Decontamination of wet-processed phosphoric acid

US4200620A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Klaus-Peter Ehlers
• Wolfgang Scheibitz · Frankfurt am Main, DE
• Klaus Schrodter · Cologne, DE
• Gero Heymer · Lechenich, DE

Key dates

• Filing date: Dec 12, 1977
• Grant date: Apr 29, 1980
• Expiry date: Dec 12, 1997

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01B25/234
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Wet-processed phosphoric acid is decontaminated. To this end, the phosphoric acid and an organic solvent, which is partially miscible with water and capable of absorbing phosphoric acid, are contacted countercurrently with respect to one another. The resulting organic phosphoric acid solution is separated from contaminants unabsorbed by the solvent, termed primary raffinate, decontaminated phosphoric acid is recovered either in the form of free acid by re-extracting the organic phosphoric acid solution with water, or in the form of an alkali metal phosphate by reacting the organic phosphoric acid solution with an alkali, and the primary raffinate is treated countercurrently with a solvent containing a mineral acid. More specifically, the organic phosphoric acid extract, which orginates from the primary raffinate treatment and contains more than 0 up to at most 10 weight% of water, is mixed with an anhydrous solvent in a ratio by weight necessary to ensure the formation of a mixture containing more than 0 and less than 50% of water than would correspond to the saturation concentration of water in the solvent; and the mixture is contacted countercurrently with the phosphoric acid whi…