PREPARATION OF FEED GRADE DICALCIUM PHOSPHATE FROM COMMERCIAL PHOSPHORIC ACID

Abstract

Feed grade dicalcium phosphate was prepared by treatment of uranium barren commercial phosphoric acid with calcium hydroxide, and precipitation of dicalcium phosphate in two stages. The undesired contaminants, such as SO42- and F- were isolated in first precipitation stage using calcium hydroxide at pH 2.7–2.9, where the concentrations of cadmium and other trace elements were reduced by adding a small amount of ammonium sulfide in this stage, then dicalcium phosphate was precipitated by addition of calcium hydroxide in second stage at pH 6–7. X-ray diffraction study showed that the resulting product was mainly a brushite (CaHPO4·2H2O).