Rare Earth Elements: A Review of Production, Processing ...

Rare Earth Elements Review Appendix C – Process Flow Diagrams
Figure C-1. (continued)
It is recognized that the reference date for the figure above is 1988. Given the opportunity to comment on this
diagram, Molycorp’s Scott Honan provided the following clarifications (personal communications, 2011):
“– after the dissolution step, the insoluble fraction was a cerium product that contained about 60% REO by weight.
The other product from dissolution was the liquor that fed solvent extraction.
– the light RE elements are La, Ce, Nd, Pr. The first SX step separated these from everything else (Sm and the
other heavies). Molycorp did run solvent extraction and other unit operations to further separate the heavies,
and produced Eu products, Y-Eu co-precipitates, Sm, Gd and Tb products. As far as I know, Y was never
produced at Mountain Pass, but it was purchased to combine with the Eu to make co-precipitates.
– the chemical form of the Nd, Nd-Pr, Ce and La products varied. I would simply call these "products" instead of
specifying a chemical form.”
C-2