Material
Bentonite
Answer in brief
Bentonite is a clay that was selected for its ability to swell and stick, and it brings both properties into your silo.
It arches over small outlets, coats walls and turns into an immovable gel wherever water reaches it.
- Size the outlet from measured flow properties, not from volume.
- Keep water away from the storage, including condensation.
- Plan for dust, because the dry powder is extremely fine.
Reviewed October 21, 2026 · Updated October 21, 2026
Handling challenges
Bentonite handling problems are usually silo problems, and silo problems with bentonite are usually sizing problems.
Flow and discharge
The clay has a high flow function value, which means it needs a large outlet and a well-designed hopper to move at all.
- Mass flow geometry with liners selected from measured wall friction.
- Bin activators or screw dischargers rather than vibration alone.
- Level monitoring that reveals a developing rathole before discharge stops.
Swelling
Water contact produces a gel that cannot be pumped, conveyed or dug out easily.
Sealed silo tops, dried venting air and prompt attention to roof leaks are cheap compared with emptying a gelled silo.
Dust
Dry bentonite powder is fine and persistent, and some grades contain crystalline silica.
Enclosed transfer, extraction at bag and big bag emptying and monitoring at operator positions are the controls.
Dosing
Drilling mud and foundry sand preparation need a defined addition rate from a cohesive powder, which points to loss-in-weight feeding with an agitated hopper.
What to establish before buying equipment
- Flow function and wall friction on the delivered grade.
- Moisture content on receipt and the storage humidity.
- Silica content and the applicable exposure limit.
- Required dosing accuracy and turndown.
Material behavior
- Flowability
- Poor, cohesive
- Abrasiveness
- Low to moderate
- Cohesiveness
- High; ratholes in funnel flow silos
- Moisture behavior
- Swells strongly with water and forms a gel
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