| 摘要 |
The invention relates to a combined process for the manufacture of feed grade dicalcium phosphate and pure phosphoric acid. The process comprises the reaction of an excess of phosphate rock with aqueous solutions of a mineral acid selected from hydrochloric acid, phosphoric acid and nitric acid, characterized by the fact that the free acidity of the dissolution liquor does not exceed 60% and that in the clear solution feed grade dicalcium phosphate is precipitated with calcium hydroxide, calcium carbonate or mixtures thereof. The solids comprising the unattacked phosphate are decomposed with hydrochloric acid solutions, gases containing hydrogen chloride or mixtures thereof and the acidulate containing the phosphoric acid is extracted with an organic solvent selected from butanols, pentanols or mixtures thereof, the phosphoric acid-solvent extract is separated and washed, thus obtaining the pure phosphoric acid. |
