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Research on the apatite family of minerals to determine their suitability in the Flouride Extraction (FLEX) Process, which is part of the radioactive waste management stream.

1) KRI has fabricated and tested special high temperature furnace for fluorapatite synthesis. This equipment might be installed into glove box in order to carry out experiments with real actinides and technetium. The same equipment might be fabricated and installed in Actinide laboratory at HRC by KRI technical staff;

2) Samples of undoped polycrystalline apatite, Ca5(PO4)3F, of low porosity were successfully obtained by sintering in air at 1300°C. Part of these samples was already delivered to UNLV for additional study;

3) Samples of Sr-apatite, Sr5(PO4)3F, of low porosity were successfully obtained by sintering in air at 1300°C. In order to improve yield of Sr-apatite phase in final ceramic it is important to control stoichiometry of starting precursor, in particular, amount of H3PO4. It was demonstrated that excess of phosphoric acid causes formation of minor phases Sr2(PO4)2 and Sr2P2O7 in the matrix of Sr-apatite ceramic;

4) It was found that formation of fluorapatite loaded with actinide surrogates is essentially affected by stoichiometry of starting precursor. Excess of actinide surrogate causes formation of separated monazite phase, AnPO4 (where An is trivalent actinide surrogate, i.e. Nd, Eu etc). The lack of H3PO4 used for precursor preparation might cause formation of separated actinide-oxide phases into final ceramic matrices;

5) Future experiments should identify fluorapatite capacity to actinide incorporation. Other important goal of future work will be development of simple methods of control of starting precursor stoichiometry.


Apatite – Properties; Fluorides; Phosphates; Radioactive wastes – Purification; Separation (Technology); Strontium compound

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Apatite; Radioactive wastes--Purification; Separation (Technology)


Chemistry | Oil, Gas, and Energy | Physical Chemistry

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