Patent · US Expired

Process for the separation of hydrogen cyanide from gases and waste gases

US5200161A · kind A · utility

2Cited by

4References

7Claims

0Family size

Assignee

Degussa AG · DE

Inventors

Joachim Fischer · Rodgau, DE
Hubert Wolf · Hammersbach, DE
Manfred Diehl · Frankfurt am Main, DE

Key dates

Filing date	May 6, 1992
Grant date	Apr 6, 1993
Priority date	—
Expiry date	May 6, 2012

Classification

Technology area (CPC B)Performing Operations; Transporting
CPC primaryB01D53/346
WIPO fieldChemical engineering
WIPO sectorChemistry

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.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.