The Mountain Pass mine solved that problem years ago. What they couldn't solve was making money during periods when China cut rare earth prices.

And china cut the prices by ignoring the environmental impacts of their mines.

If only there was a giant money fountain with a vested interest in keeping mountain pass functional for the long haul.

The by products come after processing the concentrates from mining.

The largest non-Chinese supply chain globally is Lynas, concentrates from toxic waste free mining in W.Australia are shipped to Malaysia for processing where pools of low level radioactive waste and associated acids are created as by product.

Texas, USA, very much wants in on having "oceans of toxic sludge left after the" processing:

    The United States Department of Defence will contribute $US288 million ($442m) to develop Seadrift, with a view the construction will be finished by mid-2026. Lynas bought the southern Texas site in July last year from Dow and planned to turn first sod before the end of this year.

https://en.wikipedia.org/wiki/Lynas

https://lynasrareearths.com/wp-content/uploads/2023/12/Lynas...

The US expansion is funded by a US DoD initiative to secure critical resources for the US.