Process for purifying urea-containing waste water and process for preparing melamine

Patent 4308385 Issued on December 29, 1981. Estimated Expiration Date:

May 8, 2000. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3697521

Method of hydrolyzing urea contained in waste water streams
Patent #: 4087513
Issued on: 05/02/1978
Inventor: Schell

Isolation of pure ammonia from gas mixtures containing ammonia and carbon dioxide
Patent #: 4120667
Issued on: 10/17/1978
Inventor: Gettert , et al.

Process for separation of ammonia and carbon dioxide Patent #: 4163648
Issued on: 08/07/1979
Inventor: Biermans

Inventor

Goorden, Josephus J. P. M.

Assignee

Stamicarbon B.V.

Application

No. 06/147714 filed on 05/08/1980

US Classes:

544/201, Processes utilizing urea or biuret reactant423/358From organic material containing nitrogen

Examiners

Primary: Vertiz, O. R.
Assistant: Langel, Wayne A.

Attorney, Agent or Firm

Cushman, Darby & Cushman

International Classes

C01C 1/00 (20060101)
C01C 1/12 (20060101)
C02F 1/02 (20060101)
C07D 251/60 (20060101)
C01C 1/08 (20060101)
C07D 251/00 (20060101)

Foreign Application Priority Data

1979-05-09 NL

Abstract

An improved process for the removal of urea from urea-containing waste water by hydrolysis and desorption of the ammonia and carbon dioxide thus formed. Urea-containing waste water is treated in a process for the separation of ammonia and carbon dioxide from mixtures thereof, which process has (a) an ammonia separation zone wherefrom ammonia, substantially free of carbon dioxide and water, is obtained, (b) a carbon dioxide separation zone wherefrom carbon dioxide, substantially free of ammonia and water is obtained, and (c) a desorption zone wherefrom water, substantially free of carbon dioxide and ammonia is obtained. The urea is substantially completely hydrolyzed and the ammonia and carbon dioxide produced thereby can be recovered.