Provided is a hydrolysis reaction device for dechlorination and decyanation of blast furnace gas, including a tower body, where a top of the tower body is provided with an air inlet channel, and a bottom of the tower body is provided with an air outlet channel, and functional zones are arranged in the tower body. The functional zones are sequentially an air inlet zone, a first protective agent zone, a first transition zone, a second protective agent zone, a second transition zone, a hydrolysis zone and an air outlet zone along a gas direction, and adjacent functional zones are communicated. Feed holes and discharge holes are uniformly arranged on an outer side surface of the tower body. Gas in a tower radially passes through the protective agent zones and the hydrolysis zone.

A system for reducing SO.sub.2 emissions comprises a hydrogenation reactor, a tail gas cooler, a contact condenser, a hydrolysis reactor, and an absorber. The hydrogenation reactor is configured to receive a Claus tail gas and convert at least a portion of SO.sub.2 in the Claus tail gas to H.sub.2S to produce a hydrogenated Claus tail gas stream. The hydrolysis reactor is configured to convert at least a portion of COS to H.sub.2S. The absorber comprises an amine-based solvent and is configured to absorb at least a portion of the H.sub.2S and recycle the H.sub.2S to the Claus plant.

A process for simultaneous removal of hydrogen sulfide (H.sub.2S) and heavy metals from mixture includes charging a contaminated aqueous composition containing heavy metal ions to a reactor. The process also includes passing a H.sub.2S-containing gas composition via a plurality of gas spargers through the contaminated aqueous composition present in the reactor to form a H.sub.2S-containing contaminated aqueous composition and a purified gas composition. The process further includes reacting the H.sub.2S from the H.sub.2S-containing contaminated aqueous composition with the heavy metal ions in the H.sub.2S-containing contaminated aqueous composition to form a metal sulfide precipitate in a metal-sulfide-containing contaminated aqueous composition. In addition, the process includes at least partially introducing the metal-sulfide-containing contaminated aqueous composition to a solid-liquid separator and removing the metal sulfide precipitate from the metal-sulfide-containing contaminated aqueous composition to form a purified aqueous composition.