March 2012 smelt at bushfire forge

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Posted · Report post

well about time too! Mick Maxen Myself and Eli Sideris had a great smelt yesterday. I think the best yet . certainly joint best. we started with a hot furnace . pre burn wood and acharcoal. we ran the furnace well keeping the load intervals at 10 minute drops. (or at least the furnace ran well despite us) we were aiming for iron with a 1.2 to 1 ore to fuel ratio. there was a lot of slag. we used 50 kg magnetite ore and 60 kg fuel including pre burn (so we got one to one fuel ore in the end). the bloom ended up being a big flat concave centred dense bloom 11kg or so there was another 2 or 3 kg of good bits . I think we lost a lot of ore in the slag which was plentiful and dense . run time was just over 4 hours... here are some piccies.

150kg of charcoal before sizing
6884884916_e77e889553_b.jpg

cooking the furnace
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Eli modeling the ritual tatas! (got to keep the fire gods happy)
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Our furnace is endowed. 6884884928_37a88c6537_b.jpg
Owen loading wood for the pre burn 6884884932_89fcd672aa_b.jpg

first slag tap
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tapping slag with the family looking on
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dragging out the bloom
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initial forging with the 28lb sledge (too big for the job realy) 7030995095_9b7e1f933f_b.jpg

squish that bloom
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bloom to the shop
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Alldays and Onions 200 weight eats bloom while Mick fire fights
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flat bloom 6884900328_d298c249fb_b.jpg

thick dense pancake of a bloom
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bloom with a master blacksmith for size reference
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our notes jusf for my reference!
6884900336_85bffde12c_b.jpg

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Posted · Report post

quite inpressive! so what are you going to make with the finished bloom....i have to try doing this once....

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Posted · Report post

this is out 14th or 15th smelt.....
I have always wanted to make my own hammer from ore...
most probably this will be refined and carburised (some not) and made into seax , I have a big store of samples from past smelts to mix and match different carbon levels all the way from wrought iron to cast iron
all the best Owen

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Posted · Report post

owen im fascinated but confused, as usual, what did you smelt - is this cast iron i dont quite get what youve got there - the bloom or whatever - i have done a similar iron smelt years ago, but we poured it and cast it, is this similar?? the pictures are great :) and the photo of your notes is the greatest - looks MANIC!!! i like it!!!

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Posted · Report post

Beth this is a" smelt" not a cast iron melt. we are taking iron ore and making sponge or bloomery iron (in this case iron as oposed to bloomery steel) It is the basic form of wrought iron as used throughout the iron age up untill the advent of industrial iron production . This smelt used magnetite ore from sweden .It is a reduction process, the carbon monoxide produced in the stack from the heated charcoal, preferentialy combines with the oxygen in the iron oxide . the product is iron mixed in with slag . If you run a higher stack or change the ore to fuel mix you can produce steel (what the japanese would call tamahagane) . I find bloomery steel to be a pain so prefer to go down the route of making iron and then carburising it to make steel. It is possable to directly produce cast iron (what the japanese tatara smelters would call zuku) but that material has little use to a bladesmith other than using it to up the carbon content of lowe carbon material. all the best Owen

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Posted · Report post

thanks owen, so in this case the slag is useful? i presumed it was always unwanted... i know little about this.. it seems like a great roots activity to be attempting though! hardcore :)

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Posted · Report post

the slag is not particularly useful, just a byproduct of the process . better wrought iron or steel has the slag worked out of it by hammering folding and re welding.

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Posted · Report post

thanks owen, i thought you had kept it in there deliberately for some reason. i got it now!
:)

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Posted · Report post

why is this now in foundry and casting .
smelting is neither .
it is making bloomery wrought material, no melting involved in this case.
I am very confused

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Posted · Report post

i expect i queered the pitch of your post with my confusing presumptions owen :) if its any consolation i for one now know its not anything to do with casting/melting :)

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Posted · Report post

I can't add anything by way of photos from this smelt, but it was another good time had by all at Owen's. The smelt run without any dramas and just some fine tuning to get it running how we wanted it too.
The pancake piece in the photos weighs 11kgs and is about 12" diameter by 1 1/2" thick. We did not have anytime to cut it up but it will be very solid now its had a go under the 200cwt hammer.

To give you an idea of the product, here are some photos from a smelt we did in April last year. This time we let the bloom cool down and then cut it up.

This bloom weighs 18kgs

the-bloom.jpg

The bloom in two halves,

2-halves.jpg

1/4 bloom,

bloom.jpg

Mick.

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Posted · Report post

Wonderfully, so glad you posted this, thanks.

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Thank you Owen, this has been very informative, the pics and notes especially. I've contemplated giving it a try but I contemplate lots of stuff. <grin>

Frosty The Lucky.

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Posted · Report post

Gotta say I am a bit jealous. It is on my to do list.

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owen, this is, dare i say it, very very impressive. if any metal worker looked at this and didnt think so, hed either of had to be doing this every weekend of his life, or is no true metal worker. this is facinating. by the looks of it, the outside of where you housed your fire was broken up, correct? i saw a similar thing done in japan, when they did the melting of the of the iron ore into the steel that the master smiths used in their katanas every year. you really should message me sometime and tell me about all this bloomery work. i find it facsinating.

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Posted · Report post

wow that stuff looks amazing - so impressed youve got a handle on doing this :0 looks like its from outer space at the moment, im totally intrigued to see what magic you weill perform on it... ;)

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Posted · Report post

such a great thing to follow. i tried this years ago, with other smiths, but we only got a few tiny little blooms....

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I was part of a bloomery crew for about a dozen years starting around 1991 with our major smelting done during the SCA's Pennsic War---we used to dig the clay for the furnace from a local stream bed and of course our air handling was all man powered.

First several years were had very small outputs but got to getting good 15 pound blooms on a regular basis towards the end. Ore makes a big difference with magnetite being a dream to smelt compared to taconite---which is even worse than goethite!

Our rituals always included cooking steaks and sausages over the furnace as well as singing and telling tales---6+ hours feeding the furnace you need some entertainment!

I really envy you that bloom consolidator!

And slag has a very good use if you have swampy bits in your driveway or garden path...

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Posted · Report post

ramsies 11,

You are right we did break up the stack. This was to get the bloom out. We did try to wiggle the bloom out and keep the stack but this is about the 3rd or 4th smelt using this stack so we decided that it would be best to build another one for the next time.

Here is the stack before we started to patch it up,

march-12-smelt.jpg

This photo shows a glass over the air pipe so we can see how hot it is running and also see when its getting blocked up or the level of the slag is up to the tuyere,

march-12-smelt-4.jpg



Mick.

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Posted · Report post

FeS2: No close neighbors? Needs to be well roasted to change the sulfide ore to an oxide ore before smelting.

I'd think it would be more cost and work as you have to pre-process the pyrite to use it and that will take fuel as well as time.

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I have always tried to make the process as easy as I can .
smelting is a romantic pass time for a smith , however I want the end user (me) to be able to use the smelt product.
I also believe that you can not really understand a process until you are good at it.
To this aim we have always used processed magnetite ore which means we have a fixed element to the smelt and can vary our practice around that.
I understand the process of roasting but it is not what I have done......
I aim for iron as opposed to steel as I find the working of iron so much easier and carburising is a doddle!
the next smelt will try and repeat what we did with this one but processing a bit more material.

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Very interesting topic. I'm new into blacksmithing, but i'm naturaly a very curious person and want to know all about the subject.
At the moment i'm just hitting hot steel, but I do have an interest in where that iron comes from and how it is produced.

One day in the far future (got far too much to learn yet) i'd love to mine my own ore, smelt it and make an axe, or hammer from it!

Thanks for the interesting thread Owen and friends.

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Here are a few photos of a section of the flat pancake bloom. The piece is about 6 x 5 x 1 1/4" thick.

pancake-quarter-2.jpg


pancake-quarter.jpg


pancake-quarter-3.jpg


Mick.

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Posted · Report post

How do you control the temp? I know if you get to high of temp you will end up with cast Iron. Well, I realize you control it with the air flow, but do you moniter the temp at all or just go by your gut?

Great process pictures. I hope to find some more ore and try this sometime.

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Jammer,

We are running a short stack furnace to make iron. To get cast iron you would be running a much taller furnace and trying to make steel.
The furnaces we make for iron are about 36" tall and about 10-12" diameter or thereabouts. With a shorter furnace the iron ore will travel through the reduction zone (very hot area)where the oxygen will get displaced from the ore and hopefully drip into a puddle of slag to make a bloom.
In taller furnaces for steel making, the reduced ore will have further to travel to the bottom and once the oxygen is removed will take up carbon from the charcoal and make steel, if all goes well.

There are many ways of controlling the temp. Controlling air flow as you mentioned. Also the size of the charcoal has some influence as well. We try for pieces that are no bigger than 1" which to a certain degree controls the rate of drop in the furnace and heat. The ratio of ore to charcoal also influences the heat. We try for around a 1 to 1 ratio. Less ore to charcoal means a hotter furnace or more ore than charcoal means a cooler furnace.
The downside to a cooler furnace is that the slag will be very thick and gloppy with a chance of freezing up the furnace. It can sometimes form an arch above the air so not letting anything into the area where the bloom is forming.

We aim for a bright yellow colour in the furnace and also bright yellow and very runny slag.
One of the things that is very important is to dry the furnace completely before charging. We will usually run the furnace with the air blowing for about 2-3 hours, loading it with wood. Then when its very hot, will add charcoal for about 1/2 hour and then start charging with ore and charcoal.

All our observations of heat are done by eye.

Mick.

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