The mill is usually divided into at least two chambers,(Depends upon feed input size presently mill installed with Roller Press are mostly single chambered), allowing the use of different sizes of grinding media. Large balls are used at the inlet, to crush clinker nodules (which can be over 25 mm in diameter). Ball diameter here is in the range 6080 mm. In a two-chamber mill, the media in the second chamber are typically in the range 1540 mm, although media down to 5 mm are sometimes encountered.
As a general rule, the size of media has to match the size of material being ground: large media cant produce the ultra-fine particles required in the finished cement, but small media cant break large clinker particles. Mills with as many as four chambers, allowing a tight segregation of media sizes, were once used, but this is now becoming rare. Alternatives to multi-chamber mills are: pairs of mills, run in tandem, charged with different-sized media. se of alternative technology (see Roll-presses below) to crush the clinker prior to fine-grinding in a ball mill. The machine is composed by feeding part, discharging part, turning part and driving part (reducer, small driving gear, electric motor and electric control). The quill shaft adopts cast steel part and the liner is detachable. The turning gearwheel adopts casting hobbing process and the drum is equipped with wear-resistant liner, which has good wear-resistance.
The machine is with stable and reliable working condition. Moreover, according to different materials and discharging methods, there are dry ball mills and wet ball mills for choice. A current of air is passed through the mill. This helps keep the mill cool, and sweeps out evaporated moisture which would otherwise cause hydration and disrupt material flow. The dusty exhaust air is cleaned, usually with bag filters.