For choosing a crushing plant for cement raw materials it is necessary to investigate the properties of the materials to be comminuted and the range of variation of these properties. The crushing plant should be properly suited to the requirements of the quarrying operations and to the transportation of the crushed material to the cement works. The twin-rotor hammer crusher has for many years been a dependable machine for the comminution of raw materials for clinker production. Because of its design features it is substantially unaffected by varying material properties such as, for example, the feed size or the moisture content. The crusher may be installed either in a stationary or in a mobile crushing plant and is therefore suitable for virtually all relevant purposes in the cement industry.