Efficient Removal of Polyvalent Metal Impurities from KH2PO4 by Crystallization

Abstract

The separation factors of metal impurities for potassium dihydrogen phosphate crystallization from nonstoichiometric solutions have been experimentally determined. Based on the results obtained, a method has been proposed that makes it possible to obtain a material containing aluminum, iron, chromium, and titanium at a level of ~5 × 10^–2 ppm by weight from commercially available raw materials. In this method, a KH₂PO₄ solution is purified due to partial crystallization of the macrocomponent, so that the above impurities are concentrated in the solid phase. The purified solution is then boiled down with KOH additions.