Not defending AR3 in any way, but to be fair HRE's met result...

Not defending AR3 in any way, but to be fair HRE's met result averages only included the "best" results and excluded the poor ones. Even though the poor samples and best samples were drill holes next to each other. When this thing is mined, there will undoubtably be a mixture of poor/good sample feeding the plant as the met response has little consistency between neighbouring met holes, so grade control will be difficult or impossible in practice.

So, if you take the complete average of all met holes drilled (all holes being an even spread across their MRE envelope), you get 40.3 kg/t HCl consumption per tonne fines, or 15.0 kg/t HCl consumption per tonne feed ore, for 55.8% average MREE recovery within the MRE. Now HCl costs around 2.6x per molar unit of H+ compared to sulphuric acid, so to fairly compare between HCl and AR3's (and IXR, MEI) results on an opex basis you would need to multiple the acid consumption by 2.6 = 40 kg/t H2SO4 consumption equivalent. Now AR3 hasn't shared their number (wonder why?) so the question is AR3 higher or lower than 40 kg/t. But delving into these details helps to explain why Mcaps of these REE clay explorers can seem out of whack when just looking at resource size and grade. For example IXR has reported average acid consumption rate of 14 kg/t, so starts to explain why their market cap is so much larger than many others.