FMG Cost Structure

Hi Guys getting me head around this stock.

According to GS:
FMG cost structure:

Cash costs are around $15/wmt.

But this is wmt, where as the price of iron ore is quoted on dmt, correct?

So FMG cost structure:
$15/wmt

This is the cash cost, then, to input total costs:
Add:
Freight US$/wmt 11.1
Royalites US$ 8.6
G&A US$/wmt 0
Sustaining capex US$/wmt 6.1
Net Interest US$/wmt 0.9

Total costs US$wmt $41.5

But then this needs to be converted to dmt and for the fact that FMG iron is lower than 62%.

So GS product discount and moisture adjustment additional costs of US $43.5

This gives a FMG break even price (62% Fe dmt) of US$84.90

Does this sound correct?

I image the two variables in this would be Royalty (if iron ore prices drop royalty drops)
and
Freight: currently global elevated freight rates has resulted in the $11/wmt cost, but if freight rates come down in the future then this number will drop.