubber and hard alloy steel, which solves the contradiction between toughness and stiffness of the liner and reduces the impact force of the liner in the course of operation. Compared with the ordinary liner, the heat resistance and strength of the composite liner are greatly improved, especially in the service life, the composite liner is twice as effective as the traditional liner, which greatly improves the economic benefit of the enterprise. In addition, the working noise of the composite liner is small, the weight is light, and it is easy to popularize, but it is lack of practice, but it has a great deal of trouble in dealing with the aging of the liner and the wear of the liner. Show space.

 

3. Control the running state of the ball mill


Controlling the running state of the ball mill is also an important measure to deal with the wear of the liner. When the ball mill is running at low load, it is necessary to adjust the ore intake of the ball mill in time, so as to improve the grindability coefficient of the ball mill. In the installation of liner, it is necessary to dig and repair the parts that do not match, so that the liner can be fully integrated into the working system of ball mill. After the liner is installed, it is necessary to debug repeatedly and record it in detail to ensure that the internal fixed bolt of the ball mill has a certain pretightening force to prevent the bolt from loosening in the operation of the ball mill. In addition, the liner needs to be replaced in a timely manner. Generally speaking, as long as it is properly operated, 1 is required. Replacing the liner once in 2 months, doing a good job of inspection, and actively adjusting the position of the liner according to the actual situation can reduce the loss of the liner to a certain extent.

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