Effect of CO₂ on the Desulfurization of Sintering Flue Gas with Hydrated Lime

The effect of carbon dioxide (CO₂) on the desulfurization of sintering flue gas with hydrate (Ca(OH)₂) as an absorbent was investigated, and the formation of calcium carbonate (CaCO₃) and its effect on the desulfurization was discussed. The competitive relationship between carbon dioxide (CO₂) and sulfur dioxide (SO₂) with the deacidification agent in sintering flue gas is discussed thermodynamically, showing that sulfates are more likely to be generated under high oxygen potential conditions and that SO₂ reacts more preferentially than CO₂ under a thermodynamic standard state. The amount of produced CaCO₃ increases under the condition that the CO₂ concentration is absolutely dominant to SO₂ in the sintering flue gas atmosphere. The effect of temperature, humidity and CO₂ concentration on the desulfurization of Ca(OH)₂ are discussed experimentally. The increasing temperature is not conducive to desulfurization, and the humidity can promote desulfurization, while excessive humidity could inhibit desulfurization. The suitable relative humidity is 20%. In situ generated calcium carbonate has a certain desulfurization effect, but the desulfurization effect is not as good as Ca(OH)₂. However, a large proportion of CaCO₃ was produced in the desulfurization ash under the condition that CO₂ concentration was absolutely dominant to SO₂ in the sintering flue gas atmosphere.