METHOD OF PREPARING CESIUM AND RUBIDIUM SALT SOLUTION Russian patent published in 1999 - IPC

FIELD: production of inorganic compounds. SUBSTANCE: in order to prepare cesium and rubidium salt solution with density between 1.6 and 3.3 g/cu.cm, non-calcined pollucite and/or calcined lepidolite with average grain size up to 0.5 mm is subjected to hydrothermal decomposition for 0.5-3 h with aqueous calcium hydroxide solution at 200 to 280 C and pressure 15 to 65 bar, concentration of suspension ranging between 8 and 18 wt %. Decomposition is carried out in rotary-tube autoclave and silicon dioxide-to-calcium oxide molar ratio ranges from 1:2.5 to 1:1.25. Further, insoluble solids are separated and, if necessary, by removing calcium and lithium ions as carbonates after saturation of medium with carbon dioxide. Subsequent addition of acid or acid anhydride to pH at least 6 results in formation of cesium and rubidium salts. To achieve desired density of salt solution, the latter is concentrated by evaporation. EFFECT: decreased degree of grinding of starting mineral and reduced excess of calcium oxide relative to silicon dioxide. 4 cl, 6 tbl, 6 ex