There are many factors that affect the failure of the ball mill liner. Only a few main factors are analyzed below:
The liner does not match the grinding ball
The ball mill liner and the grinding ball are both vulnerable parts of the ball mill. When the ball mill is working, the lining plate is worn by the impact of the falling ball and the material, and it is also subjected to the sliding wear of the grinding ball. The grinding ball is subjected to the wear of the lining plate, the wear of the material and the wear between the grinding balls. The role and influence each other. In practice, we have found that the hardness of the material is related to the wear resistance. The wear resistance increases with the increase in hardness. The liner of the grinding ball is a pair of friction pairs. The increase in the hardness of one side will cause the wear and the memory of the other. Therefore, the correct selection of the wear amount of the liner and the grinding ball also saves the production cost. According to experience, the hardness of the grinding ball should be 2-4HRC higher than that of the liner. Studies have shown that the wear resistance of the system is good when the high hardness lining material is matched with the high hardness grinding ball material; while the low hardness grinding ball material is matched with the low hardness lining material, the system wear resistance is the worst.
The material or quality of the lining material does not meet the requirements
If the liner material is high manganese steel, the hardness after heat treatment is usually low, around HRC15-18. Due to the insufficient work hardening of the high manganese steel liner during operation, the surface hardness is not high, and plastic deformation is easy to occur, so it is not ideal The liner material. Therefore, the physical properties and structure of the hot air materials, and the characteristics of their wear on the materials during the grinding process, are used to select materials with different properties to make the best use of them. In particular, the yield strength of high manganese steel is low, and the influence of temperature during operation (including the temperature of the environment and the temperature rise of the liner during the friction process) further reduces it. Therefore, it is prone to plastic deformation under the impact of grinding balls, materials, and grinding during operation. In the production quality process, several aspects are mainly controlled: using raw materials that meet technical requirements; ferroalloys are directly purchased from the manufacturer and chemical analysis is required before use; in the microalloy modification treatment technology, the element B to improve the hardenability is scientifically used, and the use of The microalloys (including deoxidizers, etc.) must be baked before use; the molten steel must be sufficiently clean to prevent secondary oxidation; the heat treatment process must be correctly formulated and carefully executed to achieve the goal of tapping the potential of the material.
Unreasonable design and installation
In order to improve the service life of the liner, reduce the consumption of materials. Under the conditions that meet the requirements of the grinding process, it is very important to carry out a reasonable structure design. If the bolt hole of the liner of the ball mill is square, it will cause the stress concentration in the place and break easily. Adjust the size of the lining board to control the gap of the lining board at about 8mm; the installation quality of the lining board is very important to the safe operation of the ball mill. First, the fixed wedges should be tightened symmetrically, and then the lining boards should be placed in sequence, and finally tightened with a wedge; In addition, due to various reasons such as time, the gap between the cylinder under the tightening wedge will be too large and the liner will not fit well, causing the liner to be uneven, the cylinder wall is deformed, and the liner does not match the cylinder wall, which may easily cause the liner to break. .
Therefore, we have to reduce these unfavorable factors, reasonably select the matching between the grinding ball and the liner; reasonably select the size of the grinding ball; for the newly replaced ball mill, according to its characteristics, first use a grinding ball with a lower hardness After running for 1 to 2 months, after the hardness and toughness of the liner have been improved to a certain extent, use a grinding ball with a higher hardness, which can increase the service life of the liner; different materials should be selected for different parts. In order to give full play to the material performance; and after the liner is installed and debugged, the bolts of the fixed liner should be re-tightened to ensure that the fixed bolt has a certain pre-tightening force to prevent the bolt from loosening during operation.