### Cement grinding Vertical roller mills versus ball mills

invention in France which involved a tube mill with a charge of steel balls or flint pebbles for fine grinding of sand or cement. F.L. acquired the rights to his patent and started selling an improved version of this mill all over the world. For the cement industry the ball mill was really an .

### AMIT 135: Lesson 7 Ball Mills & Circuits – Mining Mill ...

For overflow ball mills, the charge should not exceed 45% of the mill volume . For grate discharge mills, the charge should occupy about 50% of the mill volume . Bond developed a relationship that can be used to determine the percent charge by volume as a function of the vertical height above the charge, He, and the radius of the mill, R, i.e.,