METHOD OF TREATING MATERIALS CONTAINING URANIUM AND THORIUM RADIONUCLIDES Russian patent published in 1998 - IPC

FIELD: radiation protection. SUBSTANCE: invention focuses on removing radionuclides from placer platinum containing precious metals and uranium and thorium radionuclides. To that end, polluted placer platinum is oxidatively fired in air atmosphere at 1473-1773K for 0.50-0.66 h. Condensed uranium and thorium oxides are separated and radionuclide-depleted solid residue is melted in air in presence of flux, namely, CaO•SiO₂ taken in ratio from 1:10 to 1:12 relative to weight of original material. Melt is heated to 2123-2173K, kept isothermally in air atmosphere at attained temperature for 0.33-0.50 h, and freed of slag. EFFECT: increased extent and selectivity of recovery of uranium and thorium. 1 tbl