US patent granted - "Lithium recovery from phosphate minerals", page-14

In a nutshell, the patent and flow-sheet looks like L-Max. We already know that the process is amenable to Lithium micas (ie, lepidolite, Zinnwaldite etc), and we know it is amenable to lithium phosphates.

In the last quarterly, you see;
"Preliminary results are encouraging with this being the 19th lithium mica/lithium phosphate deposit successfully tested using L-Max®"

https://www.lepidico.com/wp-content/uploads/2020/11/LPD-201030-September-2020-Quarterly-Activities-and-Cashflow.pdf

The steps are the same as L-Max, milled particle size, the acid, amount of acid, temperature, reagents etc are the same as L-max.

One difference, as you mentioned, is the phosphate group contain phosphates. They removed as Calcium Phosphate

"Limestone is a cheap base and removes sulfate as gypsum and as well as phosphate as calcium phosphate"So where the brine related patents attach to the L-Max process for the production of Potassium Sulphate, Caesium/Rubidium Sulphate, they would potentially need an additional process to recover the phospate/calcium phosphate