Abstract: The present invention relates to the process of purification of boric acid by ion exchange method. Boric acid is dissolved in hot demineralized water. The hot solution is pressure-filtered. The hot saturated solution, which is purified from water-insoluble, is passed through a column containing strong cation exchange resin, followed by a column containing weak anion exchange resin at the same temperature and cooled afterwards. The crystals settling by cooling are separated from the mother liquor, the amount of aqueous solution within them is reduced and then dried. The waste solution formed during crystallization and filtrate formed after separation of crystals from aqueous solution are mixed and used in boric acid dissolving process. The developed method enables the reduction of sodium, sulfate, chloride and iron impurities of technical grade boric acid to less than 1 ppm and is more economic and environmental friendly than current methods.

Abstract: The present invention relates to the process of purification of boric acid by ion exchange method. Boric acid is dissolved in hot demineralized water. The hot solution is pressure-filtered. The hot saturated solution, which is purified from water-insoluble, is passed through a column containing strong cation exchange resin, followed by a column containing weak anion exchange resin at the same temperature and cooled afterwards. The crystals settling by cooling are separated from the mother liquor, the amount of aqueous solution within them is reduced and then dried. The waste solution formed during crystallization and filtrate formed after separation of crystals from aqueous solution are mixed and used in boric acid dissolving process. The developed method enables the reduction of sodium, sulfate, chloride and iron impurities of technical grade boric acid to less than 1 ppm and is more economic and environmental friendly than current methods.