Application
Bulk Bag Discharge in Plastics Compounding
Answer in brief
In compounding the bulk bag station is where fillers and additives enter the process and where most of the dust is released.
Fine fillers bridge inside the bag and flood once they start, which makes the connection and the flow aid as important as the frame.
- Seal the spout connection; the cuff over a hopper is not enough.
- Expect bridging with fine fillers and specify massaging.
- Feed from a conditioned hopper, not straight from the bag.
Reviewed October 21, 2026 · Updated October 21, 2026
The problem
Fine fillers such as calcium carbonate and talc bridge in the bag and then flood through the spout once the bridge collapses.
An open cuff releases dust into the room at every bag change.
Desired outcome
A station that empties the bag completely, releases no dust at the connection and delivers a stable flow to whatever is below it.
Process approach
A sealed spout connection with integrated extraction keeps the dust inside the equipment during untying and discharge.
Bag massaging or agitation addresses bridging, and a conditioning hopper below the station gives the feeder a stable inlet.
Where the additive is dosed accurately, loss-in-weight feeding takes over below the station rather than metering from the bag.
- Sealed spout connection with extraction.
- Massaging or agitation sized for the most cohesive filler.
- Conditioning volume between bag and feeder.
Selection factors
- Flow behavior of each filler and additive, including the worst case.
- Exposure limits for the additives handled.
- Required dosing accuracy below the station.
- Bag size, weight and the lifting method.
- Part-bag handling and storage.
Common failure modes
- Open cuff releasing dust at every bag change
- Filler bridging in the bag and then flooding
- Feeder fed directly from the bag with no conditioning volume
- Part-used bags stored without resealing
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