Steel Ball Mills Lined Ball Mills. Particle size reduction of materials in a ball mill with the presence of metallic balls or other media dates back to the late 1800’s. The basic construction of a ball mill is a cylindrical container with journals at its axis. The cylinder is filled with grinding media (ceramic or.The starting point for ball mill media and liquid charging is generally as follows 50 media charge. Assuming 26 void space between spherical balls (non-spherical, irregularly shaped and mixed-size media will increase or decrease the free space) 50 x 26 = 13 free space. Add to this another 45 to 50 above the ball charge for total of 58.