Guyana Goldfields published its ammended FS on the Aurora project on Friday after market close. While not a comparable project (high(ish) grade Au, O/P+U/G project in Guyana) it is interesting to see how much an effect a reoptimized mine plan had on its economics.

Feb 2012 - FS
IRR (after-tax) - 13%
NPV (after-tax) - $476M
Initial (total) capex - $525M ($1.3B)

Jan 2013 - Ammended FS
IRR (after-tax) - 38%
NPV (after-tax) - $800M
Initial (total) capex - $205M ($714M)

All pricing assumptions look to be the same ($1300/oz).

Going from 13% IRR to 38% is no small feat. It looks like GUY did it by changing its U/G mining method and gradually ramping up production.

It would be nice to see CUU better describe how the economics on SC could similarily improve. Adding the inferred won't really matter unless capacity is expanded or there is higher grade mineralization near surface. And even this needs to be better described if CUU wants to get value for it.