As an important part of the ball mill, the lining plate can not only effectively protect the barrel of the ball mill and effectively increase the load, but also enhance the impact and grinding between the medium and the material, thereby improving the grinding efficiency. However, in the production process, the long-term action makes the lining plate very prone to wear, deformation, fracture, etc., which reduces the grinding efficiency, and even needs to be stopped and replaced in severe cases. So, what are the reasons for the rapid wear of the ball mill liner? How should we extend the service life of the ball mill liner?
I. Mutual wear between ball mill liner and steel balls
The ball mill liner and steel balls are both wearing parts. During the grinding process, the ball mill steel balls and materials do a parabolic falling movement in the cylinder. At this time, the ball mill liner, the steel ball and the material will collide with each other to produce friction.
In continuous operation, the lining plate and steel ball of the ball mill will be seriously worn, which is directly related to the hardness of the material. The greater the hardness of the material, the faster the wear rate of the ball mill liner and steel balls, which may cause equipment damage or even safety accidents in severe cases. In addition, the wear of the ball mill liner is also related to the steel balls. The size and quantity of the steel balls will affect the service life of the ball mill liner. During the operation of the ball mill, if the amount of steel balls or steel balls with larger diameters is increased, the wear of the lining plate of the ball mill will be aggravated.
Solution: Reasonable selection of ball mill liner and steel balls is one of the main ways to reduce the wear rate of the liner.
- Relevant staff need to know the ratio of the ball mill liner to the steel ball, and select the corresponding steel ball size and quantity according to the ratio. Under normal circumstances, the hardness ratio of the liner of the conventional ball mill to the steel ball is about 1:0.8.
- Control the ratio of materials and steel balls, and it is appropriate that the material is twice that of the steel balls.
- When choosing a ball mill, it is necessary to select the appropriate ball mill liner according to the type of minerals, control the hardness of the ball mill liner and the steel ball, and make a reasonable match between the steel ball and the liner.
II. Unreasonable material of ball mill liner
The material of the ball mill liner and its heat treatment process are the keys to determine the mechanical properties of the ball mill liner. If the material of the lining plate is improperly selected, its fatigue strength and life will be greatly reduced, and it will not only fail to meet the working requirements of the ball mill, but even plastic deformation or bulging will occur.
Solution: Choose a new type of wear-resistant lining material. At present, the commonly used ball mill lining materials are high manganese steel, high chromium steel, alloy steel and wear-resistant rubber. Among them, wear-resistant rubber is a newly emerging lining material in the past decade. The composite liner composed of wear-resistant rubber and alloy steel not only improves the toughness of the liner, but also solves the contradiction between its toughness and stiffness.
III. Unreasonable heat treatment process for ball mill liner
The unreasonable heat treatment of the lining plate of the ball mill will not only increase the wear of the lining plate, but also affect the yield strength of the lining plate, resulting in the fracture of the fixing bolts of the lining plate of the ball mill under the action of large shearing force. In actual operation, if the staff lacks understanding of the material of the lining plate, the heat treatment of the lining plate of the ball mill is unreasonable. It is easy to cause the strengthening effect of the ball mill liner is not in place, and deformation often occurs when it is hit by the steel ball and the material.
Solution: Preheating the ball mill liner can effectively reduce the wear degree of the ball mill liner, and a suitable preheating process can be selected according to the liner material.
IV. Pulp concentration
Most of the grinding pulp of the wet ball mill is neutral or weakly acidic, and the liner of the ball mill is easily impacted and corroded by the pulp after being immersed in the pulp for a long time. In addition, the pulp concentration is also related to the fluidity and adhesion of the pulp. When the pulp concentration decreases, the fluidity is strong, and the impact on the lining plate is strong, which is easy to damage the lining plate.
Solution: Generally speaking, ore with high hardness and coarse particle size will have a slightly higher slurry concentration. In actual production, generally, the first stage of grinding pulp should be controlled between 72 and 82%, at this time, the grinding efficiency and the service life of the lining plate can be guaranteed. According to the difference of production conditions, this reasonable range will also be adjusted appropriately, which needs to be determined according to the test.
V. The operation of the ball mill is abnormal
When the ball mill is in an abnormal operating state, it will also bring adverse effects to the ball mill liner. When the ball mill is in normal operation, the steel balls and the material are mixed together, and when the steel balls are thrown to the lining plate, they form a barrier with the material, which plays a buffering role and gradually grinds the material. If the ball mill is running at low load, the steel balls will directly impact the liner, causing serious wear and even breakage of the ball mill liner.
Solution: Relevant staff need to adjust in time according to the running state of the ball mill. When the ball mill is running under a low load state, it is necessary to adjust the ore input of the ball mill in time to ensure the grindability of the material.
The working environment of the ball mill liner is complex. In order to improve the use efficiency of the ball mill liner, it is necessary to analyze the cause of the wear of the liner in order to formulate a reasonable solution. It is recommended to comprehensively consider the production environment, process conditions, investment costs and other factors when purchasing a ball mill, and choose a professional and qualified manufacturer to extend the service life of the equipment and avoid economic losses.