Iron ore roasting on an open fire. Jack Frost need not apply

[Frosty]

A friend lent me a copy of "The Craft Of The Japanese Sword" by: Leon and Hiroko Kapp and Yoshindo Yoshihara. It has some good detailed info on tests for and pictures of the grades of iron and steel coming from a tatara and how they're re-processed and used in initial billets. Just stacking the pieces for the first billet weld is a high art. The master visualizes the characteristics of the sword, be it wall hanger or functional weapon, appearance, color, pattern, hamon, everything while placing the broken and flattened pieces of the bloom for the first weld.

 

One big piece of bloom isn't what a tatara produces according to this book. The bloom is always broken up and sorted by grade.

 

Accounts I've read about large blooms going from the furnace to the hammer to make wrought iron seem to be much larger operations and contain much more slag as a result. The Japanese method selects the slag out of the bloom so slag inclusions are much reduced. This book also points out that during the Japanese empire periods, there were many hundreds of sword smiths scattered all over the islands, each with his "secret" techniques, ore, charcoal, masters, helpers, etc. so, there was never ONE kind of Japanese sword till VERY recently when the post WWII ban on owning a sword was lifted.

 

Frosty The Lucky.

[Nobody Special]

Still haven't spark tested or cut one open (work plus household stuff), but did run through with a magnet, and learned a little I think.

One - some of the heavy black stuff I thought was iron, ain't. Slag. Doesn't look like the stuff I tapped, but definitely much weaker magnetic attraction than the "good iron". Sure they've got wrought iron bits stuck in them, and I'll recycle them.

Some of the slag....well, looks like slag. Like a clinker does sometimes, or a piece left over from casting copper. Runny.

Two - The wrought iron looks like one of two things, either like coral, or like the extra cement you get around the edge of foundations. I think part of the variance comes from the size of the ore I crushed, and some, by how much slag is helping hold it together.

You can definitely tell the stuff that was fines in the ore (cement looking) from what was the larger pieces (coral). I generally tried to crush about the size of a dime or smaller, but since I wasn't sifting, some the pieces were about up to the size of a nickel.

Three - What I think is cast iron. Hard to describe......more solid than the wrought, but tended to be in small chunks. Some of it looks very much like the thick, solid slag, but has more of a grain, and definitely has a strong attraction to the magnet.

Four - Even after sorting out the non-magnetic slaggy bits, got a lot yield for a first. I don't think it's anything I did right, I think it was due to using the nice, hi-yield red/brown hematite that brought iron mining to this area rather than something like bog ore or a lower yielding limonite.

I know. Descriptions without pics. Well, tonight I plan to spark it and start playing with it on the fire. Not necessarily in that order. Pics to follow. Really. No dealing with chickens or home maintenance tonight.


Also, Frosty, I've seen several documentaries on the subject. Beautiful and mind boggling. The one's I've seen claim they can grade the bloom pieces' carbon content, with a very high degree of accuracy just by looking at them. I was also impressed by the level of specialization and teamwork used for every aspect of the sword making process.

Not there yet. Analogy? I'm to them like a 13th century guy who's read a couple of books by Galen and the other Greeks, and wants to cut up cadavers to see how the body works next to a modern neurosurgeon. Just feeling my way along.

[Nobody Special]

Or maybe I'm completely wrong. Consolidating not going well. Very crumbly. Powers that be think I may not have cooked it hot enough, long enough.

 

Spark test gave very short sparks, mostly orange, some pieces with a few yellow. Little to no forking. Might be not doing it right, might be didn't extract enough and needs to be saved and rerun in next batch. Sigh............I need a drink.

[ThomasPowers]

Was there shiny metal evident where you ground?

[Nobody Special]

Some, but more like specks and trickles here and there in the black/grey of the bloom rather than looking like a piece of ground metal.

 

I think Steve's right and it didn't cook hot enough/long enough, and only partially extracted the iron. Looked like...i dunno, when you get veins of impurities running in small lines in a rock? There was definitely shiny metal, but it wasn't the main body of the ground bits.

 

Sigh..........chalk it up to a learning experience, and know that I won't have to look for as much ore for next time. Still was fun, and a cool way to waste a lot of man-hours/charcoal. Gotta find someone close that's done it and get with them.

 

Think I'll do something simple today. Nails, or twists on bottle openers or something. Keep my hand in, but something that's easy enough i feel like i did something successfully.

[DanielC]

Can you possibly build this with the aid of fire brick? Using the clay as a mortar. Very similar to how Ric Furrer built the middle age furnace for crucible steel.

[Nobody Special]

Probably, there's a video somewhere of him and a few others making a huge bloom on a tatara type furnace, and i think it was mostly clay lining firebrick.

[Kilroy]

I have a question. Let's say I did this but with pig iron or scrap metal. Would it have the veins of slag in it? I've been trying to find wrought iron but it's impossible, and I can't get any ore in my area.

[ThomasPowers]

WHERE IS YOUR AREA?  I've found wrought iron all over the USA and in several foreign countries and have been able to source high grade iron ore commercially as 100 mesh magnetite sold as pollution control supplies.

 

AND no, a bloomery won't do that as it uses iron ore not cast iron and scrap steel. 

 

If you want to make wrought iron from cast iron look up puddling: note it will probably be much more expensive than having real wrought iron shipped from England to you!

[Joe111]

Real wrought iron is not easy to find these days.

 

About the melt. You will never get it hot enough to melt the iron in that pot. You need a yellow to white hot heat and where is your flux? Limestone works well.

Red riverbank clay works well. You will never get wrought iron. Only a form of semi steel depending on carbon content. Wrought iron comes from all the impurities being removed from the pure iron then the melt will melt no more and become like dough and can be rolled up.

 

If you are serious on melting it. Grind up your ore and add some red clay and powdered charcoal. Roll it into balls about 1/2" in diameter. Let it dry well. Put the balls into a crucible and put a lid on it. Fill up all the voids in the cruicible with powdered charcoal .Place it in a already hot furnace and heat it as fast as you can. Keep looking at the crucible and when you stop seeing gasses come out between the crucible and lid turn the fire off and let it cool. If you got it hot enough you will find all the iron at the bottom covered by a hard layer of hardened slag.

[Steve Sells]

not all red cray is created equal.  have fun

[Joe111]

Not all but pretty much most of it will melt at quite low temperatures. The red refractory clay isnt very easy to come by.

[ThomasPowers]

I've always found the taconite pellets to have too much flux in them and to be too large for a typical bloomery as they are *ENGINEERED* for a blast furnace!  Trying to recreate them seems wasted effort.

 

Wrought iron is hard to find???  I have never found it so.  But for folks who have to *buy* it:

http://www.oldglobewood.com/real-wrought-iron.html or http://www.realwroughtiron.com/

 

It is pricey buying it that way instead of finding it in the scrap stream.

[Nobody Special]

Joe,

 

First, of all, I'm not trying to melt the ore. I'm making a bloom, just melting off the slag, which that much at least it did in abundance, and let the iron sinter together. I can melt steel or make pig iron now with coal, it's not what I'm after.

 

If it's like most blooms, I'll probably get varying amounts of carbon, mostly wrought iron, but some all the way to some cast iron depending on location in relation to the tuyere.

 

This one failed for a couple of reasons.

 

One. Hard to maintain temperature. My fault, not enough oxygen, it needed a larger tuyere, or better yet more and larger tuyeres. So the tuyere would get blocked up, and the temp would fall. I'd clear it, and it would go back up to a light lemony yellow for 10 minutes or so, then fall off and have to be cleared again.

 

Two. Didn't go long enough. I got hit by a thunderstorm. Nothing was wrong with the clay, it held up fine......until 50 degree raindrops hit the side of a 2100 degree furnace during a hour and a half downpour. If ya read the earlier post, I used red Georgia clay and sand, fireclay, and some wood chips for the burnout material. I had failed structural integrity from thermal differences with the rain making the walls spall. I might have run out of charcoal anyways, but I had enough for two or three more hours at least.

 

Three, I'm a newb at bloomeries, and it was a first try. I'm tickled pink as much went right as it did. Inexperience and trying to do it on my own. Basically, I ended up with some half-cooked hematite, that was a LOT more magnetic/reduced when it was done, with a few pieces that had some metallic streaks through 'em in places when ground, but not a decent bloom.

 

Oh well, I saved it, slag and all, will improve the tuyere design, use thicker walls, plan for weather better, and take more of Steve Sells' advice prior to running it again. He was spot on on what went wrong. I'll try to set in on a bloomery or two with someone more experienced than I, then post my next experiment when I get the inclination and have made way too much charcoal, probably in a couple of months or so.

[ThomasPowers]

I was answering Kilroy's post---did you miss it?

 

"I have a question. Let's say I did this but with pig iron or scrap metal. Would it have the veins of slag in it? I've been trying to find wrought iron but it's impossible, and I can't get any ore in my area."

[Joe111]

Ive made many hundreds of tons of malable iron and much, much more cast iron using simple furnaces such as this.

 

The only real difference in the processes is the amount of o2 you add. Too much you get cast iron and just a little you get malable iron. Either way you still need the flux. This photo is of a malable iron heat. The iron drops out the trap door in the bottom after the heat has cooled. It is pretty much layered between solidified flux and iron. There is some pieces of slag and carbon in in but you are absolutly sure it is iron. No guess work there. It is a half to all day affair for one heat depending on the quality of the ore you use.

[Nobody Special]

Not sure if you're addressing me Mister Powers, I was answering Joe111, definitely not arguing with you. You've given me nothing but good advice.

 

Also, still to Joe111, I believe you've made lots and lots of iron, that's a fair, if simple description of melting iron, and that's a lovely cupola, but you're missing the point.

 

I'm not making a puddling furnace, I'm not doing a cupola, reverbatory furnace, a Bessemer process  blast furnace, or even a Catalan furnace.

 

I'm trying to make a bloom, using a bloomery.

 

I am familiar with cupolas. And making different grades of iron by adding carbon or burning it out with the oxygen. Really. I'm not vastly experienced with using them, but familiar with how they work.

 

Deliberately primitive. Deliberately semi-primitive methods and full of slaggy crud and silicates. I thought about using a kite bellows, and clay tuyeres, but really, really didn't feel like pumping for hours on end. The fact that it's made  of clay instead of a metal  or  firebrick shell is a  big indicator.

 

While I enjoy casting metal, goal this time - bloomy bloomy. Consolidate/knock slag out, forge weld. Cut, fold, weld again to refine. Repeat. Repeat. Repeat. I say again, no melty melty.

[Joe111]

That is not a cupola. It is a bloomery. Just not your version of one.

If you want to make a primitive one out of primitive materials, then you need time. lots of time. You will need to build a clay shell and fire it. Then take days to run your campaign. There is a reason it is called a campaign. It takes lots of time. If you are using clay as a liner, it will need to be thick 4-6 inches at least. and before you add your ore, you need to bring the entire thing up to temperature. A cupola burns fast and hot. A bloomery burns slow and hot. It is deficient in both air and fuel. This is the condition that produces the mallable iron that you want. Otherwise you will only get a lump of hard, high carbon white iron that is useless for anything.

Melty, melty is just what you want. But you want the conditions right to reduce the liquid iron to a solid form in the furnace at the correct temperature.

[ThomasPowers]

Well our bloomeries were built one day and fired the next evening and let sit when we went to bed

15 pound blooms which is not bad with hand powered air!