Regards PGE recoveries while we're still on that market, these are my thoughts on met recovery implications at Dante Reefs.
In detail across the HG magnetitie reef likely to represent the most economic ore lode, peak Cu concentration are offset from the highest PGE conc (common in many layered intrusion reefs apparently). This is almost certainly due to PGE reporting primarily to different sulphides/minerals than Cu (ie ratio is not proportional) and these minerals concentrating at slightly different layers in the main basal reef. Implications are that PGE will probably report to different mineral con than Cu, so probably no PGE credits in a clean Cu-con.
Also from the same paper by Karykowski et al, 2016 below, is a description of the minerals hosting PGE within the basal Ti-Mag reef. To be fair, these rock chips are oxidised, so whatever sulphides they were in a replaced with very, very fine Pt-Fe alloys and Pd-rich phases that are difficult to impossible to recovery to any payable con. This is also not particularly unusual in oxidised ore, more work required to establish where the PGE is held in fresh rock and what the mineral size/dist'n is to see what recoveries might look like... Does mean that the top 20-30m above fresh ore would not carry any PGE revenue, and maybe reduced copper recoveries given different Cu minerals to the fresh rock sulphides any p lant would be designed for.
"Platinum-group minerals (PGM) in surface samples from thebasal magnetite layer were previously studied by Goemann(2012). The author identified 14 grains mainly representingtwo groups of PGM: (1) a Pt-Fe alloy and (2) a Pd-rich phasewith varying proportions of Pt, Pb, Cu and Sn. These mineralsare typically associated with fractures in Fe-Ti oxides and alteredsilicates. Some lath-shaped PGM reach up to 30 μm in length,whereas most grains are anhedral and smaller than 5 μm."Nickel is so low grade as to be unrecoverable to a payable con that covers extra plant opex, or simply low payability as a minor part of the Cu con? The nickel sulphide pentlandite has been identified in thin section, so there would be some chance of biproduct credits in a rougher con maybe. Ni not material to Dante Reefs in any case. I think the same can be confidently said for Ag and Co...
It's looking more and more like a Vanadium play, with Cu-PGE+Au credits to try and make bank imo. 0.3% Cu even with good recoveries (which I expect) and low biproduct credits for the PGE-Au is simply very low grade unless processed in extremely high tonnes... and cheaply. Nebo-Babel is running with a 13.5Mta plant on 0.36% Cu and 0.34% Ni LOM ore feed, which is approx 0.9% Cu equiv excluding minor PGE++ credits for similar reason of recovery dropping with grade and/or oxidation state. Below is Oz Minerals 2020 DFS Update met table... note that recovery falls with grade (Dante basal reef doesn;t even average 0.15% Ni from results to date), and the oxidised PV (pyrite-violarite) ore has lower recoveries, especially for Ni. Further, PV ore "poisons the fresh ore recovery, and so has to be batch treated separately every 10 weeks"...
The biggest risk for recoveries/payability/revenue for Dante Reefs imo is the very low Ni content (because the nickel all crystalised into olivine/pyroxene leaving the residual magnetite reef to crystalise from very Ni-poor magma). As per Nebo-Babel DFS, they produce a clean Cu-con with only Au-Ag credits because the PGE's report to the Ni-concentrate. That is good for Cu-payability (refiners don't want Ni contam'n in their Cu-con) but with very low Ni content leaves open the possibility of no/low economic Ni-con and thus no/low PGE credits in the Ni-con where PGEs typically report?
Of course, discovering a step up in PGE and/or Ni grades in the reefs would change the situation... but until that happens you have to love the one you're with. That means the V-Ti in has to seriously stand up or what has dante got at 0.3% Cu below 25m depth, in 3.5m true thickness reefs?
(20min delay)