FIELD: chemistry.
SUBSTANCE: invention relates to a method of extracting rare-earth elements from phosphogypsum formed during sulfuric acid treatment of apatite concentrate. Method involves treating phosphogypsum with ammonium carbonate solution to obtain a chalk containing rare-earth elements. Chalk dissolution is carried out in excess of nitric acid 120–150 % of stoichiometry to obtain a pulp which is filtered from a residue which is not dissolved in nitric acid, and obtained filtrate is cooled to temperature of −10 ÷ −15 °C and crystallized calcium nitrate tetrahydrate is separated. Solution is deposited with an alkaline agent at pH from 0.7 to 1.3 and filtered to obtain a rare-earth element.
EFFECT: method increases content of rare-earth elements in obtained concentrate.
1 cl, 3 ex
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