Ann: Pre-Feasibility Study Completed for Mackay SOP Project, page-136

Panda

I don't think the use of specific yield and drainable resource (DR) accurately reflects what must be a very dynamic environment once recharge and groundwater movements are in play. These comments are directed to both AMN & RWD.

I view the drainable resource as a point in time resource. Hypothetically if we slice off the top 6M of each lake and suspend them in the air, the DR is what will seep out of the hypothetical slab of lake bed material. A 2558km2 slab of Mackay will give 9.8MT and a 749km2 slab of LD gives 7.48MT.

If you think very carefully about the "Slab to drainable resource ratio" it becomes very clear that the argument being put forward about large lake bed/low risk is bull. I wonder how much thought the BCom trained broking analysts have put into this.

LD yields 13-15%, MacKay 10.5% of the fluid component of the lake bed material (as defined by SY). The total fluid component is represented by the total porosity and we know that Mackay has a TP of 45% and LD 52%.
We also know that LD has a grade of 13.4, Mackay 8.25.
In essence LD is wetter, gives up more of its fluid. The fluid it gives up is 50% more concentrated.

If we go back to the TP/in situ resource (0-6M) we know that the Mackay has 26MT and LD has 33MT (accessible zone).

If we think about recharge after we start pumping brine, in the case of LD there will be the balance of 33MT sloshing around trying to refill the brine drained. In the case of Mackay there will be the balance of 26MT (over an area that is much greater).

As it stands AMN predict that they can recover 427tpa over 20 years. RWD predicts that it can recover 407ktpa over 27 years.

AMN with a DR of 9.8MT will mine 8.5MT of SOP. RWD (accessible zone) with a DR 0f 7.48MT will mine 10.8MT.

Somebody has suggested that RWD has over estimated its capacity and that AMN has been conservative. I suspect the numbers that have been given have been generated using sophisticated hydrogeology software packages and take into account the ability of the insitu resources to recharge the drainable resource.

The question in my mind is whether 2M trenches at LD will be sufficient.

Finally trench depth and pumping studies conducted thus far brings us back to predicted trench flows.
We have argued about calculated trench flow in term of flow per KM, what we haven't done is standardise trenches for depth. I think I am correct in saying that the AMN tests trenches have been much deeper than those at LD.