RE:Stuart MacDonald interviewJust the EV portion of TESLA is projected to need 90 million pounds of copper a year.
https://midasletter.com/2020/01/copper-how-teslas-biggest-ingredient-could-make-you-rich-in-2020/
Let's say that Tesla is going to pay 3.50 usd a pound on the open market. Thats a $315 million USD cost. So a 20% stake in Florence would give them 16 million pounds a year at $1.10 instead of $3.50. That's a $40 million savings. A company like Tesla would recoup that investment in 2.5-3 years.
My guess is that if the JV partner is this type of company (even if not Tesla) then they are trying to negotiate for as large a stake as they can in the company.