A thin hotface medium/low mass beer keg (drum size) furnace for melting Iron

The interior of the furnace is definitely pressurized quite a bit.
I don't see any way around this.
I did some early testing with a large lid opening, and while it did melt iron, it was not an ideal setup.

 

Sounds like a plan; I am going to go with it.
Thanks.
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They were used by scavenger for structural support/backup rigidity for the thin hot face, and he poured his hot face directly into them.
I don't really want a solid connection like that, but I think the cracked hot face will need the support of the IBF's against it.
I could shape the IBF's, but no time for that now.

I like that idea.

Thanks much.
I hope I don't have a major failure in front of folks from all over the country.
Nothing ventured, nothing gained as they say.

I am out to put it all back together and transport it.

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Good advice from Kelly as usual.

I liked your siphon video. You might have had control issues but the crucible was warm.

Notice the inside of the Mizzou was red and the outside was not. That is because the outside was not insulated and was getting air cooling. It would probably get red over time but not like when it is insulated.

Have you tried the large lid opening with your atomizing burner? You really can't pressurize a furnace, you have to let the hot gas out so you can get more fuel and air in. If you want more combustion time you need a larger firebox. Most of the ones I see in home furnaces look really small to me. I like to give the fuel and air plenty of time to burn and transfer heat to the walls and crucible.

Sometime when you're melting and waiting for everything to warm up try putting your thermocouple in the flue stream. Pull it back before it gets to 2,000F to not damage it, but we might learn something.

 

I was ramping the fuel flow up and down to find out what ran the hottest.

The Mizzou gets very red hot on the outside during an iron melt.
It takes about 15 minutes.

Yes, you can melt iron that way, but it does not seem very efficient.

We would learn that pyrometer tips that are not iron rated melt off quickly in the flue stream.

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Of course it is less efficient, but it may make your refractory last much longer by not forcing hot gas through the cracks.

I didn't mean leave it in until it gets over 2,000F. I was wondering how long it takes to heat. I haven't done that on mine in a while, I need to do that again. Mine was colder than I assumed it would be.

 

Got some patching done today.
Getting ready to start putting it back together.




Edit:
Now that I think about it, I need to find out where they get the Plastic Super A.
If it works to patch a cupolette, it would work to patch a furnace.

 

What did you patch with that you can fire tomorrow?

 

I am using ITC200, and since it is very thin and only fills in the cracks, I seldom let it dry long.
Generally for small cracks, I fire the furnace right after filling the cracks; no problem.
At best it is 1/8" thick at the crack, but generally maybe 1/16" thick maximum.

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Thanks, about like Satanite.

 

Looks like I will be working down to the wire.
Got the bricks cut.
Need to cup them so they fit tight to the shell.

 

Here's the four piece shell. http://forums.thehomefoundry.org/index.php?threads/segmented-castable-furnace.588/

And where I ordered my Satanite: http://www.hightemptools.com/refractorycoatings.html

 

Thanks.
That is a cool method.
I need to try that.

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Thanks, I don't see any reason you couldn't do it with 1" of Mizzou. And a simple lap joint with mud on the inside surface would seal mismatch and give you a single crack for expansion.

Hope everything goes great today!

 

Page 40 to about 45 of the MIFCO manual is interesting regarding lid assembly and band tightening and adjustment of their segmented lid and segmented firing chamber segments (which they sometimes seem to refer to as bricks). This information would seem to apply directly to assembly of the nicely made segments OIF made. They do use bands and mortar in their assembly process and do recommend loosening band bolts one turn prior to firing. They also use mortar and recommend wetting the segments with generous application of water prior to cementing If I ever make a segmented furnace I would follow their established procedures until I knew better

Scroll down in this document.

http://mifco.com/B & C Manual-2014.pdf

Denis

 

I used an angle grinder to curve the face of the top row of the IFB's last night, and got them to fit pretty close to the hot face, but the hot face is not precise, so there is still somewhat of a gap in places between the IFB and the hot face shell.

I think the exhaust gasses will follow the cracks and go between the IFB's and the hot face, and could cause some problems, so the plan right now is to use a ceramic blanket gasket to get me through the demonstration pour.
Not an ideal solution, but a stopgap measure.
I really only need to open the lid once at the end of the melt.

For a permanent solution, I will probably go with a band of hard fire brick at the top, laid flat and cut in a circle, and cemented to the hot face, but not cemented to the IFB's.
The hard fire brick will rest on the IFB's for support though.

I will make do with this design until I have time to work up something else, which will probably be next year.

I am loading the furnace and am off to the melt.

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I got the furnace back from the FIRE show relatively intact, although I have not opened the lid and done a close inspection.
I brought the furnace home on the trailer with it fully assembled, and it bounced around a bit, but I drove very slowly, so hopefully the bounce damage is negligible.

I made it to the refractory supplier today, and bought two types of Plastic material (apparently the term "Plastic" covers a wide range of materials).
One type is more of a putty, and it can be thinned with water if desired.
It is rated for 3,200 F.

The second "Plastic" material is not recommended to be mixed/thinned with water, and it is rated for 3,800 F.
I think it is a more dense material, and not so readily formed (that is the impression I got).

I figured I would try them both.

And while I was there, I noticed a boss hog of a mixer that was most impressive.
Up on three pallets it stood almost 6 feet tall.
A very serious mixer.

And I found what looks like Rev.02 of my hot face for this furnace, which is curved hard fire bricks.
I did not have time to check the radius, but they looked like just the ticket for a hot face.
Hard fire bricks do work at iron temperatures (so I am told by one individual's posts elsewhere).
These curved hard fire bricks are basically the same as the cast refractory units that others have proposed, and this would eliminate most of the need for using cast refractory, although the lid may still need to be cast into a dome shape.

So my plan for the next furnace rebuild is one layer of IFB's on the base, one layer of 1" hard fire bricks on top the IFB's (to make the bottom of the furnace), vertical curved hard fire bricks for the hot face, one layer of IFB's outside the hard fire bricks, and one 1" layer of ceramic blanket over all of that, with a stainless steel shell.
I believe this configuration would be the same weight as the cast refractory furnace I have (about 120 lbs), but would make repairs/rebuilds very easy.

I am going to get a quote on curved hard fire brick tomorrow.

 

I will have to inquire about temperature ratings and cost tomorrow.
The advantage to rolling your own is that you could cast it at the exact height needed, as opposed to the pre-cast hard fire bricks that may only be 9" tall (I did not get a chance to measure them).
It is somewhat a matter of time available.

The cast members require mixing, and so in order to make all of them at once, you would need multiple molds.
If you cast them one at a time, that will go on for days at a time and require multiple mixes/castings, with a full clean of the mixer each time, since the castable refractory dries hard like granite on the mixing bowl.

At this point in my life, time = money, so if the rating of the hard bricks is above 3,200 F, then I will probably buy a batch of them.
I could literally make the entire furnace in less than a day using the curved hard fire bricks, and I can't do that with cast refractory members.

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