[fodrv7]

A post today, asking how to dress your scotchbrite wheel with a piece of steel, prompts me to bring attention to the fact that this could prove very hazardous.
Aluminium powder makes great solid rocket fuel and can react very violently with Iron Oxide.

I recently read an article about an extremely high temperature flash fire from mixing steel and Aluminium on the same grinding wheel.

Here is the Australian safety Website with the article.
http://www.hanford.gov/rl/?page=542&parent=506

After grinding the heads of 12 pop rivets the wheel was used to grind iron. The resulting fireball reached 6300F and although it only lasted 1 sec it caused the unfortunate operator 1st and 2nd degree burns

Pete.

 

[szicree]

HOLY COW!!! I never would have seen that hazard in a million years! Very informative and surprising. On a positive note though, I'm gonna be the only guy in my neighborhood with thermite fireworks this year. Woo-Hoo!

 

[markerthebarker]

Flash Fire

This may seem like a stupid question, but does anyone know if it was the wheel itself, or just the debris on the table that flashed?

George Henson
Tooling Up

 

[mdredmond]

Aluminium powder makes great solid rocket fuel and can react very violently with Iron Oxide.

Aluminum + Iron Oxide = Thermite

It doesn't burn quickly enough to use as a rocket fuel and its major byproduct is molten iron. The basic reaction is Aluminum + Iron Oxide --> Aluminum Oxide + Molten Iron + scads of heat. I suppose alumimum with a different oxidizer might be good rocket fuel, maybe.

I'm really surprised the guy's grinding wheel was able to light the mixture. We made some when I was a kid - a blowtorch wouldn't light it. We ended up using a magnesium strip. And this was with atomized (like talcum powder) Al and Fe3O4.

 

[hevansrv7a]

Aluminum powder and sulphur makes a terrific rocket fuel. DON'T TRY IT! I had a crazy chem. teacher in high school (around the time of Sputnik) who gave us the formula. The problem was you have to melt the sulphur and mix in the aluminum powder. The second problem is that the flash point of the mixture is quite near the melting point. Get it?
I'm here to remember it because I was working with less than a teaspoon of the stuff.
h

 

[Davepar]

I posted on the Mythbusters board a while back asking them to try this one. I thought it was an urban myth, as it takes a lot of heat to get the thermite reaction going. Guess it's happened at least once. I'll be getting out the broom tonight.

 

[mlw450802]

Aluminum + Iron Oxide = Thermite

It doesn't burn quickly enough to use as a rocket fuel and its major byproduct is molten iron. The basic reaction is Aluminum + Iron Oxide --> Aluminum Oxide + Molten Iron + scads of heat. I suppose alumimum with a different oxidizer might be good rocket fuel, maybe.

.

Actually the solid fuel boosters for the space shuttle use aluminum for fuel and ammonium perchlorate for the oxidizer and a wee bit of iron oxide to tune the reaction rate.

 

[BJohnson]

similar reaction

Iron deposites on the scotchbrite wheel can be embedded into the aluminum while deburring causing corrosion down the road.

Best to not mix metals on scotchbrite wheels for that reason also.

 

[Mike S]

thermite

This was the forerunner of arc welding------------vee the edges, build a dam of clay, fill with thermite, and light it off-------result was amazingly strong.

Used a lot by the railroad

Old dregs from a welding class back in '67.

Mike