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I guess I have a new learning curve to climb. The added stand created a cold area at the very tip of the crucible the cotton pad I placed on the bottom, before dropping metal into the crucible, did not incorporate into the melt. I may have also place the crucible a little low in the furnace and may have been too frugal with the propane as not all my anchor chain got incorporated...so it will be cut in half and remelted at 50% at a time  I will post some pics later. melting 1636 grams must take a little longer than 600 grams of metal.

Jan

Edited by Jan Ysselstein
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In planning the next melt(s) I have some serious problems to consider, the crucible showed a lot of tearing cracks indicating a great degree of shrinkage  ( I could see the height of the crucible getting smaller during the melt) . To assure a greater degree of melting I will boost the carbon content to 2.0% carbon by adding 800 grams of cast iron to the ingot. I am stuck with this particular crucible for about 8 more melts and will have to shift to a higher carbon content. now I should get a  2000 gram or a 2400 gram ingot ( that is good ). I will need to make a new furnace having the air/gas inlet closer to the bottom.

Jan

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OK that was 0/4 and I am taking some steps back to rethink this baby..I know what I want but am not sure how to get it. Si se puede.

 

Edited by Jan Ysselstein

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Steeping back was a good idea.

I am not sure what I am doing is realistic. The crucibles are holding up as I just melted an 1800 gram ingot. I took an optical pyrometer to my furnace and found I am running over 3000 F  at  way below my normal V setting...I was burning up crucibles for no reason (ouch).  I should be able to go over 2000 grams but not much more. Have encountered some beautiful microstructures and will post pictures after I write it up.

 

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So here is a picture of the 1800 gram ingot ( the goal is a large ingot to allow for a large forging, at least 2000 grams ). Also shown is a picture of a couple of 1600 gram ingots. One of the ingots did not complete the diffusion of carbon process.  Next step is to cut the  1800gram ingot to make sure the ingot is as sound as the other two. The microstructure image is of the large ingot. Very exiting stuff going on  .......... furnace , crucible handling and the microstructures seem to be falling in place.  I think I have to redefine the definition of "at heat " ...the four ingot halves were all put into one crucible and the crucible failed 15 minutes before the furnace was to be turned off.

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Edited by Jan Ysselstein

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he 1800 gram ingot looks very good . The mix was half homemade cast iron and half anchor chain. When cast iron was incidental to the bloomery process the carbon  content of that cast iron was  about 3.2% carbon....now I am targeting cast iron only as a product in the stack furnace and It looks like the carbon content is moving up and I will have to adjust for it. Now that I am getting more confident with the new crucibles I will not need to split the ingots anymore. All low carbon iron was properly incorporated by extending the "at temp" time. So 2000 grams plus ingot  is on the horizonzon. We will melt a few more ingots then move the crucible furnace to make room for the forge.

 

 

 

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Edited by Jan Ysselstein

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Dug up some cast iron and melted an ingot today ...looks really good ...;about 1450 grams .......the crucible was cracked but not all the way to the metal ( luck ). Here are some pics and I will be cutting it in half tomorrow. The crack was created by the  shrinkage of the low bisque fired crucible shrinking agains the high fired lid.

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Edited by Jan Ysselstein

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Today I did another run of the same material shooting for a lower carbon content ( which I may regret ) . I am on a mission to destroy my crucible furnace so I can switch back to placing a forge furnace in its place ( either one or the other not both )...it just will not die. The ingot is 1500 grams and should be 1.5 to 1.4 % C. I will be cutting both of these in half before forging.

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Edited by Jan Ysselstein
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Nice dendrites, Jan!  I hope they forge out well for you.  

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They should, though they look alike,  their chemistry is quite different. I seem to have run into a couple of forgiving crucibles. I did do a 2000 gram tall narrow ingot but did not hold it long enough at high temperature. I will run a few of those again this week. Now back to the Oct 4 post of last year looking for a way to make that pattern. That is not my ideal  pattern, I am hoping to finish up with a pattern showing at least some very recognizable dendrites ( or dendrite fragments 0.

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Posted (edited)

The little furnace is still going ...though the bore is getting too small due to frequent applications of kiln wash. Here is todays ingot 1.9 % carbon because I did not add all the ingredients ....but it looks good. All I have left now is a really low carbon run about 1.4% C . I think I have the melting process down .  Here are a couple of pics.  The 3 ingots are very different and should provide a mix of patterns.

 

Crucibles (2 of these) are ready to go ..after that I will take the furnace down after Cecil von Schwartz gets a chance...I have done some preliminary testing on that subject.

 

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Edited by Jan Ysselstein
addition of image

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Posted (edited)

I will not bother to post the ingot of the day..a few pits but all in all it went very well. Tomorrow is my last run and the forge will be back in place. All ingots will be cut in half , only one section of each will be forged. The ingots all have a different life history/chemistry and should provide some insight into the historical methods. The virus has me in the shop more than normal. Each melt requires 3 hrs of furnace time plus material prep. I am using my  homemade cast iron about 3.2--3.5% carbon. and a material called Norway iron ( an early steel from Sweden very clean just like wrought iron but no  slag and low P  ).  There is enough material on hand to do about a dozen more ingots. I am including some pictures from the early days when my crucibles were a bit thicker in the walls...( I will be going back to this type before leaving the subject altogether) . These pics are from 2006 or 2007.

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Edited by Jan Ysselstein
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The furnace died today...I will take a poker to the cast iron bottom on the inside ...if it comes loose, I try that last one again ( it is a valuable point for the data).  If that does not work, a forging we will go, lots of material to forge.

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Here are a couple of pics of the durable furnace which finally gave it up.  Looking back at why the crucible failed ...I would say it was too big for the furnace and heated very unevenly....when some of the surface got hot the stresses were just too much. I had never encountered that type of problem before so live and learn.

 

I have used that furnace shell to make a new one ( 2 hrs time including the demolition of the old one). This furnace will not last as long but I just have to get at least 1 more melt to complete my experiment with various carbon concentrations. I will post a picture of the new furnace when I get a camera in the shop. 

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Posted (edited)

I have spent a lot of time experimenting with various  ingot carbon content and still want to do two more tests before my temporary crucible furnace is demolished. I find all this very exiting as it connects me with the steel workers of the past..same problems similar solutions. Soon I will not be allowed to have a charcoal fire outside and fire prevention regulations will go into effect.  So I will give the Konasamudram' Process a shot , I will try to duplicate the original ceramic ( I have done so in the past )...but in any case I will become familiar with the concept of holding a crucible in afire at high temps and for a long time. I will post some pictures as we go along. 

The fir charcoal I make in the fire pit is fine for a short furnace iron run but too fragile for hanging a crucible in and constantly lifting it/letting it settle and so on. I will use some old hardwood charcoal and some purchased charcoal.

 

https://www.jstage.jst.go.jp/article/isijinternational/54/5/54_1030/_pdf/-char/en

 

https://www.academia.edu/38120945/Similar_like_White_and_Black_a_Comparison_of_Steel-making_Crucibles_from_Central_Asia_and_the_Indian_Subcontinent._In_Man_and_Mining_Mensch_und_Bergbau_Studies_in_honour_of_Gerd_Weisgerber_on_occasion_of_his_65th_birthday_..pdf

 

The above paper (upper one ) will give a little context to the topic. The actual contents going into the crucible are assumed to be cast and soft iron but that has a degree of uncertainty. The description in the above paper of the ingredients as described by Voysey are of particular interest to me and you. The crucibles sitting in the colander in the photo just above were ( the dark ones ) made with charred rice husks ..some fared better than others...but we have to try.

 

Edited by Jan Ysselstein
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This post probably should go to "Pit Charcoal" as the bloom was made with my charcoal a few days ago.. I was shooting for cast iron and have a good supply from the first two runs. The third run is too beautiful to smash as an ingredient...I would if I were desperate. Here are some pictures of the runs ( they all kind of look the same ) . The Key here is match ing the charcoal to the furnace and the method ( method = rate of everything ).

 

Regarding the current topic it is worth reflecting on the variables that might have made the (  Konasamudram Process ) a successful way of making beautiful steel. I am open to suggestions. The chemistry of the melt...the melting/cooling process/ the forging process / heat treating process...all of these contribute to the final product. The only options I have is to use my steel which I think qualifies as a very clean steel. I will start by taking an old graphite crucible ( with a hole in it ) and cutting it in half adding a mix of soft and hard iron to a carbon content around 2.3- 2.5% Carbon. Then I will create ( carve from soft brick ) a conical top. The reason for the high Carbon is to do a run that is easier to melt than a lower carbon mix. If I get comfortable with heating by charcoal and getting a good  melt I will do it a gain with a higher melting point mix. Though the conical lid is a good solution for grabbing a crucible in a fire I am not confident and have a lack of familiarity. My biggest fear is the varying rates of expansion and contraction of the ceramics involved ( causing breakage).

 

Here are some pictures of cast iron .  First, the bloom as pulled from the furnace cold,,,,,,,,,then the 16 lbs. cleaned bloom....then the bloom power washed to remove most of the charcoal ...That was run 3 of 3..runs 1 and 2 gave me plenty material to work with.

 

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Posted (edited)

Made my last batch of charcoal today and probably will not go back to doing that in the future.....done. I tried heating a large chunk of metal in my charcoal furnace and could not get beyond a yellow heat. The 14 inch diameter tube allowed the heat zone to spread too far too quickly ...considering other configurations.

 

Edited by Jan Ysselstein

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Posted (edited)

The volume  of charcoal not going into the furnace is probably 30 %, the % weight is probably 40 %...that is a lot of material going into biochar for the garden. I am starting to test methods which may allow me to use all the charcoal ......that would be a quantum leap for this process . The  last two runs of cast iron making were  58% and 53% efficiency...now if I can get the charcoal yield ( as % of total made, going into the furnace ) up to over 75%, I will be very pleased. I do not think the iron akers we are trying to duplicate threw the "fines " away ...very exiting regardless of the outcome.

 

The use of the fines has to be accomplished at a reasonable amount of labor or it will not be cost effective.

 

 

 

 

Edited by Jan Ysselstein

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..another area to work on is improving the charcoal making/handling methods so there is less loss...you can be sure they were dialing in the quality on all parts of this intensive process...

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I am sure nothing was wasted..the charcoal I make is very different than the pine charcoal made in Japan. This big fire pit goes until there are no=Zero volatiles left in the wood. I have had to shorten my furnace and tune in my air flow to match this material. I am poised to do another couple of runs as we have had a decent rain today and are expecting another next week. I will be making cast iron and high carbon steel ( the cast iron has priority....the high carbon steel is mainly to see if I can still do it ). Also the amount of charcoal sitting around has to be reduced ..all is in metal containers but I only need a few barrels go hardwood charcoal. 

BY the way the charcoal fines  test was quite positive I ran the furnace like the Catalan forge ( horizontal air going in though )..the temperature of the ore did not go high enough for the ore to fuse as it does very high up in the normal charcoal furnace. So I ended up with an iron powder having varying degrees of reduction ...I have a crude way of estimating the degree of reduction /carburization but it is really rough. I combined this partially reduced ore with old similar material for a future run. There are a couple of other ideas I will try when I have nothing to do. Now I have  a lot of biochar which seems to work pretty well in the garden. Below a couple of pics of recent runs ...they are not directly related. I f I run hard and soft wood , I do the harwood first and top off the pit with the soft wood as that charcoal is more friable. Below is also a picture of a flower not grown in biochar but doing quite well.

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Edited by Jan Ysselstein

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I am hoping to do a large cast iron run in the next two-three days....larger furnace,  more room for the cast iron down below. ( there will literally be a fire in the belly of that furnace ).fingers crossed ...first time I have tried that.  Longest run to date is 3.5 hrs  at a 16 lbs yield...hoping for more this time. The ore is mixed with some material that has made a pass through the furnace  but did not consolidate due to getting to a low temperature area ..I pick it out with a magnet and use it as a mix.This will be it from as far as blooming is concerned I have a guy coming over to participate in a day or two and will give him my furnace..I have plenty of material to work with.

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Lots of time constraints today...did not run the bigger furnace. Ran for about 3hrs and used 33pounds of ore (mixed magnetite and recycled unconsolidated ore ). Had to slow way down as the recycled ore wanted to fly out of the furnace. Next shot is on Saturday butI will post a picture of today’s run when it has cooled manana.

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Posted (edited)

I am not exited about running the recycled ore...it seem fresh ore does just as well...the yield of clean cast is about 40%.... Here are some pictures of the cast iron that little cupcake like thing was sitting on top of the cast iron until I broke it off. Yield is about 11-12 pounds of clean cast iron.

So Saturday I will be running the large furnace and the small furnace to clean up all the charcoal prior to things getting really dry ..by the way this charcoal at zero volatiles produces no spark when burning in the furnace. 

 

The big furnace is somewhat based on an article  ( Tatara Costruction and Operation. ), no longer around on the internet it was written by Yoko Yamabe-Mitarai and suggested warming up the furnace by heating the initial charges through the slag tap hole located below the normal air inlet ( this is a slag tapping furnace while mine is not ). The big furnace will heat and operate for about 1- 1.5 hrs. using an air inlet about 6 inches from the bottom...then the air supply will move up about 6 to 8 inches more and the run will be finished ..end of the run will be dependent on the condition of the operator..I will have another masked guy running around helping me. 

Top surface of the bloom

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Cup cake type shape of cast iron sitting on top the bloom during smelting

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Bottom view of the bloom 

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Edited by Jan Ysselstein

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The bigger furnace ran for 6.5 hrs. and used 78 lbs of ore as well as lots of charcoal today and I am tired. Charcoal is sorted and brought to the site  during smelting....that can be a real challenge for an old guy. I will have a look in the morning to see how it looks. I can predict a best case outcome based on previous yields...A 33-35 lbs. clean cast iron bloom would be a very good result .. I will be happy with what I get. Making really pretty blooms is a mixd blessing..how am I going to smash up a beautiful bloom/.

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Yesterday, I tried and experiment in cast iron smelting by running for about two hrs. with an air inlet about 6" from the bottom of my furnace, then at a scheduled time changed the air supply to a higher inlet by about 8"..this combination allowed me to run for 6.5 hrs straight. The yield came in two main blooms and lots of bits as I had to get a little rough extracting the fragile blooms. The clean bottom bloom is 13 lbs the top bloom is 17 lbs the clean bits are 7 lbs. 78 lbs of ore was added to the furnace giving a yield of 66 % . I have posted some pictures below. The ore was magnetite the charcoal homemade 50/50 hard and fir. The furnace was operated by one person, charcoal was sized at the time of smelting.

Below are some pics of the bottom bloom and the top bloom  top bloom is in the center.

 

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