Archaeology, Archaeology Research

Iron ore reduction in a bloomery furnace – part 3

Well it looks like I’ve wrapped up the first draft of my iron smelting chemistry and processes piece and sent it off to my supervisors. It’s not the literature review they hoped for, but I figure this way I won’t have to explain anything when I talk about why this paper is ground-breaking or that paper is facile. I also didn’t want to assume my secondary supervisor, who isn’t a technologist, knew much about iron smelting.

During the writing process I went looking for a schematic diagram of a bloomery furnace, just for illustration, but for some reason I couldn’t find one – not even using Google image search. As a result I knocked one up on Word and thought I’d post it here in case anyone needs one. It’s not particularly artistic or complex, but it is handy.

Simple schematic diagram of Romano-British slag-tapping bloomery furnace

In addition I also wrote up a quick simple flow chart for Romano-British iron smelting. Again it’s not complicated, but I like the way that ‘observation’ sits at the centre of the smelting operation. By this I mean observation of the level of the charge as it sat in the furnace chimney, observation of any fire or smoke at the top of the furnace, and observation of the slag levels, either through listeing to the furnace (slag covering the tuyure gives rise to a ‘booming’ sound during the smelt) or through opening a slag-tapping hole.

Basic flowchart of Romano-British slag-tapping iron smelting

The flow chart is meant to be a simple introduction – as I said before I’ve tried to make a more complex one containing everything, but it’s just so tricky! The actual chemistry of reducing iron ore to iron is really simple, but the practicalities of the process are much more complex.

For earlier posts, see:

Iron ore reduction in a bloomery furnace – part 2
Iron ore reduction in a bloomery furnace – part 1

2 thoughts on “Iron ore reduction in a bloomery furnace – part 3”

  1. You’re ability to “knock up” diagrams and charts will never cease to amaze me. Keep up the good work!

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