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Intranetusa t1_j1kbsrt wrote

>. By the 1st-2nd century CE, the Roman Empire were producing an estimated 50,000 tonnes of iron a year

I've read that the estimates of those Roman iron production figures aren't really reliable. This is because those numbers are based on estimates of per capita production from a single Roman province (Roman Britain) that incidentally was a high iron production region, had a lot of iron ore, and had a relatively large military garrison. And that estimate of a disproportionately high iron rich & producing region was then extrapolated to the rest of the empire based the Empire's population.

Edit: You are correct. The unreliable Romano-Britain iron production extrapolation estimates are the estimates for 80k tons, and not estimates for up to 50k tons.


War_Hymn t1_j1mcv5m wrote

The estimates you're referring to I believe go up to 80,000 tonnes.

It's hard to extrapolate the exact number since a lot iron production in the Empire at the time were done by small-scale private operations that was spread all over. I think 50,000 tonnes is probably close to what was actually produced for an economically strong state like the RE with a population of 50 million. We know Roman iron smelters were especially good at their craft, running bloomery furnaces that had nominal yields of 20 kg of processed bar iron per furnace run at the upper end.

Assuming 8 men worth of labour needed for smelting/processing 15 kg of bar iron per furnace run, 100 furnace runs per year with spare days in between for processing the bloom, repairing furnaces, restocking, and rest - to produce 50,000 tonnes of iron a year will require an estimated manpower of ~270,000 men. Which will account for ~0.54 percent of a population of 50 million (or 1 worker per 185 people). A bit high but not an impractical ratio given how important of a commodity iron was. At 30,000 tonnes of iron per year, that ratio goes down to 0.32%, or 1 worker per 312 people. My guess is the actual production at peak was 20,000-50,000 tonnes per annum.


Intranetusa t1_j1n3i7r wrote

Ah, you are correct. The unreliable Romano-Britain iron production extrapolation estimates are indeed 80k tons, and not 50k tons. Yeh, your explanation of a range of 20k-50k iron production makes sense and that range seems more reasonable.