Kinetics of magnetite oxidation under non-isothermal conditions
来源期刊：International Journal of Minerals Metallurgy and Materials2017年第5期
论文作者：Aref Sardari Eskandar Keshavarz Alamdari Mohammad Noaparast Sied Ziaedin Shafaei
文章页码：486 - 492
摘 要：Oxidation of magnetite concentrates,which occurs during the pellet induration process,must be deeply understood to enable the appropriate design of induration machines.In the present paper,the kinetics of the magnetite oxidation reaction was studied.Primary samples were obtained from the Gol-e-Gohar iron ore deposit.Magnetic separation and flotation decreased the sulfur content in the samples to be approximately 0.1wt%.Thermogravimetric analysis was used to measure mass changes during the oxidation of magnetite and,consequently,the conversion values.The aim of this study was to use isoconversional methods to calculate the kinetic parameters.The Coats–Redfern method was also used to obtain the activation energy.Thermogravimetric analyses were run at three different heating rates.The Coats–Redfern results were too ambiguous for a meaningful interpretation.In the case of the isoconversional method,however,the mean activation energy and pre-exponential factor of the oxidation reaction were obtained as 67.55 kJ and 15.32 × 108 min-1,respectively.Such a large activation energy implies that temperature strongly affects the reaction rate.The oxidation reaction exhibits a true multi-step nature that is predominantly controlled by chemical reaction and diffusion mechanisms.
Aref Sardari1，Eskandar Keshavarz Alamdari2，Mohammad Noaparast3，Sied Ziaedin Shafaei3
1. Department of Mining Engineering,Science and Research Branch,Islamic Azad University2. Department of Mining and Metallurgical Engineering,Amirkabir University of Technology3. School of Mining Engineering,University of Tehran
摘 要：Oxidation of magnetite concentrates,which occurs during the pellet induration process,must be deeply understood to enable the appropriate design of induration machines.In the present paper,the kinetics of the magnetite oxidation reaction was studied.Primary samples were obtained from the Gol-e-Gohar iron ore deposit.Magnetic separation and flotation decreased the sulfur content in the samples to be approximately 0.1wt%.Thermogravimetric analysis was used to measure mass changes during the oxidation of magnetite and,consequently,the conversion values.The aim of this study was to use isoconversional methods to calculate the kinetic parameters.The Coats–Redfern method was also used to obtain the activation energy.Thermogravimetric analyses were run at three different heating rates.The Coats–Redfern results were too ambiguous for a meaningful interpretation.In the case of the isoconversional method,however,the mean activation energy and pre-exponential factor of the oxidation reaction were obtained as 67.55 kJ and 15.32 × 108 min-1,respectively.Such a large activation energy implies that temperature strongly affects the reaction rate.The oxidation reaction exhibits a true multi-step nature that is predominantly controlled by chemical reaction and diffusion mechanisms.
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