METHOD FOR ISOLATION OF RARE-EARTH MINERALS FROM ACIDIC SOLUTIONS Russian patent published in 2001 - IPC

FIELD: industrial inorganic processes. SUBSTANCE: invention provides method for isolation of rare-earth minerals from acidic solutions with low initial rare-earth mineral level, which method can be utilized in integrated processing of phosphate stock, in particular when isolating alkali-earth minerals from phosphogypsum acidic leaching solutions and from solutions obtained in phosphate stock nitric acid decomposition. For that, initial solution is supplemented by organophosphorus collector in the form of dialkyl phosphoric acid by blowing solution with gas to form foamed rare- earth product, which is then separated. Separated product is treated with nitric or hydrochloric acid with concentration at least 4N at 70-100 C to transfer rare-earth mineral into solution, which is separated from thereby regenerated collector. One volume of nitric or hydrochloric acid is used to successively treat at least 2 portions of foamed product. In addition, initial nitric-phosphoric acid solution with 2.7 g/l of calcium ion is used, which is preliminarily neutralized to pH 0.3-1.0. When collector is being added, temperature of solution is maintained no higher than 60 C. To initial solution, in which molar ratio Ln₂O₃:CaO≅0.015, sulfate ion before neutralization with ammonia is added to provide molar ratio CaO:SO2-4

= 1:(0.5- 1.0) and crystallizing calcium sulfate is separated. EFFECT: increased rare-earth mineral isolation efficiency in the form, which is most suitable for further utilization, and simultaneously achieved regeneration of expensive dialkyl phosphoric acids. 4 cl, 1 tbl, 8 ex