Kinetics of iron ore pellets reduced by H2N2 under non-isothermal condition

Bai, Ming; Hu, Long; Li, Liejun; Dong, Lixin; Ren, Subo; Zhao, Chang-Fu; Cheng, Jiayuan

doi:10.1016/j.ijhydene.2018.06.116

Cited by 17 publications

(8 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…More generally, a number of empirical relations for r [e.g., 61,62] deviate from the law of mass action. Experimental results for (2) [63,64] are consistent with the empirical form…”

Section: Reaction Modelsupporting

confidence: 76%

Chemo-Mechanical Phase-Field Modeling of Iron Oxide Reduction with Hydrogen

Yang¹,

Mianroodi²,

Ma³

et al. 2021

Preprint

View full text Add to dashboard Cite

e reduction of iron ore with carbon-carriers is one of the largest sources of greenhouse gas emissions in the industry, motivating global activities to replace the coke-based blast furnace reduction by hydrogen-based direct reduction (HyDR). Iron oxide reduction with hydrogen has been widely investigated both experimentally and theoretically.e process includes multiple types of chemical reactions, solid state and defect-mediated di usion (by oxygen and hydrogen species), several phase transformations, as well as massive volume shrinkage and mechanical stress buildup. However, studies focusing on the chemo-mechanical interplay during the reduction reaction in uenced by microstructure are sparse. In this work, a chemo-mechanically coupled phase-eld (PF) model has been developed to explore the interplay between phase transformation, chemical reaction, species di usion, large elastoplastic deformation and microstructure evolution. Energetic constitutive relations of the model are based on the system free energy which is calibrated with the help of a thermodynamic database. e model has been rst applied to the classical core-shell (wüstite-iron) structure. Simulations show that the phase transformation from wüstite to α-iron can result in high stress and rapidly decelerating reaction kinetics. Mechanical stresses can contribute elastic energy to the system, making phase transformation di cult. us slow reaction kinetics and low metallization are observed. However, if the stress becomes comparatively high, it can shi the shape of the free energy from a double-well to a single-well case, speed up the transformation and result in a higher reduction degree than the lower stress case.e model has been further applied to simulate an actual iron oxide specimen with its complex microstructure, characterized by electron microscopy.e experimentally observed microstructure evolution during reduction is well predicted by the model. e simulation results also show that isolated pores in the microstructure are lled with water vapor during reduction, an e ect which in uences the local reaction atmosphere and dynamics.

show abstract

“…More generally, a number of empirical relations for r [e.g., 61,62] deviate from the law of mass action. Experimental results for (2) [63,64] are consistent with the empirical form…”

Section: Reaction Modelsupporting

confidence: 76%

Chemo-Mechanical Phase-Field Modeling of Iron Oxide Reduction with Hydrogen

Yang¹,

Mianroodi²,

Ma³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Bai et al [7] Investigated the thermal reduction of pellets by H 2 . An un-reacted core and interfacial chemical reaction are reaction rate controlling steps in function of the operating temperature.…”

Section: Hydrogen Reduction Of Iron Oresmentioning

confidence: 99%

The Direct Reduction of Iron Ore with Hydrogen

Zhang

Nie

et al. 2021

Sustainability

View full text Add to dashboard Cite

The steel industry represents about 7% of the world’s anthropogenic CO2 emissions due to the high use of fossil fuels. The CO2-lean direct reduction of iron ore with hydrogen is considered to offer a high potential to reduce CO2 emissions, and this direct reduction of Fe2O3 powder is investigated in this research. The H2 reduction reaction kinetics and fluidization characteristics of fine and cohesive Fe2O3 particles were examined in a vibrated fluidized bed reactor. A smooth bubbling fluidization was achieved. An increase in external force due to vibration slightly increased the pressure drop. The minimum fluidization velocity was nearly independent of the operating temperature. The yield of the direct H2-driven reduction was examined and found to exceed 90%, with a maximum of 98% under the vibration of ~47 Hz with an amplitude of 0.6 mm, and operating temperatures close to 500 °C. Towards the future of direct steel ore reduction, cheap and “green” hydrogen sources need to be developed. H2 can be formed through various techniques with the catalytic decomposition of NH3 (and CH4), methanol and ethanol offering an important potential towards production cost, yield and environmental CO2 emission reductions.

show abstract

“…Un-reacted core model has been largely applied in previous investigations [13][14][15][16] to study the kinetics of chemical reactions which progress topochemically. In this model, four mechanisms can contribute to reaction progress: gas diffusion in micro pores of solid product, gas-solid interfacial chemical reaction, mass transfer, and a mix of these mechanisms.…”

Section: Kinetic Modelmentioning

confidence: 99%

H2-reduction Behavior of FeS-CaO Mixture during Microwave Heating

Amini

Ohno

Maeda

et al. 2019

Proceedings 17th International Conference on Microwave and High Frequency Heating

View full text Add to dashboard Cite

Microwave irradiation is an energy-efficient and a rapid-heating method to decrease the activation energy of chemical reactions via both thermal and non-thermal effects of microwave photons 1). Recently, hydrogen-reduction during microwave heating has been proposed for magnetite reduction to combine the advantages of microwave irradiation and using H2 as a reducing agent during iron production 2). In the present study, as a novel idea, the traditional microwave heating system was equipped with thermobalance to investigate the kinetics of H2-reduction of FeS-CaO mixture (FeS(s) + CaO(s) + H2(g) = Fe(s) + CaS(s) + H2O(g)) under microwave heating at 2.45 GHz to further mitigate CO2 emission and prevent SO2 release during iron production from a sulfide mineral. Microscope observations revealed that the un-reacted core model can be employed for such a kinetic study. Linearity (R2) of different rate-controlling mechanisms after a 10-minute reduction reaction demonstrated that the gas diffusion in micropores of reduced metallic Fe is a dominant rate-controlling mechanism while the interfacial chemical reaction is progressed rapidly. This is attributed to extraordinary effects of microwave irradiation on speeding up the chemical reactions 3), while the formation of Fe shell on the surface of FeS/FeO particles decreases the accessibility of gas to un-reacted parts, resulting in a lower rate of gas diffusion in micropores. Moreover, the diffusion coefficients (De) at 460, 570, and 750 °C were calculated from the plot of the gas diffusion, as illustrated in Fig. 1, wherein the X is reduction degree: where Wi (g) is the initial weight of the sample, Wt (g) is the weight of the sample after treatment for t seconds, Wht (g) is the weight change of the sample owing to the dehydration reaction, and WO (-) is the stoichiometric weight ratio of oxygen in the sample, which is 0.111. Consequently, the activation energy of 22.3 kJ.mol-1 was attained from the Arrhenius equation for the hydrogen-reduction reaction of FeS-CaO mixture under microwave heating.

show abstract

Kinetics of iron ore pellets reduced by H2N2 under non-isothermal condition

Cited by 17 publications

References 14 publications

Chemo-Mechanical Phase-Field Modeling of Iron Oxide Reduction with Hydrogen

Chemo-Mechanical Phase-Field Modeling of Iron Oxide Reduction with Hydrogen

The Direct Reduction of Iron Ore with Hydrogen

H2-reduction Behavior of FeS-CaO Mixture during Microwave Heating

Contact Info

Product

Resources

About