Fe_2O_3-SiO_2体系深度还原过程动力学

Kinetics During Coal-based Reduction Process of Fe_2O_3-SiO_2 System

采用等温法和非等温法,分析了Fe2O3-SiO2体系深度还原过程的动力学.等温法试验表明,在一定范围内升高还原温度,有利于焦炭气化反应的进行,进而增加反应的还原度和还原速率.等温法确定的Fe2O3-SiO2体系深度还原反应符合Avrami-Erofeev模型,金属铁颗粒的成核及长大是还原过程的限制性环节,反应的表观活化能为235.33 kJ/mol,指前因子为3.22×107min-1.非等温法试验表明,该体系深度还原反应在温度达到400℃之后开始发生,700℃之后还原反应速度加快,最终反应趋于平衡.非等温法确定的主要反应阶段的表观活化能为238.66 kJ/mol,指前因子为1.04×107min-1.

The kinetics during coal-based reduction of Fe2O3-SiO2 system was studied isothermally and non-isothermally. The isothermal experiments showed that reduction degree and reduction rate increased with the rise of reduction temperature in a certain range, which was beneficial to the gasification of coal. The coal-based reduction reaction of Fe2O3-SiO2 system accorded with Avrami-Erofeev kinetic model, and the reaction was controlled by the process of nucleation and development of iron particles. The apparent activation energy and pre-exponential of isothermal coal-based reduction process were 235.33 kJ/mol and 3.22×10^7min respectively. The non-isothermal experiments showed that coal-based reduction reaction started at 400 ℃ and accelerated after 700℃ then reached equilibrium eventually. The apparent activation energy and pre-exponential of main reaction stage were 238.66 kJ/mol and 1.04 ×10^7 mint determined by non-isothermal method. Key words： coal-based reduction; Fe203-SiO2 system; isothermal method; non-isothermal method; kinetics