It's good that you are trying to model the value, not sure how...

It's good that you are trying to model the value, not sure how many posts there are actually trying to quantify the value....
I'm having trouble however squaring your model with Argosy's own that was provided as part of the PEA.

https://www.argosyminerals.com.au/sites/default/files/presentation_file/agy-asx-20181130-pea-nov2018.pdf

The PEA assumes 100% ownership for simplicity.
Of course AGY will own 90% of Puna when funding for the 10ktpa plant has been provided as per JV agreement.
So $141M for 12.5% stake in Puna? Apparently the JV is worth US$1128M haha.

Their base case... case v. Used a discount rate of 10% and came to a pre tax NPV10 of US$399M for the 10ktpa @ US$13,000.
case vi estimates the pre tax NPV10 of US$580M ( eye balling the graph there )
If I extrapolate those numbers for a US$17600 lithium price then the NPV10 is US$730 ( I'm sure it's more complicated than that )

This does not compare at all with the modelling numbers you posted above.

Where do you think the difference is coming in?
Would be nice if you post more details of your modelling?

Some of the other values are 3% revenue royalties and 4.5% installed equipment "sustaining capital".

These models ignore any potential side income from the byproducts created in the production process.
35,000 t/y of potash and 25,000 t/y of magnesium hydroxide.
I could not really find prices for these and the devil is in the details but it seems like US$200+ at least.
Not huge amounts but hey, it's another US$12M+ per year, it adds up.

Then there is TLP.
We are on the line for another A$500k (cash or shares ) if we announce a 1million ton JORC or start commercial production.

But I digress a bit.

If we stick to the lithium only NPV at Rincon.... can we align your model with the PEA in a meaningful way?