Introduction: Beer Keg Metal Melting Furnace

Picture of Beer Keg Metal Melting Furnace

So there is a long list of instructions on building a metal melting furnace. But I have decided to show you my process anyway.

I have turned an old beer keg into a portable metal melting furnace, This will cover both the furnace and the propane torch burner. I being in Canada relay heavily on Canadian Tire store and online product availability.

The metals were acquired locally at a metal recycler and the chems were from a not so local chem supplier, OH and the melting material from a previous employer.

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Step 1: Destroy the Keg

Picture of Destroy the Keg

NOTE: No beer was harmed in this step.

I acquired a defective stainless keg from a local brewery.

Measure and cut the top portion away. I needed a lid to control the burn so I cut away the top 3 inches of the keg using an angle grinder and custom make bottle cutter jig. The keg drop tube was removed leaving a perfect vent hole in the lid.

Next I cleaned the cut line of all metal burrs.

Finally I cut a 2 inch hole approximately 4 inches from the bottom if the keg in the sidewall as shown.

Step 2: Fiddling With Science

Picture of Fiddling With Science

I have found over a long experimental range that a two bottle per bag ratio seems to work best. I am referring to a 1L bottle of Sodium Silicate 37 to 40% from my favorite online store to 1 bag of Perlite from my favorite local store.

This mixture is thoroughly packed into the open cavity of the Keg using any mechanical means necessary.

Step 3: Pack Until Full

Picture of Pack Until Full

I used a concrete form and old plumbing pipe for this bit.

Wrap the forms in wax paper to prevent sticking.

Place the forms as shown and carefully pack the Perlite to fill the sides and top.

NOTE: This may need more than 1 week to dry depending on your environmental conditions. Too soon and the mixture will fall apart. I actually needed 8 days for mine due to the cold nights.

Carefully peel the cardboard tube out and remove the plumbing tubing. The wax paper may stick but be sure the Perlite doesn't crumble. if it does then coat the surface with more Sodium Silicate liquid to adhere it together then let it dry.

Step 4: Refractory Lining

Picture of Refractory Lining

I mix a 1 to 1 ratio of Prolab Sodium Silicate with 1200 grit white aluminum oxide abrasive.

This is used as a refractory lining to prevent degradation of the Perlite. Without, I find that the Perlite will melt and become brittle after only 1 or 2 burns.

NOTE: Sodium Silicate eats Nitrile gloves. I am shown here with Nitrile gloves but these didn't last more than a couple of minutes in the mixture. luckily i had no allergic reaction.

Carefully and completely coat the entire surface of the furnace with the mixture. this will form a kind of ceramic coating over the Perlite and allow for hotter burns in the future.

Fire the furnace to set the Aluminum oxide coating. A nice glow of orange will indicate the completion of the set.

Step 5: Make It Portable

Picture of Make It Portable

As shown. Fabricate a frame and moving platform for the keg. measurements are based on the keg size.

I used some pneumatic wheels and 2X1 steel tubing.

The frame houses the base of the keg yet allows for quick moving via a dolly like design.

The bolts are sized to attach the wheels. In this case they are 3/4 but they may vary depending on your wheel of choice.

The handle is galvanized conduit so if welding make sure to use a respirator or open air or safety.

By the way... a flap disc is the bad welders best friend. Massive metal removal and smooth finish. get one and thank me....

Step 6: The Burner

Picture of The Burner

Now that you have waded through the furnace it is time to reveal the quiet burner.

This utilizes a .20 mig tip as the primary orifice.

I also use a commercial propane torch as a regulator as shown.

The mig tip is fitted into a 1/4in waterline adapter as shown. The adapter is then threaded into another brass fitting as prepared earlier.

I have found that drilling at a 45 degree angle air inlet holes in relation to the airflow greatly reduces the amount of noise generated. In this case I have made 5 holes that are approx 3/8 in diameter. These are intersecting with the point of the mig tip as shown.

The brass is 1 inch in diameter and will expand to 1.25 inside diameter with an adapter.

Inside of the 1.25 pipe is a steel screen that will produce turbulence and make the flame burn hotter.

There is exact science here but I circumnavigated it to produce a hot and reliable flame. On full power it will not stay lit outside of the furnace but will work properly when in place.

It takes about 20 minutes to melt the contents of the crucible with this torch and furnace.

Step 7: The Firey Crucible

Picture of The Firey Crucible

OK so there is a problem that needs to be addressed.

The crucible I use is actually steel tube with a laser cut steel circle for a base.

These were all found at the scrap recycler over the course of a couple of months.

basicly there are 2 holes drilled at 180 degrees near the top and a full base cover welded in position.

I find that a 6 inch tube will allow to melt a hard drive case without any folding or breakdown.

I use a 1/4 inch steel rod bent into a handle to pick and pour the metal.

Step 8: Between Projects

Picture of Between Projects

So I have decided to melt aluminum but have no current project.

The scrap is melted and poured into cast iron pans. This yields ingots of high purity and ease of use.

I have a project coming soon that will use these ingots and more...


christopher cramer (author)2017-04-21

Hey I am planning to line the outside of my foundry with ceramic fiber blanket, but I cant seem to find any place that sells ITC 100 or any other sealant to seal the fibers. Would the sodium silicate mixture work for protecting the loose fibers?

sammcleod97 (author)2015-08-17


Can I get an Item number/manufacturer name of the line attached to the propane?

I purchased this from a Canadian Tire store 85-1084-2 but the manufacturer is Mr. Heater number F273704.

The torch is an older Bernzomatic number JTH-7

dave Dunn (author)2015-07-22

Hi Random
I can get refractory cement mate it's fairly expensive even for a small pot but I dare say it would still be a lot cheaper than Althea other alternative you mentioned

dave Dunn (author)2015-07-22

Thanks random
I was also looking at another idea I saw from another site where the guy used perlite mixed with sodium silicate then after that had dried out completely he gave it a little burn and then used an inch of refractory cement over the top . He said that worked for him

dave Dunn (author)2015-07-05

Thanks I just found this and man that's exactly how I want to build my own . I have several different sized pipes including large gas cylinders and I have filled them with water before doinany work on them

I wish you the best on your build. Sounds like you are playing safe! If you can get refractory cement, use that instead of the aluminum oxide. Make an insulation layer of perlite then coat it with cement about 3/4 to 1 inch thick, that way you will be able to use more heat and melt all the way up to steel... I just did a 4 pound aluminum pour and noticed some cracks forming on the ceramic layer as the furnace cooled.

Thanks Random
I will use refractory cement . Would you suggest using ceramic type lining under the cement or use something different . I noticed some insulation down my way which is like fiberglass insulation. Any more suggestions please shoot them my way mate .

The ceramic blanket insulation will work as well. The goal here is to contain as much heat in the furnace. Make sure the get the blanket that is rated for the max temperature you want to go up to.

Mine can be handled with bare hands immediately after a burn is done. If you use solid refractory cement the whole assembly will take many hours to cooled down before it can safely be handled. Just be sure to wear a respirator since the ceramic fibers are considered toxic to breathe.

Note that with the refractory cement there is an additional item needed. These are called stainless needles, these work as a kind of rebar binding agent and will greatly extend the life of the lining and reduce cracking. Plus they are available in bulk and super cheap. Where you buy refractory cement should stock them.

Sorry for the late reply.

Garadin (author)2015-06-23

I love reading instructables about metal melting/casting. I found tons of information on the topic at over the years. This is the best one yet, primarily because of the ceramic layer to extend the life of the refractory.

Random_Canadian (author)Garadin2015-06-29

That is exactly how I got started... This coating seems to work wonders... I had a minor spill but after cooling the aluminum just pealed off. I'm now at burn 26 and it still looks new!

Hobopetter (author)2015-06-17

Can this melt bronze or cast iron?

Bronze, copper, brass ... yes. Iron... I will say no although I haven't tried.

LarryW3 (author)Random_Canadian2015-06-21

It would seem to be a function of your heat potential vs the melting point of the cast iron scrap. Steel melts at 1371 c. and cast iron at 1200 c., so if the crucible is some form of steel and your forge heats to above 1200 c. but below the melting point of your crucible, you should (theoretically) be OK to melt cast iron scrap. See

Excellent .ible!!!

Random_Canadian (author)LarryW32015-06-25

Thanks and possibly but I have no where near the protective gear to even want to try it. I'm not even sure if the refractory would withstand the heat.

carneeki (author)LarryW32015-06-21

Melting point is one thing, but metals get soft when heated. I'd be extremely cautious with iron. The crucible lifting points might bend out, or the welds holding the base could fail, dumping molten iron everywhere.

Graphite is the common choice for a crucible.

LarryW3 (author)carneeki2015-06-21

Very true, but what' the availability of maleable graphite in usable form? Being on a fixed income, my first concern after finding a useable source of carbon would be "can I afford it?".

Some very affordable clay graphite crucibles like this one can be found here.

carneeki (author)LarryW32015-06-21

My first concern would be "can I afford time in hospital?".

kunibert (author)2015-06-17

a flap disc is the bad welders best friend. - Well, don´t I know! You just made my day!

Random_Canadian (author)kunibert2015-06-19

Glad you like... I was horribly lost in mediorcarty until I discovered the combination of 20000 RPM and sandpaper!..

Dinoman217 (author)2015-06-19

You're a genius!

EurekaFactory (author)2015-06-17

Nice! A lot of people ask us about variations on our little Itty Bitty Mini Forge, and I"m just going to send them over here to your 'ible, because it addresses a lot of the questions and extra functionality some people are looking for. Cool build! Thanks!

Thanks for the feed. I have built several of these and have found that the ceramic coating far outperforms the bare perlite. I like your build by the way. Simple is usually the best solution. I will continue to update this build as the experimental tech continues. I am working on a cool project that needs this so I will post more when I get to figuring out the mechanics.

Jobar007 (author)2015-06-17

How many pounds of aluminum does your crucible hold?

It sounds like you've made one of these before with the same refractory combination. Using sodium silicate seems like it would be a bit brittle. Do you have to be careful around it (like dropping tools)?

I like the idea of using the keg as the shell of the furnace. It seems like it is the right combination between capacity and portability.

Random_Canadian (author)Jobar0072015-06-17

I'm not sure of the poundage (estimate 1 kilo) but I have melted 11 hard drives in one crucible without any overspill. Yes there is a brittle shell but with dropping molten aluminum, the furnace is of my least concern. Yes it will break as with any ceramic coating but I use extreme caution when working with hot metal.

so far I'm 17 melts in and there is no degradation like there is with just 2 burns with bare perlite.

Jobar007 (author)Random_Canadian2015-06-18

1 kilo ~ 2.2 pounds.

Good to know that while it is brittle, it is durable to heat. Thank you for sharing your build!

TheFrankTurk (author)2015-06-17

OK - this project is a cool remix of some other versions of the Homejob Furnace, and I commend you for it. I think the construction of the outer furnace is the easy part. Finding the inner part -- the actual crucible for melting the aluminum -- seems to be the part I can't master. Where did you find yours and how much did it cost?

I added a step to answer your concern. I hope that this helps...

Brilliant. Thank you.

Jobshopper (author)2015-06-17

I used to smelt aluminum as an after school job in the winter, our smelter was on a hinge with a carousel on the side it tipped towards. It was a very nice set up, I don't remember what the floor of the chamber was lined with but the aluminum was allowed to pool on the bottom and when enough had accumulated we skimmed the trash off the pool and tilted the whole furnace to make the pour. We castes ingots about 16" long they were triangle shaped being 6" or wide at the base. It seems that handling the crucible is a big choir and this rig was easy enough a high school kid could go through a pile of transmission chases in an evening. The furnace you've made is sweet , caring molten metal is scary endeavor to me though.

About This Instructable




Bio: Bit of a background in various electrical and mechanical fields, obscure sense of humour and typically willing to help...
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