Method of recovering ammonia from an aqueous effluent which contains NH.sub . .sub.2 and H.sub.2 S

US4738754A · kind A · utility

Assignees

• Metallgesellschaft AG · DE
• Chemie Linz GmbH · AT

Inventors

• Wolfgang Hilsebein · Frankfurt am Main, DE
• Gert Ungar · Frankfurt am Main, DE
• Hans-Martin Stonner · Eschborn, DE

Key dates

• Filing date: May 23, 1986
• Grant date: Apr 19, 1988
• Expiry date: May 23, 2006

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S203/09
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

An aqueous effluent is supplied to a stripping column (total stripping column) from which a mixture that is rich in NH.sub.3, CO.sub.2 and H.sub.2 S is withdrawn as a head product. In at least one additional stripping column the mixture is separated into a mixture which is rich in NH.sub.3 and a mixture which is rich in the sour gaes CO.sub.2 and H.sub.2 S. The mixture which is rich in NH.sub.3 is scrubbed with liquid ammonia. The overhead product from the total stripping column is cooled in a condenser under a pressure of 1 to 7 bars and is thus transformed into a liquid phase to such an extent that the liquid phase contains 70 to 100% of the NH.sub.3 which has been supplied to the condenser. The liquid phase is supplied at a temperature of 30.degree. to 90.degree. C. to a second stripping column (NH.sub.3 stripping column), which is operated under a pressure of 1 to 4 bars and from which a gas mixture that is rich in NH.sub.3 is withdrawn as a head product. The gas mixture is scrubbed with water and ammonia and the NH.sub.3 gas which has been scrubbed is condensed.