Gas-Phase Conversion of Oxide Phases of Lanthanides and Uranium to Water-Soluble Compounds

Abstract Gas-phase conversion to water-soluble compounds of individual rare-earth element (REE) (La, Ce, Pr, Nd, Sm, Eu, Dy, Ho, Er, Tm, Lu) oxides and oxide systems (U,Ce)O x and (U,Nd)O x in the atmospheres HNO 3 (vapor)–air and NO x –H 2 O (vapor)–air was examined. It was shown that water-soluble compounds are formed in the gas-phase conversion of REE oxides in the atmosphere of both HNO 3 vapor and NO x gases. In the case of (U,Ce)O x in the atmosphere of HNO 3 (vapor)–air, water-soluble compounds of uranium are formed, with a part of cerium remaining in the phase of the water-insoluble precipitate. The conversion of (U,Nd)O x under the same conditions yields water-soluble compounds of both uranium and neodymium. It was found that these gas media can be used in principle to extract uranium from fuel systems containing rare-earth elements.