机械活化石墨-Fe2O3体系碳热还原反应的热力学分析

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。

Thermodynamic Analysis for Carbothermal Reduction ofFe2O3 in Mechanically Activated Graphite-Fe2O3 Mixture

For the purpose of revealing the mechanism of mechanical activation of graphite impacting on thermodynamics in carbothermal reduction of graphite-Fe₂O₃ mixture, impacts that stored energy of graphite brought on thermodynamics in gasification and carbothermal reduction of Fe₂O₃ 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 Fe₂O₃ in graphite-Fe₂O₃ 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 after reduction of Fe₂O₃. With 19.05 kJ/mol as the critical stored energy, carbothermal reduction of Fe₂O₃ in mechanically activated graphite-Fe2O3 follows two different sequences: Fe₂O₃→Fe₃O₄→FeO→Fe(if stored energy is less than 19.05 kJ/mol), Fe₂O₃→Fe₃O₄→Fe(if stored energy is more than 19.05 kJ/mol).