Five reasons that may cause low grinding efficiency of ball mill
The grinding efficiency of ball mill is affected by many factors, including: the movement of steel balls in the barrel, the rotation rate, the addition and size of steel balls, the material level, and the use of grinding aids. These factors have an impact on the efficiency of ball mill to a certain extent.
1. Movement pattern of steel balls in the barrel
To be precise, to a certain extent, the movement pattern of the grinding media in the barrel affects the grinding efficiency of the ball mill.
The working environment of the ball mill is divided into the following categories:
(1) In the surrounding and falling motion areas, the filling amount in the barrel is small or even non-existent, so that the material can make uniform circular motion or falling motion in the barrel, and the probability of collision between steel balls increases, causing wear between the steel balls and the liner, further reducing the efficiency of the ball mill;
(2) In the falling motion area, the filling amount is appropriate. At this time, the steel balls have an impact on the material, making the ball mill efficiency relatively high;
(3) In the area around the center of the ball mill, the steel balls have a circular motion or a mixture of falling motion and falling motion, which limits the range of motion of the steel balls and reduces wear and impact;
(4) In the blank area, the steel balls do not move. If the filling amount is too large, the range of motion of the steel balls is small or does not move, which will cause waste of resources and easily cause the ball mill to malfunction.
2. Rotation rate
An important working parameter of the ball mill is the rotation rate, which directly affects the grinding efficiency of the ball mill. When considering the rotation rate, the filling rate should also be considered. The filling rate is positively correlated with the rotation rate. When discussing the rotation rate here, keep the filling rate constant. No matter what the motion state of the ball load is, there will be an optimal rotation rate at a certain filling rate.
When the filling rate is constant and the rotation rate is low, the energy obtained by the steel ball is low, and the impact energy on the material is low. It may be lower than the threshold of the ore particle crushing, resulting in ineffective impact on the ore particles, that is, the ore particles will not be crushed, so the grinding efficiency at low speed is low.
3. Addition and size of steel balls
If the amount of steel balls added is inappropriate, the ball diameter and ratio are unreasonable, then the grinding efficiency will be reduced. The ball mill is subject to greater wear during operation, and a large part of the reason is that the manual addition of steel balls is not well controlled, resulting in the accumulation of steel balls and the phenomenon of ball jamming, which in turn causes certain wear on the machine.
4. Material level
The material level affects the filling rate, which in turn affects the grinding effect of the ball mill. If the material level is too high, it will cause coal blockage in the ball mill. Therefore, effective monitoring of the material level is very important. At the same time, the energy consumption of the ball mill is also related to the material level. For the intermediate storage type powder making system, the power consumption of the ball mill accounts for about 70% of the power consumption of the powder making system and about 15% of the power consumption of the plant. There are many factors that affect the intermediate storage type powder making system, but under the influence of many factors, effective inspection of the material level is very necessary.
5. Liner selection
The liner of the ball mill can not only reduce the damage to the cylinder, but also transfer energy to the grinding medium. One of the factors affecting the grinding efficiency of the ball mill is determined by the working surface of the liner. In practice, it is known that in order to reduce the damage to the cylinder and improve the grinding efficiency, it is necessary to reduce the sliding between the grinding medium and the liner. Therefore, the main method is to change the shape of the working surface of the liner and increase the friction coefficient between the liner and the grinding medium. High manganese steel liners were used before, and now there are rubber liners, magnetic liners, angle spiral liners, etc. These modified liners are not only higher in performance than high manganese steel liners, but also can effectively extend the service life of the ball mill.
Targeted improvements in the movement of the ball mill‘s steel balls, rotation speed, addition and size of the steel balls, material level, and liner material can effectively improve grinding efficiency.