Iron, these cross sections are from their April 15 announcement,...

Iron, these cross sections are from their April 15 announcement, and the faint blue pit shell demonstrates their 10 year surface mining plan. The average strip ratio for this blue pit shell, if I recall correctly from a previous news piece, is 2.6:1. I've then done some back of the envelope calculations on these cross sections to determine where the marginal strip ratio would reach 4:1. In my experience, open pit shells in Australia generally get pretty close to their marginal economic limit at 2.5 times the CuEq grade, (i.e SR of 4 in CDU's case). This is being reasonably generous and assuming that a 1.5% CuEq grade continues into the blue circled parts. This pushback (shown with the blue dotted line) is where the marginal open pit mining takes place, which I alluded to as a transition stage. The remaining ore, shown in green, is outside the economics of open pit mining and would need to be accessed with UG methods. The drawings are pretty basic, but I've kept it that way for the sake of not littering my explanation with jargon.



Cannington is one of the largest underground base metals mines in Australia, and is just up the road from Rocklands. It pushes out 3MTpa of ore from numerous orebodies within many levels across multiple declines. Dugald River is also within the region, and they will be hard pressed to reach 2MTpa of output. Eloise currently produces ore at 0.6MTpa. If CDU can get even close to 2MTpa of output they'll be doing very well, even if they bring in the best contractors in the business.

Hope that helps.