Raw material is brought into the crusher for initial grinding and size reduction. Trucks or conveyor systems will bring material into the crusher where it is ground into smaller pieces. A screen (grizzly) may be included below the crusher to sort the rocks so that the smaller pieces go through and the larger pieces are caught for re-grinding. A minimal amount of material should be maintained on the screen to act as a buffer to protect the screen from the impact of larger rock. As the material is brought into the crusher, it moves quickly through the crushing process.
The fast-moving level must be monitored to determine when the material reaches a minimum level so that the next load can be started. The material is irregularly shaped and very dusty. The overall distance may be a far as 30 m (98 ft).