Purification of wet-process phosphoric acid by solvent extraction

ABSTRACT

High grade phosphoric acid can be obtained using liquid-liquid extraction technique. The influence of type of solvent, solvent concentration, organic/aqueous phase ratio, temperature, shaking time and phosphoric acid concentration on P2O5 extraction was studied. Scrubbing and stripping were also investigated, n-octanol proved to be the most efficient and selective. The temperature has a slight positive effect and the extraction was enhanced by increasing P2O5 and with the increase of organic/aqueous phase ratio. The stripping efficiency slightly increased with shaking time and the optimum organic/aqueous phase ratio was determined to be 2.0. For 9.2 M H3PO4, 99.90% of iron, 97.99% of fluoride and 99.99% of manganese were removed whereas complete removal of copper, cadmium and zinc was attained