Material

Alumina

Answer in brief

Alumina flows like a liquid when aerated, and that is exactly how smelters move it.

Air slides and fluidised systems exploit the behavior, while any line that relies on high velocity pays for it in wear.

Use fluidisation where the layout allows it, because it is gentle and cheap to run.
Keep pneumatic velocity low, since alumina erodes bends quickly.
Contain dust at loading and at every open transfer.

Reviewed October 21, 2026 · Updated October 21, 2026

Alumina is one of the few powders where fluidisation is the primary transport principle rather than a flow aid.

A gently inclined air slide moves large tonnages with little energy and almost no moving parts, which is why smelters are built around them.

The requirements are dry, clean air at the right pressure and a fabric in good condition; a blinded or torn membrane stops the flow without warning.

Where pneumatic conveying is used, velocity decides the service life of bends and valve seats.

Alumina takes up moisture from humid air, and damp material neither fluidises nor discharges properly.

Dry conveying and fluidising air is a process requirement, and a failed air dryer shows up quickly as a flow problem.

Loading and open transfers generate respirable dust, and smelter environments add fluoride-bearing dust from the process side.

Enclosed chutes with extraction and sealed loading interfaces are the usual controls.

Flowability: Free flowing, fluidises readily
Abrasiveness: High
Cohesiveness: Low
Moisture behavior: Picks up moisture; wet alumina builds up and loses fluidisation

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