Jump to content
Jesus Hernandez

New furnace: Bigger bloom.

Recommended Posts

I wonder if the elevated carbon problem(if that's what it is) is connected to your refractory recipe. The portland is mostly calcium, the vermiculite has magnesia and alumina, all those are bad things for the slag, reduce the slag's potential for decarburization.

 

 

Lee, I agree with you on this point. I wonder myself what the vermiculite could have done here. This is the first smelt I mixed vermiculite in the bricks. Before it was either plain sand or sand and ash. Vermiculate is Silica 31-41%, Alumina 10-17%, Iron oxide 5-22, Magnesium oxide 11-13% or higher. I don't think that neither Si, Al or Fe would be bad in the mix. I am not sure about the Mg. I really would love to have the chemical analysis of the steel available. EPK kaolin is 45% Silica and 40% Alumina.

 

There are many factors that contribute to the final composition of the bloom. The problem is controlling the factors in the equation one by one to achieve the final goal. Our goal is steel with a minimal amount of alloying elements and a carbon content of about 1-1.5%. It will take us a long time and many more furnace runs to sort out all the factors that will get us closer to the final goal. I welcome all opinions and suggestions but we have a limited amount of time in our hands.

Edited by Jesus Hernandez

Share this post


Link to post
Share on other sites
...I wonder if the elevated carbon problem(if that's what it is) is connected to your refractory recipe. The portland is mostly calcium, the vermiculite has magnesia and alumina, all those are bad things for the slag, reduce the slag's potential for decarburization.

 

The elevated carbon problem, is not a problem. It's the end goal, in the manner that we are doing this. Why do you think that we are having a problem?

 

I disagree with Mike's idea that making iron and steel are really different. I think the stack reduction in any bloomery produces a high carbon product, and then is decarburized in the hearth. How much it's decarburized depends on how much slag you keep in there, and what the chemistry of that slag is. Iron in the slag decarburizes the bloom, other stuff in it doesn't.

 

I agree to disagree. IMO the furnace doesn't work like that, and, it's not slags that make the difference. On the surface, both stack processes appear similar. But it's not the surface where the main events are taking place. And there are a great many more variables than slag peformance. During my first several burns, I could make low carbon melted iron without any problem. But the furnace wasn't producing the end product I wanted, sword grade steel as near to the Japanese chemistry as I could get. Having failed a few times, I was able to ask questions of Prof. Potratz and Mr. Kihara, the master smelter from Japan. Slag can serve both our purposes if used correctly. I don't believe you're correct about decarburization in the hearth either. The most efficient means to decarb steel is expose it to oxygen. There isn't much oxygen in slag, or below slag because it keeps the bloom out of the tuyere blast.

 

"The other stuff" like calcium in cement comes in the form of calcium carbonate which at temperature should give calcium and carbon monoxide or dioxide providing a richer carbon source not a lesser one. That dissociation will also scavenge oxygen quite rapidly so there won't likely be much available for decarburizing the steel. While iron in slag solution is available for carbon diffusion, melted droplets of iron or steel will likely gravitate through a thin solution of slag fairly rapidly to accrete on the bloom below where diffusion is much more likely due to intimate rather than random contact between molecules of iron carbide suspended in a puddle.

 

While yours is an interesting theory, it is still supposition. There is simply not enough time, temperature or volume in the slags to achieve your desired end result. I think you should look to other variables. But, then, I agreed to disagree.

 

That's why, to make lower carbon stuff, we try to keep wall erosion out of the equation. I think one reason the tatara makes steelier stuff is because it continually adds the eroding sand/clay mix to the slag (the bottom sacrificial section is mostly sand.) Seems like if you want to approximate that process, with wall erosion contributing to the slag, you ought to try to make sure the slag you're making is chemically similar, or you could chase down a lot of dead end roads.

 

Chasing down dead ends happens anyway. That's what makes doing these burns so exciting. I always learn something. The last burn was humidity. Very cool. Next time, like Jesus and Walter, I'll change one variable and burn again. It's costly experimentation for sure. Sometimes dead ends are quite surprising. The Chinese went through a lot more trial and error than any of us and they figured it out. But then they were fluxing copper with irons and thought the iron was a contaminant.

Share this post


Link to post
Share on other sites
. I don't believe you're correct about decarburization in the hearth either. The most efficient means to decarb steel is expose it to oxygen. There isn't much oxygen in slag, or below slag because it keeps the bloom out of the tuyere blast.

 

"The other stuff" like calcium in cement comes in the form of calcium carbonate which at temperature should give calcium and carbon monoxide or dioxide providing a richer carbon source not a lesser one. That dissociation will also scavenge oxygen quite rapidly so there won't likely be much available for decarburizing the steel. While iron in slag solution is available for carbon diffusion, melted droplets of iron or steel will likely gravitate through a thin solution of slag fairly rapidly to accrete on the bloom below where diffusion is much more likely due to intimate rather than random contact between molecules of iron carbide suspended in a puddle.

 

While yours is an interesting theory, it is still supposition. There is simply not enough time, temperature or volume in the slags to achieve your desired end result. I think you should look to other variables. But, then, I agreed to disagree.

Chasing down dead ends happens anyway. That's what makes doing these burns so exciting. I always learn something. The last burn was humidity. Very cool. Next time, like Jesus and Walter, I'll change one variable and burn again. It's costly experimentation for sure. Sometimes dead ends are quite surprising. The Chinese went through a lot more trial and error than any of us and they figured it out. But then they were fluxing copper with irons and thought the iron was a contaminant.

 

Mike,

 

I am a little confused reading your comments.

 

It is my understanding the "iron in slag solution" is in the form of an iron oxide FeO incombination with silica SiO2,existing in various proportions. The carbon in adjacent steel reacts with this FeO thus decarburizing the steel (or cast iron) . At 2400 Deg F this may go at a fairly rapid rate. The point is slag does have oxygen. The furnace walls would not erode if FeO were not in great supply to flux the material. I don't think there is any controversy regarding oxygen in the blast being effective at decarburizing steel (or cast iron).

 

Regarding the CaCO3 decomposition to CaO and CO2 , the CO2 will scavenge Carbon not Oxygen. CO2 by itself is an oxidizer.

 

Somehow I feel we have bumped Walter and Jesus off the track too early in their description of what their observations were.

 

Some of us on the West Coast are doing almost exactly what Walter and Jesus are doing and reading their descriptions are very inportant to us.

 

 

Jan

Share this post


Link to post
Share on other sites
Mike,

 

I am a little confused reading your comments.

 

It is my understanding the "iron in slag solution" is in the form of an iron oxide FeO incombination with silica SiO2,existing in various proportions. The carbon in adjacent steel reacts with this FeO thus decarburizing the steel (or cast iron) . At 2400 Deg F this may go at a fairly rapid rate. The point is slag does have oxygen. The furnace walls would not erode if FeO were not in great supply to flux the material. I don't think there is any controversy regarding oxygen in the blast being effective at decarburizing steel (or cast iron).

 

Regarding the CaCO3 decomposition to CaO and CO2 , the CO2 will scavenge Carbon not Oxygen. CO2 by itself is an oxidizer.

 

Somehow I feel we have bumped Walter and Jesus off the track too early in their description of what their observations were.

 

Some of us on the West Coast are doing almost exactly what Walter and Jesus are doing and reading their descriptions are very inportant to us.

 

Jan

 

I certainly had no intention of hijacking Jesus' thread. However, one theory about how stacks operate was introduced by Lee and Co. To this date that theory has had a lot of press as it were. Another theory about stack operations, which could be argued has significantly older roots, was introduced and found itself criticized. I'm only attempting to balance the argument so each learner has a spectrum of ideas to choose from.

 

Jesus got a good portion of this information from me, I got it from Prof. Potratz by way of the Japanese. I've had my thoughts about this process reviewed and discussed with the master smelter. I do not claim to have all the answers, but using the process I have been and changing variables within the context that I've learned and modified, I'm producing an ultra high carbon steel routinely, to a satisfactory degree, plus lesser steels and some melted to sintered irons. Lee and Co. have been attempting to produce irons, where carbon is considered a contaminant. These are two entirely different end points, however, they both have common ancestral processes. The differences between us are beliefs about how the chemistry works inside the stack - where it is difficult to directly observe things.

 

I'm going to pose a question and ask everyone to think about it for a moment. Just to refresh the starting point for us all. How does iron oxide, the black or brown stuff going in the top of the stack, get converted into either melted iron or steel?

 

Each furnace operator has to think this through for themselves. If you only want to follow a recipe, there are a lot of dead ends and wasted fire time.

Edited by Mike Blue

Share this post


Link to post
Share on other sites
I'm going to pose a question and ask everyone to think about it for a moment. Just to refresh the starting point for us all. How does iron oxide, the black or brown stuff going in the top of the stack, get converted into either melted iron or steel?

 

I don't feel like anyone is hijacking the thread. I welcome any healthy dialog.

 

As for the question... is this a rhetorical question Mike?

What I think we are doing is "removing/reducing" the "oxygen/oxide" of the "iron oxide" to turn it into "iron." We are not contributing oxygen to the process, we are taking it away. I have read about the change on atmosphere from a reducing one in the stack to an oxidizing one at the tuyeres but I have questioned myself how much oxidizing really occurs when the end product is reduced iron plus some carbon. I don't believe that there is that much oxidation of the bloom occurring at the tuyeres. I may be wrong of course. There is also an issue as to what happens below the tuyeres and how much the slag components may contribute at that level to a reducing atmosphere. All I have read and heard are theories and interpretations of what happens inside the furnace. I don't know of any published information beyond theories.

Share this post


Link to post
Share on other sites

Hey Guys

I just wanted to say if there's going to be a big tatara type three day smelt I'm in. Let me know the time, place and how much to bring.

 

Matt

Share this post


Link to post
Share on other sites
As for the question... is this a rhetorical question Mike?

What I think we are doing is "removing/reducing" the "oxygen/oxide" of the "iron oxide" to turn it into "iron." We are not contributing oxygen to the process, we are taking it away. I have read about the change on atmosphere from a reducing one in the stack to an oxidizing one at the tuyeres but I have questioned myself how much oxidizing really occurs when the end product is reduced iron plus some carbon. I don't believe that there is that much oxidation of the bloom occurring at the tuyeres. I may be wrong of course. There is also an issue as to what happens below the tuyeres and how much the slag components may contribute at that level to a reducing atmosphere. All I have read and heard are theories and interpretations of what happens inside the furnace. I don't know of any published information beyond theories.

 

Yes, in some ways it is for us. You and I have already discussed the question. But, I can't be sure that everyone is thinking through this from the same starting point. An easy starting point is that the stack is built and the fire is lit; what happens next?

 

If this "question" continues, I'd like a discussion over stack chemistry to be over the whole of stack chemistry rather than isolated processes in limited portions of the fire. I don't think that what is happening can be taken outside the context of the influences of the whole fire. I admit, I've never had this conversation with Lee, although I believe I did with Skip at Harley's. And to some degree I can't say that I relish delving into the discussion because some comments on earlyiron do not lead me to believe that a contrary supposition will receive much light of day. The focus, from that perspective and based on archeological residual, is that slags are important and no one seems able to redirect that focus. There is a lot more to a stack fire than one portion of the chemical activity.

 

But, that is a good summary of how one portion of the process works. Oxygen has to be removed from the iron before it can start absorbing carbon. Carbon is desirable because it lowers the melting point of the iron, which seems to be the whole point behind smelting in the first place.

 

For beginners, depending on what you want as the end product, you need to look to the folks who are producing that product. Their product will prove their methods, regardless of what is happening inside their furnaces. So, there is a huge difference between what you need to know, e.g. how to make iron/steel, and what is nice to know, e.g. why it happens. Nice to know is frankly irrelevant if what you want is some bloom to heat and beat because you have a job to get done.

 

But, each end product has a beginning. Whether a hundred blooms or 25 or still thinking about doing a bloom, each project manager needs to have a common entry point to the process.

 

In any event, I'd prefer that this stay in the domain of an academic exercise where the process is subject to further discovery and a balance that accomodates all the theories that are in play.

Share this post


Link to post
Share on other sites

Mike,

 

Don't forget, we are taling about one of the most studied and most documented subjects known to man. A little "Nice to Know" is unavoidable and essential. Just because we are scaling it down to these cute little furnaces does not mean we need to throw established knowledfge out the window and start all over.

 

The "stack" ( the whole furnace is a stack) chemistry is what it is, even if the individual operator interprets it based on his/her own biases. These biases will shift over time and eventually a common perception and interpretation will align with established data on the subject. Some people's biases shift faster than others.

 

I do not think we can describe what is happening in the stack without breaking it up into areas where certain events dominate. Where this particular process gets tricky to describe is the effect of unreduced ore traveling down the furnace

shaft at varying rates. I appreacite the dialoge, it has already conviced me to change my smelting process.

 

Jan

Edited by Jan Ysselstein

Share this post


Link to post
Share on other sites
I do not think we can describe what is happening in the stack without breaking it up into areas where certain events dominate. Where this particular process gets tricky to describe is the effect of unreduced ore traveling down the furnace

shaft at varying rates. I appreacite the dialoge, it has already conviced me to change my smelting process.

 

I agree here. To best perform a study of this process we'd have to be willing to build a whole bunch of stacks, as exactly alike as possible, and burn one for a set period of time, shut it down, then burn another a little longer and so on. Then tear down each fire and observe the changes at each phase.

 

Personally, that is a little too much Newtonian-Cartesian thinking and much too heavy in terms of time and investment. Qualitative research with single or dual variable control will produce much more information over the same period of time with a lot less heartbreak monetarily.

 

Which leads to the next question. How can unreduced ore reach the bottom? The only way I see that happening is exceptionally high temperatures, at or near the melting temperature of iron alone. Then you're at the near limits of most refractories.

Share this post


Link to post
Share on other sites

Which leads to the next question. How can unreduced ore reach the bottom? The only way I see that happening is exceptionally high temperatures, at or near the melting temperature of iron alone. Then you're at the near limits of most refractories.

 

Mike,

I am with you regarding establishing a "standard furnace" as well as some reference points regarding important controllable variables,(ore, charcoal type and size, blowing rates etc. ). This has been done by the "Early Iron" group.

If enough people show an interest here such a "standard" furnace associated with this particular process and this particular ore,could easily be established. I have a lot of suggestions and am completely unbiased (really). I will document my next run (we are in a drought and fire danger is still high) here on this site. The furnace will be based on my experience +/- about 8 runs using a shaft furnace and some class notes Dr. Potratz kindly forwarded to me.

 

Regarding ore traveling down the shaft, I use a very fine magnetite ore which is essentially tiny bbs of magnetite. These things flow like liquid and are easily blown out of the furnace top as well. Unless this ore lands on a plateau of charcoal or a counter current of gas, it will flow where gravity tells it to. I used to beat on the side of my steel shelled furnace with a large wooden hammer which only made it worse (I did get a lot of really low carbon iron though).

 

Jan

Share this post


Link to post
Share on other sites

Dr. Potratz is one of the most gracious fellows I know.

 

My question was poorly asked, I should not have used the word "only". I was thinking of iron reaching the bottom in a melted state. There are three or four variables present in your method that contribute to the problem of iron falling through the stack too quickly and those should be addressed. These stacks are like Pachinko games, the balls go everywhichaway.

Share this post


Link to post
Share on other sites

Wow, didn't mean to set you off Mike, take it easy.

 

I only commented on elevated carbon as a problem, because Walter said he thought that might be why his iron is hot short.

 

I think that when you're running any bloomery, it's the kind of system in which everything affects everything, there's no simple key or recipe, it's an art not a science. Still, I think the biggest determinant of carbon content is slag chemistry (including a lack of slag). Yeah, it's "just a theory", that is, a hypothesis tested by lots of experiments. Honest, I didn't just make this stuff up, I've smelted and forged a literal ton of bloom iron, in many kinds of furnaces, with a wide array of results.

 

 

 

Jesus, Walter, Everyone: If any of my comments were percieved as rude, or arrogant, or anything other than an open-hearted sharing of ideas, I apologize.

 

If anyone is unconvinced that iron- rich slag decarburizes iron,don't take my word for it. A few simple experiments melting cast iron and iron ore together should give you some facts to go on.

 

For some reason, my contributions here seemed to turn this thread from a discussion into some kind of weird negative thing, so I'm shutting up. Again, I apologize to the forum for anything I did to create that, I assure you it was not intended. Keep up the good work-

 

Over and out-

 

Lee

Share this post


Link to post
Share on other sites
Wow, didn't mean to set you off Mike, take it easy.

 

... it's an art not a science. Still, I think the biggest determinant of carbon content is slag chemistry (including a lack of slag). Yeah, it's "just a theory", that is, a hypothesis tested by lots of experiments. Honest, I didn't just make this stuff up, I've smelted and forged a literal ton of bloom iron, in many kinds of furnaces, with a wide array of results.

 

...

 

If anyone is unconvinced that iron- rich slag decarburizes iron,don't take my word for it. A few simple experiments melting cast iron and iron ore together should give you some facts to go on.

 

For some reason, my contributions here seemed to turn this thread from a discussion into some kind of weird negative thing, so I'm shutting up. Again, I apologize to the forum for anything I did to create that, I assure you it was not intended.

 

I'm hardly set off. Art but not science. Running a fire like a musical instrument, that's art, and one of my best friends is very good at it. There is room for both in this endeavor. Especially when speaking about a carbon diffusion experiment like melting cast and iron together. That would be science not art. Been there and done that, and plan heavily for it to happen in a predictable fashion when making high carbon steel inside a bloomery.

 

Hmm, I'm sorry that disagreement some small theoretical point is perceived as negative when there has been some agreement about most of the processes up to now.

 

Anyone else that's offended, for my part, I will also apologize.

Share this post


Link to post
Share on other sites
Wow, didn't mean to set you off Mike, take it easy.

 

Still, I think the biggest determinant of carbon content is slag chemistry (including a lack of slag). Yeah, it's "just a theory", that is, a hypothesis tested by lots of experiments. Honest, I didn't just make this stuff up, I've smelted and forged a literal ton of bloom iron, in many kinds of furnaces, with a wide array of results.

 

If anyone is unconvinced that iron- rich slag decarburizes iron,don't take my word for it. A few simple experiments melting cast iron and iron ore together should give you some facts to go on.

 

For some reason, my contributions here seemed to turn this thread from a discussion into some kind of weird negative thing, so I'm shutting up.

 

Over and out-

 

Lee

 

Lee,

We need your input and all of us are not creating a negative atmosphere here, we really want to learn. Your experience is very valuable to all of us smelting or planning a smelt. Having contributions from people like yourself is just what this forum needs, more facts,less hocuspocus.

 

I have done the crucible melting of cast iron and iron ore....it sputtered violently and deposited a plug of pure iron at the lower edge of the Kaowool lid...I still have that sample.

 

My iron furnace operates without slag and am able to produce cast iron as well as a heterogeneous bloom with significant amounts of very high carbon content. So it is either avoid very low carbon steel or add some silica sand back into the ore. The lowering of the furnace bottom,while blowing slower and at a 90 Deg. angle to the shaft creates a reducing environment around the bloom (provided there is no bridging of charcoal).

 

 

Please do elaborate on the "lack of slag" situation as you see it and why it could be a problem. I would really like to avoid tapping slag. If you are interested I can post some pics of blooms and a spark test.

 

Jan

Edited by Jan Ysselstein

Share this post


Link to post
Share on other sites

We are all benefiting from this exchange of information (I am feeling like a moderator saying that.) I hope no one is offended by anything said and that we all continue to contribute what we know from our own perspectives. My personal goal out of these furnaces is to produce steel. The steel has to be of good quality and with enough carbon so that taking into account the lost of carbon during the processing of the bloom I will be left with about 0.5-0.7% carbon in a blade forged out of it. Others here have different purposes for running these furnaces, like making iron with more or less silica. Maybe we should have clarified our own purposes and expectations of the process.

 

My own understanding of the bloom inside the furnace is that it represents a very hot reactive element that interacts with its surroundings. If the atmosphere contains carbon in excess, the bloom will uptake the carbon. If the atmosphere or whatever comes in contact with the bloom (slag) has no carbon or little carbon then it will steal carbon away from the bloom. Other factors will affect this too, to me mainly how much carbon is already in the bloom (from coming down the reducing stack) to begin with. Is this interpretation incorrect?

 

Jan, I appreciate your input too. I am curious about how do you manage to run the furnace without forming any slag. Is it based on walls that don't erode like the type of rammable refractories or clay suggested by Lee? When I first started doing this I was working on a furnace design that could be reusable but I had to give up on the idea as I run into the problem of extracting the bloom from the furnace without destroying the walls.

 

I hope Lee and others will continue to contribute to every one's knowledge here. We are all learning valuable information.

Share this post


Link to post
Share on other sites

Jan, I appreciate your input too. I am curious about how do you manage to run the furnace without forming any slag. Is it based on walls that don't erode like the type of rammable refractories or clay suggested by Lee? When I first started doing this I was working on a furnace design that could be reusable but I had to give up on the idea as I run into the problem of extracting the bloom from the furnace without destroying the walls.

 

I hope Lee and others will continue to contribute to every one's knowledge here. We are all learning valuable information.

 

Jesus,

 

I do not really run without any slag but not enough to have ever tapped it . After not getting any significant slag out of the first 5 or 6 runs I just quit attempting it. My ore (up to now) contains no silica (though my furnace bottom is made of sand), so only the eroding furnace wall (clay) contributes to the small amout of slag I do have. My runs are relatively short 1-4 hrs. I may add a hand full of sand to my next run to reduce oxidation of the bloom by the blast, but not tap it . My bloom does not sit in the direct path of the blast (like yours seems to), it sits about 6" below that point and my blast is just about horizontal. The blooms are covered in black slag some of it is very strong and difficult to powerbrush off.

 

During the next week or two I will be testing a new ore which still has bits of the granite adhering to it, we will see what I run into then.

 

I do think if you make the furnace you had out of clay you would be fine as long as you were confident your material was not hanging up in the shaft.

 

Jan

Share this post


Link to post
Share on other sites

Jan,

 

I will consider trying the clay. It has always been hard for me to get "unusual" supplies around where I live without having to spend quite a bit in shipping. That's why I have been working with materials that are available locally. I also prefer the cheaper materials since I have not come up with a furnace design that did not needed to be broken apart to extract the bloom.

 

My blooms have never grown above the tuyeres either. They don't sit as low as yours though, they just sit below the tuyeres.

 

If you run your furnace for a short amount of time (1 hour), how many charges are you actually doing? and what is the final product of those short runs? if you don't mind me asking.

Share this post


Link to post
Share on other sites
Jan,

 

I will consider trying the clay. It has always been hard for me to get "unusual" supplies around where I live without having to spend quite a bit in shipping. That's why I have been working with materials that are available locally. I also prefer the cheaper materials since I have not come up with a furnace design that did not needed to be broken apart to extract the bloom.

 

My blooms have never grown above the tuyeres either. They don't sit as low as yours though, they just sit below the tuyeres.

 

If you run your furnace for a short amount of time (1 hour), how many charges are you actually doing? and what is the final product of those short runs? if you don't mind me asking.

 

Jesus,

 

If you are not planning to do another run within two weeks, hold on until I post my run, it may give you some ideas you can use. If you are doing one sooner, I would go to the local buiding yard and buy bulk sharp sand, some mortar clay and a large mortar mixing pan (this a fiberglass box about 1ft high by 2 ft wide by 3 ft wide) and a bale of straw. You may want to take off your socks but mix a batch pretty high in sand, ram your bricks. If you are concerned about the furnace falling appart wrap it with chicken wire or back it up with some sheet metal and wire it in place.

 

 

My runs are for example:

 

77 minutes 60 lbs of ore 16 lbs of low carbon iron with an upper surface of very high carbon iron beause at shutdow we were eating and I ran it out at very low voltage. I would say about 10% of this ore was blown out of the furnace.

 

90 minutes 60 lbs of ore I don't know the weight because it was auctioned off at an event, I would guess between 16

and 20 lbs, again much of this ore was blown out, the iron was very low carbon

 

These runs were in a narrow shaft furnace similar to yours...10" clay flue tiles (2) in a 14' diameter steel tube, the gap filled with sand, sand bottom, tap hole dead center of the bottom.

 

 

The furnace I am now using is a 20" dia. steel tube 36" high , an old transformer can (the next one will be a 55 gallon drum with 5 or 6 air blast pipes).

 

This furnace was run for various experiments, the last was 3 hrs, 80 lbs of ore, 14 lbs of really good bloom ( with lots of high carbon and or cast iron incorporated) plus a few pounds of bits protruding from the bloom and located below the bloom.

 

I am happy with either furnace, the latter one fits the design of a furnace which does not have to be broken up and can be patched for the next run very quickly. This is the design I am going to play with for a while, I will use the old one for doing demos.

 

A caution about running without slag, recently I was playing with an inverted blow pipe (furnace 2) , I noticed my CO flame was looking a little redder than usual and so was the air beyond the flame. That is an expensive way to make hematite dust. I did get it to work by fussing a lot and have not yet written it off.

 

Jesus , (an edited correction) furnace 1 the hole in the steel tube is at 6" above the end of the tube, I then ram slightly damp sand (little clay) in place using a bowling ball on a broom stick. So I guess we are now at about 4.5" below the center of the air pipe.

 

Jan

Edited by Jan Ysselstein

Share this post


Link to post
Share on other sites

Jesus, I believe most kaolin is mined in south Georgia, only a few hours' drive from you. It may be tricky to talk the mine out of some directly though, as I believe many of the kaolin mining companies are now foreign owned. But if you could, a day trip with a truck might get you a lifetime supply of the stuff.

 

Michael

Share this post


Link to post
Share on other sites

Interesting discussion!!

 

What I did on my last furnace is a kind of a compromise.

The furnace was built in refractory brick but the inside was lined with what in french is called "brasque" a mix 50/50 of clay and fine charcoal. About one thick inch of the mix 1/3 of the height of the furnace (the hottest part).

 

Antoine

Share this post


Link to post
Share on other sites
Interesting discussion!!

 

What I did on my last furnace is a kind of a compromise.

The furnace was built in refractory brick but the inside was lined with what in french is called "brasque" a mix 50/50 of clay and fine charcoal. About one thick inch of the mix 1/3 of the height of the furnace (the hottest part).

 

Antoine

 

 

How did that set up work for you Antoine? Did the walls hold up? I assume that you had to break the walls to extract the bloom at the end. Or not?

 

 

Jan,

 

I don't plan any more runs of the furnace until next year. I will be glad to hear from your next experience.

Share this post


Link to post
Share on other sites

Interesting Antoine. Not quite the same mixture ratio but similar elements of the brasque at our last burn. It does save brick for the next run instead of losing them to glazing.

Share this post


Link to post
Share on other sites

Jesus and Walter sorry this OT text!

 

 

Mike!

 

Do you still have the text that i send you some time ago?

 

I like this topic a lot...but why anyone has mention titanium / titanium oxide.

Acording whit text TiO2 ( satetsu sand Masa whits contais 1-2% of TiO2...will carburised better and any slag that will

procuses is more liquid and runs easyer out fron slag hole...so it not decarb the bloom...

 

But then agane i have done only two runs...but 2 run i used TiO2 powder and slag was more " liquid"...But then agane i didnt get any slag form 1st run..just hematite ore and charcoal..

And that is good steel...acording sparktest.

 

I like this...all makes can give some info and learn more...at least me ;)...im all ways hunry for more info about smelting.

 

N

Edited by Niko Hynninen

Share this post


Link to post
Share on other sites
Interesting Antoine. Not quite the same mixture ratio but similar elements of the brasque at our last burn. It does save brick for the next run instead of losing them to glazing.

 

 

Jesus,

There was about half inch of melted stuff over the most exposed bricks near the tuyere. Dont know how much of it was brasque or brick or both...The bricks did not fuse together as in the first furnace, and the bloom did not stick to the walls; it sticked to the tuyere... :rolleyes:

Mike, I tought that a 50/50 mix would give a better insulation, but it seems to be quite soft and tender, I'll probably go with more clay next time.

I tried to leave the furnace intact, but did not put much efforts in it as it was made during a public demonstration and the site had to be cleaned up. The bricks does not allow for keeping the structure much...maybe with a HEAVY layer of clay on the outside and a BIG door.

 

The bloom was nice, about 5kg, and it sparked like yours, did not forged it yet...

 

Antoine

Share this post


Link to post
Share on other sites

×
×
  • Create New...