A feed stream is heated to a preheat temperature. The feed stream includes hydrogen sulfide. After heating the feed stream, at least a portion of the hydrogen sulfide in the feed stream is converted into hydrogen and sulfur to form a mixed product stream. The mixed product stream includes the hydrogen, the sulfur, and a remaining, unconverted portion of the hydrogen sulfide. The preheat temperature is a temperature that is sufficiently hot to maintain a desired reaction temperature while converting at least the portion of the hydrogen sulfide in the feed stream into hydrogen and sulfur. At least a portion of the mixed product stream is cooled to condense the sulfur to form a sulfur stream. The sulfur stream includes the sulfur that has condensed from the portion of the mixed product stream.

A hydrogen sulfide purification method includes removing a lithium raw material by using an ejector that utilizes a cleaning liquid as a driving fluid, from a mixed gas containing unreacted hydrogen sulfide and the lithium raw material which is generated in a process of producing lithium sulfide by a reaction of hydrogen sulfide and the lithium raw material.

A hydrogen sulfide purification method includes removing a lithium raw material by using a cyclone, from a mixed gas containing unreacted hydrogen sulfide and the lithium raw material which is generated in a process of producing lithium sulfide by a reaction of hydrogen sulfide and the lithium raw material.

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.