METHOD OF EXTRACTION OF RARE-EARTH ELEMENT PHOSPHATES FROM APATITE CONCENTRATE Russian patent published in 1998 - IPC

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: invention relates to technology of extraction of rare-earth elements from apatite concentrate at its nitric acid processing to complex fertilizers. Method involves addition of lanthanum concentrate at amount 20-50 wt.-% of total rare-earth elements content in nitrate-phosphate solution to nitrate-phosphate solution. The latter is obtained after decomposition of apatite concentrate with nitric acid, strontium removing, calcium nitrate freezing out, fluorine removing. Lanthanum concentrate is added before neutralization of nitrate-phosphate solution with ammonia. A mixture of light rare-earth elements containing lanthanum oxide at amount 25 wt.-%, not less, is used as lanthanum concentrate. Neutralization of nitrate-phosphate solution is carried out with potash or soda partially (10% of ammonia, not less). Method ensures to increase extraction degree of middle and heavy rare-earth elements and yttrium and improve filterability of rare-earth element phosphate precipitate. EFFECT: improved method of extraction, increased extraction degree. 3 cl, 1 tbl, 5 ex