What Is vertical shaft impact?
All roads, you might say, lead to the Vertical Shaft Impactor because these crushers make it possible to create roadways and just about everything else. Francis E. Agnew of California patented one of the first Vertical Shaft Impactors in 1927. His configuration stacked three vertical shaft impacts atop each other to produce sand, thus starting the ertical Shaft Impactorevolution.
Today, vertical shaft impact crushers – and the folks who rely on them – have produced many configurations to include everything from the addition of cascading material into the crushing chamber, to air swept separation of lighter product. One version suspends the shaft from above like a sugar centrifuge. It’s also one of the most feature-patented crushers, so some of the things mentioned here might be unique to a single manufacturer. VSIs apply a large amount of energy to crush material and that’s why it’s one of the most versatile crusher configurations today.
Vertical Shaft Impact Crusher Benefits
When it comes to producing materials such as aggregate for road making, vertical shaft impact crushers use a high-speed rotor and anvils for impact crushing rather than compression force for the energy needed for size reduction. In a vertical shaft impact crusher, material is accelerated by centrifugal force by a rotor against the outer anvil ring, it then fractures and breaks along natural faults throughout the rock or minerals. The product is generally of a consistent cubical shape, making it excellent for modern Superpave highway asphalt applications. The rotor speed (feet per minute) controls final particle size.
The vertical shaft impact crusher’s high cubical fracture percentage maximizes first-pass product yield and produces tighter particle size distribution. It has a high-throughput capacity ideal for beneficiation (elimination of soft material). Properly configured the vertical shaft impact crusher accepts highly abrasive materials. It has simple operation and maintenance. You can quickly change product size by changing rotor speed or cascade ratio. Some models have reversible wear parts to reduce downtime. The VSI typically has low operating costs even in high-moisture applications because of reduced energy costs and low wear cost per ton.
Vertical Shaft Impact Crusher Disadvantages
There are some feed size limitations with a vertical shaft impact crusher because of the small feed area available in the center of the rotor. Tramp material in the feed such as gloves, tools, etc. can cause problems with imbalance. The high RPM and HP require careful balance maintenance such as replacing shoes on both sides of the rotor at the same time. High wear part cost may be a problem for some hard abrasive materials, but the vertical shaft impact crusher may still be the best option.
Vertical Shaft Impact Crusher Applications
Major limestone applications are for Superpave asphalt aggregates, road base, gravel, sand and cement. Industrial uses include: corundum, corundite, ferro silicon, glass, refractories, silicon carbide, tungsten carbide and zeolite. Mining applications include: bauxite, burnt magnesite, iron ore, non-ferrous metal ore, perlite and trona sulfate. vertical shaft impact crushers are excellent for everything from abrasive materials to waste and recycling applications.
Vertical Shaft Impact Crusher Crushing Method
The VSI is typically used after a primary or secondary crusher. This makes a vertical shaft impact crusher ideal for making sand and for making coarse and medium aggregates for concrete/asphalt production.
Feed size and characteristics will affect the application of a vertical shaft impact crusher. The feed size is limited by the opening in the center of the rotor. Normally less than 5-inch material is desired, but very large vertical shaft impact crushers can handle up to 12-inch feed. Another feature that will affect application is moisture, which can make the feed sticky. Required production capacity is the final limiting criteria. Large primary horizontal shaft impactors can output up to 1600 TPH and more. 1000 TPH is about the maximum for a vertical shaft impact crusher because of the limiting motor size and the rising G-force of a high-speed rotor, which is calculated by multiplying the radius times the square of the RPM.