Raw Grinding Systems

When dry grinding is applied, the grinding installation serves the double purpose of grinding and drying.

The most economical and simple installations are obtained by using the kiln exhaust gas for the drying process, and
carrying out the process in one machine.

The main factors influencing the selection of the most suitable raw grinding systems are:
1. Moisture content
2. Capacity of plant
3. Abrasiveness of raw materials.
4. Energy consumption
5. Installation costs.


Vertical mills can be used for moisture contents up to 16-18% as long as the raw materials are not very abrasive. In case of moisture contents lower than 3-6% (highest for small-sized plants) roller mills may not bring about any significant saving in energy and installation costs compared with ball mills.

Ball mills are suitable for low and medium moisture contents and should always be used for very abrasive raw materials. The drying capacity can be increased by installation of a flash drier at the mill inlet or by predrying in a crusher.