	US 11,905,179 B2
	Efficient method for decontaminating waste gases and waste water containing cyanide in a method for producing alkali metal cyanides
Jens Henkel, Meuselbach-Schwarzmühle (DE); Jürgen Rassbach, Arnstadt (DE); Klaus Trenkmann, Rudolstadt (DE); Markus Jafeld, Frechen (DE); and Bernd Glöckler, Bruchköbel (DE)
Assigned to Cyplus GmbH, Darmstadt (DE)
Filed by CyPlus GmbH, Darmstadt (DE)
Filed on Mar. 2, 2020, as Appl. No. 16/806,341.
Application 16/806,341 is a division of application No. 15/575,624, granted, now 10,730,758, issued on Aug. 4, 2020, previously published as PCT/EP2016/062939, filed on Jun. 8, 2016.
Claims priority of application No. 102015211233.0 (DE), filed on Jun. 18, 2015.
Prior Publication US 2020/0198981 A1, Jun. 25, 2020
Int. Cl. C01C 3/10 (2006.01); F23G 7/06 (2006.01)

CPC C01C 3/10 (2013.01) [F23G 7/06 (2013.01); F23G 2202/101 (2013.01); F23G 2209/14 (2013.01)]

18 Claims

1. A method for producing alkali metal cyanides as solids, comprising at least the following steps:

i) an absorption step, in which hydrogen cyanide from a synthesis gas containing hydrogen cyanide is absorbed in an aqueous alkali metal hydroxide solution to produce an aqueous alkali metal cyanide solution;

iii) a crystallization step, in which the alkali metal cyanide solution is introduced into an evaporative crystallizer, which is heated by heating and in which a pressure below 1013 mbar is provided;

iv) a step of condensation of cyanide-containing vapors arising in step iii) to form a cyanide-containing vapor condensate; wherein the step of the condensation iv) is performed using a multistage steam jet compressor, which suctions the exhaust vapors out of the crystallizer;

characterized in that the steam jet compressor is used so that the compression ratio over all stages is approximately 1:33 to 1:10.