was the announcment deserving of a 2 day tradi, page-27

tccham,

In every tonne of FMSs high grade ore you have
583kg Fe
69kg Al2O3
38kg SiO2
0.8kg P
57kg water
Total 748kg (and, lets say 252kg oxygen to go with the Fe: there's also Ca, Mg, Mn etc which will likely sit still during calcination)

If you calcine it, you burn off 57kg of water. Which means, in 943kg of calcined ore you have;
583kg Fe = 60.54% Fe
69kg Al2O3 = 7.3% Al2O3
38kg SiO2 = 4.02% SiO2
0.8kg P = 1% P
Remainder is oxygen locked up in the hematite.

So. Lets say your silica is as sand, and you can wash out 50% of it; and aluminium is as clay and you can wash out 50% of it. You'll be left with:
583kg Fe
35kg Al2O3
19kg SiO2
0.8kg P
252kg oxygen in the hematite for a total of 891kg of ore.

The final washed, calcined grade will now be:
583kg Fe = 65.4%
35kg Al2O3 = 3.92%
19kg SiO2 = 2.13%
0.8kg P = 1.1%

This would be quite saleable. But its not DSO. I can't say what it would cost to build a wash plant and what it would cost to run it, but this is all just added cost front-loaded on to the mining cash costs - they'd still get paid, effectively, for their 58.3% Fe at the going rate, regardless of the jiggery-pokery needed to make it palatable for market.

The lower grade stuff, if you start with 55.4% Fe, 9.8% SiO2, 4.6% Al and 5.7% water, can be calcined and washed (50% less deleterious elements) to get a product with 63.89% Fe, 5.19% SiO2, 2.6% Al and 11% Phos.

Likely blend feed.

So, thats the proper way to calculate the calcined grade. Note the differences with bungy's 57.8% Fe calcined grade which didn't mass balance properly.