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New lining for the iron furnace

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tom osselton:
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. I’m going to have to build a oil burner I’m still using propane.

vtsteam:
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.

vtsteam:
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?

ironman:
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.

vtsteam:
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.

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