高炉共处置固体废物低温段Pb Cd的吸附/冷凝动力学特征

利用管式回转炉和控温立式炉联用装置模拟炼铁高炉,对Pb、Cd在共处置过程中低温段的吸附/冷凝特性进行了研究,通过建立吸附/冷凝动力学模型,分析共处置过程中Pb、Cd在非热力学平衡状态下的迁移转化规律.结果表明:高炉共处置固体废物低温段对Pb、Cd的吸附/冷凝作用以冷凝为主.进入控温立式炉的重金属去向分三部分:①冷凝在管壁上,这部分的Pb、Cd分别占Pb、Cd入炉总量的42%～49%、45%～50%；②吸附在炉料上,其中Pb、Cd分别占各自入炉总量的23%～26%、23%～25%；③随烟气释放到空气中,这部分Pb、Cd分别占各自入炉总量的25%～35%、25%～32%.Pb、Cd在炼铁炉料上的吸附/冷凝量均随时间的增加而升高,随温度的升高而降低.炼铁炉料对Pb、Cd的吸附/冷凝动力学可采用双常数速率方程拟合,研究得到Pb、Cd的吸附/冷凝表观活化能分别为6.813、5.839 kJ/mol. 

Research on Condensation and Adsorption Kinetics of Pb and Cd at Low Temperatures during Co-Processing of Solid Wastes in Blast Furnaces

The condensation and adsorption characteristics of the blast furnace burden for Pb and Cd were researched through a coupling device of a rotary tube furnace and a vertical furnace with automatic temperature control. Meanwhile, a kinetics model was set up to explore the regularity of condensation and adsorption for Pb and Cd during the co-processing of solid wastes in blast furnaces. It illustrated the migration and transformation under the non-thermodynamic equilibrium state for heavy metals. The results showed that the behavior of Pb and Cd in the vertical furnace could be summarized as follows: some condensing on the wall of the vertical furnace, which accounted for approximately 42%-49% for Pb and 45%-50% for Cd； some were condensed or adsorbed on the blast furnace burden, occupying 23%-26% for Pb and 23%-25% for Cd； and some others were released into the atmosphere, which occupied 25%-35% for Pb and 25%-32% for Cd. The quantity of the condensation and adsorption of the iron-making furnace burden for Pb and Cd both increased with time, but decreased with temperature. The condensation and adsorption kinetics could be well described by the double constant rate equation, and the apparent activation energy of Pb was 6.813 kJ/mol, and Cd was 5.839 kJ/mol.