What is Vertical Shaft Impact Crushers (VSI)?

What is Vertical Shaft Impact Crushers (VSI)?

Vertical Shaft Impact Crushers (VSI) also known as sand producing machines are used as a tertiary stage crusher to get high ratio of fine material and to give cubical shape to the products that are coming through the secondary crushers. Any type of materials, especially the hard stones such as basalt and granite with maximum 50-45 mm size which are crushed by secondary crushers are fed to Vertical Shaft Impact Crushers.

Vertical Shaft Impact, or VSI, crushers are types of impact crushers whose rotor is oriented vertically, allowing raw material to be fed into the center of the rotor and thrown outward with high speed onto a stationary anvil or a bed of rock. The mechanism of VSI crushers enables the production of a unique, cubical product shape, which is highly sought after in the concrete and asphalt production industries and other related processes where uniformity in particle size is imperative. VSI crushers work effectively for the creation of fine materials and shaping and are, therefore, very useful for specific applications that involve particle shape.

Operating Principles

The operating principle of Vertical Shaft Impact (VSI) crushers is based on high-speed impact. The rotor accelerates material and ejects it at high velocity against the stationary surface, usually an anvil or a rock bed, therefore fracturing the material. This is a closer view of how this process works:

1. Feeding and Rotor Design:

Material is fed through the top of the crusher, typically via a hopper, and into the center of a high-speed rotor.

The rotor is the key component, and it’s typically designed with multiple ports or passages for the material to flow through.

As the rotor turns at high speed, centrifugal force pushes the material through these channels at an increased velocity.

2. Material Acceleration:

The rotor provides the material with an extremely high velocity, about 60-90 m/s (about 200-300 feet per second).

This high-speed acceleration is key to the unique capability of a VSI crusher to crush material by impact rather than by pressure or compression.

The acceleration develops enough kinetic energy so that when it hits a contact surface, it shatters the material.

3. Crushing and Impact:

After acceleration in the rotor, material is thrown radially outwards towards the stationary impact surface.

Depending on the design of a crusher, the crushing surface may be either a rock bed or metal anvils. There are two types of crushing action:

Rock-on-rock: Stuff strikes other stuff, breaks due to impact.

Rock-on-metal: Material strikes a stationary metal anvil, breaking it.

4. Cubical Shaping:

It’s the combination of impact energy and particle-to-particle interaction that gives VSI crushers their unique benefit of producing a cubical product.

This way, the desired shape and even size distribution are achieved because the particles fracture along their natural lines of weakness during the high-speed impact.

5. Pick-up and Departure:

Once crushed, the material exits the crushing chamber, usually through a discharge outlet at the bottom of the crusher.

The VSI crusher can produce particles of a uniform size, and this makes it suitable for applications where high-quality, well-shaped aggregates are required, such as sand and concrete. The high-speed rotor of the VSI crusher, along with its unique rock-on-rock or rock-on-metal impact system, actually enables it to produce fine materials with uniform shape in a highly efficient manner. With the rotor speed being fast, it is actually a process where the VSI crusher parting fragments at extremely high rates separates itself.

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Applications of Vertical Shaft Crushers in Different Industries

The vertical shaft impact crushers are highly versatile and the unique crushing mechanism makes them suitable for a wide range of industries where particle shape, size control, and efficiency are vital. Here are some applications across different industries:

1. Construction and Aggregates

Concrete and Asphalt Production: VSI crushers produce a cubical-shaped product, which is ideal for high-quality concrete and asphalt mixes, improving workability, compaction, and durability.

Road Base and Pavement Materials: VSI-produced materials, with controlled particle sizes and shapes, are vital to building strong, stable foundations and smooth surfaces for roads.

Railway Ballast: The accurate and uniform output of VSI crushers can be used in railway ballast too, where the particle consistency has to be perfect.

2. Mining Industry

Fine Crushing of Ore: VSI crushers are used in the mining industry to produce fine, uniform materials from ores such as copper, iron, and gold, especially after first-stage crushing.

Heap Leaching: The high-quality, fine materials produced by VSI crushers optimize the leaching process, increasing the surface area for chemicals to penetrate and extract valuable minerals.

Metal and Non-Metal Mining: VSI crushers generally have higher throughput rates and better extraction efficiency in both metal mines—like gold and silver—and non-metal mining applications—like phosphate and limestone.

3. Production of Gravel and Sand

Manufactured Sand: VSI crushers are excellent for creating manufactured sand that meets specific size and shape requirements, offering a sustainable alternative to natural sand.

Crushing Riverbed and Granite Materials: VSI crushers are good for those hardest materials, such as granite, or the most irregular, softest riverbed materials, producing well-graded sand and gravel.

4. Recycling Industry

Reclaimed concrete and asphalt reprocessing using VSI crushers allows producers to take the material and turn it into a reusable material for construction of new buildings, resulting in sustainability and less waste sent to landfills.

Glass and Ceramics Recycling: VSI crushers crush glass and ceramics into a finer particle, which can then be reused in various applications, such as roadbeds or new glass products.

5. Energy Sector

Coal Processing: Although VSI crushers are not typically used in the primary crushing of coal, they are helpful in the creation of fine coal particles, which are used in fluidized bed combustion or coal gasification.

Solar Panel and Wind Turbine Materials: VSI crushers will create finely shaped silica-based particles that can be used in the production of solar panels, and in some cases as components in wind turbine construction materials.

6. Industrial Minerals and Chemicals

Chemical Processing and Fertilizers: VSI crushers are used for manufacturing extremely fine and uniform material—inputs for chemicals and fertilizers. The precision in controlling the particles improves the performance of these products.

Silica Sand and Glass Production: VSI crushers produce high-purity, finely graded silica sand for use in glassmaking and industrial applications.

7. Specialized Manufacturing and Ceramics

Ceramics and Abrasives: VSI crushers help to produce finely controlled ceramic powders and abrasives with the ideal shapes for optimum performance in abrasive and ceramic products.

Metal Powders: VSI crushers, in some metal powder manufacturing operations, assist in the production of finely crushed particles used in metallurgy and powder coatings. Each of these applications leverages the VSI’s ability to produce precisely shaped, fine materials, resulting in greater product quality, reduced operational costs, and enhanced efficiency in diverse industries.

Advantages of Using a VSI Crusher

1. Enhanced Particle Shape: VSI crushers produce a highly cubical, uniform product ideal for applications requiring specific particle shapes, such as concrete and asphalt.
2. High Reduction Ratios: The high-speed impact of VSI crushers enables significant size reduction, efficiently producing finer materials from coarse feed.
3. Energy Efficiency: VSI crushers use less energy than compression-based crushers, making them cost-effective and reducing their environmental impact.
4. Versatility and Flexibility: With configurations like rock-on-rock or rock-on-metal, VSI crushers can handle different material types and hardness levels.
5. Low Operating Costs: The rock-on-rock configuration minimizes wear costs, resulting in reduced maintenance and downtime.

Key Applications of VSI Crushers

• Construction and Aggregates: Producing high-quality concrete and asphalt aggregates, road base materials, and railway ballast.
• Mining Industry: Fine crushing of ores and processing in heap leaching for better mineral extraction.
• Sand and Gravel Production: Creating manufactured sand and processing riverbed or granite materials.
• Recycling Industry: Breaking down concrete, asphalt, glass, and ceramics for reuse.
• Industrial Minerals: Producing silica sand, glass materials, and inputs for chemical processing.
• Ceramics and Abrasives: Shaping powders for ceramic and abrasive products.

Choosing the Right VSI Crusher Model

Selecting the appropriate VSI crusher model depends on the application, feed material, desired output size, and specific production needs. Some models are optimized for producing finer aggregates, while others handle coarser feed materials. Matching the crusher configuration—whether rock-on-rock for reduced wear or rock-on-metal for higher impact—with the desired outcome ensures optimal performance and efficiency.