Centrifugal Sifters

Centrifugal sifters—also known as rotary screeners—sift, filter, and separate particles from a bulk material. They are often used to remove unwanted particles from a product, to grade particles according to their size, or to separate different materials.

Available in dual configurations and sizes that can sift up to 100 TPH, centrifugal sifters are most commonly used instead of vibratory screeners when product won’t go through a screen by gravity alone. But there are other material properties and line configurations that will also make centrifugal sifters necessary. Some manufacturers have sifters that can be run wet or dry, but Russell Finex, for example, has one model for wet applications and another for dry. Contact us to find out what make and model will be best for your line.

Operating Principle

Centrifugal sifters use centrifugal force to separate particles from a material. The material is fed into the sifter, and as it rotates, the centrifugal force causes the heavier particles to move towards the outer edge of the screen while the lighter particles remain in the center. The screen separates the particles, and the desired size range is discharged through the screen while the unwanted particles are rejected.

Options

Centrifugal sifters come in a variety of sizes and configurations, making them suitable for many different applications. Some of the options include:

• Screen Material: The screen material can be made of various materials including stainless steel, polyurethane, or wire mesh.
• Screen Size: The screen size can range from small to large, depending on the desired particle size range.
• Drive Mechanism: Centrifugal sifters can be driven by an electric motor, air motor, or hydraulic motor. Also some manufacturers will use wipers to help push product through the screen whereas others will rely solely on centrifugal force.
• Screen Configuration: Not only can centrifugal sifters can have one or multiple screens to allow for multiple stages of separation, but the screen itself may need to be customized beyond perforation size and spacing. Perforation shape, roughness, or direction of perforations if rough can all greatly impact performance depending on the material.
• Dust Collection integration: Some centrifugal sifters come equipped with a dust collection system.

When to Use Them

Centrifugal sifters are most commonly used for dewatering and separating large particles from smaller ones. The drawback here is that there is only one “overs” discharge, so you can only separate material into “too big” and “too small” whereas with a 5 deck vibratory screener you can classify product into 5 divisions.

• Gravity Isn’t Enough: As product gets lighter or bridges more, gravity may not be enough to pull it through a vibratory screener at the desired mesh. That’s when the force of paddles and/or centrifugal force of a centrifugal sifter can help.
• Line Configuration Requires It: Let’s say gravity is enough to pull product through a vibratory screener, but you don’t have enough space in your line to achieve the throughput you would need. You can get a higher flow rate for the same footprint with a centrifugal sifter.

When Not to Use Them

• Heat Sensitive Materials: Centrifugal sifters generate heat during operation (primarily a concern for dry applications) and can cause heat-sensitive materials to degrade.
• Fragile Materials: Centrifugal sifters generate high amounts of mechanical energy, which can cause fragile materials to break.
• You need Multiple Size Divisions: If your product is heavy enough to fall through the screens and you need more divisions, use a vibratory screener.

There is some wiggle-room regarding these types of products and conventional knowledge, so our sales team will help you understand if there are any mitigating strategies available for your material.