The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 16, 1979
Filed:
Jul. 13, 1977
Klaus P Ehlers, Erftstadt Lechenich, DE;
Gero Heymer, Erftstadt Liblar, DE;
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
Process and apparatus for purifying crude wet-processed phosphoric acid containing free sulphuric acid. To this end, the wet-processed phosphoric acid is treated in a reaction zone, at a temperature of 70.degree. C to 100.degree. C, with a calcium compound and with calcium sulphate seed crystals; the sulphuric acid is precipitated in the form of calcium sulphate semihydrate with the resultant formation of a suspension; a proportion of the suspension, with the calcium sulphate semihydrate seed crystals present therein, is recycled to the reaction zone; the balance of the suspension is treated for separation of purified phosphoric acid from the accompanying precipitate; the precipitate is transformed into an aqueous suspension and the calcium sulphate semihydrate in said suspension is converted into calcium sulphate dihydrate; the aqueous phase of the suspension is separated from the solid matter therein, and the solid matter is water-washed; a proportion of the aqueous phase so separated is recycled together with a proportion of the wash water, for use in suspending and converting calcium sulphate semihydrate to dihydrate; and the balance of the aqueous phase and wash water are combined with the said purified phosphoric acid.