oldguy Posted July 18, 2011 Posted July 18, 2011 (edited) Today made a few 5 lb batches of water quenched 50/50 Mg/Al. Once done, I had about ½ lb of Al & ½ lb of Mg left over unused. Bink , a light goes on & I remember wanting to make an Mg/Al/Sb alloy. So, I go to the shop, gather up a ½ lb chunk of Stibnite. Insert Al in crucible, insert crucible in gas fired metal melting fire brick kiln. Wait a few minutes, withdraw crucible, insert Mg in it & return crucible to kiln. Wait a few minutes , withdraw crucible, insert Sb in it & return crucible to kiln. Wait a few minutes, withdraw crucible, stir content & reinsert crucible in kiln. Okay, now what, just let it cool. Or, water quench the Mg/Al/Sb alloy. I decide water quench it. Carry crucible over to my water quenching shield, in front of an 8 gallon metal stock pot ¾ full of water. Position myself carefully, use tongs to remove crucible lid. Position crucibles 36 inch handle on top the 4ft tall plywood shield, with the crucible over the bucket. With my right hand, I reach up & flip down my full face shield, then grasp handle with both hands. I twist the handle a little so the molten alloy will start pouring slowing out & into the bucket. A stream of molten alloy about ½ inch in diameter flows out & pours down into the bucket. About 2 seconds after that stream of alloy hit the water. It was as if the water bucket turned into a giant JET ENGINE Alloy ignited, bucket shot a white flame about 6ft in diameter 20 or so ft into the air. In that flame were molten drops of deflagrating Mg/Al/Sb alloy. I stood immobile paralyzed, somewhat blinded by the flash. As the flash died down (about 3 seconds), I felt some searing pain. I rotated to my left with the crucible on a 36 inch handle in hand . Crucible was emitting a 5 ft jet engine white flame & set it on the ground & ran. As I ran I stripped of my cotton sweat shirt, as I thought my shoulder was on fire. Started to hobble, tripped, as 1 shoe was smoking, rolled on the ground stripped off gloves & that shoe. Hobbled into the shop, straight to first aid kit that I knew had gel packs for severe burns. End result, a bunch of tiny blister burns & 3 burns about dime to nickel sized from deflagrating molten alloy & almost 3rd degree. One on my foot, one on my shoulder & one on my upper wrist. THE REST OF THE STORY Had I not had a shield in front of me, had on a hat, heavy gloves, full face mask & welders apron. I would probably be in a burn unit of the local hospital horribly disfigured. Edited July 18, 2011 by oldguy
Xtreme Pyro Posted July 18, 2011 Posted July 18, 2011 Holy CRAP! Glad to hear your okay oldguy, it was a smart idea on your end to have that shield. Also another great reminder how important safety really is. Hope you heal up quickly .
oldguy Posted July 18, 2011 Author Posted July 18, 2011 Jack Daniels is helping me out................ Wife is muttering “you have to stop this pyro BS”……… I wonder why it did that? I think it had to do with the Stibnite in the mix.
optimus Posted July 18, 2011 Posted July 18, 2011 Had I not had a shield in front of me, had on a hat, heavy gloves, full face mask & welders apron. I would probably be in a burn unit of the local hospital horribly disfigured. Something for everyone to think about that, thanks for posting details. Very glad to hear you're OK, hope you have a speedy recovery.
dagabu Posted July 18, 2011 Posted July 18, 2011 Jack Daniels is helping me out................ Wife is muttering "you have to stop this pyro BS"……… I wonder why it did that? I think it had to do with the Stibnite in the mix. Sorry to hear the bad luck OG, gonna have to get the wife involved in making rockets and get her used to the "BS". Glad to hear you are pretty close to alright. -dag
oldguy Posted July 18, 2011 Author Posted July 18, 2011 (edited) Sorry to hear the bad luck OG, gonna have to get the wife involved in making rockets and get her used to the "BS". Glad to hear you are pretty close to alright. -dag That was a learning lesson. Natural raw Stibnite has a sulfide content, which may have something to do with the ignition.It seems when the alloy was exposed to open air, then hit the water, some flamable gas was generated that ignited.Which in turn appears to have ignited the molten alloy.Ignition ran up the alloy to the crucible, which also ignited. It was not a stream type explosion, it was more like the after burner on a jet engine kicking in. Wife saw it & said it was about 6 ft in diameter, 4 times as tall as me & I am 6.1.The bucket rim acted like a large nozzle directing the flash mostly upward.Thank heavens I had a 1/2 sheet of plywood in front of me as a sheild & had a face shield on. I wish I had a video of this as it happened. Edited July 18, 2011 by oldguy
dagabu Posted July 18, 2011 Posted July 18, 2011 I wish I had a video of this as it happened. I'm glad that you didn't, I have seen enough of stuff like that live to last me several lifetimes. Good luck and get to healing already! -dag
moondogman Posted July 18, 2011 Posted July 18, 2011 Hmmm sounds like a new rocket fuel. glad your not hurt too bad.Steve
Mumbles Posted July 18, 2011 Posted July 18, 2011 I'm sorry to hear about this mishap. Are you sure you added metallic antimony, and not the trisulfide? Generally if you have the mineral stibnite, it's all antimony trisulfide, which I could forsee causing problems. I could see that being an issue, as stibnite crystals are quite metallic looking. Both aluminum and magnesium sulfide decompose in water quite readily producing H2S (flammable). I don't know for sure, but I'd bet that both could reduce antimony trisulfide. When that hit the water at an elevated temperature, I could see the reaction getting quite out of control.
oldguy Posted July 18, 2011 Author Posted July 18, 2011 Are you sure you added metallic antimony, and not the trisulfide? Generally if you have the mineral stibnite, it's all antimony trisulfide, which I could forsee causing problems. I could see that being an issue, as stibnite crystals are quite metallic looking. Both aluminum and magnesium sulfide decompose in water quite readily producing H2S (flammable). I don't know for sure, but I'd bet that both could reduce antimony trisulfide. When that hit the water at an elevated temperature, I could see the reaction getting quite out of control. What I added was a chunk of mineral Stibnite, as pictured below:In other words, antimony trisulfide.Oddly, it melted in the crucible & didn't react while melting.But, that was probably because of the lack of oxygen in the kiln & crucible.
Ralph Posted July 19, 2011 Posted July 19, 2011 thats the Trisulfide there glad your ok mabey the antimony prevented passivation from occuring so when it hit the water magnesium (and aluminium) did what it loves to do
usapyro Posted July 19, 2011 Posted July 19, 2011 (edited) I thought you were supposed to cool down alloys by just covering them with charcoal or ash and just waiting. Magnesium and Aluminum combined with water as powders in near 50/50 ratios make good rocket fuel. The solid rocket fuel ALICE that nasa and college research departments are working on is a mixture of nano aluminum and frozen water. I have personally tested Al/Water and MgAl/Water rocket fuels with 1.5-3 micron powders and some larger micron sizes and they are hard to light with a torch, but when you get them going DAMN they are HOT! It is possible in theory that the molten Al may also be combined with water to make a liquid fuel for rockets... However, it wouldn't exactly be possible to keep the Aluminum hot and flowing in storage... LoL! Also, to be efficient the molten aluminum would have to be sprayed together directly with the water as a super fine mist... Interesting idea anyway. I think you discovered an alloy that is more effective in breaking apart water into hydrogen and oxygen... That's my thought. Edited July 19, 2011 by usapyro
Peret Posted July 19, 2011 Posted July 19, 2011 Shoot, I'm glad you weren't too badly hurt, though even small burns are very painful. There would have been only steam in direct contact with the metal as it was poured in. Lots of things can reduce steam to hydrogen and oxygen - hot carbon for one - so it wouldn't surprise me if magnesium or aluminum could do it. I don't know what part the antimony may have played, though I'm more inclined to suspect the sulfur, but perhaps you were just lucky with previous batches and this was always a hazard.
dagabu Posted July 19, 2011 Posted July 19, 2011 I thought you were supposed to cool down alloys by just covering them with charcoal or ash and just waiting. Magnesium and Aluminum combined with water as powders in near 50/50 ratios make good rocket fuel. The solid rocket fuel ALICE that nasa and college research departments are working on is a mixture of nano aluminum and frozen water. I have personally tested Al/Water and MgAl/Water rocket fuels with 1.5-3 micron powders and some larger micron sizes and they are hard to light with a torch, but when you get them going DAMN they are HOT! It is possible in theory that the molten Al may also be combined with water to make a liquid fuel for rockets... However, it wouldn't exactly be possible to keep the Aluminum hot and flowing in storage... LoL! Also, to be efficient the molten aluminum would have to be sprayed together directly with the water as a super fine mist... Interesting idea anyway. I think you discovered an alloy that is more effective in breaking apart water into hydrogen and oxygen... That's my thought. Water quenching is not going to light up Mg/Al, it does not have to be sprayed over water. This accident was not related to water quenching of Mg/Al, it was in all probability the antimony trisulfide that caused the fire. -dag
oldguy Posted July 19, 2011 Author Posted July 19, 2011 Water quenching mgal can be done safely, so long as you use proper precautions & safety measures. I have done large batches multiple times, without any issues. The stupid MISTAKE I made was adding antimony trisulfide to the mix, rather than the metal antimony. Antimony trisulfide deceptively looks like pure metal, but is not. Hence the trisulfide name. I should have thought of that. I suspect the sulfide content formed a highly combustible gas as the molten alloy hit the water. As more alloy hit the water, more gas was generated. In milliseconds the gas ignited, causing the jet engine like effect, which in turn ignited the string of molten alloy poring out of the crucible.
stckmndn Posted July 19, 2011 Posted July 19, 2011 I'd really miss your threads and links if you were gone, oldguy.
oldguy Posted July 19, 2011 Author Posted July 19, 2011 I'd really miss your threads and links if you were gone, oldguy. Thanks for the kind words. I'm on a mission & a little inferno isn't about to stop me.
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