METHOD OF PROCESSING PHOSPHATE RARE-EARTH CONCENTRATE ISOLATED FROM APATITE Russian patent published in 2000 - IPC

FIELD: inorganic chemistry, chemical technology. SUBSTANCE: invention relates to methods of extraction of rare-earth elements from the secondary concentrates obtained in apatite processing. Decomposition of phosphate rare-earth concentrate is carried out at heating in 1-2 N nitric or hydrochloric acid at ratio solid : liquid = 1:(2.5-3.5) in the presence of oxalic acid taken in the amount 10-50 wt.% above stoichiometric ratio as measured for rare-earth element oxides. Precipitate of rare-earth element oxalates is separated, washed with water and calcinated. Method provides increase of extraction degree of rare-earth elements in precipitate oxides up to 97-99%, decrease of consumption of nitric or hydrochloric acid by 2-3-fold and that of oxalic acid by 2.0-2.5-fold. EFFECT: simplified method, decreased consumption of reagents, increased extraction of product. 2 cl, 6 ex