コークス炉ガスの微量成分を利用する化成品合成法の研究 (II)

脱硫廃液からのスルフジミン酸アンモニヴム製造

抄録

In the production of coke, substantial volumes of effluent are generated from a liquid redox desulfurization plant of coke oven gas. The effluent typically contains NH4SCN and (NH₄) ₂S₂O₃ in high concentrations, and has generally been converted into H₂SO₄, (NH₄) ₂SO₄ or CaSO₄·2H₂O by means of burning or wet oxygen oxidation under severe conditions.
A method was developed for production of NH4SO3NH2 from the effluent.
1. The effluent is treated with wet oxygen oxidation under mild neutral conditions where (NH₄) ₂S₂O₃ is selectively oxidized to NH₄SO₃NH₂ and (NH₄) ₂SO₄. The ratio of NH₄SO₃NH₂ to (NH₄) ₂SO₄ is changed with the concentration of NH₃ and S₂O₃^2-.
2. The resulting solution is oxidized again under more intensive conditions to transform NH4SCN into (NH₄) ₂SO₄.
3. After the oxidation of effluent, the solution is concentrated to saturation point of NH4SO3NH2 under reduced pressure at 70-80t in order to crystallize (NH₄) ₂SO₄. The crystallized (NH₄) ₂SO₄ is filtered and washed with water at the same temperature.
4. The filtrate is cooled to crystallize NH₄SO₃NH₂, which is separated by filtration.
5. The purity of NH₄SO₃NH₂ obtained is about 97%, and the recovery is about 98%. This process affords a commercial procedure for the preparation of NH₄SO₃NH₂ from the desulfurization effluent.