pillyg Posted February 4, 2011 Posted February 4, 2011 I have some magnesium chips used for fire starting. I am trying to make MgAl but am failing. I am trying first to melt the Mg into blocks for easier melting. I put some chips into my furnace and put the lid on. I waited a while and opened it. It was burning but not a magnesium fire. It was a soft orange fire like a wood fire. The Mg never really melted. It made little crumbly bits. I covered it while "melting" it but that didnt seem to help. I am wondering if i wasted my money on the chips or if i am just doing something wrong.
Mumbles Posted February 4, 2011 Posted February 4, 2011 Typically the aluminum is melted first. You can bundle the chips up in aluminum foil and add it to the aluminum melt to use the chips. Generally ingots or larger chunks work better. With such a high surface area, you're going to have to expect lots of oxidation loss with just trying to melt chips.
pillyg Posted February 4, 2011 Author Posted February 4, 2011 I am premelting the Mg to make it into chunks for easier melting when making MgAl. l will try wrapping them in Al foil as soon as i can
dagabu Posted February 4, 2011 Posted February 4, 2011 It's really a waste of time to make ingots. You lose material every time you melt ig down and expose yourself to the hazards of a Mg fire. Al is everywhere so just make the MgAl all at once.
pillyg Posted February 5, 2011 Author Posted February 5, 2011 Well i tried but the Mg seems to oxidize completely and burn with a cool orange flame. Not the white Mg flame. I dont know what is up. It makes little bits that dont melt.
Bonny Posted February 5, 2011 Posted February 5, 2011 Well i tried but the Mg seems to oxidize completely and burn with a cool orange flame. Not the white Mg flame. I dont know what is up. It makes little bits that dont melt. Did you wrap the chips in foil as Mumbles suggested? I'm sure if you wrap them TIGHTLY (maybe several layers of foil) it will work. When you add the "packet" make sure it is completely submerged in the molten Al right away,I think that should work.
pillyg Posted February 5, 2011 Author Posted February 5, 2011 I haven't tried that yet because there is 2ft of snow here. I will try that as soon as i can.Do you know the purity of Coke cans? I have been melting them down then pouring them into chunks.
WSM Posted February 5, 2011 Posted February 5, 2011 I haven't tried that yet because there is 2ft of snow here. I will try that as soon as i can.Do you know the purity of Coke cans? I have been melting them down then pouring them into chunks. I believe drink cans are pure aluminum, but have a plastic coating on them. A source of pure aluminum is electric wires, especially the larger sizes. Be aware that some aluminum conductors (ACSR, or aluminum conductor, steel reinforced) have a steel wire strand running in the center of the bundle (for strength) that needs to be removed first. If you have access to scrap yards ask about purchasing scrap aluminum pieces for casting. They may have magnesium scrap too, since you're already there . WSM
Bonny Posted February 5, 2011 Posted February 5, 2011 I believe drink cans are pure aluminum, but have a plastic coating on them. A source of pure aluminum is electric wires, especially the larger sizes. Be aware that some aluminum conductors (ACSR, or aluminum conductor, steel reinforced) have a steel wire strand running in the center of the bundle (for strength) that needs to be removed first. If you have access to scrap yards ask about purchasing scrap aluminum pieces for casting. They may have magnesium scrap too, since you're already there . WSM A plastic coating will quickly burn off in the melt, so can could be used. Aluminum wire is what I use. If you have ACSR, you'll figure that out pretty quickly when you cut it up.
pillyg Posted February 5, 2011 Author Posted February 5, 2011 I have noticed the plastic or whatever coating burning off. It is to protect the can from the acidity of the drink. Dont know where there is a scrap yard around but thats a good idea.
mike_au Posted February 6, 2011 Posted February 6, 2011 Dont know where there is a scrap yard around but thats a good idea. If you can't find a scrap yard, go find someone who deals with a lot of old computers. Some universities have recycling programs, some shops refurbish second hand machines, etc. See if they have any old heatsinks or hard drivers. These are mostly Al and in fairly thick chunks so relatively little surface area/mass.
oldguy Posted February 6, 2011 Posted February 6, 2011 (edited) Motorcycle, lawnmower & small engine repair shops often have Mg scrap parts, as many of the engine casings etc., are Mg. Sometimes transmission repair places have damaged Mg transmission housings they will sell as scrap. Mom & Pop tire & wheel shops sometimes have damaged Mg wheels they will sell as scrap cheap. It's out there cheap sometimes, you just have to look.I found a trunk full cheap in a day of running around looking. Edit to add:Take a small eye dropper & bottle of white vinegar with you. A few drops on Mg will fizz, on Al it will not. Edited February 6, 2011 by oldguy
dagabu Posted February 6, 2011 Posted February 6, 2011 To add to Oldguys reply, check auto scrap yards, there are usually heaps of Mg wheels around there. Remember, take a pocket knife with you to scrape the Mg down to bright metal, you will not get a reaction on clear-coat or on oxidized Mg. Most mag wheels are an alloy and not 100% Mg so be prepared to espirement some.
pillyg Posted February 6, 2011 Author Posted February 6, 2011 Ok i will try that. I just wanted to use the shavings because i spent $30 on them.
pillyg Posted March 7, 2011 Author Posted March 7, 2011 I tried but it seems the fire either isn't getting hot enough or drink cans are like 50% junk because there was a bunch of crusty stuff that cane from the cans I melted. Do you know any way to make the fire hotter? I have seen the use of a blow dryer but I dont really have one that I could use for this.
MadMax Posted March 11, 2011 Posted March 11, 2011 Here's an idea. SF6 - Sulfur hexafluoride. It's an inert gas that is very heavy. It's so heavy that you can "pour" it into a bowl and float little paper boats on it. It also gives you a cool Denzel voice if you breath it. (do at your own risk). You could get a tank of the stuff and cover your melting pot with it. The cool thing is due to it's weight it would squeeze out any oxygen and nitrogen making the contact with the Mg and Al completely inert. This layer would stay in place and not need replenishing due to it's weight. It can also stay in place until after the mix has cooled and is no longer in danger of reacting with the atmosphere on exposure to air. It's not cheap but I can think of a million uses to have such a chemical. Ball milling for example - you could submerge your entire ball mill in a box of SF6 and mill up some aluminum. Instead of letting it oxidize little bit by little bit you could add in your own choice of passivation like stearic acid - Eckart style baby! "The magnesium industry commonly uses sulfur hexafluoride (SF6) to prevent the rapid oxidation and burning that occurs when the molten metal directly contacts air. Many companies apply a cover gas of dilute SF6 mixed with dry air and/or carbon dioxide (CO2) to maintain a protective layer on the molten metal surface." According to....http://www.epa.gov/magnesium-sf6/documents/tms_paper.pdf
pillyg Posted March 11, 2011 Author Posted March 11, 2011 Hum. If I could get some SF6 I would try it
MadMax Posted March 11, 2011 Posted March 11, 2011 Yeah its unfortunate its so damn expensive. I asked a supplier if they would ship me a small amount of it. Still waiting to hear back.
Bonny Posted March 16, 2011 Posted March 16, 2011 I tried but it seems the fire either isn't getting hot enough or drink cans are like 50% junk because there was a bunch of crusty stuff that cane from the cans I melted. Do you know any way to make the fire hotter? I have seen the use of a blow dryer but I dont really have one that I could use for this. When aluminum melts, it first enters a "slushy" state before fully melting to a liquid state.IF you got it hot enough, the crusty stuff is probably aluminum oxide. When trying to melt cans they essentially burn up before melting due to the low density and high surface area that is exposed to air.This can be fixed a bit by crushing/hammering the cans, folding and crushing again to make a thicker piece. A plain fire might not be hot enough. A fan or blow dryer will increase the temp of a fire...think of the bellows(?) used by blacksmiths back in the day.The type of wood used can also make a big difference.
dagabu Posted March 16, 2011 Posted March 16, 2011 Charcoal starters work great to melt Al. Don't remove the skim until you have fluxed the melt.
Bonny Posted March 21, 2011 Posted March 21, 2011 Charcoal starters work great to melt Al. Don't remove the skim until you have fluxed the melt.What do you flux it with Dag? I've never added any sort of flux...
dagabu Posted March 21, 2011 Posted March 21, 2011 I use Mica for a flux, it has always worked well in lead so I tried it in Al and it worked well too.
Bonny Posted March 26, 2011 Posted March 26, 2011 I use Mica for a flux, it has always worked well in lead so I tried it in Al and it worked well too. Do you notice much improvement fluxing the mix? I've never had a real problem with too much slag forming when melting Al...
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