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New lining for the iron furnace

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And there you have it. A fast 10" aluminum foundry melt. Fueled by the dregs of a very small wood fire. On a cold winter day. With no blast, and only a small port inlet.

I'm going to be interested to see what it does with an oil burner and furnace blast.  :bugeye:

My only concern is that the lining seems so physically fragile. But we'll see what we see........  :dremel:

Impressive result Steve  :thumbup:

Just goes to show how much energy is lost through the walls with a conventional lining.

Yes, Andrew, I'm wondering now whether this furnace might manage to melt iron with propane. Ironman built a smaller propane furnace that handles up to an A3 crucible.

Interestingly it takes just about the same amount of expensive lining materials for this size furnace as it does to make a the smaller one. Both require about 2" of fiber blanket thickness, so that isn't reduced for a smaller furnace, and the area  of coverage inside doesn't increase as fast as the volume does -- the old square-cube law. Before I decided to line this furnace, I priced out what it would cost to line the smaller propane furnace I use all the time. The bore would have been 7" and the total cost would have been about $20 in savings. So I opted to line the bigger furnace.

Another interesting point, if you do have a conventional heavy refractory lining, I bet this hot face coating would make a noticeable difference in melting speed, by reflecting a lot of the the coating would be well supported in that lining application, compared to applying it to a blanket. I can see why larger commercial outfits would plunk down the money for this stuff.

Today I tried the furnace on propane. As a test I loaded a small clay lined crucible with scrap glass-cutting diamond holesaws, which are basically a nut shaped heavy brass collar with a thin stainless steel ring. The burner was the atmospheric propane torch I made in another thread here. There was no blast -- just the torch.

Brass melted in about 20 minutes, and I fished out the rings before pouring into an ingot mold. The melt was a success, though it could have been hotter and better skimmed. But I was beginning to get zinc fuming out of the melt, and I didn't want to lose too much, so hurried it a little.

A larger blown burner will probably melt much faster, and also reduce zinc loss, while pouring hotter. I'd probably also cover the crucible and maybe add charcoal to the pot to protect the melt if I was going to pour a mould. But it was fun today to at least melt brass in mid winter.  :dremel:

This was the burner:,8633.0.html .

For more heat with propane, I may just try Ironman's much simpler blown burner, like the one on his small iron furnace:

(Although I do like an atmospheric burner like my present one -- maybe I'll find a larger design for one that will work for the furnace)


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