The Circle Feeder
The unique design allows for first in, first out processing and can eliminate any problems with bridging or ratholing giving you smooth, steady discharge of all your materials.
Powder Handling
Circle Feeder® powder feeders for hard-to-flow materials
The Circle Feeder discharges and meters sticky, fluffy, lumpy, flaky and fibrous materials from hoppers, bins and silos without bridging or ratholing. A large round inlet and slow-turning vanes keep the whole bed moving in mass flow: first in, first out.
What is it
What is a Circle Feeder?
A Circle Feeder is a table-type powder feeder that mounts at the bottom of a hopper, bin or silo. Its round inlet is sized larger than the material's critical arching diameter, so bridges cannot form. Slow-rotating vanes move material outward under a fixed flow adjusting ring to one or more discharge ports, giving steady, first-in, first-out mass flow.
The same unit both discharges the hopper and meters material into the next step of your process, at a consistent rate. Every Circle Feeder LCI supplies is designed and engineered for your material and your process requirements.
Materials
Powders, granules, fibers, flakes and wet cakes
Flow pattern
Mass flow, first in, first out, with no material hold-up
Turndown
Up to 10:1 with a variable-speed drive; up to 20:1 adjusting ring height and speed together
Inlet size
Round openings up to 12 ft (about 3.7 m) in diameter
Temperature
High-temperature designs up to 500 °C (932 °F)
Lowest feed rate
As low as 1 ml per hour with the MicroDischarger
Why should you choose the Circle Feeder
The Best Solution
For Feeding Difficult
Materials
Every Circle Feeder we provide is specifically designed and engineered to achieve your specific process requirements.
- Prevent Bridging
- Achieve Mass Flow
- Prevent Ratholing
- Low Noise
- Prevent Segregation
- Low Maintenance
The Circle Feeder has a variety of features but widely known for its ability to prevent material arching, bridging, and ratholing.
In 1997 LCI Corporation formed a partnership with Yoshikawa Corporation. As a result of our partnership, LCI is the exclusive supplier to the process industries in North and South America for Yoshikawa's unique, patented Circle Feeder, the best solution for many difficult-to-flow solid materials.
Why powders bridge, rathole and segregate in hoppers
Many feeding problems start in the hopper, not the feeder. When the outlet is narrower than a material's critical arching diameter, cohesive, sticky or fibrous particles can lock together and stop flowing, even though the hopper is full.
Problem
Bridging (arching)
Material forms a stable arch over the outlet and flow stops. Plants often fall back on hammers, vibrators or air knockers to break it.
Problem
Ratholing
Material drains through a narrow channel above the outlet while the rest stays on the walls. Usable hopper capacity shrinks, and stagnant material can cake or degrade.
Solution
Mass flow with Circle Feeder
The inlet is wider than the critical arching diameter, so no arch can span it. Vanes draw from the full cross-section and the whole bed moves down evenly.
How it works
How the Circle Feeder works
The design uses gravity and slow mechanical motion rather than force. Four parts do the work.
Flat, slow-rotating vanes
At the center of the feeder, flat vanes move material radially outward from the middle of the inlet.
Flow adjusting ring
Material passes beneath a fixed ring. Ring height is one of two ways to set capacity; shaft speed is the other.
Rotary vanes
In the outer channel, rotary vanes carry material around toward the outlet.
Discharge ports
One or more ports release material to the next process. Several ports can feed separate downstream lines or split one stream.
The vanes turn slowly, at 0.05 to 7.2 rpm depending on the model, so the feeder runs quietly, handles products gently and needs little maintenance. As material leaves the outlet, the level in the hopper drops evenly, creating mass flow conditions.
Benefits
Features and benefits
What each part of the design does for your process, from LCI's Circle Feeder technical bulletin and product literature.
| Feature | Benefit |
|---|---|
| Large round inlet, up to 12 ft in diameter | Exceeds most materials' critical arching diameter, so it prevents bridging and ratholing. Fits existing silos. |
| Patented mass flow design | No material hold-up in the hopper. First in, first out, which also prevents segregation. |
| Slow-rotating vanes | Gentle product handling, quiet operation, low maintenance and minimal downtime. |
| Simple design that uses gravity to help discharge | Low energy consumption. |
| Two-way capacity adjustment: flow adjusting ring height and shaft speed | Wide turndown: up to 10:1 with a variable-speed drive, and up to 20:1 using both adjustments. |
| Multiple discharge ports | Feed several downstream processes or split the process stream from one hopper. |
| Discharging and metering in one unit | A consistent discharge rate straight from the hopper. |
| Easily accessible motor and gearbox | Minimizes downtime for service. |
Materials and industries
The Circle Feeder handles powders, granules, flakes, fibers and wet cakes, including sticky, fluffy, lumpy and flaky materials that defeat conventional feeders.
Chemical
- Chemical intermediates
- Inorganic salts
- Polymer flakes and powders
- Soap powders and ingredients
- Pigments
- Resin flakes
- Fertilizer components
- Ink
Food and feed
- Corn, rice, potato starches
- Corn, soybean, wheat flours
- Residual vegetable cuttings and pulp
- Minced meat
- Seed hulls and components
- Fermented products
- Seasonings
Biofuels, energy and environmental
- Recycled plastic/paper flakes and grind
- Wood chips
- Shredded bags
- Biomass
- Fibers
- Fly Ash
- Mixed garbage (waste)
- Sawdust
- Carbon
- Shredded rubber
- Industrial waste
Pharmaceuticals
- Precise feeding of small amounts of pharmaceutical ingredients
- Wet granulation for extrusion
Battery manufacturing
- Electric vehicle battery powders
Other materials
- Carbon black
- Sewage sludge
- Metallic powders
- Cellulose derivatives
- Fibers
- Paper pulp
- Cement
- Cosmetic powders
Products
The Circle Feeder family
Five versions of the same principle, from bench-top R&D to silo discharge and dust collector hoppers.
Circle Feeder (CF series)
Production-scale hoppers, bins and silos
The industrial feeder and discharger for difficult materials. Standard models run from CF-500 to CF-2400, and models up to CF-4000 can be supplied.
GMP Circle Feeder (CS series)
Pharmaceutical and clean room processes
A clamshell design for complete cleaning, a 400-grit mirror finish, sanitary clamps and casters for moving in and out of clean rooms. The central vane comes out by removing one bolt. Suitable for powders or wet cakes.
MicroDischarger (MD series)
Ultra-low feed rates with high precision
Combines a Circle Feeder with a disk feeder and replaceable scraper in one compact unit. It feeds powders with poor flowability without pulsation, at rates as low as 1 ml per hour. Models MD-120 and MD-180, in 304 stainless steel.
Mini-Feeder laboratory Circle Feeder
R&D and scale-up trials
A compact bench-top unit that feeds very small quantities of difficult powders at a uniform rate. Use it for R&D or to evaluate the Circle Feeder before production scale. The speed-adjustable motor changes feed rate easily, and assembly takes minutes. A hopper is optional.
Circle Feeder for Dust Collectors (CFD)
Dust collector hoppers, new or existing
A Circle Feeder built to discharge dust collector hoppers. It stops bridging without vibrators, air knockers or replacement hoppers, handles sticky, fine and high-temperature dusts, and is available in heat-resistant designs up to 360 °C.
Design Options
Every Circle Feeder LCI supplies is custom designed for your needs. Options include:
Multiple discharge ports
With manual or automatic slide gates, to feed several lines from one hopper.
Special coatings
For abrasive materials.
Sanitary and cGMP construction
Including clamshell designs for easy cleaning.
Load cells and loss-in-weight control
For high-accuracy gravimetric feeding.
Vertical or horizontal drive
To suit the space under your hopper.
High-temperature construction
Designs up to 500 °C.
High-moisture capability
For wet cakes and other high-moisture materials.
Airtight design
For feeding pneumatic conveying systems.
Explosion-proof motors and electricals
For hazardous areas.
Heavy-duty reducers
For high bulk density materials.
Comparison
Circle Feeder vs. other powder feeders
LCI customers have used the Circle Feeder in place of screw, belt, rotary, bulk, hopper and weigh feeders. The main difference is where the flow problem gets solved.
| Approach | How it draws from the hopper | Common issue with cohesive, sticky or fibrous materials | Circle Feeder Solution |
|---|---|---|---|
| Screw feeder | Material enters the screw through a trough opening under the hopper outlet. | If the opening is narrower than the critical arching diameter, arches and ratholes can still form. A rotating auger can also overwork shear-sensitive materials. | A round inlet sized larger than the arching diameter, with slow vanes that handle material gently. |
| Rotary valve or rotary feeder | Pockets fill by gravity from the outlet above the valve. | Depends on material flowing freely into the valve. Sticky or fluffy materials can bridge above it or fill pockets unevenly. | Actively moves material from the full inlet area to the discharge port. |
| Flow aids: vibrators and air knockers | Added to hopper walls to break arches once they form. | Treat the symptom rather than the cause, and add noise, maintenance and wear. | Removes the cause, so flow aids and replacement hoppers are often unnecessary. |
Need gravimetric accuracy? A Circle Feeder can be supplied with load cells and loss-in-weight control, combining reliable discharge with weigh-feeder precision.
Case Studies
Proven on difficult materials
Two documented installations from LCI's case histories.
Synthetic paper recycling
Four Circle Feeders run 24/7 on confetti-size paper trim
Challenge
Granulated paper trimmings arched severely in surge silos. With a bulk density under 10 lb/ft³ they needed very large silos, and the process demanded steady discharge of about 10,000 lb/h. A single blockage meant manually removing and cleaning hundreds of feet of pneumatic tubing, shutting down the process.
Solution
After pilot testing, the customer bought four large Circle Feeders. The inlet matched the silo diameter, allowing straight-walled silos with no cone and much less headroom. Stoppers inside the hoppers kept the light paper from turning, so it moved in mass flow.
All four started up with only one issue, caused by a downstream malfunction, and run 24/7 to the original design. Feed rate can be varied reliably over a 10:1 range. During the same trials the customer also successfully tested micronized calcium carbonate and a cohesive titanium dioxide, and bought a Circle Feeder for each.
Agrochemicals: biological insecticide
Uniform metering of a centrifuge wet cake
Challenge
A Midwestern manufacturer needed to store a centrifuge wet cake and meter it into an extrusion process. A cone feeder with an internal auger overworked the cake, releasing bound water that made the material stick to the auger and bridge in the cone.
Solution
The test sample reached the LCI Test Center as a slurry, yet the Circle Feeder still discharged it without bridging. The trial feeder was then shipped to the plant, where its slow shaft speed and large inlet metered the cake uniformly.
Material that sat in the hopper for 24 hours could still be discharged, greatly reducing cleanout time after plant upsets. The result was higher productivity and better product performance.
Downloads
Technical literature
Technical bulletins and case histories for the Circle Feeder family.
Common things to know
Frequently Asked Questions
Answers to common questions about the Circle Feeder
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Last updated: October 2026
