@Thesi easier to discuss here without getting into old arguments
I think the cost curve is not as clear cut as the presentations have shown to date
Generally speaking you can produce either battery grade LC or hydroxide with 8 tonnes of 6% concentrate and $1500 worth of materials, energy, transport, labour and plant D&A etc.
So for PLS including only 50% of expected tantalum credit (IMO not a reliable by-product, I think recovery is problematic and market is small), is 8 * 220 + $1500 = $3260USD per tonne of battery grade LC or hydroxide.
I believe the equivalent for Talison / Greenbushes is ~$2900USD without worrying about transfer pricing and profit splitting.
Now to compare to a real world cost leader - SQM. In their last quarterly SQM COGS on lithium products was $2700 / T. I have read that as a primary product of the plant battery grade LC is much smaller than industrial grade, meaning to ramp battery grade they convert industrial grade through an extra process, similarly hydroxide is produced through an extra process that costs an estimated $1000/T. I think its reasonable to assume the real world blended cost of battery grade LC output and hydroxide per ton would be $3000+.
I think the cost of brine vs hard rock has really been overblown by including a margin for the spodumene miner in the final LCE cost. However the only thriving hard rock business is in fact an integrated conversion and mining operation (Tianqi as you know them well) and similar can be achieved through JV. This is before considering the chemical suitability of the battery grade LC produced with my research showing quite a difference in the impurities contained in the remaining 0.5% from brine vs hard rock.
There are brine projects with costs targeted at $1500/T, $2000/T, for battery grade but I think need to be taken with a pinch of salt considering the source material they are planning to work with in all cases is not as good as the Atacama. I would also struggle with PLS forecasting a lower opex per ton than Talison, and have read some comments saying similar but I think that's just enthusiasm.
I also think SQM, the brine leaders, by far, are not going to drive prices down and make production cost an issue as they are going to run into real issues with potash pricing next quarter, and I think they will solve it with long term lithium price hikes. See historical pricing relationship below:
