RE: I have no special knowledge of ... Some clarification. The mine will not be open pit. Its too deep. See below excerpt from the current technical report (emphasis mine).
14.1 Base Case Mining Scenario
14.1.1 Horizontal Limb
Underground room-and-pillar mining is defined to be the base case mining scenario in the horizontal limb of the deposit. PFS-level project economics have been developed for base case mining in the LPZ, as discussed in Items 16 through 22. The PFS analysis demonstrates strong economic potential for mining the LPZ resource.
The PFS was on the lower zone only but my reading from the statement above (referring to the entire horizontal limb - meaning upper zone and lower zone), the preferred base case for the whole deposit is room and pillar underground mining, not open pit.
Testing has suggested the high grade LPZ material can be made into fertilizer without beneficiation - so direct ship product is possible if target grades are achieved during mining. UPZ material will require beneficiation to make a saleable product.
All of the above is in the technical report.