Smelting aluminum cans

[Norbert]

This is just a hypothetical question, I am not planning on actually smelting any metal, at least not at the moment. I have a collection of aluminum cans that I amassed over a period of 6 months on my long walks along the forest preserve trail (along a river) and the surrounding area/neighborhood. A lot of my cans were at some point in the river and have accumulated some river sediment on the inside. Some of them were found by the side of the road and have sand and even small pebbles embedded in them. Other cans contain cigarette butts, gooey substances that resemble thick saliva, ants and other dead bugs and insects, small and assorted pieces of plastic, etc. I have a 15 heavy-duty garbage bag collection of flattened cans, quite a lot. Cleaning them all out by hand would be a very onerous and not to even mention dangerous task. I'd rather not do it. What if I were to melt these cans down together with all their non-metallic impurities? I am aware that normally the less dense impurities come up to the top and the denser ones sink to the bottom, but would the presence of plastics, some of which might contain traces of other metals, be a particular concern? What about sand and small rocks? Would the silicon in them separate from the oxygen and sink to the bottom as slag?

 

I think I'll sell my collection to a scrap yard eventually, once the price of aluminum gets to a reasonable level. If that doesn't happen I might want to smelt them and make ingots for easier storage.

Edited August 2, 2012 by Norbert

[Moontanman]

In a pinch you could build a camp fire out of them... Aluminum cans burn quite well...

[Norbert]

I see I've asked a stupid question. But it's genuine. It might be obvious to most people here but it is not obvious to me.

[Moontanman]

I see I've asked a stupid question. But it's genuine. It might be obvious to most people here but it is not obvious to me.

 

 

Not stupid at all, i was trying to point out that aluminum burns, trying to smelt it requires special electrical equipment. If you are looking to concentrates it just smash the cans, they sell little devices that can flatten them out so that many of them fit in the same place one can would. melting them down will be a problem because they burn quite well...

[CaptainPanic]

I am guessing your cans are mostly soda/beer cans? Please note that not all producers of beverages use aluminium. Some use steel.

To test, get a magnet. Some will be magnetic, some won't.

 

A large recycling plant will be able to (automatically) split those two, and it can also separate other (non-magnetic) metals from other waste (here's a wikipedia link about the process). It uses an Eddy Current Separator for that. To be honest, I think any attempts to melt it down to ingots at home will turn into a disappointment, because you won't be able to remove the other goo/sand/pebbles/insects/etc...

 

In all fairness, you should just sell the bags to a recycling plant. A quick Google search suggests that the price for mixed scrap metal is about 100-200$/ton, but it depends how dirty your cans are if they will give you such money...

[Greg H.]

First, be aware that aluminum melts at something like 933 K (660 C) - whatever you smelt it in has to be able to withstand that temperature long enough to actually melt the aluminum and hold it until you pour it off.

 

Second, check out http://www.submarineboat.com/casting_aluminum.htm

 

It seems to cover at least the basics, and tells you how to build a foundry to actually melt the aluminum (as well as how to make interesting parts from it, should you desire).

[imatfaal]

Although Aluminium will burn like crazy once it gets going - I am sure that I melted and tried to cast Aluminium as a kid (I did lots of stupid and dangerous things - thermite is the prime example of both Al's desire for oxygen and the stupid things we used to do for kicks). I seem to remember a large super scummy layer of muck, oxide (i guessed), paint, etc and a disappointing casting - but no bursting into flames. I was trying to cast boule - and their spherical nature left a lot to be desired, although the flat sides did allow for some great shots.

[Norbert]

Not stupid at all, i was trying to point out that aluminum burns, trying to smelt it requires special electrical equipment. If you are looking to concentrates it just smash the cans, they sell little devices that can flatten them out so that many of them fit in the same place one can would. melting them down will be a problem because they burn quite well...

 

Interesting. I did not think aluminum would be any different from a metal like lead for example, I just figured it would require a higher temperature to melt. I guess it's more reactive with oxygen than lead so you need to smelt it in an oxygen-free environment.

 

In all fairness, you should just sell the bags to a recycling plant. A quick Google search suggests that the price for mixed scrap metal is about 100-200$/ton, but it depends how dirty your cans are if they will give you such money...

 

 

Yeah, that's plan A, B and C, etc. The self smelting was something like plan W.

 

Will they just assume my collection is mixed scrap? I'm pretty much 100% sure my collection is not mixed because I did a magnet test on each new can that I encountered and it never stuck. I can usually tell what an aluminum can looks like as opposed to a steel can, the shape and the sound it makes are different. I guess some cans can be made out of a non-magnetic metal that isn't aluminum but I haven't read of any such alternatives.

[Moontanman]

Aluminum was one of the metals i never was able to smelt when i was young, i did the same thing some of the others mention, I managed to melt tin, copper, lead, solder, and I managed to get steel so hot is was like taffy but it never really melted. I had several accidents not the least of which was my fire enclosure exploding because i made the first one out of sand stone, i was lucky, i ended up with molten lead all over me...

 

All i ever got out of aluminum cans was a fire...

[Norbert]

Aluminum was one of the metals i never was able to smelt when i was young, i did the same thing some of the others mention, I managed to melt tin, copper, lead, solder, and I managed to get steel so hot is was like taffy but it never really melted. I had several accidents not the least of which was my fire enclosure exploding because i made the first one out of sand stone, i was lucky, i ended up with molten lead all over me...

 

All i ever got out of aluminum cans was a fire...

 

Wow, that must have been scary. You were indeed quite lucky if you came out of that relatively unscathed.

 

I guess I could have used my observations with aluminum foil to get an idea of what might happen if I tried melting aluminum cans. I always wondered why it didn't melt down in a fire, just sort of burned. I figured the reason was because it wasn't pure aluminum or that it was so thin and coated with some other substance.

Edited August 2, 2012 by Norbert

[elementcollector1]

Whoa there! Aluminum isn't as difficult to *melt* as you might imagine. (I have a problem with the misuse of the word smelt. It means 'to refine from ore'.)

Step 1: Get a good coal fire going inside a large steel soup can. This will have an empty, smaller soup can in the center of the fire.

Step 2: Place a crushed aluminum can inside the smaller can, being careful to avoid burning yourself.

Step 3: Wait until the first can melts, then add more aluminum.

Step 4: Repeat until you have a good, can-sized bit of molten aluminum.

Step 5: Wait until the fire dies completely, and remove the can. Cut it open if you have to to remove the aluminum ingot.

Step 6: BAM! Aluminum ingot. Repeat for a ton of aluminum that looks cool, but is basically useless.

 

I do this regularly with my Scout Troop, and do have a few notes to add to the procedure:

-Some, if not most of your aluminum WILL oxidize to a gray, useless flaky mix of aluminum and its oxide. If you really want to get rid of this, take a stainless steel strainer and pour your molten aluminum through it.

-Don't cast into water. BAD THINGS HAPPEN.

-Use relatively clean cans, otherwise they're much harder to melt and have carbon in them from all those organic impurities.

 

So, you need a few soup cans of various sizes, coal, a lighter, and of course the aluminum in question. Again, be careful, this is molten metal at 1000 C we're discussing.

[Moontanman]

Whoa there! Aluminum isn't as difficult to *melt* as you might imagine. (I have a problem with the misuse of the word smelt. It means 'to refine from ore'.)

Step 1: Get a good coal fire going inside a large steel soup can. This will have an empty, smaller soup can in the center of the fire.

Step 2: Place a crushed aluminum can inside the smaller can, being careful to avoid burning yourself.

Step 3: Wait until the first can melts, then add more aluminum.

Step 4: Repeat until you have a good, can-sized bit of molten aluminum.

Step 5: Wait until the fire dies completely, and remove the can. Cut it open if you have to to remove the aluminum ingot.

Step 6: BAM! Aluminum ingot. Repeat for a ton of aluminum that looks cool, but is basically useless.

 

I do this regularly with my Scout Troop, and do have a few notes to add to the procedure:

-Some, if not most of your aluminum WILL oxidize to a gray, useless flaky mix of aluminum and its oxide. If you really want to get rid of this, take a stainless steel strainer and pour your molten aluminum through it.

-Don't cast into water. BAD THINGS HAPPEN.

-Use relatively clean cans, otherwise they're much harder to melt and have carbon in them from all those organic impurities.

 

So, you need a few soup cans of various sizes, coal, a lighter, and of course the aluminum in question. Again, be careful, this is molten metal at 1000 C we're discussing.

 

 

How do you keep it from catching on fire and burning up?

[elementcollector1]

We don't have to. It melts without ever catching with this method. (It takes a while, though.)

[chilled_fluorine]

We don't have to. It melts without ever catching with this method. (It takes a while, though.)

 

You guys think aluminium is hard to melt! I've made magnalium in my "ghetto foundry". My secret? Put a lid on the crucible. Herp derp. I have ruined a few ghetto foundries over the years, when the lid has fallen off, before I added the aluminium to the molten magnesium. That stuff BURNS. Anyways, just wanted to say that I've melted most everything. Lead, silver, gold, aluminium, iron/steel, bronze, brass, pewter, copper, tin, bismuth, manganese, zinc, and probably a few others. Once I tried lithium, but that didn't turn out so well... :cringes: If you have a question about casting, ask me, or google backyardmetalcasting. Sorry, I'm too lazy to post a link. Don't use charcoal as fuel, make yourself an injector style waste veggi/ motor oil burner. Propane is good too, although not very cheap. I couldn't quite get steel with charcoal, but my wvo burner does it easy. Try using "the brute" from backyardmetalcasting. It's what I got my first iron melt from. Now I've made a more sophisticated burner, but the brute is simple and very effective. Sorry to ramble, sorry to brag, but I am good at melting things...

[elementcollector1]

You guys think aluminium is hard to melt! I've made magnalium in my "ghetto foundry". My secret? Put a lid on the crucible. Herp derp. I have ruined a few ghetto foundries over the years, when the lid has fallen off, before I added the aluminium to the molten magnesium. That stuff BURNS. Anyways, just wanted to say that I've melted most everything. Lead, silver, gold, aluminium, iron/steel, bronze, brass, pewter, copper, tin, bismuth, manganese, zinc, and probably a few others. Once I tried lithium, but that didn't turn out so well... :cringes: If you have a question about casting, ask me, or google backyardmetalcasting. Sorry, I'm too lazy to post a link. Don't use charcoal as fuel, make yourself an injector style waste veggi/ motor oil burner. Propane is good too, although not very cheap. I couldn't quite get steel with charcoal, but my wvo burner does it easy. Try using "the brute" from backyardmetalcasting. It's what I got my first iron melt from. Now I've made a more sophisticated burner, but the brute is simple and very effective. Sorry to ramble, sorry to brag, but I am good at melting things...

 

Ha! Lithium. I gave up trying to melt lithium a while ago, there's just no way to do it short of argon flow, a steel injector, and immediate ampouling under argon.

Also: Can't find 'the brute'. Found plenty of other interesting designs, though.

[chilled_fluorine]

Ha! Lithium. I gave up trying to melt lithium a while ago, there's just no way to do it short of argon flow, a steel injector, and immediate ampouling under argon.

Also: Can't find 'the brute'. Found plenty of other interesting designs, though.

 

Five seconds' worth of google searching yielded this http://backyardmetalcasting.com/oilburners09.html link. I did have that lithium melted, I swear it! It just exploded before it could solidify. Lolz

[elementcollector1]

Five seconds' worth of google searching yielded this http://backyardmetal...lburners09.html link. I did have that lithium melted, I swear it! It just exploded before it could solidify. Lolz

 

Not bad, but I have no access to welding supplies...

How on earth did you manage to melt lithium in the first place? Every time I try, it either burns into a hopeless lump of oxides, nitrides, etc. or eats its way through the container (there is almost no known container that can handle molten lithium, for various reasons).

[EPhantom]

Back to the first questions for a bit... I heard cigarett filters are made of fiber glass, it will act just like sand and either sink or float, same with the rocks. the insects will burn... to some degree, and the rest of them (all the other elements besides oxygen carbon and hydrogen) will stay in your crucible. I have not melted any metals yet, but I've done a little bit of research into them.

As for plastic... don't worry about it, there is "some" on the outside as coating for the labels, but that will just burn off,

And I wish Silicon released it's oxygen that easily your silicon dioxide will stay that way unless you can heat it to extremes.