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:
Apr. 06, 1993
Filed:
May. 06, 1992
Degussa Aktiengesellschaft, Frankfurt am Main, DE;
Abstract
A process is disclosed for the separation of hydrogen cyanide from gases and waste gases by a throughflow or circulation scrubbing, in which formaldehyde is added at a controlled rate to the aqueous scrubbing liquid to form glycol nitrile. This addition is controlled by measuring the HCN tension in a measuring stream which has been branched off and which is first treated with hydrogen peroxide so that free H.sub.2 O.sub.2 is still detectable after 1 to 100 seconds and the pH is adjusted to a constant value before measurement of the HCN tension is carried out. The process prevents overdosing with formaldehyde which could not always be prevented in previously known processes in which the addition of formaldehyde was regulated by measuring the cyanide specific redox potential.