Reasons and solutions for the coarse particle size of the ball mill

Too coarse particle size of the ball mill discharge may be due to many reasons, and the solution to each cause will be different. We need to come up with a corresponding diagnosis and treatment plan.

The main reason for the excessively coarse particle size of the ball mill: the “roughness” of the ball mill refers to the abnormal phenomenon that the fineness of the mill product is significantly coarser and difficult to control. It generally appears in the double-chamber open-circuit tube mill with a relatively small length and diameter. Excessive capacity of the coarse grinding chamber and insufficient capacity of the fine grinding chamber are the main reasons for “roughness”. In this case, even if the output of the ball mill is appropriately reduced, the fineness of the product is still relatively coarse. The coarseness of the product due to the excessive feeding volume does not belong to this example.

The reason why the grinding capacity of the coarse grinding chamber is significantly higher than that of the fine grinding chamber:

1) The filling rate of the grinding body of the coarse grinding chamber is too much higher than that of the fine grinding chamber;

2) The average ball diameter of the steel balls in the coarse grinding chamber is too large;

3) The length of the fine grinding chamber is too short;

4) The wind speed in the mill is too high;

5) Unreasonable grinding body gradation;

6) The grate seam of the compartment board or the discharge grate board is too large.

When “rough running” occurs, the cause should be found out, and specific measures should be taken to solve it. Generally speaking, if there is no such phenomenon and other conditions have not changed, it is just that the grinding body is newly equipped. It is likely that the average ball diameter of the coarse grinding chamber is too large, the filling rate is too high, or the grinding body gradation is unreasonable. For small tube mills with a small length-to-diameter ratio, use 1 to 2 balls more in the grading of one bin, or appropriately increase the filling rate of the fine grinding bin, and appropriately increase the lifting capacity of the fine grinding bin liner, which can solve this problem. problem.

Measures to improve the lifting capacity of the lining of the fine grinding chamber include: on the one or two circles of the lining before the feed end, every other piece of the lining can be welded with a steel bar or square steel that can form a 15-20mm convex corner. The first few laps of the liner were replaced by a flat liner with a corrugated liner: the severely worn flat liner was replaced with a new liner every few rows.