In stone crushing production line, the feeder or screens separate large blocks from finer rocks that do not require primary crushing, thus reducing the load to the primary crusher. Jaw, impactor, or gyratory crushers are usually used for initial size reduction. The stone that is too large to pass through the top deck of the scalping screen is processed in the secondary crushing plant. Cone crushers are commonly used for secondary crushing. The output from the secondary crusher and the throughs from the secondary screen are transported by conveyor to the tertiary circuit, which includes a sizing screen and a tertiary crusher.