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Jake Howard

First Tatara Smelt

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Hey guys! First post here on bladesmith forum. I have been reading a lot of posts here and have doing research for my first Tatara smelt. Would like to hear what you guys think of my plan. Open to any criticism. For some reason i could not upload a picture of the plan i drew out, so i will describe it the best i can.

Inner Dimensions: 10" wide/ 15 1/4" long

height: 48"

The dimensions are based off of the brick ill be using and the amount of Iron oxide/charcoal ill be smelting.

I am thinking of running about 60 lbs. of black iron oxide sand with about 150 lbs. of charcoal. Does that sounds right? 

The inside will be composed of a clay/sand mixture to make room for the bloom. The outside will be brick for support. Not planning on using too much clay/sand. Mostly just for the funnel where the bloom will go. The rest of the brick will have a thin layer of clay/sand.

should I use clay to mortar the brick together? Or should i just go with a regular brick mortar for that?

There will be 4 tuyeres, 2 on each side. There will be 2 tap arches on both sides of the funnel.

I am still very new to this so any help/criticism is much appreciated.

Thanks guys!

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I just ran a 9x9 chamber.
The size of firebricks at 46" tall, same amount of ore you are using, same amount of charcoal and we made a 22 pound bloom with one tyurre.
I think your chamber is too big for what you are running.
Also, just a heads up, if your iron oxide is too fine it will blow out of the top of the smelter.
We mixed our ore with charcoal fines and water and made cakes that we charged in 6 minute intervals around 1 Kilo of ore per charge.

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17 minutes ago, JJ Simon said:

I just ran a 9x9 chamber.
The size of firebricks at 46" tall, same amount of ore you are using, same amount of charcoal and we made a 22 pound bloom with one tyurre.
I think your chamber is too big for what you are running.
Also, just a heads up, if your iron oxide is too fine it will blow out of the top of the smelter.
We mixed our ore with charcoal fines and water and made cakes that we charged in 6 minute intervals around 1 Kilo of ore per charge.

Awesome! Thanks for the input JJ. Sounds like the 9x9 chamber is the way to go unless I run more material. Great tip! if the ore i get is too fine I will definetly keep that in mind.

How long did you run the furnace for with 6 minute charges?

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3 hours ago, JJ Simon said:

I just ran a 9x9 chamber.
The size of firebricks at 46" tall,

JJ, I'm not following this. 9x9 is the open area in a square of fire bricks? So 6 bricks per course stacked 46" tall? Is that correct?

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4 hours ago, Jake Howard said:

Awesome! Thanks for the input JJ. Sounds like the 9x9 chamber is the way to go unless I run more material. Great tip! if the ore i get is too fine I will definetly keep that in mind.

How long did you run the furnace for with 6 minute charges?

Really the charges were 12 minutes but broken it to two.
It amounts to the same thing.
We ran an hour of preheat about 3 hours of charges.
We used all but 2 pounds of the ore I had.
And an hour of burn down.
If you are using a steel tyure the furnace is going to eat a lot of the material which needs to stick inside the furnace a few inches.
A copper tyurre is whats needed.
You can see a video of how Lee Sauder made his newest one.
You have to have an air supply or a water cooler for it.
If you do the air, check out Mark Greeen's set up.
He has a plus sign junction connecting the Tyurre, the air supply a plug and a pipe that comes out the other side and turns back on the tyurre and blows excess air on it it to keep it cool.
You have to be able to see down the Tyurre and run a rod down it to clear it of any slag that builds up.

59 minutes ago, Joshua States said:

JJ, I'm not following this. 9x9 is the open area in a square of fire bricks? So 6 bricks per course stacked 46" tall? Is that correct?

Yes thats correct. 6 bricks per layer.
Probably don't need it to be 46" tall, that's just what I made.
Also dig out the bottom by 8-10" and fill it with ash so the bloom can A: grow there and B: be easily dug out.

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2 hours ago, JJ Simon said:

Really the charges were 12 minutes but broken it to two.
It amounts to the same thing.
We ran an hour of preheat about 3 hours of charges.
We used all but 2 pounds of the ore I had.
And an hour of burn down.
If you are using a steel tyure the furnace is going to eat a lot of the material which needs to stick inside the furnace a few inches.
A copper tyurre is whats needed.
You can see a video of how Lee Sauder made his newest one.
You have to have an air supply or a water cooler for it.
If you do the air, check out Mark Greeen's set up.
He has a plus sign junction connecting the Tyurre, the air supply a plug and a pipe that comes out the other side and turns back on the tyurre and blows excess air on it it to keep it cool.
You have to be able to see down the Tyurre and run a rod down it to clear it of any slag that builds up.

Yes thats correct. 6 bricks per layer.
Probably don't need it to be 46" tall, that's just what I made.
Also dig out the bottom by 8-10" and fill it with ash so the bloom can A: grow there and B: be easily dug out.

Ok was not expecting the furnace to run that fast. I was planning for a 12 hr run haha. I would be happy with a 20 pound bloom with a 5 hr run! I might end up running double the ore and coal and go with my original dimensions, but then again I should probably keep it small for my first smelt.

I was planning on running the tuyere about an inch into the side wall so its not sticking through and doesn't melt. Is this not a good option? I think I've read couple posts where people do this.

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It sounds to me like you are going for a tamahagane bloom rather than iron.  The rectangular shape and multiple tuyeres clued me in, not to mention you said tatara rather than bloomery furnace...;)

So: I have watched and sort of assisted on two or three runs of this type several years ago, conducted by Mike Blue, Randal Graham, and Ric Furrer.  They used a hopper-section (narrow at the bottom, wide on top) rectangular brick base one year (can't find my pictures...) and the same section but smaller size made of clay another year.  The brick base used an insulated steel stack and the clay base used a compressed ceramic fiber stack made of foundry riser tubes.  Both worked well.  Air was supplied by a V-4 arrangement of 1" black iron pipe tuyeres inclined around 20 degrees, with the tips flush with the hopper walls.  Ore was loose taconite, pre-pelletization.  and the runs were four to six hours.  These furnaces were not true tatara, since they had short stacks, but that was necessary for the small scale involved.  Even at that, it kept three or more guys very busy for several hours straight. A true tatara is even more labor-intensive, more like a Catalan forge.

That said, furnace shape and number of tuyeres is not as important as you might think.  Tuyere angle and rate of burn combined with ore-to-charcoal ratio is what determines if you get iron, steel, or cast iron.  Too hot and too fast with a lean ore ratio and/or too flat or too high on the wall a tuyere angle and you get cast iron, because there is not enough time/oxygen to burn off the carbon.  Oddly enough, too slow can do this as well, but seems to be more dependent on the tuyere angle and height above the floor since once the bloom is below the blast there is no more oxygen to scavenge carbon from the bloom.  Then you rely on the slag bath to decarburize, and you risk losing a lot of iron to the slag, up to the point of risking no bloom at all, just a big puddle of iron-rich slag with little prills of cast iron floating around.  You can add a deep floor of charcoal fines to aid in keeping the carbon content up, but this is not really required.  Stack height plays a role as well, since a tall reduction zone will tend to add more carbon.  It's all a series of balanced reactions, and those vary quite a bit for each particular furnace size and shape. 

Lee Sauder and Skip Williams have done a lot of work on this using single tuyere shaft furnaces and I suggest you study their data.  They are usually trying to keep the carbon content down, but if you read carefully you will get an understanding of how to tweak it the other way.  I could go back and look it up myself, but it's your smelt and I'm busy today.:P

One last comment: If you use flush tuyeres in the base, you will need a poker to clear the slag that inevitably clogs up the holes.  This means you also need a way to get into the tuyeres without removing them.  Just an added complication, not insurmountable.

 

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And of course I just found my pictures. :rolleyes:

The brick furnace, and it was actually a V-6!:

furnace base.jpg

furnace 1.jpg

furnace 2.jpg

and the clay furnace, which was a V-4, I haven't processed the pics to fit.  Same idea, though, just smaller.  It produced a more compact bloom, but both furnaces did make nice-looking tamahagane.

 

 

 

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5 hours ago, Alan Longmire said:

It sounds to me like you are going for a tamahagane bloom rather than iron.  The rectangular shape and multiple tuyeres clued me in, not to mention you said tatara rather than bloomery furnace...;)

 

Great pictures Alan! And thanks for all the info! I think i saw a short video on youtube of one of these runs actually! This is the design i am looking for, as my goal is to produce tamahagane.

How much oar and charcoal did you guys feed those furnaces? I think in the video he said something about a 60 pound bloom!?!

So should I keep my tuyeres low as seen in the pictures?

Edited by Jake Howard

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There is a video by Chris Price, Tidewater Forge, called something like "steel from dirt." It's probably on this site somewhere, those pics are from March of 2006.  The bloom was nowhere near 60 lbs, more like 15 or so.  I do not remember how much ore they used, but we chopped around 200lbs of charcoal and did not use it all.  I still have a piece of the tamahagane, though!

We also used crushed oyster shell in the charges as flux.  Nobody does that any more unless they're going for cast iron, but it makes some nice slag.

If I were you I'd do a few runs on a single-tuyere short stack furnace using Lee Sauder's plans to get a handle on how your ore behaves, then branch out from there.  You can get a nice steely bloom in that kind of furnace, and there are fewer variables to screw up.  This is an expensive and laborious way to get steel, but if you want the real thing it works out to about the price of the real Japanese stuff if you don't count your labor at more than around 50 cents an hour...

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If your furnace returns 20 pounds from 60 pounds of ore you have had a good run.
This is the return from my furnace.

 

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Nice one JJ.

11 hours ago, Alan Longmire said:

Tuyere angle and rate of burn combined with ore-to-charcoal ratio is what determines if you get iron, steel, or cast iron. 

So how does one determine the proper ore-charcoal ratio? Is this a factor of furnace size, type of ore, some other variable, or is it fairly constant across the spectrum?

I am assuming that this ratio is the one used for the charges, not generally speaking, 160 lbs of charcoal for 60 pounds of ore type of data.

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Beautiful steel JJ!!

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13 hours ago, Joshua States said:

Nice one JJ.

So how does one determine the proper ore-charcoal ratio? Is this a factor of furnace size, type of ore, some other variable, or is it fairly constant across the spectrum?

I am assuming that this ratio is the one used for the charges, not generally speaking, 160 lbs of charcoal for 60 pounds of ore type of data.

Yes, and maybe...  For a starting point with a short (~40-48 inches above the base) stack single-tuyere furnace of 10 to 12 inch bore a 1:1 ratio by weight with a burn rate of one charge of ore and hardwood charcoal every seven to ten minutes to keep the stack full using roasted and crushed limonite/goethite or hematite will usually yield wrought iron of 0.1 - 0.2% carbon.  If you use less ore at the same burn rate you have greater reduction of the existing ore, which usually results in greater carbon uptake to yield steel or cast iron.  More ore at the same burn rate gives you less reduction, which usually results in wrought iron of less than 0.1% carbon but with greater losses as unreduced ore and slag. This is assuming the same furnace height and an ore that is composed of around 40-50% available iron.

The extra charcoal is used to fill the furnace before starting the ore charges.  Softwood charcoal is lighter than hardwood and I have never used it, so you'll probably have to tweak the ratio a bit to find out what works. The thing about a faster burn rate tending towards cast and a slower burn rate tending towards iron is a generality as well.  You'll find each ore and batch of charcoal has a preferred rate, anywhere from every five minutes to every twelve or so.  It is not an exact science by any means.

Again, Lee has all this on his site, and it turns up in various threads throughout the bloomers and buttons subforum, both this one and the one for pinned topics.

Joshua, if you go out and troll the arroyos with a magnet you'll get a fair bit of magnetite sand.  This is a different critter altogether and is more difficult to reduce, but also tends to produce steel rather than iron for some reason, most likely related to the slag chemistry.  Mark Greene has a fair amount of info on magnetite in his facebook group, but since I don't do facebook I don't have access to that info.  Plus our east coast magnetite is in the form of big rocks, not sand, which also makes it harder to deal with.  I think Owen in England is using pre-roasted and crushed Swedish magnetite with excellent results. Magnetite runs up to 72% available iron, but it's harder to get loose than the iron from soft ore like limonite/goethite.

I am still very much a rank beginner at this smelting thing, so take that under advisement.  I have only done two furnace smelts start-to-finish with one kind of ore, but I have been present for many more using other ores.  Most of these have used the same basic type of shaft furnace, except for the two tamahagane runs mentioned above and a couple or four of direct crucible reductions, two of which were not successful.  You can understand the chemistry and read all about it, but actual experience is required for consistent success!

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I'm not one to just try stuff without doing a fair bit of research before expending lots of time & money, but the more I read and the more questions I ask, the more it seems like the best course of action is to pick one of these furnace designs, sacrifice a goat, and give it a go. Luckily enough, my neighbor has a small herd of goats and might not notice one missing.

The smelting plan involves 4 of us, two of whom have plenty of experience in the subject, to gather the ore material. Frankly, this sounds like a lot more than "trolling the arroyos with a magnet" to me, but I really don't know squat about it. I have hiked through a lot of the Arizona countryside (northern and central) and the thought of lugging 5-gallon buckets through the washes collecting sand is slightly less than appealing. Maybe I'm getting old, but I'd rather spend some money buying it so I can spend more time smelting it. Time becomes more valuable than anything else the older I get.

In the meanwhile, I'm still making that pine charcoal. I have a 30-gallon trash pail (maybe 50 pounds) full of it and I'm only about 20% through my wood pile. It is slow going.

I have read much of Lee's material and the Aristotle furnace paper is intriguing. Sort of a second stage refinement of bloom iron/low-C steel. I cannot locate any significant amount of information on Mark's fb page, Iron Smelters of the World, but that's probably because I am technically challenged. His video posts are always entertaining and typically educational as well. 

I think we have sufficiently hijacked Jake's thread now, so I will shut up.

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The charge rate was 2-3 kilo per 0-12 minutes broken in half for managability.
My magnatite was powder so we made cakes from the powder and charcoal fines and water.
It worked great.
And yes a 1:1 ratio is what we ran.
Basically you measure your ore and mark a clear container so you have it every time.
If you're going the cake route I would premix them.
Thats done by feel, not too stiff, not too sloppy or wet.

Then measure your charcoal charge and burn rate by the drop of the furnace.
Ours measured out to basically a shovel full.

Jesus ran the smelt and he basically listened to the furnace.
We never looked down the tyurre and never had to tap the furnace or the tyurre.
That's because the magnetite was 99% pure and because I dug a deep hole under the the ground level of the furnace so the slag could collect into it.
Do yourself a huge favor and make your tyurre out of copper.
 

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On 3/10/2017 at 5:07 PM, JJ Simon said:

The charge rate was 2-3 kilo per 0-12 minutes broken in half for managability.
My magnatite was powder so we made cakes from the powder and charcoal fines and water.
It worked great.
And yes a 1:1 ratio is what we ran.
Basically you measure your ore and mark a clear container so you have it every time.
If you're going the cake route I would premix them.
Thats done by feel, not too stiff, not too sloppy or wet.

Then measure your charcoal charge and burn rate by the drop of the furnace.
Ours measured out to basically a shovel full.

Jesus ran the smelt and he basically listened to the furnace.
We never looked down the tyurre and never had to tap the furnace or the tyurre.
That's because the magnetite was 99% pure and because I dug a deep hole under the the ground level of the furnace so the slag could collect into it.
Do yourself a huge favor and make your tyurre out of copper.
 

JJ how long did you wait for the magnetite cake to dry or did you put it in the furnae wet?

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They went in wet.
They held together it was just to make sure the ore didn't blow out the top of the furnace.

Didn't cause any problems.

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