"Following low-cost extraction and beneficiation and increase in...

"Following low-cost extraction and beneficiation and increase in grade"... You quite missed the point, which is ARR are comparing HCk post-concentration beneficiation grades (4% TREO up from 4000ppm) with hard rock insitu pre-concentration grades, ICD in-situ grades (picked the lowest grade ICD example I've ever seen btw). Not even apples v oranges, it's complete deception... either you compare deposits head grades (ie 4000ppm vs 60,000ppm HCk vs MP) or compare the beneficiated concentrate (4% vs 60%) which then feeds the leach tanks.

"I think any mining engineer would prefer to work with standard air pressure leach than cracking minerals with a 600 degree pressure cooker"... you have been reading too much ARR sales material. Monazite and bastnasite (MP's deposit dominant mineral) are acid bake/cracked at atmospheric pressure, albeit high temperature and acid concentrations. HPAL (high pressure acid leach) for minerals like nickel is another game and rightly presents more difficult conditions and risks. HPAL can be done for REE I'm sure, but don;t think it has ever been adopted?


" Your doubt about WHIMPS is not too worrying because density separation is the more important method that ARR has reported it will be using to concentrate the rare earths"... from their met release flowsheet, WHIMS rejects 23 out of 28 feed units, or approx 80% of the feed prior to final con (rounding errors in maths I assume). The whole premise of HCk being economic is minimising the weight pull to the leach tanks on account there onwards is where most of the cost sits. They will look at finer grinds to maximise RE recovery while minimising weight pull to con and grinding costs etc to get there... but every incremental downgrade of performance assumption is leveraged into a large change in opex given the large tonnage leached compared to peer hard rock deposits with 30,40, 60% TREO in the leach feed. I have never heard of a hard rock RE con being lower than 30% that even pretends to be economic...

In case my main point has been lost, in short it's that there are already some very major discrepancies between SS assumptions and test results, any of which may tip it over into uneconomic. They haven't looked at Al removal yet, which can be very tricky, or done any RE-Ox separation test work. It's very early in the piece, yet I can see a lot of room for disappointment in what is novel and interesting idea of making a very low grade hard rock deposit work. Time will tell, I'm just highlighting some risks and misdirection.

GLTAH