Method for purifying phosphoric acid

The invention relates to the technical field of phosphoric acid purification, and discloses a method for purifying phosphoric acid, which specifically comprises the following steps: S11, extracting crude phosphoric acid by using an extracting agent, pre-washing dilute phosphoric acid by using an extracted organic phase obtained by extraction, carrying out primary standing phase splitting on a pre-washed mixed solution, and carrying out secondary standing phase splitting on the pre-washed mixed solution; the water-phase acidic solution after primary standing and phase splitting can be recycled and reused; s12, removing calcium from the organic phase after primary standing and phase splitting by using an aqueous solution containing sulfate radicals, and then carrying out secondary standing and phase splitting; and S13, performing acid radical removal on the organic phase subjected to secondary standing phase separation, and then performing third standing phase separation. The method can effectively remove calci