Greendig, the answer is something you and I will never work...

Greendig,
the answer is something you and I will never work out.Too many variables.

For example if ARI ups pit mined ore production from MBR to 11Mt from the targeted 10mt,then fixed infrastructure costs likely fall 10% per ton and incremental costs will rise by 10% or less.
Its not as if the train wagons,track or train unloading facilities are going to cost that much more if made greater use of.
Just as the SI ore was factored in as viable by blending with ore that would have needed upgrading expensively through plants that didn't exist at the time.

At the moment ARI appears to be chasing the same tons with less mobile plant and infrastructure(including shutting down the 40+ year outer port loading facility) to bring costs down.
The next alternative they have is to UP tons beyond the 9-10MT they have planned for MBR at the cost of resources ahead and possibly pushing the magnetite stream harder adding to tons for export and blending up of lower grade ore.

OR ARI could start selling pellets and use lump in its blast furnace once again and collect the bigger premium on the pellets at the cost of Raw steel tons as ARC furnace steel is now cheaper than new steel.

The one problem I see is ARI mines complicated ores and its a bit of this and that,so it needs to process it all once dug for maximum yield of IO,using its benefeciation plants to lower costs.
That may not be viable,so increased costs may fall on the steel stream in years ahead.

There is no simple answer.e.g.If AGO goes that does not necessarily mean its loading facilities won't be loading out ore for one of the survivors at 15mt.

China may very well decide mining ores at grades as low as 22%FE is not economic and for a country that increasingly views IO as a strategic material that it is actually short of,may decide to leave it where it is as the US and other countries have done with oil and buy it elsewhere while its cheap.

Your guess is as good as mine.

Obviously the big players have laid big bets on the one usual logical market outcome (if your not Chinese) that hasn't occurred yet.i.e 4-500mt of expensive Chinese ore leaving the market at sub $50US a ton,most of which is in the $US80 a ton plus bracket.
Some has gone,but how much and the rest when?
The pressure is on the Chinese steel producers who have used imported ore to subsidise local purchases for years,but are now in mass losing big money.

DYOR + DYODD