METHOD OF EXTRACTING RARE-EARTH METALS AND PRODUCING GYPSUM PLASTER FROM ANHYDRITE Russian patent published in 2017 - IPC C22B59/00 C22B3/06 

FIELD: technological processes.

SUBSTANCE: invention relates to a method of processing apatite with extraction and obtaining a concentrate of rare-earth metals and gypsum plaster from phosphogypsum – wastes from sulphuric acid technology of producing phosphoric acid from apatite. Method includes preliminary mechanical activation of calcium sulphate anhydrite with subsequent leaching of rare-earth metals in a solution with recrystallisation of phosphogypsum from calcium sulphate anhydrite to dihydrate. Leaching is carried out with 5 % solution of HNO₃ with addition of 15 % Ca(NO₃)₂ at normal conditions for 6 hours. Degree of extraction of rare-earth metals into solution is higher than 95 %, degree of conversion of anhydrite into gypsum is higher than 97 %. Obtained effect achieved through properly selected conditions for preliminary mechanical activation of anhydrite. Maximum degree of extraction of rare-earth metals into solution is achieved at values of total amount of energy stored in form of surface areas of coherent dissipation and microdeformations, more than 5.8 kJ/mol.

EFFECT: disclosed is a method of processing of apatite.

9 cl, 1 tbl, 1 ex