Inhibition Mechanism of MgO Addition on High‐Temperature Oxidation of Magnetite: Density Functional Theory and Ab Initio Molecular Dynamics Methods Joint Research and Experimental Verification

Abstract

In order to investigate and analyze the effect of MgO gangue on the surface adsorption and oxidation behavior of magnetite, the physicochemical properties of substances in the magnetite oxidation process are investigated in this study by using thermogravimetric experiments, density functional theory, and ab initio molecular dynamics methods (AIMD) methods. The oxidation mechanism of magnetite and the inhibition mechanism of magnesium oxide on the oxidation properties of magnetite are elucidated. The results of the thermogravimetric experimental study show that the initial oxidation temperature of magnetite tends to increase with the increase of MgO content. At the same time, the presence of MgO leads to the migration of oxidation reactions to the high‐temperature region. AIMD study shows that the presence of the gangue element Mg prolongs the adsorption and dissociation time of O2 molecules on the surface and reduces the interfacial chemical reaction rate of Fe3O4. Moreover, the chemical bonds formed in the system after doping Mg atom are more stable, which is not conducive to the migration of oxygen atoms between Fe3O4 crystal structures, thus affecting the comprehensive oxidation performance of minerals.

Oxidation Mechanism of Ti‐Doped Fe3O4 (111): A Combined DFT and AIMD Study with an Experimental Verification

“…In order to quantitatively characterize the temperature characteristics of the oxidation reaction of different types of magnetite, the oxidation starting temperature (T i , °C), rapid oxidation temperature (T f , °C), and oxidation termination temperature (T e , °C) were defined as the oxidation characteristic temperatures of magnetite. [17] In order to quantitatively characterize the oxidation performance of magnetite powder, based on the comprehensive evaluation index of pulverized coal combustion characteristics, [18][19][20] a comprehensive evaluation index S O of magnetite oxidation characteristics was proposed except for the oxidation characteristic temperature. [17] For the oxidation process of magnetite, the initial stage of oxidation can be considered as the kinetic limiting condition for the oxidation chemical reaction.…”

“…[17] In order to quantitatively characterize the oxidation performance of magnetite powder, based on the comprehensive evaluation index of pulverized coal combustion characteristics, [18][19][20] a comprehensive evaluation index S O of magnetite oxidation characteristics was proposed except for the oxidation characteristic temperature. [17] For the oxidation process of magnetite, the initial stage of oxidation can be considered as the kinetic limiting condition for the oxidation chemical reaction. Therefore, the Arrhenius equation can be used to represent the control of the oxidation rate according to the kinetic factors of the chemical reaction and is derived and simplified to obtain the S O calculation equation as shown in Formula (1).…”

“…XRD-Rietveld method map fitting analysis of magnetite. a) TiO 2 = 0%, [17] b) TiO 2 = 1%, c) TiO 2 = 2%, d) TiO 2 = 3%. In general, the binding energy of chemically adsorbed oxygen on the surface of minerals and surface lattice oxygen (O s ) is higher than that of lattice oxygen (O n ).…”

“…The effect of TiO 2 on the oxidation performance of magnetite. a) TiO 2 = 0%, [17] b) TiO 2 = 1%, c) TiO 2 = 2%, d) TiO 2 = 3%.…”

“…XPS spectrum of Fe 2p orbital of magnetite. a) 1-1 magnetite (TiO 2 = 0% [17] ), b) 2-3 magnetite (TiO 2 = 3%). break.…”