FRACTIONAL REGENERATION OF A WEAKLY ACIDIC ION EXCHANGER LOADED WITH BIVALENT METALLIC IONS

摘要

The invention relates to a method for the fractional regeneration of a weakly acidic ion exchanger loaded with bivalent metallic ions selected from nickel, zinc and manganese ions, obtaining a phosphoric acid solution of valuable substances, containing said metallic ions. At least two portions of aqueous phosphoric acid are successively loaded onto the ion exchanger, each successive portion of aqueous phosphoric acid having a weaker concentration of phosphoric acid than the precedent. After loading the first portion of aqueous phosphoric acid onto the ion exchanger in the form of a phosphoric acid solution of valuable substances containing metallic ions, a fraction of the concentrate is discharged. Said fraction contains at least 0.5 wt. % of metallic ions and the volume thereof is no larger than double the volume of the first portion of aqueous phosphoric acid. Further fractions of the regenerated product are collected, the respective volumes thereof not differing by more than 50 % of the volumes of the portions of aqueous phosphoric acid loaded onto the ion exchanger in order to produce the respective fractions of the regenerated product. After the last portion of aqueous phosphoric acid is loaded, a rewashing is carried out with enough water to drive the last portion of aqueous phosphoric acid from the ion exchanger and collect it as a last fraction of the regenerated product. Either so much phosphoric acid having a concentration of between 60 and 95 wt. % is deposited on the ion exchanger that the loss of phosphoric acid of the first fraction of the regenerated product is compensated for in relation to the first loaded portion of aqueous phosphoric acid and, for the next regeneration cycle, the fractions of the regenerated product which are obtained in the preceding cycle are loaded in the form of portions of aqueous phosphoric acid in the order obtained, or, the first fraction of the regenerated product collected following the discharge of the fraction of concentrate is mixed with such a quantity of concentrated phosphoric acid that the phosphoric acid concentration in said fraction of the regenerated product and the volume of said fraction of regenerated product correspond essentially to the phosphoric acid concentration and the volume of the original first portion of aqueous phosphoric acid before being loaded onto the ion exchanger. For a corresponding succeeding regeneration cycle of a weakly acidic ion exchanger loaded with the appropriate metallic ions, the individual fractions of the regenerated product from the preceding regeneration cycle are loaded onto the ion exchanger, in the order obtained, in the form of individual portions of aqueous phosphoric acid.