andyh22, I too would be very interested to hear of mines in Sudbury (or Timmins) that pump concentrate, or for that matter, that crush to -1/2" (cone crushers??) underground. I must have missed something on my visits of these mines.
Kivi, are the Cameco operations that I cited along the lines of what you are looking for? I was also involved in some preliminary investigations into this subject for a Placer Dome property in Nevada a few years ago (it didn't go ahead).
I think it has always been the miner's dream to do the milling underground. It cuts down on ore transportation and handling costs, and reduces surface infrastructure. However, to my knowledge, it has not proven economical for base metal mines.
Cheers,
CanuckMiner