采用热重法在1173-1373K、全CO气氛条件下,对首钢烧结矿进行还原动力学实验,确定了还原反应的表观活化能,进而推断在还原反应的前期烧结矿还原速率均由界面反应控制,还原反应后期的控制环节为固相扩散.分别由未反应核模型和固相反应动力学模型,分段给出不同温度下控制环节突变的时间点;通过动力学公式计算,得出不同温度下的反应速率常数和固相扩散系数.利用光学显微镜观察了烧结矿在各还原阶段的微观形貌,验证了烧结矿还原动力学的机理,同时也证明了扩散控制阶段使用体积缩小的未反应核模型与实际情况是吻合的.
The reduction kinetics tests of Shougang sintering iron ores were performed from 1173 to 1373 K with 100% CO by thermogravimetric analysis, from which the values of reduction reaction apparent activation energy were determined. It could be predicted that the reduction of iron ore sinter is controlled by interracial chemical reaction at the initial stage, and solid-state diffusion at the final stage. According to the unreacted core model and the kinetic model of solid-state diffusion separately, the mutational timing of each rate controlling step was given at various temperatures by using phasewise analysis. The reaction rate constants and solid diffusion coefficients were derived from the kinetic formulas at various temperatures. Changes in morphology were analyzed with an optical microscope, and the mechanism of reduction kinetics was also verified. At the same time, the use of the volume-dwindled unreacted core model in the diffusion stage was proved to be feasible.