Research on the Carbothermic Reduction Kinetic of Oolitic Hematite with Graphite at 1 173~1 473 K

The carbothermic reduction kinetics of oolitic hematite with graphite was investigated at temperature of 1 173~1 373 K by using thermogravimetric method.The effects of temperature on reduction degree and reaction rate were studied.The reduction reactions were fitted to several solid-state reaction mechanisms.The reaction restrictive mechanisms at different stage were analyzed.The phase composition,morphology and elementary composition of reduced samples were characterized by using XRD,SEM and EDX techniques.The research results show that the reduction degree and reaction rate increase with the increased temperature,and the reaction rates firstly increase and then decrease with the increase of reduction degree.At 1 173~1 273 K and 1 273~1 373 K,the carbothermic reductions are well fit to the interface chemical reaction model of 1-(1-α)^1/3 and the Jander model of [1-(1-α)^1/3]²,respectively.The corresponding activation energies are 60.657 and 301.662 kJ/mol respectively.The measured phase composition and microstructure for reduced samples are well consistent with those of reaction kinetic mechanism analysis.