xstrata to close mt isa smelter, page-14

Leroy23,

CDU will have to use some form of heap leach operation to recover the oxide component of the Rocklands mineralisation. This will produce either copper cathode (no need to smelt), copper cement (carbonate; smelted elsewhere) and in the case of native copper....copper (no need to smelt).

The supergene/hypogene mineralisation will produce chalcocite potentially - this is not able to be smelted by Mt Isa anyway, so that would head off to a third party smelter.

Then, finally, they'll dig down to the fresh chalopyrite mineralisation (couple of years, say c. 2014) and put in a concentrator and produce chalco cons. By now, XST has closed their smelter, and CDU will be exporting to Towny.

The viability of leaching? At the Rocklands bulk grade as per existing JORC, yes its viable. Oxide copper operations would get costs of US$80-160/lb via heap leach. It will be interesting to see how much of Rocklands CDU intends to treat via heap leach.