Ball mill is one of the commonly used equipment in mineral processing equipment. Rotation speed is one of the main parameters in the design and operation of the ball mill. The rotation speed directly determines the movement state of the grinding medium in the barrel and the effect of grinding operation. Too fast or too slow rotation speed will weaken or lose the crushing effect. Fodamon engineers introduce you to different grinding effects at different speeds.
In order for the ball mill to perform normal grinding operations, its working speed must be less than the critical speed. Ball mills generally work in a “dropped” state. There are many working speeds to achieve this working state, but there must be the most favorable working speed.
In order for the ball mill to perform normal grinding operations, its working speed must be less than the critical speed. Ball mills generally work in a “dropped” state. There are many working speeds to achieve this working state, but there must be the most favorable working speed.
1. If the rotating speed is low, the ball in the ball mill will be lifted to a small height. The ball will slide down from the top of the ball load by the gravity of the ball itself. At this time, the impact force of the ball is very small, but the grinding effect is strong. The ore is mainly peeled and crushed, and the grinding effect is not high.
2. If the speed is higher, the height of the ball is also higher. After the ball rises to a certain height, it leaves the cylinder and falls along the parabolic trajectory. It has a greater impact at the drop point, the ore is mainly crushed by the impact, and the grinding efficiency is higher.
3. If the rotation speed of the ball mill exceeds a certain limit (the rotation speed is very high), the steel ball rotates with the barrel without falling, and is in a centrifugal operation state. At this time, the steel ball has no impact effect, and the grinding effect is very small to stop the grinding effect.
The theoretical suitable speed of the mill is 76% of the critical speed. The actual mills fluctuated around 76%. In the current production, when the rotation speed of the ball mill is less than 76% of the critical rotation speed, it is called low-speed grinding; when the rotation speed is higher than the critical rotation speed of 88%, it is called high-speed grinding; Speed grinding.
Therefore, according to the corresponding production capacity and production requirements of the ball mill, the speed of the ball mill should be determined, which can not only reduce the abrasive cost, but also prolong the service life of the ball mill accordingly.
In the actual production, considering the rotating speed can not only get the maximum grinding power, because the material grinding has both impact crushing and grinding effect. Therefore, from the point of view of achieving the best economic index, it is required that the production capacity of ball mill is the highest, the power consumption per unit output is the smallest, and the wear consumption of grinding body and lining plate is the least. Therefore, the selection of the working speed should not only consider the diameter of the mill, the production mode, the shape of the lining plate, the filling coefficient of the grinding body, the type of the grinding body, but also consider the nature of the grinding material, the particle size of the grinding material and the grinding fineness. In order to fully reflect the influence of these factors, the actual working speed of the ball mill should be determined through scientific experiments.
For large-diameter ball mill, the actual working speed is lower; for wet ball mill, due to the lubrication of water, the friction coefficient between media and between media and lining plate is reduced, resulting in relatively large sliding.
Therefore, under the same conditions, the speed of the wet ball mill should be slightly higher than that of the dry ball mill. The surface of the liner with ribs can reduce the relative sliding amount of the medium and increase its relative lifting height. The actual working speed should be smoother than the Lower liner and so on.