Author Topic: New lining for the iron furnace  (Read 2783 times)

Offline tom osselton

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Re: New lining for the iron furnace
« Reply #50 on: February 16, 2022, 05:32:09 PM »
I had some pieces that had to be anchored on mine as well I used nicrome wire as pins or bent as staples and found no problems after that. Iím going to have to build a oil burner Iím still using propane.

Offline vtsteam

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Re: New lining for the iron furnace
« Reply #51 on: February 16, 2022, 08:05:32 PM »
Tom I can heartily recommend the Kwiky burner. I like it because it doesn't require furnace pre-heating with propane. Instead, it  produces a very fine atomized oil mist that I believe results in a more efficient flame with better mixing than other burners I've seen. There's no welding, it's physically compact compared to most other burners and uses off-the-shelf quite small plumbing fittings.

http://metalshop.homestead.com/How-to-Build-The-Kwiky-all-Fuel-Foundry-Burner.html

The results I'm getting show how well it works.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: New lining for the iron furnace
« Reply #52 on: March 02, 2022, 10:03:37 PM »
Well I've had several very successful Iron pours (detailed elsewhere) The lid has been a little problematic as the blanket insulation has shrunk and detached from the steel shell in several places. I've had to add sheet metal screws through the rim into the insulation all around, and done several patches of the hot face compound in damaged areas. That gets expensive. Damage was caused by the insulation dropping a half inch and scraping across the top of the furnace when the lid was rotated out of the way.

I think I've got it mechanically fastened today so it won't drop more, and also I've increased the lift mechanism's throw.

The only other problem was the burner attachment and support, since the blanket provides none. Today I fabricated a heavy metal bracket the is welded to the outside of the furnace on a removable plate. The burner sits on top of that and is fastened to it with two SS hose clamps. That makes it removable but very firmly fixed. where it penetrates the furnace, 2" of ganister surrounds it in a plug, rather than the blanket. That seems to have solved any leakage and support problems.

I'm looking forward to my next melt - possibly tomorrow. I need a third cylinder casting, and I'd also like to try to do better with the Westinghouse twin. Mainly in making a core for it (somewhat complicated in shape), and in using facing sand and disk brake rotor metal (per Ironman) and 0.25% ferrosilicon.

One question I have is that I've reported quite a lot higher metal loss than Ironman. I'm wondering whether that's in slagging, and/or oxidation? Spills are understandable losses, but I'm wondering whether I'm running too hot too fast with diesel fuel?
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline ironman

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Re: New lining for the iron furnace
« Reply #53 on: March 03, 2022, 07:59:28 PM »
The zircon paint I used on the furnace is no longer made but I still have plenty for my needs. A lot metal casters on youtube use satanite and it seems to work quite well for coating ceramic fiber used for iron melting.

Offline vtsteam

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Re: New lining for the iron furnace
« Reply #54 on: March 05, 2022, 04:17:06 PM »
Thanks Ironman, I'll look into Satanite.

After yesterday's pour the furnace showed some serious damage to the lining, which up til now had done quite well. I'm not sure of the cause but most of the damage occurred where the flame from the burner impinged on the wall near the bottom of the furnace. There was definitely melt-back. I believe the cause was either too much heat or possibly an oxidizing flame that I didn't notice -- I do tend to run slightly rich by preference. The only difference between this melt and all prior ones was that I used an off-road diesel fuel instead of regular auto diesel.

The off road diesel seemed slightly thicker, and startup with it was a little less easy in this cold weather. It didn't seem to atomize as well early on. I'm thinking it's denser with possibly higher energy content. I might have to cut back on the burner in future.

To repair the sunken and damaged spots near the bottom, I decided to use ganister. There really seems no way to easily repair ceramic blanket with more blanket. I find that blanket joints tend to become a focus location for overheating.

In any attempted repair with more blkanket, the new blanket patch seems to shrink after  re-heating, leaving a bigger crack at the joint. That exposes more raw blanket to the heat, unprotected by hotface compound . You can't just solve those new cracks with hotface compound, because it is so thin-- basically a paint coat, and it's impossible to get it into joints. The hotface compound is also very expensive -- at about $50-60 a pint.

So I am patching with ganister (fireclay and coarse silica sand and/or ceramic grog). That does a good job of filling the  sunken blanket damaged area, and bakes to a hard exterior, easily paintable by the hotface compound. Since there still is a fair amount of insulating blanket behind the ganister patch, I don;t think the melting rate of the furnace is affected at all and it is MUCH tougher than the blanket and hotface. This is particularly important near the bottom of the furnace where the burner flame is playing directly on the wall.

I think that for non-iron furnaces, with lesser burners, these problems probably don't occur, but in my case witha possibly hotter fuel than I was using before, and very efficient burner I think we're at the limit of how intense a flame the blanket and hotface can absorb -- in that particular area.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline ironman

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Re: New lining for the iron furnace
« Reply #55 on: March 07, 2022, 07:39:45 PM »
Have a look at chirpys tinkerings channel on youtube , he copied my furnace from the video showing how it was built. Because he could not get the zircon paint he used satanite instead. He has a video making a furnace using ceramic fiber and coating it with satanite. I have never used satanite but it seems to be a good substitute for the zircon paint I use.
« Last Edit: March 10, 2022, 09:43:34 PM by vtsteam »

Offline vtsteam

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Re: New lining for the iron furnace
« Reply #56 on: March 10, 2022, 09:44:34 PM »
I've received some Satanite, and will be trying it out.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: New lining for the iron furnace
« Reply #57 on: May 07, 2022, 03:24:58 PM »
An update on my furnace:

I received the Satanite, and it's a good and inexpensive fireclay based coating. It is high in strength and you can put it on thicker than ITC100 (which requires thinning with 50% water). However, it isn't a highly reflective coating, like the ITC100. Best practice would be to put on the Satanite first to a reasonable thickness to protect the blanket, fire it to harden, and then paint on a light coat of ITC100 over that for the benefits of a reflective coating.

On my furnace, the lid insulation has been a continuing problem, despite mechanical fastening. The cause was in trying to piece the blanket on in layers horizontally.  Ironman in the propane furnace construction video below shows doing the lid in many vertical profile pieces, which are adhered to the lid with sodium silicate.

In my experience, horizontal blanket layers cannot be cemented together successfully with sodium silicate. In using sodium silicate, the blanket-to-steel bond is good, but the blanket-to-blanket bond is poor. the adhesive is absorbed by the blanket and yields a dry joint.

When I first built mine, I pieced the blanket in horizontal layers because I only had remnants of 2" thick blanket to work with, (not 1" thick, as Ironman used in the propane furnace lid). The remnants were irregular in shape, and weren't large enough to cut out the numerous vertical sections required for vertical piecing. I did split the pieces into 1" thicknesses, in order to create two layers, which would allow staggered joints.

However after half a dozen melts, my lid insulation was continuing to loosen and drag across the top of the furnace when opened. Pieces would flake off -- and the lid required continued patching with expensive compound. An attempt at reinforcing with metal fasteners horizontally through the rim of the lid also did not completely solve the problem. Where there were vertical joints in the lower layer of blanket, cracks widened and blanket shrank away from the joint because hotface compound couldn't reach very deep into the cracks to protect it. Large sections of blanket would loosen and sag.

Finally, yesterday, I removed all of the insulation from the lid. I now have sufficient 1" thick blanket to do the vertical layer type blanket insulaation. I've ordered some more sodium silicate, and hope the lid built this way will last better

Ironman's propane furnace build:

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

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Re: New lining for the iron furnace
« Reply #58 on: May 21, 2022, 10:19:49 PM »
Today after some delay I attacked the lid. Well I guess attack isn't the word -- I trashed it and started again.

New (scrap) metal welded together. new insulation blanket installed. The philosophy this time WAS to do only vertical piecing. Horizontal layers don't work, because there is no reliable way to laminate layers together. Vertical piecing means that every individula section of blanket is in contact with the top of the lid and is cemented there with a generous amount of sodium silicate.

I started out trying to do the vertical half-width slice-of-pie method, as shown in the above video, but pretty quickly that showed it wouldn't work. My furnace lid is about 17" in diameter, while the oil can in the video is about 12" Maybe you can cram the inner ends together in a 12" circle, while the outer ends expand enough to fill the spaces, but not on a wider lid.

So I ended up doing a sort of roll-up method, with strips and pieces attached concentrically, except at the center. The final 3" around the exhaust hole was done in the pie wedge method -- and it made sense there -- especially because I wanted to have a leg of each piece extend up through the hole -- similar to the way Iron Man did it in the video above.

Here is the new lid packed with insulation:

I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg