Ann: West Arunta Project - Luni Assay Results, page-233

@Clairvoyant239

Your question can be answered here (keep in mind the 2015 date): https://www.sciencedirect.com/science/article/abs/pii/S0301751615000101

Key extract

At present, nearly 99% of the world's niobium concentrate is produced by the Catalão (CMOC) and Araxá (CBMM) mines in Brazil and the Niobec mine (St. Honoré) in Canada. In total, Araxá produces approximately 150,000 tonnes of niobium per annum (tpa), while Niobec and Catalão produce 5300 tpa and 4500 tpa, respectively. Niobium recovery at all three operations is near or above 60%, with final concentrates grading 55–65% Nb2O5.

If we want to be taken seriously we need to be at least on par with them. In this presentation here, Paul discusses the preliminary metallurgy at the 11min mark. The slides say 70-74%. Now if that eventuates then we will be the ones naming the takeover price.