Exploring ball size distribution in coal grinding mills
WEBD L are mill dia length respectively. Nc is mill speed as a fraction of critical speed. J is the ball filling fraction. ρcharge is the overall charge density calculated as follows: ρcharge ¼ ðtotal coal mass þ ball massÞ=ð J Mill volumeÞ: α is the angle of repose, which is estimated to be about 35°.