Cement ball mills typically have two grinding chambers. The first chamber is filled with larger diameter grinding media and lined with lifting liners. The first chamber coarse-grinds the feed material and prepares it for the second chamber. The second chamber is the fine grinding chamber. It is lined with classifying-type mill shell liners and provided with finer ball charge. Classifying liners ensure that the ball charge is segregated along the length of the chamber keeping larger grinding media at the beginning of the compartment and smaller media towards the end of the chamber.
An intermediate partition, called the central diaphragm, separates the coarse and fine grinding chambers. The purpose of the central diaphragm is to retain the grinding media in their respective chambers, provide adequate opening for the airflow and, in some special types, regulate the feed to the second compartment.
The mill is equipped with a discharge diaphragm at the end. This diaphragm retains the grinding media in the second chamber and allows the discharge of finely ground material.
Clinker, Gypsum and other desired additives are fed to the ball mill in specific proportions based on the quality requirement. Feed material is ground in the ball mill, discharged and fed to a classifier with the help of a bucket elevator for classification of the ground cement into two streams – coarse and fines. The coarse fraction is sent back to the mill and the fines are collected in cyclones and / or a baghouse as finished product.
The mill is ventilated by an induction fan. The air required for classification is provided by another fan. The fans pull the gases through independent baghouses which clean the vent air and return the cement dust to the system.