Type of Mill Media Size, in. Tip Speed, ft./sec. Ball mill ½ and larger — Attrition mill 1/ 8 – 3/ 8 600 – 1,000 Sand mill 1/ 64 – 8 2,000 – 3,000 Small media mill 0.1 mm – 3 mm 1,000 – 3,000 Choose the Right Grinding mill Consider the feed material's nature and the milling's objective By Robert E. Schilling, Union Process Inc.