Roll Crushers are compression type crushers.
Roll crushers have a maximum reduction ratio of 4:1
The gap between the rolls is set to the size of product desired, with the understanding that the largest particle can only be 4 times the gaps dimension.
The material is drawn into the gap between the rolls by their rotating motion and a friction angle formed between the rolls and the material, called the nip angle.
Coal is the main user of roll crushers.
Coal plants will use roll crushers, either single roll or double roll, as primary crushers
- These crushers will have teeth or raised forms on the face of the roll.
- Roll crushers used for minerals and metal ores are smooth faced.
Some major advantages of roll crushers
- Very fine product size distribution
- Produces very little dust.
Rolls crushers are effectively used in smaller scale production mining of more abrasive metal ores, gold for example.