Process for removing ammonia, hydrogen sulfide and hydrocyanic acid from

Abstract

A process is provided for removing ammonia, hydrogen sulfide and hydrocyanic acid from gases such as coke oven gas. In carrying out the process, the gas to be cleaned is first washed with an alkaline solution to remove the hydrogen sulfide and hydrocyanic acid. The hydrogen sulfide is oxidized by air to produce elemental sulfur, which is removed, and the alkaline solution is recirculated for reuse, a portion of the solution carrying cyanide and other compounds being diverted for further treatment. The gas to be cleaned is subjected to a second washing operation with an inorganic acid solution which removes the ammonia from the gas by formation of an ammonia salt solution. The salt solution is regenerated to recover the acid which is recirculated for reuse. The ammonia-containing solution, which may be the ammonia salt solution itself or a portion of the regenerated acid solution if it contains ammonia, is mixed with the diverted portion of the alkaline solution from the first washing step and the mixture thus formed is burned with a fuel gas and with air discharged from the oxidizing step at a temperature high enough to decompose the compounds in the mixture to nitrogen, carbon dioxide and water vapor which can be exhausted to the atmosphere. This is a continuation, of application Ser. No. 500,712, filed Aug. 26, 1974, now abandoned.