| 摘要 |
<p>A method of treating an aqueous alkaline alkali metal sulfide-containing liquor to remove the sulfur values therefrom. Broadly, the method comprises introducing an alkaline liquor containing at least about 60 mole % of an alkali metal sulfide into a neutralization zone. In the neutralization zone, it is intimately contacted and reacted with a sufficient amount of a gas containing a major amount of H2S to produce a product liquor of reduced alkalinity comprising a major amount of an alkali metal bisulfide and a minor amount of an alkali metal carbonate and bicarbonate. The product liquor is withdrawn from a neutralization zone and introduced into a carbonation zone. In the carbonation zone, the liquor is contacted with a sufficient amount of a dilute CO2-containing gas to produce a product stream comprising alkali metal carbonate and bicarbonate crystals substantially free of alkali metal sulfide and sulfite and an H2S-rich product gas. The H2S-rich product gas so produced is recovered, and about 35 to 65% of it is introduced into the neutralization zone. Advantageously, the remainder of the H2S-rich product gas is passed to a conventional Claus plant for recovery of the sulfur values therefrom. The product stream of alkali metal carbonate and bicarbonate is thermally decomposed to produce a CO2-rich offgas and an aqueous slurry containing a major amount of alkali metal carbonate and a minor amount of alkali metal bicarbonate. At least a part, and preferably all, of the CO2-rich offgas from the thermal decomposition is recovered for introduction into the carbonation zone. Additional CO2 is provided in the carbonation zone by the introduction therein of a waste gas containing less than about 35% CO2 by volume.</p> |
