METHOD OF OBTAINING A SOLUTION OF CAESIUM AND RUBIDIUM SALTS

摘要

PCT No. PCT/EP94/03651 Sec. 371 Date Sep. 18, 1996 Sec. 102(e) Date Sep. 18, 1996 PCT Filed Nov. 2, 1994 PCT Pub. No. WO95/13986 PCT Pub. Date May 26, 1995The process for preparing a cesium and rubidium salt-containing solution includes a hydrothermal digestion of an uncalcined pollucite and/or calcined lepidolite particulate having an average particle size up to 0.5 mm with an aqueous solution of Ca(OH)2 in a suspension with a mole ratio of SiO2 to CaO of from 1:2.5 to 1:1.25 in a rotary tubular autoclave at a digestion temperature of 200 to 280 DEG C., under a pressure of from 15 to 65 bar and at a suspension density between 8 and 18% by weight for from 0.5 to 3 hours; filtering the suspension to remove insoluble solids and to form a digestion filtrate; adding at least one acid or acid anhydride to the digestion filtrate to adjust its pH to 6 and to form the cesium and rubidium salt-containing solution; and performing an evaporation after the hydrothermal digestion to obtain an increase in concentration of cesium salts and rubidium salts in the cesium and rubidium salt-containing solution and to adjust a density of the cesium and rubidium salt-containing solution to from 1.6 to 3.3 g/cm3. An optional aeration of the digestion filtrate with carbon dioxide to remove lithium and calcium ions in precipitated carbonates may be performed.