I tried to find sources for this for a few days now. Looked at the sources of that German fellow, that wrote about mining in medieval times and tried to find contemporary mines, that could technologically be compared to a pre-dynamite era like the Pontosi mine in Bolivia. None of these sources ever talked about actual iron yield, that was produced. I am interested, because I try to simulate a medieval economy and am stuck with estimating iron production in relation to workforce. Maybe someone has knowledge of a good source for this.
From my answers to https://www.reddit.com/r/AskHistorians/comments/8y6u5g/how_iron_mining_differed_from_bog_iron_harvesting/ and https://www.reddit.com/r/AskHistorians/comments/941eyp/what_was_the_productivity_of_forging/ in summary:
Medieval English mining appears to have averaged about 15-20kg of ore extracted per working day per miner.
Where available, bog iron and iron sand can provide ore more quickly, 10kg per hour per worker for bog iron where plentiful, and 50kg of iron sand per day per worker.
If using iron sand, the labour required to produce the charcoal required for smelting is approximately that needed to collect the ore. This ratio will be similar for bog iron. For underground mining, with higher labour costs, the labour required to produce the charcoal will be about half that of the mining.
Smelting the ore will require a similar amount of labour to the charcoal-making, and if using a bloomery furnace, the labour required to convert the bloom into consolidated billets is again similar to the charcoal-making labour.