I have worked with the Chinese REE industry, and we've often bumped heads and shared ideas together with them and I can confidently tell you, the Chinese don't use anything novel that has not been established in Western science already. What they do have is executing rarely-used techniques confidently at scale, but all of that is already often published in the West. The only reason the West hasn't done it is because these techniques are less profitable, and, surprise, the CCP actually forces processors to minimize ecological damage, which further bumps up the costs to the point only large-scale players can exist making such lower profits. You'll often find them using some obscure process alteration that was published minutely in the West.
As an addendum, companies in the REE Sinosphere are often encouraged by the CCP to exchange ideas with each other quite often, while Western companies often lock them behind proprietary patents and competition. While both systems have their pros and cons, the former allows for faster process proliferation (and a lower profit incentive for the innovator).