Dave,
Yes, we have been to the Puits Ricard museum site. Sadly the underground museum, Mine Temoin, is closed all this year, don't know why, looks a bit like it went bust to me.
Andrew,
In my experience, the French local authorities may like the history on the surface but they are terrified of old mines when it comes to actually entering them. Caving seems fine but mine exploration is something else, best done quietly......
Many of the best Pyrenees mines have been blown in to stop access.
Les