METHOD OF RARE-EARTH ELEMENTS EXTRACTION Russian patent published in 1998 - IPC

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: invention relates to processing phosphate-containing raw: apatites and phosphorites to extract rare-earth elements from their. An aqueous solution of rare-earth element phosphates, calcium and mineral acid obtaining in the process of phosphate-containing raw opening is neutralized with ammonium or sodium hydroxide before precipitate formation. Then solution is evaporated by 1.3-3-fold depending on concentration of the parent components. During evaporation rare-earth elements are precipitated as phosphates that can be filtered or centrifuged. Precipitates are separated from solution and fed to mineral fertilizer production or for other technical aims. Precipitate of rare-earth phosphates is treated with sodium hydroxide solution at concentration 100-400 g/l or sodium carbonate solution at concentration 100-200 g/l, or their mixture at 100-130 C for 2-6 h. After treatment mother liquor is decanted, precipitated is washed out with water and dried a little. Mother liquor has trisodium phosphate that can be used for detergents producing. Precipitate has rare-earth metal hydroxides or hydroxocarbonates. Rare-earth elements content in precipitate is 85-90% as measured for oxides. Extraction of rare-earth elements in one-stage process is 80-90%. The obtained ready concentrate exhibits good filtering property. EFFECT: improved method of extraction. 3 cl, 4 ex