Ann: FYI HPA Pilot Plant Trial Delivers, page-112

Anther poster on KKK, seems very knowlegable on chemistry/geology.
https://hotcopper.com.au/posts/48064630/single
see below..

"I should also add, that A4N is proposing to buy aluminium sulfate, and use a SXEW back end, and their cost of production of 4N/5N/~6N HPA is coming out within par of FYI's route where the aluminium in the kaolin is dug up for basically free. So what's KRR's entirely rock-independent route going to come out at? It's not necessarily going to come out much cheaper than a high-grade kaolin clay deposit (28-32% Al2O3) if you buy alum salt 99% purity, off Orica or others, for $300-1200/t at a contained 8% to 15% Al2O3 grade (depending on hydroxide content of course)."