Although you may have opened the mine and hired the miners to work in the mine, the ore you dug up did not belong to you in the medieval period. The ore belonged to the lord of the land in some places and to the king in other places like France and England. Because of this, they would had the ability to take a percentage of the best ore, were paid royalties on the ore, and were paid for the use of the land.
A few problems that came about from mining were that as they dug deeper, they increased the chance of flooding the tunnels with ground water. A few ways they did this was to dig trenches to drain the water into lower areas, or to have people filling buckets with water and taking them to the surface.
The theme of this paper was how technology increased the depths of mines and what could be mined. Better furnaces could smelt harder metals, and waterwheels could help crush rocks using the force of water.
http://www.wrexham.gov.uk/english/heritage/minera_lead_mines/miners_medieval.htm
This link talks about the lives of miners at the Minera Lead Mine In England and gives a good view on what the miners did and went through.
http://medieval-europe-paris-2007.univ-paris1.fr/U.Meyerdirks.pdf
This link is a doctoral thesis on mining in the Black Forest of Germany and is a good look at mining in Germany and the effects on communities.
Daniel Cissel (233)