RE:Dear BobThe best material on MP's plans are in the presdentations and 2022 earnings calls (listed to the audio to get the best info) at https://investors.mpmaterials.com/events-and-presentations/default.aspx .
I don't think MP haqs any need or plans to separate light REEs mined at other than Mountain Pass, but it probably could if it wanted to
I think MP is leaving options open regarding buying heavy feedstock from other mines to supplement the heavies in the SEG+ concentrate (from its Mountain Pass mine), in order to produce magnets in Texas. I believe MP can expand beyond 20 tons per annum light separation if they want, but that will cost money, and is not planned now (Molycorp was supposed to have a 40,000 tons per assum capacity, after doubling its initially planned 20,000 tons per annum, but wound up with essentially zero tons per annum, because it was run into the ground by the idiot CEO Mark Smith).