Nancy Reading wrote:
Do you think that a rocket forge just won't get hot enough Joshua? Or that I won't be able to get the right mix in my crucible? I'd really like to try the 'low tech' approach and not use a blower and charcoal if I can help it. I know that doing something different is sometimes a bad idea, but I can't see an obvious problem at the moment, other than the unknown.
The backyard smelter is really about as low-tech as it gets. You could knock it down a peg or two by digging clay out of the creek bed instead of using bricks, make a bag bellows (or use a foot pump) instead of the blower and get your husband to switch off with you pumping the bellows.
:-)
If we go back to that short
video in the post above where they are trying to use a
RMH for simply forging mild steel (800-900 deg. C) and see how big a furnace they are using and still struggling, I seriously doubt you can get the
RMH up to the temps needed to smelt iron ore (1400-1500 Deg. C).
Toward the end of that video, they are talking about using charcoal inside the RMH over the brick they have drilled holes in to raise the temperature. Charcoal will burn hotter and faster than raw
wood, but it needs forced air to do it. The RMH is basically just a fireplace with an elongated draft.
Considering the size of what they are using in that video, and the little furnace I built in the back
yard, I'd have to say my little furnace is a cheaper, faster, better method, but I could be wrong.
You can give it a try, but humans have been smelting all sorts of metal ores with charcoal and a bellows for a couple thousand years. If it could have been done in a simple wood fired hearth, I think we would have invented steel much sooner.
As for using the crucible, I have tried that in very small quantities, like a tablespoon of sand, and made a
cast iron button. (
https://permies.com/t/270554/permaculture/steel-making-process) It still took a propane furnace with forced air blower to achieve the required temperature to melt the iron out of the sand. I tried it with a larger amount of sand in the crucible and a propane furnace to get to temp and had a disastrous mess. (see above) You may have a different result than I did, but after talking with other smiths doing the same thing, they had the same
experience that I had doing what I did.
The ancients who made the first crucible steel in India, made it in huge furnaces with many crucibles stacked up inside it. They then filled the rest of the furnace with wood and/or charcoal and pumped bellows into it for hours. That little backyard furnace I built is just a miniature version of that. If you built a similar furnace, loaded a small amount of sand into your crucible and nestled it inside a load of charcoal, you could probably get up to temp to melt that sand, but you would still need forced air to do it.
I don't want to rain on your parade, but I would like to see you have a successful experiment with as little struggle, work, and mess as possible.
Another YT video of crucible steel making with two renowned smiths added for your viewing pleasure:
https://youtu.be/namXt4Etn_o?si=6BpiAKjFv3w7OxtS
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