Introduction: Small Propane Tank Crucible (No Weld)
So I had made myself a decent propane tank based, coal fired smelter for melting aluminium for pouring into ingots and casts. You can view that Instructable here Propane Tank Aluminium Smelter (No Weld) and I had also made some tools to go with it, you can view that Instuctable here Tools for Use With Propane Tank Smelter (No Weld). Now all I needed was a crucible so that I could begin melting down all of the lovely aluminium that I had been hoarding for a while. So the project began after I had used up a small propane tank and was ready to start the build.
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Step 1: The Project Starts
I had purchased a two pack of Coleman small propane tanks (was just as cheap to buy two as it was for one), and seeing as I have an attachment to fill a tank from a larger tank, I was left with an empty that seemed a suitable option for this project.
The first thing that I did was to inspect the vessel and wipe it down, this gave me time to think about how I was going to proceed with the project
Step 2: 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 precautions are taken 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.
Stay safe in all of your projects, remember if you get hurt, you wont be able to create things.
Step 3: First Things First
I then had to ensure that the tank was completely empty, so I left the nozzle on overnight and in an open position to make sure it was completely empty.
On the side is a pressure nozzle that with some skill you can actually get out, I didn't bother doing that, but I did stick a small rod in it to release pressure and also left that in all night.
The next day I was sure that the tank was empty and ready to progress with the next stage, seeing as it was a small tank and I was confident it was empty, I did not do the flush like I did with the big tank, but I did decide to do it all by hand instead of using anything that would spark.
Step 4: Deciding Where to Cut
I used some green frog tape painters tape to cover around the top section and then measured out just how deep I wanted the crucible to sit in the smelter.
I made sure that it was not too tall so that the lid would close, but yet had enough room for coals to be placed under in the initial fire up.
I then marked all around as straight as I could to give an even cut at the desired position.
Step 5: Preparing the Cut
I positioned the small tank between two pieces of wood that I roughly secured to the bench so that it would not roll around on me while I was cutting and gave me more control.
I used a fine tooth metal hacksaw and began to work one small area first, slowly and with caution just in case there was still gas inside.
Once I was happy it was all safe, I then went around the entire thing, slowly to score where I wanted the cut before I continued cutting through the entire thing by hand.
Step 6: Cut and Open
Now the top came off nice and relatively even, so I was happy, it was also clean although there was still a smell from the vessel present.
I discarded the top section into the scrap pile and peeled off the tape ready for clean up.
Step 7: Clean Up
I then took a fine file and went around the top lip to ensure that there were no sharp edges or loose pieces of metal that could stick in my hands. Although I was wearing safety gloves I didn't fancy getting a metal splinter later on.
I then washed it inside and out thoroughly with decent liquid and dried it completely.
One tip is to make sure you don't go and use the scrubby for dishes and clean up after yourself or risk being told off, especially if you do it in a just cleaned kitchen,
Step 8: A Heat Up for the Lip
At this point I had considered actually using a wire brush attachment or wheel to get all the paint off from outside, but I figured it would just be as easy to burn it all off when I first used it in the smelter.
I wanted to make a pouring lip so that the melted aluminium would flow when poured.
I used my propane torch to heat the area that I had selected, it lined up front to the base hole where I would be using a bent pick type rod to pour.
On Coleman tanks you get the tank and then at the base is like an added piece with holes in, so that you can set it down and any water would drain if say it was in a puddle. The base is secured to the tank but I guess you could get it off, I wanted to leave it so the bottom of the actual vessel inside would get hot without sitting on coals all of the time.
Step 9: The Lip Is Formed
Using a method of heating up the area and while wearing good heat protection gloves, hammering a lip using a ball pein hammer I formed a lip.
I then quenched the vessel in cold water and gave it a wipe over as I inspected it.
At this pint I was happy with the way it was going.
Step 10: Adding Some Handles
Now my original idea was to use some form of tongs to pick it up, but I was concerned that it may slip while loaded with molten metal.
I then thought about drilling holes and using tongs with bolts in but during my play around I ended up with a two rod either side with hooks at the end tool that would enable me to pick the vessel up easier.
So I drilled the holes and inserted some good industrial bolts that I had stored away and tightened with locking rings and nuts.
Step 11: Testing the Pick Up Tool
Now that I had the bolts secure, I had to test, to be sure that the tool I had made to pick it up worked. So I sat it down and used the tool to pick it up, I was happy that I didn't even need to bend the rods inwards to make it pick up and felt confident that it would work.
Step 12: Tilting the Vessel
I was a little concerned that the vessel may come out of the hooks when tilted,
So I played around and it seemed to work smoothly without any other adjustments being made.
Step 13: Hooking the Vessel
I also wanted to make sure that I was able to pour using the one handed pickup and a hooking rod that I had made.
I thought it would possibly be clumsy, but when I picked up the vessel and poked the hook rod into the small hole in the vessel base section it was actually an easy smooth operation.
Step 14: Initial Fill
I have a huge mass of collected aluminium of different types and thickness's, so I filled up the crucible so that it was packed.
I knew that even though it was full the metal would melt to a small amount but provide a base of hot molten aluminium to feed more into through the top of my smelter tank.
Step 15: Ready to Fire
I then placed the full crucible into the smelter and surrounded it with coals, I packed enough to keep it secure but also make it easy to light using a propane torch and I was ready to go.
Step 16: Rapid Melting
Now at this stage I did not have time to take pictures, it seriously started melting at crazy speed. The crucible became real hot, and the aluminium melted fast, so fast that I was struggling to feed it quick enough. Also I was eager to get at the skimming off and pouring of shinny molten aluminium.
I had to pack in more charcoal now and then to keep it burning well and at a steady temperature.
But it was eating up what I fed it and I was both amazed and joyed at how effective it was all going.
Every now and then I scraped off the dirty slag from the top and got a glimpse of molten shiny goodness and everything was going to plan.
I couldn't wait to pour it all into the pans and produce lovely ingots of recycled material.
Step 17: OMG Xxxxxxxxxxxx
As you can see from the picture, it all went to hell as the crucible failed. Well actually the crucible didn't fail I did, you see as the crucible was red hot the walls were good but could be punctured.
In my eagerness to melt it all, get that shiny aluminium, I dropped a rather thick chunk that you can see of metal into the crucible. I then tried to push it down and well I punctured the bottom of the crucible.
The tip is leave it, let it all melt, don't force it and try to ram pieces in. Instead allow it all to melt and then add some more.
So as I was feeding it all in, suddenly the crucible went down half way. I was standing there horrified at what I had done and though well I cant say what I thought here.
So I stopped adding more obviously, and tried to pick it up out of the smelter.
Well, non of it pored out of the smelter, this is because the air blower that was working very effectively had cooled it all, now I was stuck in a position where the aluminium had set around the coals and also to the walls of the refractory lining.
My only option was to literal turn the smelter upside down and pour the coals out (Which I did on a dry dirt area) and then allow it to cool.
After I then ripped and smashed away at the lining until the crucible and fussed aluminium came out.
It was a stupid mistake and then I had to go ahead and smash out all of the lining and replace it.
Step 18: Final Thought and Notes
So, I think that If i had not punctured the crucible, it would have all worked out and I would have produced some nice ingots.
Now I never expected the crucible to last forever and expected to make a new one after at least a few times of using it, however I did not expect to puncture the bottom, lesson learned.
I am making another in the same way, so that I can test and see if it would have worked out ok.
This time I will get pictures and video of the feeding and melting process and hopefully the pour.
But I am also looking for other vessel ideas, one is to use an empty fire extinguisher as the walls are thicker, but having trouble finding one.
Another is to get a thick steel industrial pipe and plate an have someone weld the two together.
I will play around with own made crucibles as I do not want to pay out a load for a graphite one just to melt aluminium.
Maybe when I get around to making a gas, electric of oil smelter I will pay out but for now its salvage, junk and improvise.
Step 19: Additional Information
I have finished repairing the smelter and emptied the other Coleman tank (now I need to buy one to actually use) and as soon as I can I will form the lip (cant without tank of propane).
I have also made a heat table that I will upload an Instructable on, it is a simple thing made using the refractory lining. This is so that I can place the tool son when hot, the crucible should i need to put it down and also the molds.
Also it works out well for soldering and brazing items and should be a good addition to the whole smelter/foundry equipment.
As soon as I get a decent day that I am not working I intend to finish off the crucible and have another crack at it.
Step 20: NphRandom
Thank you for reading and viewing this NphRandom Instructable post and I hope that you have a nice remainder to your day.
Don’t forget that if you like what NphRandom is feel free to browse some more, go to other linked places, Subscribe, Like, comment and Favorite all that you want.
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Nph
