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.

A deacidification agent was prepared through incipient-wetness impregnation method, by using activated γ-Al 2 O 3 as the carrier material to loaded Na 2 CO 3 , which can simultaneously remove HCl, H 2 S and carbonyl sulfur (COS) from blast furnace gas. The pretreatment at temperature of 550 °C can improve the dechlorination performance. The maximum breakthrough time, penetration chlorine capacity, and the highest utilization rate of active component of deacidification agents were 47.5 h, 11.59%, and 75.6%, respectively. The deacidification agents can not only be used as active component to remove H 2 S from blast furnace gas, but also can act as a COS hydrolysis catalyst. HCl has no obvious effect on the desulfurization performance, while the sulfide gases inhibited the dechlorination process. The synergistic desulfurization and dechlorination experiment results show that the highest removal efficiencies for HCl, H 2 S and COS by the prepared deacidification agents were all above 99%.