That is a question that would be better put to ANSTO because...

That is a question that would be better put to ANSTO because they are running point on the metallurgy by defining and determining the standardised procedures and sample environments for the metallurgical testwork not MEI, but this is not my field of expertise, so here’s what the generic research says re: pulverisation of core samples:

All diagnostic tests are carried out on pulverised samples at high L/S ratio, where there are no effects of adsorption, co-precipitation etc. These tests will indicate the maximum extraction that could be achieved under the test conditions (at more practical lower L/S ratios, extraction could be less).

About ANSTO

ANSTO have experience in the processing of monazite, bastnasite, and xenotime, as well as from less frequently exploited REE sources such as apatite, ionic clays and complex ores containing zirconium/niobium silicates.

Further, ANSTO have undertaken process development work for clients in Australia and across the globe. Their work has included all facets of REE process flowsheets, including acid leaching, sulfation baking, caustic conversion, alkaline roasting, selective precipitation, impurity removal, solvent extraction, ion exchange, process water treatment (softening) and chemical concentrate production.

ANSTO are the world experts - they know what they are doing.

cheers,
Ice