Abstract: In view of the steel ball attrition in ball mill, analysis is made of the laws that the ball attrition speed is in direct proportion to the ball weight and that the ball attrition speed is in direct proportion to its surface area. Both laws of attrition are used to analyze the distribution of the size fractions of balls when the ball mill comes to its balance and their respective ball attrition curves are found out, providing a reference to making a proper ball supplement plan.

Key words: Steel ball attrition, Attrition speed, Attrition law, Supplement plan