It is a hard business to value. To arrive at a valuation, you...

It is a hard business to value. To arrive at a valuation, you would have to consider one of two drivers: 1. Are you buying it purely on an economic value? or 2. For strategic reasons to secure supply? Most would look at it from an economic point.
Arriving at an economic value for any lithium business is just about impossible given you have to consider what a reasonable through the cycle price for your lithium product would be. If you can find that number, then you can calculate the future value of the business. Some suggestions for spodumene concentrate have been a long term average of US$1500/t. Just a year ago everyone would have sneered at this as being WAY too low, but here we are today around US$750/t and those same people that thought US$1500/t was ridiculously low, would take US$1500/t now without argument. My view is that what happened in 2022 was Chinese craziness, they built conversion plant with twice the capacity the world needed and started them all up about the same time resulting in a huge squeeze in the raw metrials market, spodumene concentrate. So, don't expect that to happen ever again, it won't, at least not for a view years even if you are super optimistic. The lithium market is even today still very immature/young. Most capacity today did not exist 10 years ago. Maybe in about 5 years or so there will be some balance and it would be easier to answer your question. I'd start with an average of US$1500/t spodumene concentrate and see where this gets you in terms of a valuation. All in costs, for PLS over time in today's money, probably around US$700/t. Add royalties and tax on the difference between 1500 and 800. Calculate the cash flow over say 20 years and discount it to today(choose a discount rate you think is reasonable) and you should have your NPV(net present value).