METHOD FOR TREATMENT OF WET-PROCESS PHOSPHORIC ACID Russian patent published in 2004 - IPC

FIELD: inorganic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing phosphoric acid with the low content of impurities used in manufacture of phosphates of technical and food grading. Method for treatment of wet-process phosphoric acid involves step-by-step extraction of phosphoric acid with tributyl phosphate in the volume ratio of organic and aqueous phases = (2.5-5.5):1 and aqueous re-extraction up to preparing the manufacturing acid and these steps are carried out with formation of emulsion in pulse-regimen and separation of aqueous and organic phases also after each stage. Method involves feeding wet-process phosphoric acid wherein compounds are added that comprise alkaline metal ions or ammonium ion taken in the amount necessary for reducing sulfuric acid in it up to 0.002-0.005 p/p P₂O₅. Number of extraction steps is varied so to provide the concentration of phosphoric acid in formed extract to be equal 12-16% of P₂O₅. It is possible to carry out this method using stage for extract washing out. For extraction acid is fed with the concentration 48-62% of P₂O₅ and as compounds containing ammonium ion ammonia is used and its derivatives of ammonium phosphate. Number of steps in extraction process is varied in the range = 1-4. Method provides enhancing treatment degree of wet-process phosphoric acid from sulfuric acid in simultaneous elevating the yield of product.

EFFECT: improved treatment method.

4 cl, 1 tbl, 2 ex