Overall recovery to produce FeNb from ore, is the product of the...

Overall recovery to produce FeNb from ore, is the product of the individual recoveries from the typically 3 stage process:
1. Flotation Concentration
2. Leaching (CMOC and Magris Niobec) or sintering/dephosphorisation (CBMM)
3. Aluminothermic reduction
Call the recoveries R1 R2 and R3. The overall recovery OR = R1 x R2 x R3.
R1 is usually less than, and potentially much more variable than, R2 and R3 and that is why WA1 have focused on R1 at this stage and that's why they state "Overall niobium recoveries.....are generally regarded as secondary to the optimisation of a commercially viable, low cost, concentration regime. "
For example, an extract from a technical report related to CMOC's purchase of Boa Vista from Anglo American gave the following expected figures;
R1 (fresh rock plant) = 56%
R2 = 96.5%
R3 = 92.5%
giving an OR of 0.56 x 0.965 x 0.925 = 0.500 or 50%. R1 is a lot less than R2 and R3.
Another example. This diagram relates to the CBMM operation (carbothermic reduction = sintering/dephosphorisation):



and using the data in the diagram you can calculate
R1 = 74.5%
R2 = 80.7%
R3 = 96.7%
giving OR = 58.1% (Argonaut used an OR of 58% in their Jun 2023 research note on WA1).