Ann: Positive Scoping Study for the Mackay SOP Project-AMN.AX, page-41

RWD added lining to the ponds which is now not needed and what i suspect was a very hight $/t price for earth works, expect this would be a much larger driver than grade assuming the evap rates at both lakes are similar.

You can see from the numbers that once you have ticked off the ability to produce SOP (chemistry) and ability of brine to flow the driver for project value is actually in the indirects, similar to other bulk commodity projects. So transport, power and water costs, sustaining capex etc are significant or larger than mine costs. Looking at the jorc grade and recovery is just one aspect considering the capex opex split between strictly mine plant and total costs.