Aluminium and steel dust, mixed, can be hazardous. Many people in our industry know this; but there are still many people who are not aware of it. We have spent many years warning people that mixing these materials is a bad idea. Usually, customers believe us. Equally, we have met customers who laugh at this – as you would expect “They’ve never had a problem before”.
So. This is a little cautionary tale from our own experience.
In a workshop we know well, there is a small dust collector with attached arm. It is an old unit, and only rarely used. It has not been used at all for 2-3 months; however, the collector bin had not been emptied. While the unit was used generally for steel work, at some point it seems someone had borrowed it for an aluminium grinding process.
Last week, it caught fire. There was no source of ignition, no hot work taking place, and no power connected. Smoke was seen coming from the arm itself; on investigation, it turned out that the bin was on fire.
This incident was caught without fire service involvement. But it could have been hazardous if the reaction had occurred outside working hours.
For more general information on thermite risks, visit here:
Our key recommendations: Know what dusts you are storing in your dust collectors. Look not just at the material you are grinding, but other sources of stray dust that you may introduce. And ask for advice if you’re unsure.