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转炉炼钢过程存在CaCO_3在炉内分解的现象,且温度远高于传统的石灰窑煅烧温度。采用恒温热重分析的方法研究了转炉炼钢前期温度下CaCO_3分解反应动力学,并与石灰窑煅烧温度下的结果进行了对比。研究结果表明,随着温度的升高,CaCO_3的分解速率急剧加快。当温度由1 100℃升高到1 400℃,CaCO_3分解的反应性指数由0.087升高到0.16,增长率为84%;反应速率常数从0.272升高到0.475,增长率为75%。因此,CaCO_3在转炉内分解反应的速率远高于石灰窑。1 100~1 400℃温度范围内,粒度小于200目的 CaCO_3在空气中的分解反应最符合A3型动力学机理(随机成核,Avrami方程Ⅱ),其指前因子为0.373/s,活化能为29 910.1 J/mol,由此推导了CaCO_3分解率随温度和时间变化的表达式。
The process of converter steelmaking has the phenomenon of CaCO_3 decomposition in the furnace, and the temperature is much higher than the calcination temperature of the traditional lime kiln. The kinetics of CaCO_3 decomposition at the early stage of converter steelmaking was studied by the method of thermo-gravimetric thermogravimetric analysis (TGA), and compared with the calcination temperature of lime kiln. The results show that with the increase of temperature, the decomposition rate of CaCO_3 rapidly increases. When the temperature increased from 1 100 ℃ to 1400 ℃, the reactivity index of CaCO_3 decomposition increased from 0.087 to 0.16, the growth rate was 84%. The reaction rate constant increased from 0.272 to 0.475, the growth rate was 75%. Therefore, the decomposition rate of CaCO_3 in the converter is much higher than that of lime kiln. In the temperature range of 100 ~ 1400 ℃, the decomposition reaction of CaCO 3 in air with particle size less than 200 is the most suitable for the A3 kinetic mechanism (random nucleation, Avrami equation Ⅱ) with a pre-exponential factor of 0.373 / s and an activation energy of 29 910.1 J / mol, which deduced the expression of CaCO 3 decomposition rate with temperature and time.