Factors of low grinding efficiency of ball millDate: 2019-07-03 Views:
The ball mill has the advantages of simple structure, stable performance and large crushing ratio (3~100), which can be used for wet or dry grinding.This paper introduces some factors that affect the grinding efficiency of ball mill.
1 movement pattern of steel ball in cylinder
Exactly speaking, to some extent, the motion of the grinding medium in the cylinder affects the grinding efficiency of the ball mill.The working environment of ball mill is divided into the following categories:
(1) in the surrounding and falling motion area, the filling amount in the cylinder is small or even not enough, so that materials can move in the barrel at a uniform speed in circular motion or falling motion. The impact probability of steel balls with steel balls increases, causing wear between steel balls and lining plates, and further reducing the efficiency of the ball mill.
(2) drop the moving area and fill with appropriate amount.At this time, steel ball impact on the material, making the ball mill efficiency is relatively high;
(3) in the area around the center of the ball mill, the circular motion of the steel ball or the mixture of falling motion and throwing motion limits the movement range of the steel ball, resulting in small wear and impact effect;
(4) in the blank area, the steel ball does not move. If the filling amount is too much, the steel ball moves in a small range or does not move, which will cause a waste of resources and easily cause the ball mill to malfunction.
It can be known from (1) that, when the filling amount is little or no, the ball mill suffers great losses, which are mainly caused by the impact of steel balls on materials.Now the general ball mill is horizontal, in order to effectively reduce the loss of the ball mill to no material, it invented the vertical ball mill.Traditional ball mill equipment, ball mill cylinder body is rotating, the mixing barrel type equipment is stationary, rely mainly on steel ball inside the barrel and the material of screw device for disturbance and stirring, sphere and material under the action of vertical mixing device in the device, so the material only in conjunction with the effect between steel ball, until the crushing, so in the fine grinding operation and fine grinding operation is very applicable.
2 turn rate
An important working parameter of the ball mill is the turning rate, which directly affects the grinding efficiency of the ball mill.Filling rate should also be considered when considering the rate of rotation.The filling rate is positively correlated with the rotation rate.While discussing the rotation rate here, keep the filling rate constant.No matter what the ball load is, the optimum rotation rate will be obtained under a certain filling rate.When the filling rate is relatively 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 breaking threshold of ore particles, resulting in invalid impact on ore particles, that is, ore particles will not be broken, so the grinding efficiency of low rotation speed is low.With the increase of rotating speed, the impact energy of steel ball increases when it impacts the material, which increases the crushing rate of coarse ore particles and improves the grinding efficiency of ball mill.If the speed continues to increase, when approaching the critical speed, coarse grain products are not easy to be broken. This is because, although the impact energy of steel balls is increased after the high rotation rate, the cycle times of steel balls drop a lot, the impact times of steel balls decrease per unit time, and the crushing rate of coarse ore particles decreases.
3. Material level is low
The material level affects the filling rate, which will affect the grinding effect of the ball mill.Material level is too high, will cause the ball mill blocking material.Therefore, effective monitoring of material level is very important.At the same time, ball mill energy consumption and material level has an indelible relationship.For the intermediate storage pulverizing system, the power consumption of the ball mill accounts for about 70% of the power consumption of the pulverizing system and about 15% of the power consumption of the factory.There are many factors affecting the intermediate storage system, but under the influence of many factors, it is very necessary to check the material level effectively.
By improving the moving state, turning rate and material level of the ball mill, a targeted transformation can be made to improve the grinding efficiency.