WR1 General Discussion, page-14461

this may already be answered, however it is my understanding that WR1 only have to pay 95% of market value according to Asian Metal Market pricing - this is irrespective of if they manage to sell it at a much higher rate to another party.

So in the event that a buyer values it at an additional 10% - 20% due to demand and limited supply (this is where having a monopoly and being the only mine in the world comes into play) that is just a bonus for WR1 to rake in free cash.
think pilbara minerals lithium auctions

hopefully this is correct, or alternatively someone could provide a different understanding of the deal.