back of the envelope musings

With Grange resources last week securing a 69% increase in its pellet price to US$126/T, I started to look at the margins put forward by GBG in the March presentation.
http://www.wabusinessnews.com.au/en-story/1/79711/Grange-secures-69-iron-price-hike
Although there are some assumptions that have to be made here as the GBG deal is indexed to CVRD's benchmark pellet price, you would have to think that Vale will achieve somehting similar.
From the march GBG presentation;

opex - A$46/T
cash margin - $498 / $51/t (based on Hammersley fines of $97/T)

I've had a bit of a look at what Vale are currently selling pellets for...but no luck.
Again this is assumption based if Vale achieve a similar price for their pellets the figure in the march presentation would be greatly exceeded;

8Mtpa @$126/t
cash margin -$640M / $80/t.
Annual revenue - 1008M
GBG share 50% - $320M or 45.2c/share EBITDA

Happy for correction on any sloppy calcs or anything I overlooked.