WET REMOVAL OF HYDROGEN SULFIDE

PURPOSE:To enhance an H2S-removal ratio, to reduce the formation of a byproduct salt and to enhance the purity of recovered sulfur, by using a ferric salt chelate with a specific pH-value containing a mixture consisting of hydroxyacetic acid and citric acid and/or formic acid as a chelate agent. CONSTITUTION:A chelate agent prepared by mixing hydroxyacetic acid and citric acid and/or formic acid is added to a ferrous salt to adjust the pH thereof to 7-8 and the resulting mixture is oxidized by air to form an aqueous ferric salt chelate solution of which the pH is, in turn, further adjusted to 5.5-8 to obtain an absorbing liquid. H2S-containing gas is quided to an absorbing tower 2 to be adsorbed with the absorbing liquid from a line 3 and exhausted as purified gas. The Fe2S3 suspension formed in the absorbing tower 2 is sent to a regeneration tank 6 and regenerated by air 7 to form sulfur and a ferric salt chelate. The regenerated absorbing liquid is sent to a separator 10 to separate suspended sulfur and the sulfur removed absorbing liquid is sent to the absorbing tower 2 from the line 3 to be re-utilized therein after the pH thereof is adjusted to 5.5-8.