[Louie1961]

Thermite is actually not an explosive, although it is exothermic, and what you are missing from the grinding dust is a sufficient quantity of iron oxide (3 lbs of rust for every pound of aluminum dust). Note that the reaction requires iron III oxide, not steel or iron. Who has that much rust in their grinding dust? On top of that, the ignition of thermite is a tricky thing. It takes a relatively high temp. "Ignition of a thermite reaction normally requires a sparkler or easily obtainable magnesium ribbon, but may require persistent efforts, as ignition can be unreliable and unpredictable. These temperatures cannot be reached with conventional black powder fuses, nitrocellulose rods, detonators, pyrotechnic initiators, or other common igniting substances.[SUP][13][/SUP] Even when the thermite is hot enough to glow bright red, it will not ignite as it must be at or near white-hot to initiate the reaction.[SUP][citation needed][/SUP] It is possible to start the reaction using a propane torch if done correctly."

 

[Louie1961]

I have to respectfully disagree. The sheer amounts of rust required would be prohibitive. Pure iron III oxide is required, which has to be made in a lab. Rusty iron and steel filings are not going to provide the required oxides. Yes you might get an aluminum dust fire, but not a thermite reaction. the two are vastly different, and you can get an aluminum dust fire with or without the iron filings being present.