In general, a rock crushing plant will have a primary crusher, primary screen, secondary crusher(s) and secondary screen(s), and associated conveyors and stockpiles. It may also involve portable generators powered by diesel engines. Emissions of each pollutant must be less than 100 TPY for the facility to be a minor source.
Crusher Wikipedia. A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. .... Primary crushing reduces the large pieces to a size which can be handled by the downstream machinery.