EXTRACTION OF BORIC-ACID FROM BRINES BY ION-EXCHANGE

Using the chelating resin WOFATIT MK 51, which is characterized by a methylaminoglucitol group, boric acid is removed from brines containing higher concentrations of alkali and alkaline earth salts. The boric acid is eluted from the resin with 0.5 M HCl and thus a maximum concentration of boron (4.9 g l-1) in the eluate can be obtained. Solutions of smaller boron contents are recycled. By evaporating the solution, boric acid crystallizes in a very pure state. Loading and elution of the resin are controlled using pH changes. The experiments enable the transfer to a technical scale.