hill acme automatic ball forging machines are designed to meet the growing demand for steel balls used in mining to pulverize ores, cement, paint pigment and other solids in ball and sag mills. available in five sizes, each machine is fully automated, from stock feeding to discharging finished pieces.,calculating steel ball charge in ball mill,exploring ball size distribution in coal grinding mills - researchgate. abstract tube mills use steel balls as grinding media. new balls periodically to maintain a steady balanced ball charge in the mill... of the calculation of the size distribution of the equilibrium mixture of balls in a ball mill is developed.