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View Full Version : Aluminum Dust, Blow me Up, Scotty? Yep



Hollowbuilt
12-17-2008, 01:56 AM
30 years ago I bought some epoxy mold making equipment. Along with it came a small steel barrel of Alcoa powdered aluminum. About 100 pounds originally, with half of it remaining. The project didn't work out. But like a pack rat, I kept some of the equipment. Including the barrel of aluminum powder.

It ended up in the "bone yard" at my shop. By then I had been dragging it around for about 15 years. It had a heavy steel lid with an even heavier steel locking ring closure. On tight.

So one day my partner walks up to me and says, "Hey, you know that little steel barrel you got outside? Well, it's got steam coming out of it, and the side of the drum is hot!" "What the hell you got in there?"

I went outside and yep, there was smoke or steam or whatever coming out of a small gash in the lid. (Gash? Yea. And I have NO idea when that happened!) And the sides were warm. Crap. What to do.

I was hesitant to call the Fire Department. Lots of friends in the Fire Department. And I knew what could happen. EPA, OSHA, CIA, FBI, IRS....so I decided to "manage it in place".

I grabbed one of the guys working in the shop and told him to fill it up with water...put the water through the gash in the lid. He came into the office to say that he had put water in the barrel and was now ready to help me with whatever else I needed.

The two of us went out and took a couple of wrenches to loosen the bolt holding the locking ring. Bolt was frozen. Wouldn't budge.

So we used a die grinder with a cutting wheel on it. Just direct the cut so that the sparks don't go over the gash in the lid. That still had smoke coming out of it.

Was going just fine until the cutting wheel grabbed a little. Shifting the sparks over the gash in the lid.

BAM. Short very loud explosion. Blinding yellow light. Both of us flat on our butts. Wondering if the other was still ok, still with all hands, arms, legs...ears ringing.

"You ok?" "Yah. You?" "Hey, look at THAT!" He points up in the air. Hundred or so feet in the air, tumbling end over end, is the lid! It landed at the other side of the adjacent lot!

If we had been standing over the barrel instead of low to the side, I would'nt be writing this.

Fire Department did show up. Somebody called. Not us. Didn't really know what they wanted. Managed in place.

rgbai
12-17-2008, 02:27 AM
I think Aluminum powder and rust mixed together becomes thermite doesn't it.

macona
12-17-2008, 04:15 AM
More specifically aluminum powder and iron oxide. It needs to be very fine. And its hell to light. Usually need magnesium ribbon or something.

Thermic reactions are also used as part of the process of refining uranium.

Teenage_Machinist
12-17-2008, 05:09 PM
Wow that is scary!

However thermite is actually not really explosive...

Better clean up all aluminukm grindings

Evan
12-17-2008, 05:42 PM
It was just a small hydrogen bomb. Aluminum gives off hydrogen gas as it splits the water molecules to take the oxygen. Hydrogen has the particular property of burning at at very wide range of mixtures with air (4% to 71% LEL-UEL) and if enclosed the burning will switch to detonation same as a high explosive. This is one of the properties that makes it very difficult to use as a fuel in an IC engine.

When I was a kid I had an electric power model airplane. That was very unusual back then because motors and magnets weren't nearly as good as they are now. The batteries were even worse but that plane used a aluminum-air battery. Aluminum is highly reactive with air if it isn't protected by a coating of some sort including it's own oxide.



Aluminium batteries or aluminum batteries are commonly known as aluminium-air batteries or Al-air batteries, since they produce electricity from the reaction of oxygen in the air with aluminium. They have the highest energy density of all batteries, but they are not widely used because of previous problems with cost, shelf-life, start-up time and byproduct removal, which have restricted their use to mainly military applications. An electric vehicle with aluminium batteries could have potentially ten to fifteen times the range of lead-acid batteries with a far smaller total weight[1].

http://en.wikipedia.org/wiki/Aluminium_battery