VERFAHREN ZUR AUFARBEITUNG EINER ALKALIMETALLSULFID-LOESUNG

摘要

A method of treating an aqueous alkali metal sulfide-containing liquor to remove the sulfur values therefrom. Broadly, the method comprises introducing an alkaline liquor containing an alkali metal sulfide into a neutralization zone where it is intimately contacted and reacted with a sufficient amount of a gas containing a major amount of H2S and a minor amount of CO2 to produce a product liquor of reduced alkalinity consisting essentially of a slurry of alkali metal bicarbonate and alkali metal bisulfide. The product liquor is withdrawn from the neutralization zone and introduced into a carbonation zone where it is contacted with a sufficient amount of a CO2-containing gas to produce a product stream comprising a slurry of alkali metal bicarbonate crystals substantially free of alkali metal bisulfide and an H2S-rich product gas containing a minor amount of CO2. The H2S-rich product gas so produced is recovered, and about 40% to 60% of it is introduced into the neutralization zone. The product stream of alkali metal bicarbonate is thermally decomposed to produce a CO2-rich offgas and a solution consisting essentially of alkali metal carbonate. The CO2 -rich offgas from the thermal decomposition is recovered for introduction into the carbonation zone along with additional CO2 obtained from a waste gas usually containing less than about 35% CO2 by volume.