The costs to provide structure, equipment and labour to develop a mine have changed dramatically since 2013.  Copper prices haven't.

We used to talk about $3.25 copper in 2011. Price in developing a mine now when all your equipment costs are in US dollars but copper hasn't gone up since then.

Copper is curently $2.6649 US at this moment. Not $3.25 and development costs are not even  close to the same as in 2013.