GBB you might be interested in the following...

GBB you might be interested in the following link:
https://www.researchgate.net/publication/305805042_Mineral_Processing_of_Eudialyte_Ore_from_Norra_Karr
Conclusions from the study were:

"Magnetic separation is applicable for the separation of eudialyte and aegirine from feldspars and nepheline, but

the concentrate grades are not sufficient. To achieve sufficient recoveries, multiple separation stages are necessary.

Magnetic separation is suitable as a preconcentration step before flotation.

To achieve direct selective flotation of eudialyte, a mixture of mono/diphosphoric acid esters as a collector and

oxalic acid and sodium hexametaphosphate as depressants have been proven effective at pH levels below 4. To find

the optimal parameters and best achievable results, the process has to be tested in a continuous operation.

Direct selective flotation is suitable to produce high grade eudialyte concentrates, which are necessary for feasible
metallurgical processing due to the low REE-contents of eudialyte. It simplifies the processing of eudialyte ore.

Therefore, it has the potential to increase the feasibility of eudialyte as an REE source.

The proposed reagent regime could be applicable not only for the separation of eudialyte, but also for other

minerals from alkaline rock complexes. For example, Zr bearing oxides and silicates (zircon, baddeleyite, cataplei-

ite, vlasovite, gittinsit), REE-bearing zirconosilicates and titansilicates (rinkite, mosandrite, rosenbuschite), REE-

bearing silicates (REE-allanite) or phosphosilicates (britholithe, steenstrupine), and Ta–Nb-bearing minerals could

be floated from syenites or nepheline-syenites."
So separation of eudialyte from it's ore is non trivial. Not so much due to particle size as you say, but due to low and overlapping magnetic susceptibilities with other minerals for the magnetic concentration step, and difficult floataion issues.
However, a reasonably clean concentrate can be produced (essentially >80% eudialyte) but with a maximum concentration of REE's between 2 - 2.5%. Still too low IMO to make the effort of concentration worthwhile for refining.
I don't believe GGG will bother with eudialyte, at least initially.
All IMHO
Cheers