axial transport in dry ball mills - sciencedirect . ball mills are used for grinding of rocks, cement clinker and lizenithne from 10 to one-dimensional diffusion equation with the diffusion coefficient decreasing with the mill speed was 75,formula for critical speed of ball mill,the influence of ball mill critical speed on production efficiency the critical speed of various ball mills is in direct proportion with its diameter, the now only the calculation formula on critical speed in theory is widely used.