Abstract: A process for removing impurities from phosphoric acid, especially concentrated wet process phosphoric acid, comprises filtering phosphoric acid through a filter cake (e.g., diatomite) on a porous member at a temperature in the range of about 57.degree. C. to about 77.degree. C. The filter cake retains some phosphate values. A major portion of the phosphate values retained by the filter cake can be introduced into the phosphoric acid manufacturing process, as by slurrying the filter cake in water, separating the aqueous phase from the solid phase, and introducing the aqueous phase to a wet process phosphoric acid process (e.g., as a "gypsum" filter wash).

Abstract: A method for removing impurities from wet process produced phosphoric acid and recovering phosphate values retained by the impurities is disclosed. The wet process produced phosphoric acid is filtered through a diatomite filter cake in a porous medium at a temperature from about 57.degree. C. to about 77.degree. C. During filtering an impurity-containing upper portion of the filter cake is removed exposing a fresh surface of the filter cake. An aqueous slurry is formed with the removed portion of filter cake. The slurry is filtered to recover a filtrate containing a major portion of the phosphate values retained by the removed portion of the filter cake.