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The above upper bloom has been cut/wedged in half. Most of the bloom is actually low carbon iron, with the exception of a couple of areas formed early in the closure of the slag puddle above the cast iron, This time there was a small link of metal connecting the two areas of the bloom.

 

The tentative plan is to create a silica bowl bottomed furnace insulated from the metal...meditate a bit on the different action of a silica/FeO slag versus an all FeO/Fe3O4/Wustite slag. One thing comes to mind, the latter does not change in reactivity during decarburization the former will change chemically as FeO is depleted.

 

After taking a look at the results of a silica bottom ( should have at least a more all metal bloom without slag areas in unpleasant locations ) on a normal run, we will start looking into a slag modification/removal during a run.

 

I will edit this post with some pics of the split bloom.

 

Jan

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Split low carbon bloom

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Jan,   Researching for my own charcoal burns (now curtailed by the local Fire Department,) a common theme was to carefully place the wood into the pit and to start the burn at the top. I assume you

Here is a pic of the charcoal made today ( just prior to covering it),  about 5 hrs of work ( 300 gallons). I was hoping to do a smelt tonight but I am a bit tired and do not want to screw it up.....s

Well , I finally got around to doing a smelt today , using the above charcoal. The run lasted 1.5 hrs and targeted cast iron as the product..I will pull the bloom tomorrow and if all looks good I will

Posted Images

Checked some of the other blooms from the cast/soft iron smelts and all are soft iron. The burn season ends tomorrow and I will not be able to get the tests for high carbon iron done this season...so until December .

 

Jan

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...yes, i have only ever seen hot removal of the blooms, by kera-oshi tatara operators and by smiths doing oroshigane in forges or dedicated standalone furnaces.

here is an article from @pierre which hints at some interesting developments in the archeological "tatara wars":

soulsmithing.com/index.php/2009/10/home-made-steel-a-week-at-manabe-sumihiras-zuku-oshi-tatara

...until then!

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Dave,

Thanks for the article....now that I am awash in cast iron I may be encountering some Sage with my Sake. The reference to a changing in thinking about historical methods is a surprise. I do not have a Japanese style forge and probably will not build one ( I use gas and a Murray Carter bottom blown charcoal forge). I do plan to set up designated , very short, bloomery furnace ( clay lined for greater heat retention ) for Sage, converting low carbon blooms to steel and for de-slagging blooms. I will be pulling hot material from that one. Pulling material from a 10" furnace with a tuyere fixed in place will be difficult...so a removable tuyere or a drop bottom will have to be set up.

I would love to share and compare methods with Mr. Manabe, maybe I will get out there one of these days .

 

 

 

Jan

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  • 6 months later...

The rains are here , the burn season starts Dec. 1, last years charcoal was removed two weeks ago while it was still dry. I will start smelting by trying to duplicate the bloom shown in post 150 and 151 above ( cast iron and very soft iron ) . The pit is covered with a roof, as drying the bricks takes a long time and rushing it will degrade them.

 

 

 

Post 151 ( last year )

"The tentative plan is to create a silica bowl bottomed furnace insulated from the metal...meditate a bit on the different action of a silica/FeO slag versus an all FeO/Fe3O4/Wustite slag. One thing comes to mind, the latter does not change in reactivity during decarburization the former will change chemically as FeO is depleted."

This test was done as one of the last smelts last year.. a SS bowl was placed in the furnace lined with sandy mud. I could not find any mud after the smelt and the SS bowl was melted to the bottom of the bloom, eventually I chiseled it away. I tried to create a higher carbon chemistry by adding lots of bits and pieces to get some mass without slag. We will visit this test again ( no SS bowls ). I will edit a pic of that bloom into this post , before/after trying to smash it. ( it does look good on the spark test)

DSCN2893.jpg

The variables I have to work with are, the furnace, materials, height ,diameter and so on , furnace operation, ore , and though somewhat limited , the charcoal...I think I have all these dialed into a harmonious process ( I am getting close anyway). I am stuck with a fairly fine charcoal if I choose to make it as I do.

Jan

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  • 2 weeks later...

I have edited in a picture of the failed SS bowl bloom in the above post..the SS turned green in areas and seemed to have picked up a lot of carbon.

 

I should be smelting the next bloom any day now but it is very cold by local standards. The smelt will be a two part bloom attempt , cast iron on the bottom and ( correction) a high carbon bloom on top. A bi modal distribution of iron/carbon in a single furnace run.

 

Jan

 

 

Edit,

The bloom shown in the above post is not high carbon and will be forged into soft steel.

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I thought I would share what I am currently ,off/on ( for the last many years ) working on....The Use of Charcoal Fines..this problem stays with me as fines are a significant fraction of the charcoal I make ( I have large mounds of it). Here are a couple of pics showing what fines look like...the problem is, air does not move well through the fines and a special type of furnace will be needed.

Here are some fines pics. from previous posts in this thread.

post-1617-0-17551300-1424150832.jpg

post-1617-0-18624300-1393308019.jpg fines on 1/4" screen

 

As my ore is quite fine and hard to control in that form ,I thought I would experiment with various binders to glue the ore together and plan for significant porosity in the conglomerated ore form ( aside from porosity the are other criteria the cubes must meet).

My goal here is not 100% iron but a good magnetite roast.

Here are the latest bound ore samples ( which could be slightly more porous ). Now off to seeing if I can make a "fines furnace" to work with this material. I should disclose that, a probe was done in this direction about 7 years ago and it pointed to a possible way ( I may have a photo of the results). Regardless, I am eagerly awaiting suggestions coming from this group.

 

DSCN2998.jpg DSCN2995.jpg

 

Jan

 

 

 

 

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The first test will be a simple charcoal forge modification allowing the use of charcoal fines. The last effort failed and I am only guessing why...I think after partial reduction of the ore..oxygen got to the hot material and reversed any changes I might have caused.

So we are not only trying to reduce some iron ore but we have to be able to stop the process and keep it from reversing. So I will set a section of pipe over the forge grate ( if you have a copy of Agricola's " De Re Metallica " you will see a drawing of it on page 227 ) and cover the rough grate with a piece of wire mesh..then fill the pipe with charcoal fines and start a charcoal fine fire to preheat the 6" layer of charcoal above the grate and under the soon to be placed ore pieces. De Re Metallica may be on line as a free book as well.

 

After the ore is placed 1 layer of cubes thick, the whole thing is covered with charcoal and/or kaowool. I am hoping to arrive at a blood red heat in 1/2 hrs and to run at that temp for as long as possible ( at least another 1/2 hrs.) .

 

Here are a couple of pics of the failed test from a few days ago I will take some wip pics when I set up the next test ..( 1 or 2 days out). I am in the process of modifying the forge, so I can bring the bloomery furnace in under the hood and make iron inside .

 

DSCN2992.jpg section of pipe filled with charcoal and ore at full heat

DSCN2978.jpg covered furnace showing heat venting at center ( heat was escaping at the perimeter just prior)

 

Jan

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Here is a picture of the screen in the pipe on which the charcoal fines will be supported. I have added some ore with the binder to the furnace..I am hoping to find it again still as one piece.

 

DSCN3006 copy.jpg

 

I brought the smelting furnace into the shop and placed it in the forge..here are some pictures of the process of making ( I am not sure what...cast iron I assume ). I pulled 130 lbs of charcoal from storage and ended up with 24% fines ( that number varies from charcoal batch to charcoal batch ).

I will weigh the full furnace , still containing all the material added ....and again weigh the empty furnace....I know how much I add per addition but do not track the total.

 

DSCN3008.jpg watch football or make iron...done

DSCN3010.jpg the disassembled forge in the junk yard

DSCN3011.jpg early in the run

DSCN3018.jpg mid run

DSCN3020.jpg all did not go well, these hot spots indicate air leaking into an area of the furnace where it should not.

DSCN3030.jpg this is what the charcoal looks like ( 1 year old ) note the size distribution

DSCN3051.jpg end of run..about 3 hrs including a special shut down to test the ore binder

 

Jan

 

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Sundays run was odd due to an air leak below the air inlet ( due to not replacing the ceramic material over the 3" long pipe, entering the furnace). Here are some numbers, I am not happy with the bloom as it still has about 5# of slag attached and will require a bit of labor to clean it. The ore binder samples were not reduced much...one sample found in a very hot zone was converted to iron. It seems the binder is slowing the reduction rate of the ore...I will try the pipe section later this week.

 

Sunday 1/24 iron run

Weight of full furnace 140 lbs

Weight of empty furnace 53 lbs

Weight of charcoal 20 lbs

Weight of burden only 67 lbs

Weight of bloom 20 #

Weight of unconsolidated ore 30#

Weight of cast 9#

Weight of bits 9#

Weight of chipped bloom slag 3#

Total weight of run products 72#

These are approximations...I must have put about 100 lbs of ore into the furnace. Here are a couple of pics

DSCN3055.jpg the bloom has a lot of bits on top...this material has to be crushed before using again

DSCN3064.jpg

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I did a second indoor smelt Monday evening 1/25 ...the results are interesting but the yield is problematic as most of the ore did not consolidate.

 

The yields are roughly this:

Monday evening’s run 1/25/2016

Full Furnace 135 #

Empty Furnace 53#

Charcoal 20#

Total Contents 62#

Bloom 12 #

Unconsolidated 40#

Cast 1#

Bits 10#

Total Yield 63#

Inside smelting wil not work with this furnace since it has to be used at a high rate of air consumption. The charcoal size determines how hard the blower has to work to get air distributed properly ( I ran the furnace at too low an air flow ) . Here is a pic of the bloom which has a lot of iron above the air inlet ....may be as much as 3-4 inches high.....this material was nor oxidized , which startled me a bit.

DSCN3136.jpg note the air inlet inside the hole at 12:00 ( we are looking down into the furnace )

Today I took the furnace outside and let it run at it's required speed...it seemed very happy.

Jan

Jan

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Here are some pics of today's run seeking cast iron , any bloom will be a bonus. The blowing was done at a good clip and the furnace was much hotter than the previous two runs.

 

 

DSCN3149.jpg new 1" air inlet pipe nipple

DSCN3150.jpg fire brick mortar to shape the ceramic shield ( rubber gloves needed )

DSCN3151.jpg drying air inlet ceramic

DSCN3152.jpg same

DSCN3157.jpg lots of leaves and twigs in this charcoal ( this is not moisture )

DSCN3159.jpg just getting started, warming up the charcoal ...that fence is not leaning, it must be the camera warping the field

DSCN3165.jpg mid run I think

 

I have no idea what I may find tomorrow, I expect it to be good ...if not good at least informational I will post the results.

Jan

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The result of this run is so so. I have a 28 lb bloom with about 1/3 the volume being slag...so about a 20 lb clean bloom after lots of work. The cast iron weight is a bout 9 lbs.....lots of bits. Now I will put that stuff back into the junk yard and hope the crucible process goes a little better.
Jan

 

 

Edit

I will post a picture of the bloom when cleaned and weighed again. The run did prove to be very informational and a little disturbing as what I predicted did not happen ( meaning I have to adjust my model). I will get back to this a little later this Spring and adjust. The next move is slag management in a closed system.

Jan

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There are two topics in this thread I want to try to clean up ( if possible), one is the crucible steel making from partially reduced ore. Some of the ore sent down the furnace does not get drawn into a fusion zone..it is collected with a magnet and called partially reduced ore. So we are looking at posts 130 to 142 of this thread ...trying to get some info to plan the next test.

 

The other topic is the conversion of cast iron to steel, touched on briefly as attempts to make Salem Steel. The latter is going to be easier than the former.

 

"Looking at the pre-reduced or should I say partially reduced ore, plans are being made to attempt making crucible steel directly from this bloomery by product."

The first trial was done a while ago using 120 Grams of Carbon and 1000 grams of PRO ( partially reduced ore )....the results were inconclusive but seem to indicate we were using enough carbon ( white cast iron resulting).

 

We will repeat that test and make sure the process is complete before turning off the furnace....the ratio of 120 C to 1000 PRO will be maintained if the crucible will not hold the total .

1 hr at low heat, one hour at high heat low heat = orange to yellow high heat = blinding white heat

 

To make sure I can repeat a given test ...the PRO will have to be physically mixed very thoroughly as it is not a homogeneous material...and I will have to remove much of the charcoal dust clinging to the powder.

 

Jan

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your post on the consolidation of ore reminded me of pierre's articles on sumihira~san's zuku-oshi tatara steel making process...

soulsmithing.com/index.php/2009/10/the-sumihira-zuku-oshi-tatara/
soulsmithing.com/index.php/2009/10/home-made-steel-a-week-at-manabe-sumihiras-zuku-oshi-tatara/

 

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DaveJ,


Thanks fort the links , I have seen one where he converts cast iron (zuku) to a high carbon iron in the forge. It is very possible that cast iron is the most practical crucible product for this material. At the start of the crucible run I will hold at a relatively low temperature to allow carbon to enter the iron and to keep on converting more oxide to iron.....then full heat....some of the remaining unconverted oxide ( as well as any unconsumed carbon) will go to the surface and keep on reacting with what is below ( molten cast iron). If I introduce some glass into the bottom of the crucible this oxide will be diluted ,but much less viscous . Not sure which of the materials will eat through the crucible wall first.A brasque will be applied on the inner wall of the crucible where that slag/cast iron iron line is likely to form.



By the way that first trial does not look as bad as I thought ....if we added 1000 grams of what we thought was 86% iron and our result ( including discarded metal cut off , and the cut itself, _ the carbon added to the iron) was about 600 grams of iron, the yield was about 70% ( caution, lots of assumptions here ).



So the first test will be a no glass, simple repeat of the last run .



I will sacrifice 3 crucibles to this direction ...if something good is coming I will continue, otherwise back to the charcoal furnace.



The first data point for furnace fuel consumption rates should come out as I will have the propane tank on the scale.

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The first crucible is done as described above...things did not go as planned , should I say expected. 705 grams of partially reduced iron were placed in a crucible with about 65 grams of carbon. The carbon was a little guess work as well as the brasque weight was guessed to be about 10 Grams. The carbon level was reduced to allow enough carbon for completion of reduction but not enough for the conversion to cast iron. This adjustment allowed me to add 705 grams of PRO or 600 grams of "iron", based on the 86% iron composition guess. Crucible volume is a problem here.

 

The resulting solid cob of carbon free iron weighed 627 grams. I will add some details later.

DSCN3248.jpg

DSCN3257.jpg

 

I will add some more pics later, I need to polish the surface a bit.

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Cecil Von Schwarz is on the horizon.

 

My initial reaction to this result was not very positive ...but after a good rest, I realized what a learning opportunity this was. So the plan is to repeat this event without the wasted propane and the long high temperature ending. I burned about 7 lbs of propane by running 2 Hrs at orange and 1.25 hrs at white heat ( there was not enough carbon in the iron to lower the melting point below white heat) . Most of the propane was burned at the end. of the run.

DSCN3230.jpg an improvised furnace with low pressure atmosphere

DSCN3238.jpg crucible in the can for fast cooling

DSCN3240.jpg cooling crucible

frame3.jpg micro pics

frame2.jpg

frame1.jpg

 

Jan

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Here are a few more pics of that above consolidated powder. This piece will be treated as a small bloom , welded to a rod, fluxed and forged.

I did run another test and it failed as air must have gotten to the material during or after heating.

 

I am done with this effort and will start processing some bloom iron into blades.

 

frame3 copy.jpg

frame2 copy.jpg

frame1 copy.jpg

 

Jan

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I prefer to reflect on past failures and assign a probable cause as why things went the way they did.

The two crucibles with partially reduced ore fell short of what I would like to have seen because the crucibles are very porous and the high temperature glaze they are coated with never got fused during the long soak at an orange temperature ( 900-1000 Deg C) . There are many things I could do differently....prefire the crucible and add the contents while the crucible is hot, rapid fire the full crucible to fuse the glaze...this may be possible as the basque would act as a temporary insulator ...don't use the porous crucible, use a steel or a commercial crucible .........and so.

 

The low level of cast iron in the last 3 smelts ( particularly the last smelt , outdoors) ........ I am assigning that result to, too small an addition of charcoal...so I will multiply the addition by 1.3 and try again, soon. I am just about out of charcoal and hope to do at least one and a partial run of charcoal this season.

 

Jan

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So with a bit of charcoal left to smelt with, I will attempt another cast iron run tomorrow. The ore is washed and dried and I will concentrate it prior to running, to remove all the silica ( sand ) and other unwanted material.

 

Why cast iron? Cast iron made with magnetite is a very clean material ...there is an infinite amount of literature available on the conversion of cast iron to iron and steel. Many of the failed efforts at producing steel from cast iron ( failed because they were not cost effective) are methods we can use in our tool kit for making steel, all are interesting and connect to ancient historical methods.

DSCN3261.jpg beach sand is washed to remove sticky materials like salt and proteins , raking during drying,speeds drying

DSCN3265.jpg the dry material is raked extensively to make sure the sand is a free flowing material ( breaking hard water residuals)

Free flowing helps to make the concentration easier ( possible).

 

You do not want to know how many hours of crawling on the beach with a magnet this represents.

Jan

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that is a lovely looking iron sand collection!

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Thanks Dave,

It has been a lot of fun ( collecting the sand is the most pleasurable part of the whole iron making experience,due to the interaction with people who have no idea of what that stuff is). I did not run yesterday as a fellow came up to negotiate the purchase of some tools. When looking at that Japanese furnace commonly used by small scale iron makers in Japan...I see I am only using the center ( horizontal air inlet) section and for insulation I use charcoal instead refractory material .. The advantage is a faster warmup . I could use an additional bottom section and line it with GANISTER..Sometime later this year or next year I will be going to a larger size sand and will really be putting the little furnace to the test. The limitation imposed by the charcoal size distribution makes it easier to use a short stack , though as seen earlier in this thread a tall stack does a great job ( at the expense of using less fine charcoal in the mix).

I find it interesting that the little Japanese furnaces have this preheater on the top ( the top section) and the big Tatara operators add the ore before the addition of charcoal...that seems to be a sort of contradiction.

Jan

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I have duplicated the run in post 162 above. My goal is again cast iron, I will open the furnace tomorrow ...the contents of the furnace is 67 lbs of something Ferrous..I just hope the proportions favor cast iron. That will be the season for this year. I took pictures of the event today, they look just like the ones in the post mentioned, so why post. I will post some pics and numbers of tomorrows results.

 

Couple of observations about that last crucible run above.

 

The oxidized iron started to turn slightly red indicating a conversion to Fe2O3

 

The crucible which was not brought to white heat ( very porous ) is reusable .

 

I should be able to forge the fused iron/iron oxide next week .

 

Jan

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My attempt at an all cast iron bloom was unsuccessful, but an unexpected, completely high carbon bloom made the results easier to accept. If I were in Japan I would call it Tamahagane, but here in we will just call it a high carbon bloom. The bloom has an interesting slag which is much easier to clean.

In general a high carbon iron in contact with slag ( an iron rich, somewhat fluid slag) will lose carbon and will spark as low to medium carbon. That was not the case here, indicating I was very close to cast iron but it reacted with the slag and the result is high carbon bloom.

The results were, 67 lbs of material in the furnace

21 lbs of bloom ( 15 when cleaned+ 6 lbs of slag )

8 lbs of cast iron

30 lbs of unincorporated material

the remainder is bits ( I have not crushed, sorted, and weighed them yet).

 

I think it is worth noting that though I do not use the slag chipped off the bloom ( normally between 5% and 10% of the total yield) the yield of the ore is at about 90%. It is possible to gather the chipped slag , crush it and use it but it is all over the place. I am trying to get the charcoal usage yield up as well , but that is proving to be more problematic. If a fines furnace works I will get a lot closer.

So that is it for iron making, I will post some info on the the fines test in a week or so...and take this particular bloom to another thread on the possibility of creating an interesting hamon.

Here are some pics of the bloom

DSCN3295.jpg DSCN3296.jpg

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