GNR Series Vertical Shaft Impactor (VSI)

The GNR series vertical shaft impactor (VSI) accelerates material with a vertical rotor and breaks it against an anvil or its own rock bed (rock-on-rock). Its purpose is exceptional cubicity and manufactured sand rather than reduction; it gives the most cubical product to meet the Flakiness Index requirements of concrete and asphalt.

Technical data

Working principle

The vertical rotor accelerates material to about 80 m/s; breaking and shaping occur in rock-on-rock (autogenous) or anvil mode. With small feed (≤55 mm) it is the final-stage machine after a cone/tertiary in the plant. Stage: tertiary/quaternary + shaping.

Material and application

Best for: manufactured sand and cubical fine aggregate from high-silica, abrasive material (granite, basalt, river gravel, slag) — rock-on-rock minimises metal wear, so it beats a tertiary impactor on abrasive material. It also improves cubicity on limestone.

Reduction and wear (TCO)

A VSI is a shaping device, not a reduction one; the net ratio is project-specific. Wear parts are rotor tips, wear plates and anvil/bed; in rock-on-rock a "rock bed" replaces parts to extend life on abrasive material. High silica uses ceramic/tungsten-carbide reinforced tips; the cost-per-tonne advantage is clear in autogenous mode.

The VSI is the final link in the manufactured-sand → washing → dewatering chain; we supply the line with washers and fine-material screens from a single source.