Decline in ball mill output, 80% is due to “full grinding”2021-09-01 09:29 Author:Lynn
If the output of the beneficiation ball mill suddenly drops, 80% is due to “full grinding”. Today we will talk about this old topic.
“Full grinding” is a common abnormal phenomenon during the operation of ball mills. The direct cause is the imbalance of material input and output. The amount of abrasive is too large in a short time.
Reasons for the phenomenon of “full grinding”
1. Too much feed, the grinding capacity of the grinding body cannot be adapted.
2. The granularity and hardness of the material entering the mill have become larger, and the feed is not reduced in time, and a large amount of unbroken material is caught in the gap of the compartment plate, causing blockage and making the material unable to be discharged in time.
3. The water content of the material entering the mill is too large (above 2.0%), and the ventilation is poor, and the water vapor and fine material generated during the grinding process cannot be taken out of the ball mill in time, causing the material to adhere to the lining of the steel ball due to high humidity. The surface of the plate reduces the grinding efficiency, and at the same time, due to the increase of wet material, the flow rate is slowed down, causing difficulty in discharging. The phenomenon of “satisfaction” caused by this reason is more common.
4. Unreasonable grading of steel balls, too many small balls, too small average ball diameter, or too low filling rate, resulting in reduced grinding effect.
5. The partition board or the grate gap is blocked by debris, and the grate hole becomes smaller, causing “saturation”.
6. In the closed circuit system, the powder selection efficiency of the powder separator is greatly reduced, the amount of returned material is too much, and the amount of feed has not been reduced, and the grinding capacity of the mill cannot be adapted, causing blockage.
7. One or two of the compartment plates are partially broken off or perforated, causing the grinding body to move into the warehouse, and the grinding capacity is greatly reduced.
“Full grinding” treatment method
1. Reduce the amount of feed. If the effect is not obvious, you need to stop the feed immediately and make the ball mill run with little or no material to generate more heat and evaporate the water, thereby reducing sticky balls and compartment plates Blockage phenomenon.
2. Add grinding aid materials (raw mill with dry coal or quicklime, cement mill with dry slag or dry slag) when the feeding is stopped, and feed a small amount of materials after the grinding sound is close to normal. Then gradually increase the feeding amount until normal feeding.
3. Increase the ventilation of the ball mill to discharge the fine materials as soon as possible. At the same time, observe whether the current of the main motor increases. If the current increases, it means that the phenomenon of full grinding has been eliminated. At this time, the feeding amount can be gradually increased.
4. If the above method is invalid, stop the machine, open the grinding door and check the compartment plate and grate plate to see if it is blocked.
Note: When the ball mill is fully grinding, stopping the grinding can only be used as a last resort, because the load of the ball mill becomes heavier when it is full, and once it stops during the full grinding, it may cause the ball mill to fail to start.
5. When the full grinding is very serious, sometimes it is necessary to stop and reverse the grinding method. The specific methods are as follows:
Pour out the balls and materials in the bin, thoroughly chisel off the crust on the liner and steel balls, remove the blockages in the grate seam of the partition board, and then re-match the balls or load the poured balls.
How to judge whether it is “full grinding”
1. When the degree is light, the grinding sound changes from clear to low, the output of the grinding tail is reduced, and the inlet and outlet air pressure of the intermediate unloading drying mill increases;
2. When the degree increases, the grinding sound disappears, the main motor current drops to about 70% of the normal value, and the output of the grinding tail is greatly reduced;
3. When the degree is extremely severe, the grinding head will return material, the grinding tail will not discharge, and there will be no air at the outlet of the pump.
Therefore, if your ball mill has the above three conditions, you must pay attention to it, and it may be full.
When the output of your beneficiation ball mill suddenly drops, judge whether your ball mill is “saturated” based on the above three manifestations. When the phenomenon of “full grinding” first appears, users may feel that the impact is not significant and ignore it. However, as the production continues, parts will be damaged and output will be reduced. When the phenomenon is serious, it will be more troublesome to deal with, so the operator is in production. China must pay more attention and deal with problems in a timely manner.