Project Smelter - Making a Smelter for Melting Aluminium

Propane Tank Aluminium Smelter

Thumbnail Smelter

     For a long time I had been watching YouTube clips and reading about people making their own aluminum smelters and figured one day I would go ahead and make my own. Time passed and there was always another project or reason why I never got around to making one and then I decided one cold winter’s day to go ahead and make one so that it would be ready for spring when the weather turned better and I could go ahead and start melting the aluminum I had been collecting.

     The project started when a friend gave me an empty but new propane tank and I already had a full one for my barbecue along with a spare that will be filled in summer. The first thing I did with it was give it a wipe over so that it was clean. Not a necessary step but it gave me a chance to examine it and decide upon the next stage.

The Project Starts

Propane Tank Grey New.
A decent tank to start the project.

Some Health and Safety

     Firstly some Health and Safety warnings: Propane under pressure is dangerous and there is a risk of fire and explosion if not dealt with in a safe manner. So it is important to ensure before producing any sparks while drilling or cutting to ensure the gas is removed and do all that you can to prevent any risks of explosion or fire. Do not smoke while undertaking the process of prepping the tank or while cutting into it. There may also be residue inside the tank clinging to the sides of the inner walls that could possibly still be flammable even after opening it so be cautious and take care. Remember that it is a hazardous material and treat it with respect and caution. Also remember that propane is bad for the environment when released directly so try and limit that by using it first for its intended purpose to limit the contamination. In other words use the gas and try to ensure the tank is completely empty.

     Ok so now on with the project we go. After inspecting the tank and deciding on how I wanted to progress I turned the knob on top to open and released the pressure. Even when empty there will be pressure built up inside from residue of compressed gas.

First thing First

Safely Releasing Gas.
Ensuring the tank was empty completely for safety reasons.
     Now I was lucky as this tank has been stored covered and is basically a new tank, if you use an old one it may be harder to deal with along with being dirty and all bashed up. The next step is to remove the pressure screw that on this model is located on the side of the brass section. I did this using a small screwdriver and because of the decent condition of the tank it was easy to just unscrew. Again this model has one and because it was new and in good condition it came out very easily and there was a release of pressure as it popped out of place. Older ones may be in a different position or be hard to extract but it is best to do this whenever possible as the main section may not release all the built up gas.

Ensure all Residual Pressure is released

Releasing Gas Pressure screw.
To ensure the tank was safe.

Remove the Brass Section

      The next step and one that I forgot to take a photograph of was to remove the brass section on top. I did this by wrapping a thick section of cloth around the brass and by placing a length of metal pole through the holes on the side of the handle I bashed turning the brass and moving the pole to the next section until the brass came out. 

     Now because this was a decent tank that was an easy thing to do. Old ones may be harder to do as they corrode on top and the threads seize up. This is why some people drill holes in the tank to fill it with water. If you do this be very careful even though it is for the most part drained of gas it could still be a risk.  

     A slow speed drill that doesn’t spark would be best and if possible while doing that try and use water to wet as drilling to ensure no sparks happen.

Fill up With Water

Filling Propane Tank With Water.
Flushed several times.

     Next I used the garden hose and filled the tank with water allowing it to over fill and pour out. The smell was strong to start with but soon it went away.

Drain and Repeat Previous Step

Draining Water From Propane Tank.
Drained and Filled a few times.
   I then turned it upside down and allowed the water to drain before I went ahead and repeated the process twice more. I then left the tank outside overnight as I was not in a rush to get it all done and that helped the smell and any excess vapors to dissipate.

Getting Ready to Cut

Tape to mark out cutting line on propane tank.
This helped make a decent cut.
     The next day when I got home from work I took the tank back into the shed and resumed the project. I had decided where I wanted to cut and I could have used the grinder and metal wheel to cut it but instead I wanted to cut it by hand with a metal hacksaw. 

     This to me was a safer option, although at this point it seemed safe to use a metal disc and grinder I didn’t want the sparks to fly all over the place and also I wanted a more controlled cut that was as straight as possible. I began by marking off the section with painter’s tape that I had siting ion the shelf so that I could follow the line around as I cut.

Cutting the Tank

cutting empty propane tank.
The tape made it easy to cut straight.
     I began the cut by slowly cutting away at the metal just deep enough for the blade to hold like a deep scratch and then began to roll it slowly around so that I had cut through the initial layer of paint and made a line. This helped keep it all straight and made it easier to cut through.

     One tip I would give at this point is to place two sections of wood each side back and front of the tank so that it doesn’t move around while cutting and roll until you move it. So I continued the cut along the line rolling as each section was through. It didn’t take me as long as I was expecting and the cutting was relatively easy.

Finished the Cut

Cut in half propane tank.
The tank separated nicely.
     The finished result was a decent straight cut as the sections came apart and also fitted back together well. If I had used a disc cutter then it would have been faster but the lines would have probably been wobbly along with lots of marks where it had slipped during the cut.

Clean Up

Washed out cut open propane tank.
After a wash it smelt much better.
    The next stage was to remove the tape and clean up the tank so that it was nicer to work with and completely eliminate any risks from residue. The tank was actually cleaner than I had thought it would be inside and there was no real residue clinging inside. I took it inside and washed the entire thing with dish soap and hot water before drying it off and returning outside. Warning, before you do this make sure that you use an old washing scrubby and clean up inside or you may end up in trouble for making a mess in the kitchen.

Worn Down But Worth It    

Metal cleanup wheel used up.
I used a new wheel quickly down as far as I could.

     Next I took a metal cleanup wheel, to start with it was a new one and about four inches but by the time I was done it was worn down and no longer had any use. I used a drill so that I could get inside as I cleaned down the tanks. At this point it was the only real cost involved and was around two dollars but worth it to ensure clean surfaces and safe edges.

No Sharp Edges

Safe and clean edges after cut.
The edges were now free from sharp hazards.
    I cleaned up the lips with a fine file and the grinding wheel so that they were free from snags and also more level. This will endure that the lid sits better and ensure that I don’t get any cuts while making or using the tank.

Enlarging Top Hole   

Hole in top of propane tank made bigger.
Enough room to feed aluminium.
      I then used a metal hole saw to enlarge the hole at the top of the tank. I wanted a hole big enough to feed sections of aluminum into the crucible while smelting and also to ensure good venting of fumes. After I had cut it out I filed down and cleaned it up to ensure a nice clean safe edge. This was a little harder to do as there was no way to hold the pilot drill section inside so a few times the hole saw slipped but eventually it caught and cut out.

Making a Hole For Air Pipe

Hole for pipe cut out in base of propane tank.
A good size of the pipe I was using.
     The next step was to cut out the intake hole for the air to be blown in at the base of the tank. I marked out where I wanted it and used a three quarter inch hole saw to cut out a clean hole. After I leaned it up and filed it down. I didn’t want it too high and cut it out so that once filled with the lining it would ensure I had a decent thickness on the base and it would blow in adequately.

Making Inside Pipe    

Used a bike seat pipe section filed down to fit.
Filing down was easy and ensured it would fit.
      Now came the no weld pipe connection, as I have no welding equipment and did not want to use glues or anything that could cause an issue later I had to come up with a way to connect the in pipe securely. I collect scrap so after a rummage through what I had I found the suitable solution. A piece of heavy metal steel pipe from a bike seat.

Inside Pipe Brass Section

Snug fitting pipe from bike seat.
The pipe now fitted snug into the copper adapter piece.
      The idea I had was to use this bike seat piece of tubing to push firmly into a copper plumbing fitting that I had sitting in my collected fittings. Now the copper fitting was an additional cost even though I already had one from a past project and was not used it did cost around three dollars new from Lowes. 

     This section of pipe is for inside of the tank and will make the inside air inlet that will be surrounded by the lining. The first thing I had to do was file the pipe down enough for it to fit with some bashing into the copper section. A tip, do not bash on the thread end or the thread will damage and be hard to use, instead wrap the copper with a cloth and then bash down on the pipe into the fitting to ensure threads aren’t damaged.

Pipe Connector  

Copper piece inserted into propane tank no weld.
No welding needed.
      Once I was sure the pipe would fit snug into the copper fitting I attached the fitting into the hole using two screw on discs, well actually they are more hexagonal than discs. They are actually intended for electrical use and used to clamp down conduit pipe. I had these spare from remodeling but new they are less than a dollar for the pair. 

     I screwed the first on, slid the thin end with the push part inside through the hole and then screwed and tightened as much as possible the other on the outside. There was a tiny gap between the tank and the seal but after adding lining it will be ok and cause no issues. It will also withstand any heat and not require any welding. You could weld them if you have the equipment or use some form of metal bind but I didn’t see the point as it was tight and sealed enough.

Snug Seal   

Copper adapter tight fit in tank.
A tight no weld fit.
 From the inside the fitting is secure and a good seal and ready for the thick metal pipe section to be added to the inside.

Insert Inner Pipe

Pipe secured no weld to adapter.
The pipe is now a snug secure fit.
     Next I cut down the metal pole form the bike seat to a few inches, the thickness that I wanted the lining walls to be and then I bashed the pole into the fitting until it was secure and a tight fit.

Top Lining Support  

Top lining of tank bolts to securely hold in place during use.
Now the top lining wont fall out.
   Then it was onto the top of the tank, I decide to leave the handles on as they would become part of the opening and closing features of the tanks and I had no reason to remove them. So I drilled some small holes and used long screws and bolts to insert four supports for the lining. When heating and cooling the inside will expand and shrink and the last thing I want is for the lining on top to drop out while I’m melting so these will help hold it all in place.

     I decide to use four around the sides and two shorter on the top but more could have been used. The lining mix will pour in over and around and seal them in. I added a few washers to the top short bolts just to get a better grip.

Top Form

Snug fit form.
Top form through center and taped so no leaks.
     Now it was time for the forms to be made. I began by making the top form using old card rolled up and wrapped in painters tape. Once I was happy it was secured I then sealed up the outside with more tape so no mix would seep through.

Main Form

Air pipe level.
Ensured inside pipe was covered.
     I then made another form from card for the inside and figured out how thick I wanted the lining walls. I decided to go with enough space to ensure various crucibles could be used along with a decent amount of coal. I also cut out an indent in the card for the inside section of pipe to barely feed into so that when poured the lining would not clog up the pipe section.

Ready to Pour

Form covered with tape.
Painters tape covered form.

     I then covered the inside form with tape and positioned it loosely as I continued on to making the mix for the lining.

     At this point I carried it all in to the house as it was freezing outside and my feet had begun to freeze. Also it ensured that the mix would be at room temperature and be easier to use. I allowed the tank to warm up before I began the process of filling it so that it would not cause any shrink later on.

Refractory Mix

Propane tank lining mix up.
Wear a dust mask.
     I had researched a lot of different types of refractory lining and had decided to use a cheap effective one seeing as this was the first time and I didn’t want to spend out on decent lining to find something go wrong and have to waste my money. So I used a mix of fine play sand that I had siting in the shed, plaster left over from remodeling and a small amount of Bentonite clay that I had ordered for making green sand later on. 

     The mix ration I used was based on a fifty fifty equal mix of sand and plaster combined with enough water to make it a slop mix and then I added two cups of Bentonite clay at the end. It was not necessary to add the clay but I figured I had it so would use some to firm it up. 

     While mixing this all up make sure to wear a face dust mask as the plaster is very fine and you will end up inhaling it, also make sure that you clean up the dust that settled later on the counters so as to not get in trouble and mix up on a tarp or something suitable to ensure no trouble.

Pouring Refractory Mix

Smelter lining level.
A few shakes levels it off.

     Once the mix was ready to pour into the tank I began by filling the main section first to ensure I had made enough followed by the top. Thankfully I had made enough and had some left over that I discarded once dry. I poured spare sand into the center to weigh down the form and prevent it rising as I filled it with mix,

Top and Bottom Filled

Smelter lining drying.
Make sure not to ruin floor.

     Once both sections were filled I gave them a little shake to settle the mix to a level and then had to wait for it all to dry. The room was a decent warmth because it was winter but I didn’t want it all to dry too quickly as it would cause the mix to crack so I wet it all down a few times during the drying time.

Form Removal

Smelter lining in propane tank.
Dry and real thick.
      Once the mix had set overnight I then went ahead and began to remove the forms from inside. The main section was heavy but had set well and once removed the inside looked good. Sure there were a few indents where the card had warped a little but nothing to cause any issues.

Clean Up

Propane tank smelter lid.
Dry and secure.
    I then proceeded to remove the top insert and then cleaned up all the mess I had made along with giving the refractory a cleanup just to neaten it all up a little more.

Air Pipe and Blower

Pipes, blower and smelter.
All level.

     The next stage was to add the air blowing pipes and blower. Many people had used hair dryers with cold settings on, but I did not have one and the cost of a new one was not something I wanted to pay and finding one at a thrift store didn’t happen. So I used an air bed blower that I had in the shed. The force was decent and steady so I made up a connection set of pipes for it. I set it up dry as in not glued first to see how it fitted and luckily the pipe was at the same level as the blower so it was straight.

Air Pipe

Smelter with blower and pipe.
Blower and pipe fit snug.
     Because I had used the threaded copper fitting I was able to buy two three quarter inch cast iron threaded fittings and a length of pipe that all screwed together. The price was around six dollars from Lowes and made it easy to fix together. I tightened the metal pipes as much as possible as they would be staying connected and it ensured that I could screw in cpvc pipe easily.

Attaching Blower  

Fitting snug to air blower.
Fits perfectly.

    For the cpvc attachment section I used a cpvc push to male thread section on one end of cpvc pipe that would screw into the metal pipe. I forgot to take a picture but I also made another section of pipe that this section screws into and then that section screws into the metal pipe just in case I needed to make the air in pipe longer. 

     This was just in case the blower was too powerful and turned out I didn’t need it. On the end where the blower fits I used a three quarter inch push to inch push fitting in cpvc. Now I had the pipe and most of the fittings in the shed form remodeling but the pipe length and fittings cost under ten dollars from lowes new. The blower fit snug into the fitting and because level with the hole it sat nicely in place. I then went ahead and glued all the pieces together using cpvc cement and allowed them to dry.

Making a Frame Base

Frame plate base for smelter.
This is a decent piece of metal.
     Now that the main smelter was done I decided to make some additions to it. The top is heavy and although I could pick it up I wanted some type of mechanism that would allow me to easily open and close especially when it was running. After a rummage through my scrap I came up with an idea and began to build something suitable. 

     I didn’t want to spend out on this and if I ever make another improved version I will probably spend out for things I don’t have and make an improved system of framing but for now this works for me. I began with a heavy metal plate which is actually from an old bike stand that was being thrown out. It had some holes in it already and was a solid base for the tank to stand on and prevent the frame from flipping over. 

Frame Supports

Base plate and brackets.
Secure fixing to base plate.
     As I mentioned I have no welding equipment so I was coming up with something that was no weld. I intend to rectify this and learn how to weld at some point so future projects like this can be easier and have more solutions but for now this will do. I began by using two sections of an old cast iron bed frame to make riser sections on the plate. 

     Note old cast iron like this is hardcore, to drill through or even cut was a mission and in fact was the hardest part. I ruined a few good metal drill bits trying to use this metal so instead of using it like I has seeing as I had a load of it I limited it to what I could get away with as I didn’t want to ruin even more bits. Also cutting took forever so frustrated I found other solutions as I went along. I used some decent nuts and bolts through to secure the structure was secure and would take punishment over time.

Handle and Tilt Frame

Handle for propane tank.
The bike holder worked well.
     For the top section I used another part of the bike stand for a handle and attachment and only had to do a little drilling which was easy to make it usable for what I needed.

Securing the Handle

Handle on propane tank.
This was convenient and worked well.
     The stand section had a curve to it so it was easy to drill and secure it to the original handle section of the propane tank and make it secure with a few nuts and bolts.

Bracing the Frame

Length of metal for bracing frame.
Wanted an even more thicker length but this will do.
     I then used a piece of metal that I had to brace together another section of the stand, I intended to use the iron bed frame sections but drilling holes was nearly impossible so I turned to a different solution. If I could have I would have used them and welded them but alas I had to do something different. I then secured it all together with some nuts bolts and washers.

Big Bolts and Washers

Good bolts and fixings.
Good bolts and fixings.

     I then used these bolts, nuts, washer and small tube pieces to make pivots so that the frame would be movable back and forth and would last over time, also it helped fill the gap between the frame with minor bending.

Attaching Moving Frame Section

Propane tank frame support.
I left a length of base to prevent frame going down too much.

     I then positioned the frame together and secured using the bolts and tube so that it would move back and forth but yet remain secure as it held any weight.

Sturdy Moving  Bolts

Frame bolts for secure and safe movement.
Good sturdy bolts.
     The bolts system worked and I only had to bend the frame slightly for it to be a snug fit and should ensure that it withstands the abuse from moving the top back and forth.

Top Moving Frame Section

Propane tank lid flip frame.
The frame will help remove the lid.

     I then used two more sections of cut down bed frame to attach the top of the propane tank to the frame and used another bolt, washer nut set to enable the lid to be tilted before it is drawn back.

All Together

Completed propane tank smelter.
It was completed and ready to go.
     Then it was all done and put together, after an initial inspection and tightening of bolts I added a little thread lock here and there and it was ready to go.

Easy Open and Close

Propane tank flip back lid.
The lid flips back secure and easy.

     I tested the system out and was pleased that the lid now tilted all the way back away from the tank and was far easier to use than just lifting the top on every time I wanted access to the inside.

Painted Up

Ready to fire up for the first time.
It looks real nice.
     To finish it all off I spray painted the entire thing with a basic auto grey undercoating. I had already done it to tank and it made it all look clean and unified. Now the whole thing won’t if made correctly get hot enough on the outside for this paint to be an issue and it makes it all look much nicer.

Getting Ready to Fire Up 

Propane tank smelter ready to go.
Nice and shiny.

    Now at this point I will say I had no intention of melting with the smelter yet, it had snowed and I had no real area to start smelting along with no crucible to use. But I wanted to test it out first to see how well it heated up and if it needed any changes.

Fired Up

Firing up smelter for first time.
Firing up for the first time.

     I also wanted to dry it out completely, due to being outside it had absorbed some moisture and well I wanted to fire up my creation. So I used wood coal brickets, not the solid brickets that I intend to use when smelting but I had a bag of wood clumps coal from summer left over and I loaded it up and light it.

Getting Hot

Coals getting hot.
The embers begin to heat up.

     To start with the coals got hot quickly just like on a barbecue and when I turned the blower on it was soon light well and on its way to getting hot. So I popped the lid on and stepped back for a few minutes.

Real Hot

Propane tank fired up with good heat.
A nice red glow.

     Soon the smelter was real hot and burning well, the air was pumping well and there was no smoke. There was a load of steam coming from the refractory and by heating it up like this I was driving the steam out and curing inside completely. I was pleased with how it was performing and after it had all burned up the inside had held up well and is now ready to be fired up once I make a crucible later on when the weather gets better.

Air Unit Modifications

Old blower and charging pack.
The old blower with charge pack.
     There was a modification that I made to the blower for two reasons. Firstly the blower I had was one that plugged into a car charger. So I had been using a power pack to plug into. Now this is good because the power pack I have lasts a very long time and has both regular plug and car adapter plug so I can transport should I ever find myself needing to be smelting somewhere I don’t have power. But I wanted to be able to plug into a decent extension cord. Secondly the blower made some real noise a sit was old and had years of abuse.

New Blower

New less noise air blower.
The new shiny and less noise air blower.

     So I spent out one evening when I was in the clearance section of my local Walmart and noticed they had a new blower for five dollars. It came with a variety of attachments that pushed onto the blower. This means I can use one for my creation and still use the blower for other things.

Selecting the Best Attachment

New attachment to fit on pipe.
The new fitting for permanent attachment.

     I selected the one that I wanted and the one that I would have the least amount of other uses for and decided it was now going to be permanent secured to the inlet pipe.

Minor Modification

Nipple attachment cut down.
Not necessary but figured why not.

    I could have left the end nipple bit on but decided to cut it off for no real reason.

Fixing on Attachment

Secured and snug fit adapter to blower.
A permanent attachment piece.

     I then glued it into the pipe so that now it just pushes onto the blower and is one less piece that can get lost when I dismantle the pipe section.

Finished Modification

Air blower attached snug.
No with an easy to change attachment.

     Now it all fits together snug and level and will last longer, hopefully it will do the job for a while. I did keep the additional section of extending pipe so that if this blower due to being newer is more powerful I can extend the pipe and lessen the air blast into the smelter.

Fired Up and Running

     In this short movie, the creation is fired up and running well, although it seems like smoke is coming out, it is actually steam being driven out of the refractory.

     The annoying noise is due to the fact that I used the old worn out air blower while recording and have not yet made a new video using the new quite air blower.

Final Thoughts and Notes

Fact Random

     So after completing the build, testing it all, cleaning up and being happy with the results. I packed it all away in the shed ready for when I have a suitable crucible to start melting the aluminum that I have building up.

     For my first time making one I am happy with the smelter and it should perform adequately for what I want. However even though I haven’t used it at this point for melting I am already thinking about getting welding equipment, learning how to weld and keeping things I find along the way with the aim to make something better maybe further down the line.

Additional Information

ADDITION: So I created this in winter and wrote all this shortly after, since then I have actually used it to melt aluminium. It worked very well but there was an issue with the crucible that I made, the aluminium melted real quickly and was all looking great until the crucible failed and filled the base of the lining with solid aluminium.
I am currently looking into a better crucible idea while trying to refrain from spending out too much on a suitable solution. The problem is I have had issues with the crucible that I punctured being too eager to melt.
So for now I have repaired the damaged refractory and once I have a suitable crucible I will video and photograph it all in action.
Tag Nph Random
At the moment it is real hot.

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