铁矿烧结过程料层对SO_2的吸附作用机理

Mechanism of SO_2 adsorption on mixture bed layer during iron ores sintering

铁矿烧结烟气中的SO2来源于含铁原料和燃料中硫在高温下的分解和氧化,而烧结混合料对SO2具有强烈的吸附作用.本文采用动态法研究了烧结混合料对SO2的吸附机理和吸附动力学,结果表明在低碱度和低吸附量时,表现吸附速度与吸附量呈线性关系,吸附动力学曲线遵从一级反应动力学方程;并且在吸附初期,当混合料碱度越高且CaO来源于生石灰时,均有利于烧结混合料对烟气中SO2的多相反应吸附.

The emission of SO2 rises to a peak value rapidly before the sintering end point and then declines dramatically no matter how the parameters of sinter technology and the properties of raw material change. The emission of SO2 is controlled by the mechanism of transfer and cycling enrichment which consists of sulphide and sulphate pyrogenation formation—sinter bed adsorption—repyrogenation—desorption of SO2.It is revealed that the self-sustaining characteristics of SO2 emission is resulted from the selective adsorptionof SO2 by the sinter bed.While in iron ores sintering, SO2 in the flue gas originates from the pyrogenation and oxidation of sulphur compounds in iron ores and coke breeze at high temperature,and the sinter mixture has a strong adsorption capacity for SO2. In this paper the adsorption mechanism and kinetics of SO2 on sinter bed were studied by adopting dynamic methods. The results show that the relationship between apparent adsorption rate and adsorption capacity agrees linearly in the low adsorption amount at low basicity of sinter mixture,and the adsorption kinetic curve obeys with the first order reaction kinetics equation. Meanwhile, at the initial stage of adsorption, the multiphase reaction was enhanced by an increase of basicity, especially with CaO originating from burnt lime.