Golden_eagle Posted June 11, 2009 Share Posted June 11, 2009 I now it's been a while since I've been on but i had to share this, Earlier today i was melting aluminum in my furnace, my ceramic crucible hasn't come in yet- so i have been using an old steel cup, we've had a rainy spell as of late, (Rust...) so i haven't been out to do anything in the forge area, i drop some bits of aluminum into the (rusty) cup, put it into the furnace and fire it up, three minutes later the door on the furnace blasts open and (molten) cup bits spray out, aluminum is dripping down the front of the furnace, iron is collecting like stalactites of the roof, and theirs a hole in the bottom of the cup... now i have to clean up the mess. Quote Link to comment Share on other sites More sharing options...
jimmy seale Posted June 11, 2009 Share Posted June 11, 2009 i know squat about that,but glad you wern't hurt...stay safe out there Quote Link to comment Share on other sites More sharing options...
John NC Posted June 11, 2009 Share Posted June 11, 2009 I believe that's the first time I've ever seen the words 'thermite' and 'oopsie' in the same sentence... :o Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 11, 2009 Share Posted June 11, 2009 That was more likely a steam explosion than a thermite reaction though I wouldn't say it's impossible I think it's unlikely. Thermite takes some care to make and is generally pretty hard to light. The aluminum needs to be unoxidized, finely divided and mixed pretty thoroughly with the correct amount of iron oxide to get much of a reaction. I've never heard of it forming under these conditions. My bet is there was some moisture somewhere, maybe under the rust and when the aluminum above began melting it flashed into steam and kerblooey. Maybe a bit of the furnace liner spalled off and had enough residual moisture to do the deed. Also, the byproduct of a thermite reaction is pure(more or less) iron, not aluminum. The aluminum is consumed by the reaction and turns to aluminum oxide slag. The iron and aluminum swap the oxy and release some heat. Regardless of what really happened, (my opinion is just that an opinion and I could be completely wrong) I'm very happy to hear you weren't hurt. I've been the recipient of a molten aluminum shower and it's no fun. Frosty Quote Link to comment Share on other sites More sharing options...
Rikadyn Posted June 11, 2009 Share Posted June 11, 2009 I believe that's the first time I've ever seen the words 'thermite' and 'oopsie' in the same sentence... Probally, cause generally when the two words combine, there is someone dead afterwards... Quote Link to comment Share on other sites More sharing options...
Morlock Posted June 12, 2009 Share Posted June 12, 2009 Probally, cause generally when the two words combine, there is someone dead afterwards... Or a big hole in the floor. Yeah, two words that just shouldn't go together. Quote Link to comment Share on other sites More sharing options...
CBrann Posted June 12, 2009 Share Posted June 12, 2009 Saw the title and was wondering about the list of damage. I don't melt metal... yet, but I think I learned something from this. Thermite and Ooopsie don't go well together. Smacks of death and destruction. Quote Link to comment Share on other sites More sharing options...
triw Posted June 12, 2009 Share Posted June 12, 2009 Having been a comerical bullet caster I agree with Frosty that most likely it was moisture. The water most likely was in a seam of the cup or somewhere. If you are going to melt aluminum or lead and have had a lot of moisture preheat your container to dry it out. MOST INPORTANT IS SAFTY GLASSES AND PROTECTION Quote Link to comment Share on other sites More sharing options...
Glenn Posted June 12, 2009 Share Posted June 12, 2009 (edited) In order to work ANY liquid metal, full safety protection is a must. If you are really serious about safety, consider velcro or break-away closures so aprons and other protection can be removed quickly. It is no time to try to remember what type of knot was used to tie the apron strings once the apron has stopped the liquid metal and/or catches fire. You want out of the apron and leathers, fast. I agree that steam may have played a part. Bring your tools up to working temperature before you start. We are glad only the furnace took the hit, and you are safe. Edited June 12, 2009 by mod07 typo Quote Link to comment Share on other sites More sharing options...
ptree Posted June 12, 2009 Share Posted June 12, 2009 At the valve, boiler and ice machinery factory I spent 21 years working at, we had a car bottom furnace we used to stress relieve weldaments. The furnace was 70' long, by 16' wide and 18' tall, and gas fired. The weldaments were stress relieved only so not as hot as a forge. One day the furnace temp started climbing, and the operator saw the controls try to turn down the burners to maintain. The controls hit bottom of range and still climbing. He turned off the gas to try and get control and still climbed. It burned out the thermocouples above something like 3000 or 4000F. We had liquid metal leaking around the door. Took several days to cool, and then the fun began. I had suggested a "Goldsmieder's" reaction when first I had heard. They all looked at me like I was daft, so I explained that is the name I had learned for what they would find as thermite reaction. It took jackhammers and heavy equipment to break away the slag, melted refractories etc. Then a locomotive to pull the now unable to roll car bottom out of the furnace to finish cooling. We had stalactites, and stalagmites that were several feet around. The steel had been "aluminum killed" and when they looked at the test data the steel had a higher than normal level of aluminum. The weldaments were stored outside and had heavy rust. Final opinion from the metallurgists was it sure looked like a thermite reaction, but there should have been no way to get it to happen. Not a high enough ignition temp, not finely divided etc. But to this old ARMY vet the results sure looked like the results of a thermite grenade applied to an engine block. There was however NO EXPLOSION. I would lean to steam in this case. Quote Link to comment Share on other sites More sharing options...
Fe-Wood Posted June 12, 2009 Share Posted June 12, 2009 Wow! You sir are a lucy man. No fire after or personal mis-hap, phew! Get that ceramic crucible! As you found out, rust has no business in a furnace! Glad you were not hurt uuugggg, scarry Quote Link to comment Share on other sites More sharing options...
Glenn Posted June 18, 2009 Share Posted June 18, 2009 It has come to my attention via email that we need to add a safety statments here. Thermite is a highly exothermic reaction that burns to completion, and is definitely NOT something the uninformed or untrained should be associated with in any way. Ptree thank you for reminding us that even trained individuals under controlled conditions can have problems. One point that may have been missed in the above post is the documentation of all steps of the manufacturing process. Those documents and notes were on file and could be retrieved and reviewed in order to figure out what happened. Quote Link to comment Share on other sites More sharing options...
thoramighty Posted June 18, 2009 Share Posted June 18, 2009 maybe some one should put this into mythbusters to see if it was a possibility that it was a thermite reaction or if we are safe of that happening. P.S. Glad you wernt hurt i have seen what molten lead and aluminum can do to flesh its nasty Quote Link to comment Share on other sites More sharing options...
ptree Posted June 19, 2009 Share Posted June 19, 2009 In addition to Glenn's observation that we had detailed records to help investigate, we had a full service metalurgy lab and several degreed metalugists to do all the samples etc. I would echo also that thermite is a useful but once started unstoppable reaction. 5000F is temps that will melt most refractories, explode concrete, and melt down thru huge thickness of metal. The military uses thermite grenades to destroy equipment when needed in a hurry. I have seen thermite grenades go completly thru a 5 ton truck engine in seconds, leaving a hole as big as a man's arm, and the smoke and fire from the engine oil was unbelievable. Not something to "play around with" the components of thermite are also combustable metal powders that are very dangerous in and of themselves. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 19, 2009 Share Posted June 19, 2009 A note on Mythbusters and Thermite. What they use is seriously detuned thermite. Remember the car they virtually buried with hundreds of lbs of thermite and still couldn't cut it in half? They're an entertainment program, not a serious testing facility. Don't mess with thermite, it's the perfect example of "a little knowledge is dangerous." There's a BIG difference between mixing some up and properly preparing it so it doesn't blow you to kingdom come. Frosty Quote Link to comment Share on other sites More sharing options...
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