METHOD OF EXTRACTING LANTHANIDES FROM PHOSPHOGYPSUM Russian patent published in 2001 - IPC

FIELD: technology of extraction of lanthanides from phosphogypsum resulting from sulfuric acid processing of apatite concentrate into mineral fertilizers. SUBSTANCE: leaching of first portion of phosphogypsum is carried out with 2-6% sulfuric acid solution at L:S ratio of 2-3. Leaching solution is separated and used for leaching subsequent portions of phosphogypsum, sulfuric acid concentration in each stage is increased according to relation wherein is increment in phosphorus pentaoxide concentration during leaching of preceding portion of phosphogypsum, g/l. Leaching solution is used at least three times. Ultimate sulfuric acid concentration is 24 wt.%. Phosphogypsum residue is washed with water. Wash solution is used for leaching phosphogypsum. Prior to being leached, phosphogypsum is crushed to size of 100 mcm. The attained result is to improve process efficiency due to increasing concentration of lanthanides in solution by 3 times (up to 3.7 g/l) to secure high recovery (average recovery in 4-5 stages if 32.65- 38.68%). The simplifies further recovery of concentrate of lanthanides from solution. EFFECT: more efficient recovery method. 5 cl, 7 ex, 7 tbl