Grizzly (Scalping) Screen — G and M Types

The grizzly screen is built in two types and performs pre-screening in the crushing circuit: the G-type sits between the feeder and the primary crusher and separates the bypass material; the M-type sits ahead of the secondary crusher and bypasses fines to keep the crusher from being needlessly loaded. The bars are high-manganese austenitic cast steel with an adjustable gap. Capacity is 100-400 tph.

G-type vs M-type

• G-type (run-of-mine / pre-primary): two vibromotors produce linear vibration; it splits the material feeding the primary crusher from the soil/fines bypass, protecting the crusher from fines.
• M-type (pre-secondary): an eccentric shaft with belt-pulley drive and special bearings produces circular vibration; it bypasses post-primary fines to preserve secondary crusher efficiency.
• The bars are manganese (Mn13-type) austenitic castings; under impact the surface work-hardens (roughly 200 up to 450-550 HB), giving long service life.

Bars and drive

The adjustable bar gap controls the bypass size. Exact values are set to order according to the material and feed size.

Deployment points

The G-type, in primary pre-screening, bypasses soil/fines to raise crusher efficiency and reduce wear. The M-type, ahead of the secondary, removes the fine fraction to cut the secondary crusher's needless load. It is used in fixed and mobile plants processing sand-and-gravel, hard rock and run-of-mine feed.

Fit within the crushing line

Because the grizzly screen is the entry stage of the crushing line, it is sized together with the feeder and crusher choice. General Makina gathers pre-screening, primary/secondary crushing, classification and washing groups under a single project; from the austenitic bars to the jaws, wear parts are supplied from one address in a matched chain.