Sorption rerecovery and concentration of rare-earth metals from extraction phosphoric acid. Review
Keywords:rare earth metals, sorption, ion exchanger, extraction phosphoric acid, concentration, cation-exchange resin.
The review covers the methods for sorption recovery and concentration of rare-earth metals (REM) from solutions of extraction phosphoric acid (EPA). Sorption extraction of the REM seems most appropriate at the stage of primary concentration, but a significant amount of iron (III) and calcium as the most interfering impurities are the problem, both at the stage of sorption and at the stage of desorption. The results of studies on the sorption of trivalent ions of cerium, lanthanum and iron on sulfonic cation-exchange resin KU-2-8 and macroporous weakly acidic cation exchange Cybber CRX 300, are presented. It is established that the cation exchanger Cybber CRX 300 by exchange capacity for lanthanum and cerium and kinetic properties is inferior somewhat to sulfonic cation-exchange resin KU-2-8 at sorption from acidic solutions, but can be used to concentrate and separate the REM from iron. The review presents data of the pilot trials of the technology for extracting rare-earth metals from dihydrate extraction phosphoric acid (45 % P2O5) produced by «PhosAgro-Cherepovets» JSC (RU). The results of tests of sorbents TP260, Purolite S957 (Monophos), sulfonic cation-exchange resin РРС 160 and sorbent АА03 at sorption: from sulphate solution after decomposition of phosphate raw materials; from a solution of hydrolysis sulfuric acid after precipitation of titanium dioxide; from sulfuric acid solutions after sorption of uranium are presented. The distribution of rare-earth metals during their sorption by KU-2 sulfonic cation-exchange resin from solutions of phosphoric acid, as follows: dihydrate EPA partially evaporated 43.69 wt. % P2O5, «Balakovo Mineral Fertilizers» JSC; dihydrate EPA, without evaporation 26.09 wt. % P2O5, OJSC «Ammofos»; dihydrate EPA, evaporated 52.54 wt. % P2O5, «Ammofos» OJSC, was studied. The distribution coefficients of individual lanthanides are obtained. The analysis of literature data has shown that the choice of sorbent is the most difficult task when developing the technology for sorption extraction of REM from multicomponent solutions.