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Owen and I got together for our first smelt of the year. We built the furnace on Thursday and on Friday after a warm up and pre heat, we ran it for about 5 hours. Here are a few photos.

 

Pulling the bloom out,

 

may-smelt_zps32a99607.jpg

 

 

Under the 2cwt hammer,

 

may-smelt-1_zps831224ce.jpg

 

 

The flattened bloom weighs 12 kgs or 26lb with probably another 7 or 8lb of pieces scattered around the hammer. Bloom size is 12 to 13" round and 1 5/8" thick

 

may-smelt-2_zps5d930e9c.jpg

 

 

The bloom cut in half

 

 

may-smelt-3_zps5c991748.jpg

 

 

 

Mick

 

 

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Looks like a blast! Nice pictures, the second one down especially. I would love to run a smelt someday.

 

John

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HI , this was a good smelt almost clockwork.

we use Lee Sauders basic recipe for the forge material , sand , organic matter ball clay china clay and chopped hay. in reality this furnace was made fro two previous furnaces recycled with some new material added at the top and some clay added to get it all sticky again.

Thuis furnace has a 1/2 inch steel rod exoskeleton to keep it together with welded in weld mesh, raw bolted to the base block.....

we removed 1/3 around and to 1/3+ height to birth the bloom the rest seems rock solid.....

our method for our materials and available blower etc seems to have calmed down into a situation where we are getting good results our initial blooms are big and post initial compaction they are dense. somewhere along the way we changed what we were measuring so a bloom of 12kg now would have been previously measured at 17 to 19 kg pre consolidation under the hammer.

 

as always there are still questions.

Our successful smelts always eat away almost all of the furnace at the tueiron and have lots of slag (ie the furnace wall).

we are running hot (i think) our drops are a stable 8 to 10 minutes for 2kg ore 2kg fuel should we slow it down a little? ie less air?

could we up the ore to fuel ratio above equal.....

Could we make the furnace around the tue of a more robust high temp mix (ie no ball clay) .

would a copper / water-cooled tue take the heat from the furnace wall at the tue? I have a piece of copper tube now that could be used.

 

like I said good slag runs have always given good bloom so should we leave it all alone.......and accept that furnaces get eaten.

 

the "six million dollar man" arrangement with the steel in the furnace wall works amazingly.

 

any how always more thaughts....

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Looks Great!!

How thick are your smelter walls? You shouldn't need the steel frame. I tend to think that may even make it weaker in some ways.

keeping the stack alive is most always, all about the birthing of the bloom. The base/plinth is all importent!!

Seems like you can always slow down some. as long as the stack isn't cooling.
Your results look pretty good. I wouldn't change much.

What was the ore?

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Mick, Owen, nice looking bloom!

 

Most probably your tuyere wall is melting because the tuyere is melting/burning, moving the hot spot constantly toward the tuyere wall. Are you using iron or ceramic here? If you're doing ceramic it might be worth trying just starting with the tuyere further in so by the time it melts back it's where you want it to be.

 

I bet once you have a tuyere that is stable, that problem will go away. The copper pipe is not optimal, a tuyere with a generous taper will give more radiative surface- I just melt scrap into an ingot, forge the ingot to a trapezoidal plate, and wrap it up into a tube.

Another thing that can cause melting on the tuyere wall is inadequate blast pressure, it's easy to tell that's the problem if the fire is hotter on tuyere side of the stack, and things settle toward the tuyere side, instead of evenly across the whole diameter of the furnace. Assuming the fan has high enough pressure, the other fix is a smaller tuyere orifice, even a slight shrinking by a few mm can really push the fire away from the wall.

 

Of course any or all those things can combine, and then lead to all the slag flowing on that side, which of course just compounds the problem. Also if your tuyere angle is a little shallow, it can lead to a cut in the rim of the bloom under the tuyere, again making more slag flow on that side. If you can keep that rim intact, it really does improve the quality of the iron! The rim looks really good in that picture but it's kinda hard to tell.

 

Nice work-

 

Lee

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Owen & Mick

 

I think wall erosion is duo the phenomen " wall effect" that is inevitable more or less...

Front of the tuyere we have race way depending of pressure of blower, it can drill a hole in bloom if it ingreases

during smelting and bloom has all ready grown large. After the race way is hotspot...Combustion and after this deadman zone.

If burn happens hard I think it greates more chance to wall effect sens deadman zone can be higher upwards to staff..

This greates chance to gasses blow upwards and aggens to wall..soft of negative turbules above the tuyeres..

To limit this I think the fuel size needs to be right..

But I think erosion of walls is just ine feature and actually good if bloom needs space to grow...Like in Japanese tatara.

 

But when you get that nice blooms....I would not chance anything...only various blooms whit different C level...duo the ratio.

 

( some terms are industry terms but are comparable to small skale smelters too...Base to several hours of looking trough the gas weld less via tuyeres/ shape of blooms ( central - outher rim) )

 

Nice work guys.

 

Niko

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I think Lee is dead on with the potential causes for this. One other thing to consider is the wall thickness around the tuyere. The heat inside the furnace wants to find an equilibrium between containment within the clay walls and heat loss to conduction and radiation outside. If the wall is too thick, it will find the balance by eroding that wall until is thin enough to radiate evenly. This is compounded with the interaction of slag and wall that promotes that erosion. I also would agree with Mark and get rid of the iron exoskeleton. The metal just gets hot and contributes to wall erosion.

But on the other hand, you are getting very nice blooms and have a arrived to a method that works for you. So you may not want to change anything, although most of us like the "experimenting" part and love to tweak things here and there.

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I am rebuilding the furnace now , the exoskeleton stays!! it was a great help in birthing the bloom without total furnace destruction I am having to replace 1/5 of the furnace instead of a total rebuild.

I will be doing a solo smelt as a practice for Arctic fire end of this week . I am going to try and run 30KG ore through the furnace rather than the normal 50kg +.

Ill allow more space under the tue cant the tue more and run a little slower.......we shall see!

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I had another go at this on friday and changed a couple of things.

After all your advice I pushed the ceramic tue further into the smelter and fed it into the furnace as the smelt progresses , the wall erosion was a lot lot less. I had cast a castable refractory tue with a conical internal shape but the castable did not cure off that well, ill save that for next time.

I also slowed the smelt down for the first couple of hours . we normally run 8 to 10 minutes between 2kg ore 2kg charcoal fills. I slowed it down to 12 minutes and whilst the furnace looked hot there was no running slag so I sped things up again and hey presto slag.

I got a good 7kg bloom (post whacking it under the hammer) from 31kg ore and 45 charcoal in total .

the smelter has stood up well and I am a fan of the exoskeleton.

with 3/4 of the furnace fully formed and dried I managed to fully dry the remainder of the furnace with 5 kg of charcoal dumped in a handful at a time over a couple of days. A fully dry furnace also comes up to heat so quickly saving time and money.

All in all a great smelt, no 20 for me (I think). the capability of running an afternoon smelt for less than £50 in materials opens up a load more opportunity to do a lot more of this this year.

 

the bloom

8730187999_30d22c63df_b.jpg

 

 

after squishing

8730188033_1abb2d95db_b.jpg

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Very cool. Diggin the Han Solo cutout in the background XD

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Very cool. Diggin the Han Solo cutout in the background XD

 

I was wondering if that was Han or Bruce Jenner...

 

 

 

Likin' the bloomeries too, Mr. Bush

Edited by Luke Shearer
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