机械活化石墨-Fe_2O_3体系碳热还原反应的热力学分析

Thermodynamic Analysis for Carbothermal Reduction of Fe_2O_3 in Mechanically Activated Graphite-Fe_2O_3 Mixture

为揭示石墨的机械活化对石墨-Fe2O3体系碳热还原反应热力学的影响机理,以机械力储能作为活化程度的量度,探讨了石墨的储能对气化反应热力学、Fe2O3碳热还原反应热力学的影响。结果表明,随着储能的增加,石墨气化反应的平衡CO压力分数增大,从而影响石墨-Fe2O3体系的碳热还原热力学,具体为:石墨储能导致铁氧化物的碳热还原温度降低,使Fe2O3的各还原产物的热力学稳定区此消彼长。以临界储能19.05 kJ/mol为界限,石墨-Fe2O3体系中Fe2O3的碳热还原遵循两种不同顺序:储能低于19.05 kJ/mol时:Fe2O3→Fe3O4→FeO→Fe;储能高于19.05 kJ/mol时:Fe2O3→Fe3O4→Fe。

For the purpose of revealing the mechanism of mechanical activation of graphite impacting on thermodynamics in carbothermal reduction of graphite-Fe203 mixture, impacts that stored energy of graphite brought on thermodynamics in gasification and carbothermal reduction of Fe203 were studied with stored energy in mechanical activation as activation measurement indicator. Result showed that the equilibrium CO pressure fraction for gasification reaction increased with an increase in stored energy in graphite, which influenced the thermodynamics in carbothermal reduction of Fe203 in graphite-Fe203 mixture. That is, stored energy in graphite brought a decreased temperature in carbothermal reduction of all iron oxides, resulting in thermodynamically stable region changed for each product alter reduction of Fe203. With 19.05 kJ/mol as the critical stored energy, carbothermal reduction follows two different sequences ： Fe203--＋Fe304---FeO---Fe （ if stored ---Fe（ if stored energy is more than 19.05 kJ/mol）. of Fe/O3 in mechanically activated graphite-Fe203 energy is less than 19.05 kJ/mol） , Fe203----Fe304