At the time of adding steel balls to the ball mill, some elements should be considered, including the diameter of the ball, the hardness of ore and the steel ball, the feeding size of the ball mill, and the rotating speed of the ball mill.
In the common situation, there will be a run-in period for the new fed balls and the lining plates of the ball mill. The amount of the steel balls ready to be fed into the ball mill at the first time accounts for 80% of the ball mill. Besides, the proportion of the steel balls ready to be fed into the ball mill can be determined according to the sizes of the steel balls.
For example, the largest ball loading quantity of the MQG1500*3000 ball mill is 9.5-10 tons. The weight of the fed balls for it at the first time should be 7.5-8 tons. Only when the ball mill has been in operation for 3 to 4 days can the rest of the steel balls be added into the ball mill. The weight of the steel balls whose diameter is 100mm accounts for 40%, the weight of the Φ80 mm steel balls accounts for 30%, the weight of the Φ60 mm ones accounts for 15%, that of the Φ40mm ones accounts for 15%.
When the ball mill is in normal operation, there are two kinds of diameters of the supplementary steel balls. If the diameter of the ball mill is more than 2500mm, the diameter of the supplementary steel balls is 120mm. If the ball mill’s diameter is less than 2500mm, the diameter of the supplementary ones is 100mm.
However, there will be some reasonable friction between the steel balls and ore and between the steel balls and the lining plates, which will increase abrasion. Then, the big balls and the middle balls will become small. Thus, in the normal situation, we do not need to add small balls into the ball mill. In general, when the particle size of the finished products of the ball mill can not meet the required fineness, we can add some small balls into the ball mill moderately.
In fact, the most important thing for adding balls to the ball mill is feeding steel balls into the new ball mill. Only by paying attention to the proportion of feeding balls can we guarantee that the particle size of the ground ore can meet the requirement.