It seems to be 60km, or at least this is what Jack Lifton "was told". If you go to the comments section of his article, Jack Lifton touches on the point of proximity of the two mines, in the idea that that part of the country is loaded with REE:

http://seekingalpha.com/instablog/65370-jack-lifton/1255621-molycorp-mired-in-the-mud-perhaps-a-domestic-american-total-rare-earth-supply-chain-should-be-a-collaborative-project?source=kizur