Patent GB-760524-A (GB)
Title: Improvements relating to the recovery of chromic or phosphoric acid
Inventor: BRINKWORTH ALAN CHARLES
IPC: B01J47/04
Filed: 1954-05-21
Abstract: A process for treating chromic or phosphoric acid swill liquor to obtain pure water and chromic acid comprises passing the liquor through mixed cation-and anion-exchange materials which are respectively in the hydrogen and hydroxyl states so as to obtain substantially pure water, separating the two materials, when the water is no longer substantially pure, e.g. into an upper anion-exchange material layer and a lower cation-exchange material layer, regenerating the anion-exchange material with a solution of caustic soda or other alkali and passing the effluent regenerant through the separated cation-exchange material to obtain a chromic or phosphoric acid solution, the amounts of the two ion-exchange materials being such that when the anion-exchange material must be regenerated, the cation-exchange material has at least sufficient capacity remaining to take up substantially all the cations in the effluent regenerant from the anion-exchange material.  If the cation-exchange material is now regenerated with sulphuric or other acid and the effluent run off e.g. to waste, the regenerated cation-exchange material can be mixed with the already regenerated anion-exchange material and swill liquor be passed through it, making the process cyclic.  The anion-exchange material may be a cross-linked styrene copolymer containing halo-alkyl groups that have been aminated and the cation-exchange material a sulphonated styrene copolymer.  Some of the swill liquor may be circulated continuously through a bed of cation-exchange material to keep the content of metal salts low.ALSO:A process for treating chromic or phosphoric acid swill liquor to obtain pure water and chromic acid comprises passing the liquor through mixed cation- and anion-exchange materials which are respectively in the hydrogen and hydroxyl states so as to obtain substantially pure water, separating the two materials, when the water is no longer substantially pure, e.g. into an upper anion-exchange material layer and a lower cation-exchange material layer, regenerating the anion-exchange material with a solution of caustic soda or other alkali and passing the effluent regenerant through the separated cation-exchange material to obtain a chromic or phosphoric acid solution, the amounts of the two ion-exchange materials being such that when the anion-exchange material must be regenerated, the cation-exchange material has at least sufficient capacity remaining to take up substantially all the cations in the effluent regenerant from the anion-exchange material.  If the cation-exchange material is now regenerated with sulphuric or other acid and the effluent run off e.g. to waste, the regenerated cation-exchange material can be mixed with the already regenerated anion exchange material and swill liquor be passed through it, making the process cyclic.  The anion-exchange material may be a cross-linked styrene copolymer containing halo-alkyl groups that have been aminated and the cation-exchange material a sulphonated styrene copolymer.  Some of the swill liquor may be circulated continuously through a bed of cation-exchange material to keep the content of metal salts low.