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ironmaking: an unqualified success - Doug Ayen's Blacksmithing Blog [entries|archive|friends|userinfo]
Doug Ayen

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ironmaking: an unqualified success [May. 18th, 2003|03:14 pm]
Doug Ayen
It worked! I'm now the proud owner of a 3lb chunk of home made ironl!

A couple of friends helped with getting the charges made up -- thank you Carl and Deb.

Pictures were taken, soon to be up on a website somewhere. Really!

To start the day off, I assembled the bloomery, gasketing the buckets together using red clay as a sealant. This sorta worked, but around the tuyre the seal failed later -- more on that in a bit. The first load of charcoal was put in and an hour was spent preheating the furnace. While this was burning, we made up a bunch of charges of ore and charcoal -- each charge was 500g of charcoal and 200g of ore -- the ore I have is in the form of magentite sand.

Once the hour was up, we started adding the charges. The book I was following said to use a 550 - 700 watt vacuum cleaner as a blower, so I tried a 500 watt blower. Using the blower recommended in the book, (The Master and Uses of Fire) supposedly it should take between 5 and 7 minutes for each charge to burn down. Using the blower I had, we were burning down charges every two minutes or less, so I restricted flow as far as I could, and was able to get the charge rate down to about once every five minutes. I think next time I'll use a weaker blower.

After that, it was just a matter of watching the fire, making sure the tuyre was clear and adding charges as the fuel burnt down. We ran the smelting for about two hours, using about 20 charges. During the burn, in one spot the fire found a way through the clay layer, and burt a big hole in the middle of the bloomery. Fortunately, I keep a bucket of furnace cement around for just such an emergency, and so was able to keep the burn going despite the damage. Once the last charge was in, we let the fuel burn until it was down to around the middle of the furnace.

Now that the burn was done, I turned a hose onto the works. An immense cloud of steam was generated by the water, and it took a long time before things cooled down enough so we could see what we had.

What we had was a big lump of slag and, yes, IRON! We were anxious at first because the iron was surrounded by a huge amount of slag, and it wasn't clear until we knocked off a good amount of the slag that there was any iron in there, but sure enough there was a core of solid iron. Really crappy iron, with inclusions of slag and unburnt charcoal and probably some unconverted ore in the bargain, but this is indeed a small bloom, about 3lbs, ready to be made into wrought iron and then into whatever else. This one, my first, will be saved as is for demonstrations and to show that I did, indeed, make iron, but future blooms will be made for some really period medieval blacksmithing.

The bloomery will first have to be rebuilt, however. The bottom section needs to be relined, and I think I'll both move the tuyre down a few inches and add a second one, so there's opposing air flow -- the bloom was attache to the refractory near the nozzle, and I'd liketo avoid that. Also, the nozzle was of black iron pipe this time, and it just melted in the heat. I'm going to try a ceramic or refractory nozzle next time and see if that does a better job of getting the bloom in the middle of the furnace. The middle section was burnt through, the refractory melted and the iron shell burnt away for several inches, so that 's going to have to be replaced. The top section was undamaged.

Overall, a fun day. Playing with fire, recreateing an old process for making iron, and succeeding at something like this make for a very satisfying experience.

--doug
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