&gt;The plant processed Monazite sand, which, when treated with Sulfuric Acid, separates into the rare-earth Sodium Sulfate,<p>Sodium sulfate is not a rare-earth. This looks to me like a case of copying from Wikipedia without understanding. From:
<a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Monazite#Acid_cracking" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Monazite#Acid_cracking</a><p>&quot;leaving a solution of lanthanide sulfates from which the lanthanides could be easily precipitated as a double sodium sulfate&quot;<p>This is an additional step that happens after the steps shown in the diagram, to separate the different lanthanides. Sodium sulfate is added to the mixed lanthanide sulfates, some of which form lanthanide-sodium double sulfates (see <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Double_salt" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Double_salt</a>) which precipitate out while other lanthanides remain in solution. See
<a href="https:&#x2F;&#x2F;books.google.co.uk&#x2F;books?id=HPyNk-cU-nQC&amp;pg=PA402&amp;lpg=PA402&amp;dq=lanthanides+double+salts+sodium+sulphate" rel="nofollow">https:&#x2F;&#x2F;books.google.co.uk&#x2F;books?id=HPyNk-cU-nQC&amp;pg=PA402&amp;lp...</a>