Patent ID: 7166264

Claim:
A process for producing phosphoric acid comprising a purification process, wherein said purifying process comprises the following steps: removing volatile components from phosphoric acid rich in impurities, wherein said phosphoric acid rich in impurities is a phosphoric acid product produced by a wet process, to form a crude phosphoric acid liquid substantially free of volatile components; heating said crude phosphoric acid liquid to a temperature above 250° C. in order to decompose phosphoric acid in said crude phosphoric acid liquid and generate gaseous phosphoric anhydride; and introducing said gaseous phosphoric anhydride into water or a dilute phosphoric acid aqueous solution in order to hydrate said gaseous phosphoric anhydride to form phosphoric acid, wherein said step of heating said crude phosphoric acid liquid comprises heating said crude phosphoric acid liquid with a combustion heat comprising introducing said crude phosphoric acid liquid into a phosphorus combustion chamber where phosphorus is combusted.