| 摘要 |
Process for the fractionated regeneration of a weakly acid ion exchanger charged with divalent metal ions selected from nickel, zinc and manganese ions, obtaining a phosphoric-acid valuable product solution which contains these metal ions, wherein at least two portions of aqueous phosphoric acid are added to the ion exchanger one after the other, wherein each successive portion of aqueous phosphoric acid shows a lower phosphoric acid concentration than the previous one, wherein after adding the first portion of aqueous phosphoric acid to the ion exchanger, a concentrate fraction in the form of a phosphoric-acid valuable product solution containing metal ions is flushed out which contains at least 0.5 wt. % metal ions and of which the volume is no greater than twice the volume of the first portion of aqueous phosphoric acid, and further regenerate fractions are then collected the volumes of which differ by no more than 50% from the volumes of the portions of aqueous phosphoric acid added to the ion exchanger to produce the regenerate fractions in question, after adding the final portion of aqueous phosphoric acid at least enough water is used for rewashing to displace the final portion of aqueous phosphoric acid from the ion exchanger and collect it as the final regenerate fraction, either enough phosphoric acid with a concentration in the range 60 to 95 wt. % is added to the ion exchanger to balance out the phosphoric acid depletion of the first regenerate fraction in relation to the first portion of aqueous phosphoric acid added and then the regenerate fractions obtained from the previous cycle are added in the order obtained, as portions of aqueous phosphoric acid for the next regeneration cycle, or such a quantity of concentrated phosphoric acid is added to the first regenerate fraction collected after flushing out the concentrate fraction that both the concentration of phosphoric acid, and the volume, of this regenerate fraction substantially correspond to the phosphoric acid concentration and the volume of the original first portion of aqueous phosphoric acid before addition to the ion exchanger, and for a corresponding subsequent regeneration cycle of a weakly acid ion exchanger charged with suitable metal ions, the individual regenerate fractions from the previous regeneration cycle are added to the ion exchanger in the order obtained as individual portions of aqueous phosphoric acid. |
