For convenience, all my metal equivalent values are reported...

For convenience, all my metal equivalent values are reported gross. However, revenues from my model have always been reported as NSR.

My NSR per tonne estimates are roughly 60-65% of GMV. Please see my math below.




I assume 51% Zn con. Therefore, we can calculate gross value @ US$1/lb Zn:

51% * 2204.62 lbs/t * US$1/lb Zn = US$1124.36/t of Zn Con

Then take 8% unit deduction (8% 0f 51% Zn) at smelter leaving 43% Zn:

51% Zn - 8% Zn unit deduction = 43% Zn

Said differently, 84.3% of the Zn in concentrate is "payable":

43% Zn / 51% Zn = 84.3% of Zn payable

Revenue per tonne of Zn con after unit deduction:

84.3% payable * US$1124.36/t = US$947.83/t

Then subtract US$140/t treatment charge to get NSR/t Zn Con:

US$947.83 - US$140/t = US$807.83/t Zn Con



If head grade is 10% Zn, it would take 5.67 tonnes of feed to concentrate Zn to 51%:

51%/(10% Zn * 90% recovery) = 5.67 tonnes mined per tonne of Zn con

Therefore, Zinc NSR per mined tonne is US$142.47:

US$807.83 ÷ 5.67 tonnes = US$142.47/t mined

This is roughly 65% of GMV of 10% Zn @ US$1/lb which is US$220.46/t



I do not include transport/haulage costs or account for any penalties. Another reason my my NSR values seem high (as a % of GMV) is treatment charges, which has come down to around $140/t compared to $200/t+ a few years ago. Still, I would consider my revenue models very conservative as I do not include potential revenues from barite; assume site costs on the high end for UG mining, and (as you've complained many times) conservative Au recovery assumptions.