Double-shaft hammer crushers are mainly used in the cement industry for the comminution of soft to medium-hard, but also moist and tough materials: Limestone, Gypsum, Chalk, Clay and Marl, as well as Lignite and Pit Coal. The crushing of the feed material is effected by percussion, impact and shear forces.
Two counter-rotating rotors crush feed material of up to 1,600 mm edge length. An anvil is located centrally between the two rotors, which directs the processed material onto grate baskets. These grates, which serve to restrict the amount of oversize, are mounted on a grate carriage and can be completely withdrawn from the crusher housing for servicing and maintenance purposes.
The rotor body together with shaft and bearings forms the “heart” of the impact crusher.
Each rotor comprises a central shaft onto which discs are affixed. Between the discs, free-swinging hammers are mounted on hammer bolts extending over the full width of the crusher and secured at both ends to the outer discs. Turning and replacement of the hammers is facilitated by a hydraulic hammer bolt removal device together with a special lifting tool.
The feed material is processed in three stages:
- The first stage is effected by percussion and impact as the material is gravity-fed into the tip circle of the hammers.
- The material then passes onto the anvil, where it is crushed further by percussion and shear forces.
- The material flow is spread over the following discharge grates, where the product granulometry is separated and discharged through the grates. Any remaining material continues to be processed until it can pass through the grate gap. The grate bar gap spacing determines the final product size.
HAZEMAG HDS-type hammer crushers are provided with a rotor turning device, by means of which the rotors can be moved and locked in the appropriate position for hammer changing. For hammer changing, the hammers are fitted into a holding device and secured in position. With a hydraulic aid, the hammer bolts can then be extracted and/or inserted.
The use of a grate carriage enables the grates to be withdrawn from the crusher housing and returned to their original position afterwards.