RNS29 Mar 2023 09:22
"Work has started on the front end of the pilot plant, which will comprise the main phosphogypsum handling circuit that will produce a mixed rare earth sulphate intermediate solid material. An initial bench-scale program is in progress to confirm the pilot testing parameters."
I hope that the declared recovery of REE at the initial stage of the pilot plant will at least correspond to 60-65% achieved in laboratory work. At the same time, there are already patented technologies that allow you to extract more than 90% of REE.
"mixed rare earth sulphate intermediate solid material produced by the front end"
After reading the articles on this subject:
- The ability of sulfates of rare earth elements to form numerous double salts with alkali metal sulfates, as well as with ammonium sulfate, has long been known.
- This method is used in industrial practice. Thorium and rare earth elements are characterized by the formation of complex (double) sulfates with alkali metal cations, and their solubility for rare earth elements and thorium is different. This is the basis of the method for the initial isolation of complex (double) sulfates. In principle, the crystallization of complex phosphates (double sulfates) can be carried out in two ways: first, by crystallizing double sulfates of thorium and rare earth elements of the cerium group together from solutions of potassium sulfate, leaving the yttrium group in solution, and, secondly, from solutions of sodium sulfate crystallize double sulfates of the rare earth elements of the cerium group, leaving the thorium and yttrium group in solution. In both cases, rare earth elements are divided into two subgroups, and thorium remains in one of them. The use of one or another method of crystallization of complex sulfates is due to the composition of the feedstock (it is advantageous to leave thorium with the group of rare earth elements, which is quantitatively smaller).
Based on this, the question arises of the quality of the resulting mixed rare earth sulphate and, accordingly, the distribution and content of radioactive thorium.
Will thorium be present in mixed rare earth sulfate? Or will thorium accumulate in solution, and after neutralization, a waste containing thorium will be obtained?
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