Introduction: Recycling Aluminum (Aluminium) - Make Your Own Al Foundry.

It has always been a very fascinating thing to see the things that we as humans have been able to accomplish through time. How we were able to build amazing things, utilizing only our imaginations and the resources around us.

This project is no stranger to these feelings I have and can teach a lot of things to anyone attempting it. We gave it a try at our hackerspace H3 Laboratories

There are various ways that you can do this project of course, so you can take ideas and go melt some aluminum at your house or hackerspace. Invite some people over and melt Aluminum together. It may look simple but it is very enjoyable and camaraderie forming.

Have fun

Keep in mind, that you should do this outside, and stay safe. Get some goggles, welding gloves or better, and closed shoes or boots.

If you choose to follow these recommendations, I or anyone or anything mentioned in this instructable are not responsible or liable, under any circumstances for any personal injuries, accidents. death or bad things that might occur whilst the melting is underway or anything related to the actions you might take by following this instructable. Please use common sense and be safe.

Step 1: What You Need



Aluminum is quite easy to melt, it does not require much heat. Based on what we have here, you can get ideas and adapt to what you have on hand. It is also very interesting to attempt to make this project as low cost as possible.

  • Decent speed air source. We used an old ShopVac with a divergent nozzle and clothes drier duct to reduce the speed and increase the flow of air per unit area.
  • Safety gear (Dial 911 if something major occurs! Their safety gear is always better than yours) - You will need big gloves, welding gloves can work fine. A first aid kit, and some proper eye protection. Face shields are better, but get at least some goggles.
  • Fire Bricks, Granite Stones, or Brick pieces - You need some way to contain your fire. It is best to use Firebricks, you can use any material that does not have water inside and is in general non-porous and therefore cannot absorb water. You can use very dry bricks, but there is always a chance that they might have water inside, in which case they can explode in a variety of ways.
  • Sand. - Any sand can do the trick, just make a mound and arrange your fire pit as show in the pictures.
  • Steel Tongs - You need some way of feeding your crucible.
  • Crucible - This is where the actual metal will be heated, melted, and contained. Any stainless steel container will do, just make sure it fits.
  • Bread Pan - You can make very nice looking ingots with a bread pan, the more used the better, because the resin in brand new ones when burned will produce dark coloration on the surface of your solid ingot and decomposition byproducts of Teflon. Do not breathe the fumes produced by this, just to stay safe. Or better yet, just get a cast iron mold or another plain stainless steel mold.
  • Scrap Aluminum - You can get this from anywhere, just collect as much as possible so you can have a good amount to melt. Some sources are heat exchangers, heat sinks, cans, hard drive chassis. Try to pre-heat, and dry the aluminum scrap before melting as some water in the metal may cause unexpected reactions, which can be scary or dangerous due to violent failure of a vessel or container. The more solid the aluminum the better such as the aluminum in heatsinks.

Step 2: Put Everything Together

There really is no specific way that you should arrange all the components, you can experiment here and try different approaches to see what gives you the best results. 



The only thing to consider for good heat transfer is: make sure that you have good air flow from underneath the coals so that they light up really good and increase their temperature. Remember the brighter the hotter. Also make sure that you have coals high up the length of the crucible, as this will insure the best heat transfer.



You can use the Blackbody radiation temperature color chart to estimate the temperature, or if you have a thermocouple, use that.



http://en.wikipedia.org/wiki/Black-body_radiation#Explanation

Step 3: Time to Pour Your Aluminum!








Now all you have to do is pour your aluminum and let it cool, you can experimenting with cooling rates to change the crystal structure as well, but that would be for another Instructable.



Before pouring you might need to remove the slag that accumulates at the surface of the molten aluminum. In our case most of the slag stayed behind. So we didn't have to, anyways.



Thank you for reading! Post pictures of your melt! Let's Recycle!



This instructables was created by Guillermo Vargas et alia, at H3 Laboratories in El Paso, Texas for the sponsored Instructables challenge. 

Any entity or individuals mentioned in this text are not liable or responsible under any circumstances for any injuries, damage, loss , including personal injury or death, resulting from the guide or the execution of these steps.


Stay Safe!

Comments

author
askjerry (author)2013-11-12

Excellent Instructable!

However... I do have to ding you on the vertical video...
http://www.youtube.com/watch?v=Bt9zSfinwFA

Grin.

author
gavargas (author)askjerry2013-11-13

Haha that's hilarious. Sorry I had this syndrome. Never again!

author
roknorr (author)2015-02-18

Hey, I'm totally amateur in blacksmithing. How do you do about the impurities of aluminum cans when melting?

I'm having a hard job when pouring the melted aluminum in the mould, as the aluminum stays mostly with them, sometimes droping them with it in the mould..

author
ShadmonM (author)2014-09-16

Wow that was really scary. Check for water in your molds, and dry them. really well.

author
Logan Hanssen (author)2014-07-22

Try pouring the molten aluminium in a ant hill/mound. You can get very interesting results

author
kingzilla (author)2013-11-11

I have done something similar with a hairdryer on cold for the air source. I have heard of using salt for a flux, but avoided it due to concerns about producing chlorine gas.

What are you using specifically for your crucible? I seem to be able to reach temperatures hot enough to melt a hole through the steel pots I've tried using. Does the wall thickness have to be significant? Or is it to do with the specific alloy of steel?

author
ironsmiter (author)kingzilla2013-11-12

If you are burning holes in your pots on the first melt, turn down the blower and exercise patience. If you can't stand to wait the extra couple min, switch to cast iron pots. If you can melt cast iron in your fire, congratulations! Get a proper crucible and start iron pours!

Seriously though, stainless steel(at least 12gauge) or cast iron should be good enough to get started melting for ingots. After creating a stockpile of ingots, and getting familiar with the process, THEN look into carbide, graphite and ceramic crucibles. But I will bet that a nice small cast iron pot will serve you well for many months.

If you worry about the possible contamination from a steel or iron crucible, get a container of crucible wash from Amazon or your local ceramics supplier. It will keep your ingots cleaner, and make the pots last quite a bit longer.

author
gavargas (author)ironsmiter2013-11-12

Very good response(s), thank you @Ironsmiter.

I want to go into blacksmithing, do you do blacksmithing?

author
ironsmiter (author)gavargas2013-11-26

Not nearly as much as I would like to.
I actually did some of my college time chasing a 'metalworking' BFA.
Half "Small and Shiny", half "Big and Black"

You want to go into smithing.... Texas, you're probably surrounded by Farriers. Good start for getting your hands dirty, but limited in where you can go and what you can do. Probably plenty of work though.
On the upside, if you are anywhere near Austin, The welding department there has an AAS in Art metal, that is MOSTLY blacksmithing.
Probably the best(and somewhat scary?) resource is gonna be http://www.abana.org/

Or if you just want to talk with me, PM me anytime.

author
gavargas (author)kingzilla2013-11-12

I have heard that Borax can be used as flux, but I have also read that in Aluminum it is really not that necessary to use a flux.

As I understand it the goal is to keep the air from contacting the molten metal. In the case of aluminum, skimming off the slag is enough to get you a very good aluminum pour. Experts say don't stir it, because that causes gas to get in.

Aluminum is easier and safer than casting iron.

For a crucible and charcoal I found that the thinner steel pots work better, because you can heat them up quicker with not so much fuel and energy. We tried using an actual ceramic crucible we got from a donation but we never got it to heat up enough to do anything! So we went for the thinner walled steel pot.

Once we can get more energy output then we can use the ceramic crucible, was my hypothesis.

We also opted for making ingots first, and getting familiar with the process, then later on we can do more interesting things.

One thing that helped a lot was: Start with am ore solid piece of aluminum, wait to get a nice pool of molten aluminum and then put in cans and anything else that is more thin. Once you get the pool of metal, everything else gets easier.

crucible_1.jpg
author
Morganbarker (author)2013-11-14

I would like to add a word of caution to anyone thinking of doing this to condense their Al scrap to sell at a recycling facility...Don't. They will likely offer you less than half of the going price for aluminum under the excuse that you may have tampered with the alloy to raise the weight. I had this happen to me at two facilities when I was liquidating my ingot stock before a cross country move. After both lowballed me with offers of 20 cents a pound, I found it made more sense to ship my aluminum to our new house rather than start over.

author
Trooper555 (author)2013-11-13

Did you by chance remove the slag before recording?

author
Norm Fasey (author)2013-11-13

What do you plan to do with the recycled Aluminium?

author
gavargas (author)Norm Fasey2013-11-13

I made ingots, and I want to make some specimens for tensile strength testing. Maybe later make aluminum stock for a lathe? Or just making casted parts.

author
Norm Fasey (author)gavargas2013-11-13

Well whatever you decide to do, it's a very cool instructable. Well done!

author
BlackSmoke (author)2013-11-13

Pretty cool! Do the ingots eject nicely from the pie-tin molds once cooled? Very curious about other preferred potential mold materials, perhaps sand-casting?

author
gavargas (author)BlackSmoke2013-11-13

The do eject very nicely, you will see that when they contract, you do not even have to tap them or anything, they just come out.

We will try to do some sand casting for sure. That would be the next step.

author
Crimson-Deity (author)2013-11-13

And then this happens; http://www.youtube.com/watch?v=A796N_YZTm8

author
gavargas (author)Crimson-Deity2013-11-13

Wow that was really scary. Check for water in your molds, and dry them. really well.

author
Crimson-Deity (author)gavargas2013-11-13

A heatgun is the best to be sure. It preheats the mold and removes any moisture if any! =))
(Made stuff out of tin and copper with a pro a few years back)

author
Mindmapper1 (author)2013-11-12

Working with moulton metal is highly dangerous even with the right safety gear! I would be interested to know what you will use the firstaid kit for, I suggest that should something go wrong 911 would be a better call. The using of thin walled pans to pour the metal into is not a good idea.

author
gavargas (author)Mindmapper12013-11-12

The first aid kit of course is intended for something minor. I agree that if there is a serious accident, 911 would be the best thing to do. I did not include your point into the instructable because I assumed it is common knowledge (at least for the United States), but I should have, you are right. I have added it, I should never assume anything like that.

On the other subject of thin walled pans, it really is no problem. just like @Ironsmiter mentions, it is not a big amount and the temperature is not that high that it can cause a breach on the steel (because its Aluminum and the melting point is about 600ºC). Nevertheless, one can never be safe enough, so if you want, a thicker pan would also be a good idea.

Just make sure that you are not so worried about safety that you opt to not do this awesome project! Experiment, start small scale and learn from it. It can be done safely and "awesomely"!

Thank you for the comment and making this instructable better.

author
Jislizard (author)gavargas2013-11-12

911 would only be the best thing to do for a serious accident within America. 999 for the United Kingdom and 000 for Australia and I am sure there are many others. Not having a go or anything as common sense should prevail but we get so many American TV shows we have to tell the kids not to call 911 if they have a real emergency.

author
ironsmiter (author)Mindmapper12013-11-12

The thin walled steel in the mold is not an issue. The small weight and low tempature of the aluminum charge is well within the safe range for even 20 gauge steel.

author
chuckyd (author)2013-11-12

Slag is in steel or iron. For aluminum it's dross.

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