Thursday, April 10, 2008

Biting off more than you can chew?

(with a nod to Neil, who posted me privately in response to my notes on the upcoming test of the DARC Dirt 1 ore analog)

Neil Wrote:

So this upcoming smelt will have 2.5 variables?

(Are you sure you don't just want to knock off a standard econo-norse for this one and keep the focus on the ore?)

1. Smaller smelter (2/3 diameter) - this worries me the most

I'm not as concerned about that one. Especially after seeing the Aristotles Furnace in operation. We ran it maybe 20 times and got good results every time. Skip has also ran full smelts inside the same small size. We are talking 3 inch ID and about 12 inches total tall. We have run the Econo Norse successfully set with 9 bricks = 35 cm / 8 bricks = 30 cm / 7 bricks = 25 cm (the seven brick used most often). The main thing may be lowering the air flow to the required (that would be 300 - 400 LpM range) with the new blower.

So, one question will be the new or old air system! I will try to get numbers for the new blower and blast gate combination today.

2. Ore analog (the thing we are trying to test)

Still crossing fingers on getting it dry enough. Right now its sitting outside under the front awning to the shop. This gives it wind to air dry and whatever sun happens over the rest of the period. Was roughly 'leather hard' yesterday when I set it out. (I had started by putting it inside each night.) It would be usable at this point - but with extra water contained.

2.5 The thinner front plate

Not as worried about this - in terms of heat retention. The furnace always make way more than we need. This variable also follows on our smelts last fall using thin stone front plate construction. Biggest question is how well the low density brick stands up to the high temperatures. I use these in the gas forge, which does build up to just shy of welding (maybe 2200 F). Of course our internal temperatures have been pegged at as much as 2750. The experiments at Smeltfest were done using a mix of horse dung and dry clay to make similar plates. There was no problem with the plates themselves in those three smelts. Air problems - but that was the set up with the blast hole not being correct.
I ended up with a good quantity of the charcoal fines and clay mix, now in a plastic bucket ready to use. If worst comes to worse, I figure we can quickly re-enforce the area around the tuyere with this proven material.

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February 15 - May 15, 2012 : Supported by a Crafts Projects - Creation and Development Grant

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