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There are indeed a few "rules," some of which are just guidelines. I don't think anyone is trying to discourage you, it's just that since nobody has worked with YOUR ore, with YOUR charcoal, and YOUR furnace, nobody can guarantee success the first time. You can certainly get close, maybe even a nice bloom on your first try, and by analyzing what did or did not happen you can probably nail or get an even better bloom it on the second try.

 

That's the trouble with explaining stuff like this in print. It's one thing to be able to say "When the flame starts doing that little shimmery blue stuff right before it falls, you're in the proper reduction mode" because that's a rule. I can't, however, say "but when you hear the tuyere making that noise right there, the one that's impossible to describe (because every one is different and will sound different if you can hear it at all over the noise of the blower and the roar of the furnace) you need to poke out the slag that's clogging the tuyere nose" because that may not happen to you. There's just so many little things to pay attention to, especially with every furnace being slightly different, that there's really no set-in-stone instructions beyond what you've read already.

 

That is fair enough, OTOH, I would think that some general rules would carry over.....

 

 

For example:

 

1) I am not using a specific ore - but iron oxide from a pottery supply, and as such, it does not have any gangue to act as the base for slag, so I have to add slag producing materials, but which and how much is unknown to me. Surely someone who has worked with pottery supply iron oxide before can give some general rules of thumb.

 

2) Deciding on furnace design is not to bad, I am drawn to the design that Jesus and Walter have used, but scaled down a bit so that one person can handle it, but this means that a higher space velocity is going to be needed to achieve the same temperatures, which in turn is going to cause potential problems with the powdered iron oxide being blown back out. Do others have this problem and how do they deal with it if they do?

 

 

These are the kinds of general rules that others can help with even if they are not doing it exactly the way I'm planning to do it.It sounds like you are collecting info for your first go at smelting. Good luck. When you have decided what ore you are going to use, how you are going to build the furnace/smelter.

 

As mentioned above, I am using iron oxide from a pottery supply store, and a variant of Jesus and Walters tatara ( in this thread http://www.bladesmithsforum.com/index.php?showtopic=13669&view=&hl=&fromsearch=1 ) that is scaled down for 1 person use

 

 

 

The ratio of charges and timing you will employ, along with the general management of the whole affair, including the noises from the air supply and watching for the changes in the flame. All this might work fine on a hot day and then for some reason it will all go pear shaped on another day that is cold and humid. Was it because of the weather or was something else wrong.

 

Mick.

 

Some of those things like listening for the specific changes that the air supply makes, are things that will have to be learned, but knowing that they are something to be aware of and monitered for, is one of those general rules that needs to be kept in mind - I guess what I'm trying to say, is that if you know the general rule, you can be watching to see how it applies to your own situation, and take approperate action, but if you just start trying to make iron/steel, without knowing some of the general and specific rules, you will have little to no idea of how and why something worked or did not work.

 

 

Did that make sense?

 

 

I'm trying to learn of those things that I need to be aware of - to keep in mind, other wise the post smelt analysis, doesn't teach what it could.

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It was a brick stack and mudded interior with four tuyer holes...a modified kodai...should have taken the time to build it more traditional.

 

Niko's glossary..cause we do not all speak Bloomery Japanese:

Zuku--cast iron

Noro-slag. Kihara-San wanted that stuff gone rather fast..and took provisions for it to be self tapping once it reached a certain level above the bloom..and would help it when needs be.

Kera--bloom

TiO is rather stable and I doubt much gets broken down in the reduction made in the tatara..it may lead to a more viscous slag or higher temp required before the slag will flow....Though I have seen chem lists with some small amount of Ti in the final kera..which I find very odd. I have plans (how many years will I live again?) to do small runs with intentional additions of TiO to see if it matters. none of my past ores have had enough TiO to matter.

 

Also..it has been my long time belief that green glass was the result of copper content only, but iron slag can be green (and brown and black) and chromium oxide is green as well..though I have never knowingly smelted chromium bearing ores. How does that go..the craft so long to learn.

 

As has been stated the temp under the bloom is low and the ash/charcoal/other forms a different chemical soup than the top of the bloom....as the furnace changes during the heat up to cool down so too does the active and passive chemistry of the bloom environment.....also the "woosh woosh" of older bellows tech would be different than a constant electric blower.

SO

rather a lot can be going on from one time to another.

 

BUT as to Lee's question...10% may be too low depending on the silicon content in the ore or furnace body..if you have the potential for an equal or larger amount of free silicate then all of the Limestone could be bound. I think larger additions initially would allow for a carbonate rich area under and around the young bloom and then you can back off at temps spike later and judge the tapped slag for viscosity and adjust if you can keep the temp and add more limestone to keep the slag fluid. If the bottom of the bloom is cold then any chemical reaction will be slow or nil....I think there is a choice active zone of chemistry below in and above the bloom formation and that will change with what is available for reaction and the temps...so maybe only ten or so things to keep in mind there.

OR

find what works for you and do that again....at some point there is less need for experimentation and simply a desire to get good material.

 

Ric

 

 

Ric.

 

Actually ist more like Japanese glossary and all is find in net, books, journals out there.

They are not hidden secrets or too complex ideas that Japanese smelters used...its just work, skill and eye to see things chance

in different points of this graft...as you know...and im not saying that I have any of these at hi level...ex work.

 

If we go in to colours of slag...well it can be all most anything..I have old fin lake ore ( limonite) and folk back at old times ad Ca lots in this ore...slag is blue,white,turcose,gray....and graphite dark black and its FeO all most pure...actually it was used as building bricks at that area a lot..Heavy stuff.

But this was becourse of ore...it was limonite and its Fe cont was not that hi.

However its close to Viking age steel...I think.

 

Its thought that at hi reducing contioins TiO2 will increase viscosity of slag but under oxidising and lower redusing cond its not the same.

I think this was notised at ancinet times and Japanese used akome and masame ither for kera ( bloom ) or zuku ( white cast) becourse the redusing differenses. Other one Akome turns to zuku better than other and the production rate was better.

 

So If I thought this "right" Kera-oshi method will give steel by different rates of C but in other hand it will consume / waste some of ore as FeO in slag. And if all ore is wanted to use steel it need to turn to zuku ( white cast) and later turn to steel / iron if so wanted.

Base to this I would not but slag back in system...

 

 

...Lots of ways to make steel and iron there is...Slag, it might be you friend or enemy...

 

Niko

 

 

Richard & Niko,

 

Given the comments about TiO2, and the fact that some of the locally available ores are ferrous titanates, I have been doing some digging in my collection of e-copies of older books ( late 1800's early 1900's ), and found some comments about titanium that might prove of interest when dealing with Ti. I think that I have a few more early references to TiO2, but I have not found them yet.

 

My apologies for the size of the immages - I have tried to resize without much success.

 

Ti1.png

 

Ti2.png

 

Ti3.png

 

Ti4.png

 

Ti5.png

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Yesterday, I was reading Mastery and Uses of Fire in Antiquity, and Rehder specifically says that after the furnace had heated up the Romans would run a charge of old slag through the furnace, tap it and then feed it back into the furnace, and tap it again before adding any ore.

 

Does anyone have any idea why this was done?

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Yesterday, I was reading Mastery and Uses of Fire in Antiquity, and Rehder specifically says that after the furnace had heated up the Romans would run a charge of old slag through the furnace, tap it and then feed it back into the furnace, and tap it again before adding any ore.

 

Does anyone have any idea why this was done?

 

 

I'd guess that it was to absorb/slough off unwanted impurities &/or help the furnace to settle into an optimum environment

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Hi Gang,

 

I just have now had time to read through these posts.

I have some thoughts.

Being very new to blooming, these are just observations of mine during burns. I did as much research as I could on line, and spoke with people like our Jesus. All that helped in so many ways. You can read all the books you want, but until you do a bloom or two, it is all just guessing.

Like has been said, there are so many variables going on, even when you are doing everything the same as you have before, things can turn out different.

I started all this with the skip Williams Aristotle mini scrap furnace. After a couple successful goes at that, I wanted more. So, now I have been through a couple stacks., and a half dozen blooms. I have been very lucky so far, in that every time has been a success, where I didn't have a stack failure of some kind.

This luck was greatly increased by my looking at everything I could find on the subject, and contacting people like Jesus.

Greg...... I have used the 'Spanish red', iron oxide, from the pottery place, every time I have made steel. It is a very fine powder. You will not be able to keep some of it from flying everywhere. You will not loose that much so don't worry about it. I have always added 5% fire scale to my mix. With no other additives. Your stack should create your pre slag about the time your 2nd or 3rd charge gets to the bottom of the stack.

With this material, I would return the nice black slag back into the stack, until some of the larger slag dumps late in the burn. I felt that that did help. But I have no scientific proof to this. It just 'seemed' logical. Plus I was trying to duplicate what I had done before to make the nice steel. It seemed logical to do slag dumps when the air supply was being effected by too much slag. I would think, that you would want your bloom to be cradled and constantly washed by the slag. That is what I shoot for anyway. This has seemed to work.

With the local titaniferous Magnetites ore I have just decided to experiment as I go. I have tons of this material. Some is much more pure magnitite then other. My first bloom, I just used the finely crushed and roasted ore. I did a bit of magnetic cleaning, but not a lot. It quickly produced a lot of slag. My first tap was not half way. I felt that I allowed too much slag to flow, but sometimes once you make that tap, its only stopping when it wants to. This slag was gray, and a bit more fluffy. As there was a ready source in the ore itself, I didn't crush it up and add it back. The bloom I got was very workable, but 'Dry'. After more study I learned about the lime adds to this type of ore. I started to test this, but had a stack failure, and had to abort. This weekend Jesus and I will test this again. I'm using the fossilized shell for lime. I plan to go about 5% mix.

I plan to build a Catalan forge very soon to cook up a bunch of this ore. That should be great fun. That was what was used localy in the early days.

 

But I believe slag matters a lot. Let it make love to your bloom. It just seems logical.

 

Greg.....When you get blooming, and you have a big pile of slag in the yard. Do some pre-slag experiments. I may just try some of that myself. But having a clay/sand/insulation, stack I seem to have no problem with slag production. However, if you were using some kind of stone, or 3k klin brick, it may just help to do a bit of pre-slag. You will find that the price of charcoal is a bit restrictive on a bunch of experiments. Unless you live in the woods, where you can make tons of it yourself. (I wish)

Mark

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Greg...... I have used the 'Spanish red', iron oxide, from the pottery place, every time I have made steel. It is a very fine powder. You will not be able to keep some of it from flying everywhere. You will not loose that much so don't worry about it. I have always added 5% fire scale to my mix. With no other additives. Your stack should create your pre slag about the time your 2nd or 3rd charge gets to the bottom of the stack.

 

Mark,

 

I think that I came up with something that I could use if my losses of the iron oxide powder become excessive, but that was primarily major concern with a furnace that had a 6-8 inch bore ( less so with a 10-12" ). I ran across something about a month ago, where the smelters mixed the iron oxide powder with just enough flour and water so it held together like dough, it was then dried and broken up into 1/4" pieces.

 

I figure that much the same can be done only forcing it through window screen - instant sand that is not likely to get blown out.

 

Like I said, it was something I came up with I was still contemplating a 6-8" furnace.

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