METHOD FOR EXTRACTION OF RARE-EARTH ELEMENTS OF ORE CONCENTRATE OF WEATHERING CRUST OF "KYNDYBAI" DEPOSIT Russian patent published in 1998 - IPC

FIELD: extraction of rare-earth elements. SUBSTANCE: ore concentrate is ground till size of particles is less than 0.05 mm. Then it is treated by mixture of sodium hydroxide solution (having concentration 100-200 g/l) with sodium carbonate solution (having concentration 100-250 g/l), the process is carried out at 80-110 C. Said treatment takes place by two-stepped process. Excess of mixture of sodium hydroxide solution with sodium carbonate solution from the second step of the process is removed to its first step. During said treatment molar ratio of rare-earth element and sodium in reagents is maintained within 1:(4.5-9) range. Extraction of rare-earth elements is up to 90-97 %. EFFECT: improved efficiency of the method. 4 cl, 1 tbl