METHOD OF PROCESSING PHOSPHOGYPSUM WASTES TO OBTAIN A CONCENTRATE OF RARE-EARTH ELEMENTS AND GYPSUM PLASTER Russian patent published in 2019 - IPC C22B59/00 

FIELD: technological processes.

SUBSTANCE: present invention relates to a method of extracting rare-earth metals from phosphogypsum. Method comprises treating phosphogypsum with a sulfuric acid solution, filtering, extracting from the obtained solution a precipitate of insoluble REE compounds by adding acetic acid, separation of precipitate by filtration, wherein separation of rare-earth metals from solution is carried out with acetic acid or its soluble salts at consumption for deposition 250÷300 mol% on REE from stoichiometry and neutralization of solution to pH value 1.0÷2.5, subsequent separation of acetate REE sediments from mother solution, performing washing, drying and, if necessary, tempering to obtain concentrate of REE in salt or oxide form, neutralization of gypsum residue is carried out by main calcium compound, and the mother solution is successively treated with quick lime (CaO) to neutralize sulfuric acid, filtering the formed precipitate – calcium sulphate from the mother solution, which is recycled in the form of waste water, or is sent as a recycle to prepare an acetic acid solution, and the excess balance is directed to the acetic acid neutralization unit with beryllium oxalate to form an insoluble precipitate – beryllium acetate, filtering the insoluble precipitate of beryllium acetate from the mother solution containing oxalic acid, followed by neutralization with quick lime (CaO) with formation of insoluble residue – calcium oxalate, filtration of calcium oxalate from mother solution, which is recycled in the form of waste water, or is directed as a recycle for preparation of sulfuric acid solution, and balance excess is removed from installation as waste water.

EFFECT: higher degree of extraction of obtained concentrate REE up to 98÷99 %, improved quality thereof, reduced costs for its production, reduced discharges of waste water by changing types of used reagents and modes of use thereof.

1 cl, 1 dwg