This may be slightly OT, but I found Liberty Mines site (Agoracom) very interesting. They are an Ontario Nickel producer, just starting production. Somewhat further down the road  than NOT, but reading about their deposits, grades, economics and so on gave me a new perspective and understanding of the D.E./McFaulds story. They have several comparatively small orebodies (pods?) several kilometers apart, and are developing a mine on each, with one central processing plant/mill.

  Going by their example, high tonnage in any one spot is not essential to development of an economic project, though obviously the higher the grade of ore the better the returns etc. Actual figures make interesting reading. They have consolidated several small deposits to make an economic area into a single producer, with varying grades and mining strategies.