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A blacksmith friend (Mike) and myself have often discussed making our own steel, I believe I found out here that collecting "ore" with a magnet on our dunes aren't the right stuff to use....

 

Another friend recently completed a project setting up an ore refinement plant at a new iron mine in the Dordabis area of East Central Namibia, and he's given me several bags of ore. The last lot apparently even better quality than the first bag.

 

Mike has an archeologist buddy that volunteered his enormous back yard for the smelt and we were planning for August 2021, that shifted to September 2021, and considering my impending shoulder surgery that date will probably move to next year.....a huge pity

I've been itching to do this for years and now I'll have to be patient a while longer, but that doesn't mean I can't dream and plan ;)

So we have:

1. Ore

2. Blower, the industrial kind you'd use on a nice forge

3. Location

4. Lot's of relatively cheap locally produced charcoal.

 

For now my main question is regarding the ore, my buddy still has contact with the geologist at the site (who also wants to be present for the smelt) so I can maybe get some more details about the composition of the ore.

What is good? What is bad? What will work and what won't? 

I would appreciate some input from the inhouse experts, just remember I don't know what you're talking about! :lol:

 

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I am far from an expert, which I guess is why I've never had good luck with magnetic ores.  That is, the ones that are magnetic as-found (magnetite and maghemite).  The Fe2O3 ores turn magnetic when roasted, and I've had decent luck with those. 

 

If you have hematite (hard red ore) or goethite/limonite (soft brown ore), you set yourself up for success if they are at least 60% iron by weight.  It's possible to smelt iron from 30% ore, but the balancing act of keeping the iron out of the slag is hard at a small scale.  That's why medieval smelters were able to make iron from Roman slag.  

 

Anyway:  Once you have the ore analysis, this link is probably the best way to go about making iron from it with the fewest potential issues: https://s3.amazonaws.com/images.icompendium.com/sites/eliz2406/sup/3696366-furnace-construction.pdf  This is Lee Sauder's instruction manual.  You can find more of his stuff here: https://www.leesauder.com/smelting-research.  It is my understanding that he's not using the peat moss anymore, just pottery clay and sand.  Hopefully he'll stop in and correct me when I'm wrong!  What I have done in my smelting adventures with Jesus Hernandez, Mark Greene, Dennis McAdams, and Chris Price is to mix up the furnace body clay using equal parts sand, kaolin clay (the EPK Lee mentions is a brand name of kaolin clay), and peat moss or other shredded organic material like dry grass.  Add water until you can make a very stiff dough that barely sticks together, form into large (~1 Kg) balls, and put in a plastics tub for a few weeks tightly covered to temper.  Follow Lee's instructions from there to make the furnace shaft.  This is the easy part.

 

Hopefully the mine is providing you with fist-sized chunks of raw ore OR roasted ore crushed to pea size.  Roast the big chunks in a wood fire for a couple of hours.  This converts the Fe2O3 to Fe3O4 (or vice-versa) and more importantly fills it with micro-cracks.  This allows you to crush it up with little effort and also allows the gasses in the furnace to get inside and convert the oxide to pure iron. You can run crushed, unroasted ore, but it's less efficient.  Might want a slightly taller stack.   

 

Once you have the prepared ore, at least 20Kg, and at least 50Kg of 2.5cm charcoal, build your furnace with about a 25cm bore around 120cm tall off the base.  

 

You need a tuyere, too.  You can make this from clay, or thick copper (or water-cooled thin copper if you're good at that), or just plain iron pipe.  25mm diameter works well, and you can step it up to 30mm or 40mm outside the furnace if you want.  This goes in the side about 25cm from the base of the furnace pointing at a 17 degree angle down towards the center of the furnace.  It's good to have a cap on the outside end you can remove to poke solidified slag out of the business end when it clogs.  This also is your viewport to determine what's happening in there. The blower can be a shop vac running off a dimmer switch, or something more esoteric, but it HAS to be able to provide pressure.  Ordinary forge blowers won't cut it.  

 

Fire that sucker up using scrap wood with the furnace bottom open and let it fire the clay slowly.  Keep this going for an hour or two, patching cracks as they appear.  Then add the door, and poke a tap hole in the bottom about 10cm above the base.  Be sure this will direct the molten slag in a safe direction and not onto your shoes or the blower.  You may think this would be obvious, but I can show you my old boot soles...  When this is all kind of fired, plug the tap hole with some very wet clay.  Fill the furnace to the top with charcoal and start the blast.  Wait until you have flame coming off the top, then adjust the blast until the charcoal is dropping around 10cm every six to eight minutes.  Top it off and add your first charge of ore.  Add half a Kg or so, loosely tossed in a horseshoe shape atop the charcoal with the open end of the shoe where the tuyere is down below.  When the load drops another 10cm, add charcoal to fill and another half-kilo of ore.  Adjust the blast to keep this rate of drop between 6 and 10 minutes per 10cm drop.  Faster and you'll get cast iron, slower and you'll lose the iron to slag or freeze the charge in the bore at the tuyere.  

 

Repeat until you've used all your ore, tapping slag if you hear bubbling or lose blast, but don't tap until most of the ore is in the furnace.  After the last ore charge, keep the furnace running at the same rate, adding charcoal until you're sure all the ore has made it through the reduction zone above the tuyere, another 30-45 minutes after the last addition of ore.  Now it's time to pull the bloom.

 

Do this by pulling out the door bricks in Lee's article, then hooking an iron rod in the tap hole and pulling the door gently away from the furnace.  This will make you feel like you're looking directly into a volcano in mid-eruption, but you have to act fast.  Take a shovel and pull the charcoal and slag out from under the bloom, which ideally will then drop out in one white-hot slaggy piece.  Now is the fun part: one guy grabs the bloom with big tongs and puts it on a stump while the other crew take sledge hammers and pack the bloom into a solid mass.  You have to do this in one go while the whole thing is at welding heat, and then at the end you cut it into workable chunks using an old axe you hate as a hot cutter, dipping said axe in a bucket of water every few blows.

 

Lee has some good videos, and the one from Arctic Fire is around here somewhere.  Here's the one Chris Price did of one of our smelts in 2014: 

 

 

This was with an experimental portable furnace, but the general idea is sound.

 

Good luck!

 

 

 

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Hi Alan

Thanks a million for taking the time to write all that up....so much to learn!
For a start, I forgot we'd be making iron, not steel...

The ore is red in colour, exceedingly heavy for what looks like a bag of dirt, and the stuff is extremely magnetic.  They got three different guys in and got 3 different coordinates for the site, affects a lot of equipment.

Its mostly pea sized mixed with what looks like dirt, I initially got one big bag, then several smaller bags of what should be more refined ore after improvements to the plant.......huge magnets are involved.

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Sounds like they've done the concentrating for you, and that it's maghemite not unlike the Mesabi Range "taconite" ore of Minnesota in the U.S.A.  Good stuff, and if you build a slightly different furnace you probably can make tamahagane-like steel.  

 

Try the Sauder furnace first, it's the easiest. 

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  • 2 weeks later...

If you haven't already I recommend checking out the "iron smelters of the world" facebook group. Lots of people from all over the world to throw questions at. 

I recommend keeping thorough notes during the smelt in terms of time, quantities, and observations. This will allow you to start narrowing variables after the first one. 

 

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