Wurlitch - my last post on this matter.

Wurlitch - my last post on this matter.

Yes I appreciate that 1 tonne of Nb2O5 contains 0.699 tonne of Nb.
200 Mt of ore grading at 1% Nb2O5 contains 2Mt of Nb2O5, (which contains 2 x 0.699 = 1.398Mt of Nb).
You assert that after the 3 stages this produces 0.610Mt of FeNb at 66% Nb, (which contains 0.610 x 0.66 = 0.403Mt of Nb).
Therefore, you are saying that overall niobium recovery of the 3 stage process is 0.403 / 1.398 = 0.2880 (or 28.80%).
An overall recovery of 28.80% clearly doesn't make sense and even CBMM would probably go broke with that recovery (CMOC and Magris definitely would).

I don't have the patience to try and untangle your calculations - it seems you have conflated niobium recovery with what you call "concentrate recovery" and/or "conversion rate". Perhaps someone with more insight and patience can do it.