Multistep Reduction Kinetics of Fine Iron Ore with Carbon Monoxide in a Micro Fluidized Bed Reaction Analyzer

Chen, Hongsheng; Zheng, Zhong; Chen, Zhiwei; Yu, Wenzhou; Yue, Junrong

doi:10.1007/s11663-016-0883-7

Cited by 34 publications

(13 citation statements)

References 63 publications

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“…[39] Several authors have reported a high number of well-fitting models using the conventional model-fitting method. [6,24,[44][45][46][47][48][49]…”

Section: A Conventional Model-fitting Methodsmentioning

confidence: 99%

“…Various authors have used a similar approach to analyze the limiting mechanisms of the reduction of iron oxides. [24,[44][45][46]48,55,56,[58][59][60] Due to the boundaries chosen for the kinetic exponents n 1;2;3 , the fitting proceeds mainly by varying the weight factors w 1;2;3 between 0 and 1, where the sum of all three is 1, and by varying the nucleation rate constants a 1;2;3 between 10EÀ08 and 1. The starting values were varied within the boundaries of the fitting procedure, where the resulting fitting parameters did not vary significantly with different initial choices.…”

Section: ½9mentioning

confidence: 99%

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Influence of a Prior Oxidation on the Reduction Behavior of Magnetite Iron Ore Ultra-Fines Using Hydrogen

Wolfinger

Spreitzer

Zheng

et al. 2021

Metall Mater Trans B

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The reduction behavior of raw and prior-oxidized magnetite iron ore ultra-fines with hydrogen was investigated. Reduction tests were conducted with a thermogravimetric analyzer in a temperature range from 873 K to 1098 K at 1.1 bar absolute, using hydrogen as reducing gas. The experimental results show that a prior oxidation of the magnetite has a positive effect on the reduction behavior because of changing morphology. The apparent activation energies show a turnaround to negative values, depending on the prior oxidation and degree of reduction. A multi-step kinetic analysis based on the model developed by Johnson–Mehl–Avrami was used to reveal the limiting mechanism during reduction. At 873 K and 948 K, the reduction at the initial stage is controlled by nucleation and chemical reaction and in the final stage by nucleation only, for both raw and pre-oxidized magnetites. At higher temperatures, 1023 K and 1098 K, the reduction of raw magnetite is mainly controlled by diffusion. This changes for pre-oxidized magnetite to a mixed controlled mechanism at the initial stage. Processing magnetite iron ore ultra-fines with a hydrogen-based direct reduction technology, lower reduction temperatures and a prior oxidation are recommended, whereby a high degree of oxidation is not necessary.

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“…[39] Several authors have reported a high number of well-fitting models using the conventional model-fitting method. [6,24,[44][45][46][47][48][49]…”

Section: A Conventional Model-fitting Methodsmentioning

confidence: 99%

Section: ½9mentioning

confidence: 99%

Influence of a Prior Oxidation on the Reduction Behavior of Magnetite Iron Ore Ultra-Fines Using Hydrogen

Wolfinger

Spreitzer

Zheng

et al. 2021

Metall Mater Trans B

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show abstract

“…In the last period, the reduction rate decreases due to the growing iron nuclei impinging on one another . Chen et al investigated the reduction of hematite fines in a fluidized bed reactor at different temperatures using CO as the reducing agent. They also found that the conversion rate increases with temperature.…”

Section: Rate‐limiting Mechanism During Iron Oxide Reductionmentioning

confidence: 99%

“…In general, the rate constant and the apparent activation energy of isothermal gas–solid reactions can be defined as follows

\frac{d x}{d t} = k (T) \times f (x)

g (x) = {140% \int}_{0}^{x} \frac{d x}{f false(x false)} = k (T) \times t

where k(T) represents the Arrhenius rate constant, which shows the dependence of reduction rate on temperature, and f(x) denotes a mathematical function that depends on the kinetic model used and remains constant at a certain temperature and gaseous concentration . For reaction kinetics under isothermal conditions, Equation can be integrated to get the integral expression g(x) . Using experimental data for conversion over time in Equation , the rate‐limiting step can be evaluated via a model‐fitting method.…”

Section: Role Of Apparent Activation Energymentioning

confidence: 99%

Reduction of Iron Oxides with Hydrogen—A Review

Spreitzer

Schenk

2019

steel research int.

383

161

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This review focuses on the reduction of iron oxides using hydrogen as a reducing agent. Due to increasing requirements from environmental issues, a change of process concepts in the iron and steel industry is necessary within the next few years. Currently, crude steel production is mainly based on fossil fuels, and emitting of the climate‐relevant gas carbon dioxide is integral. One opportunity to avoid or reduce greenhouse gas emissions is substituting hydrogen for carbon as an energy source and reducing agent. Hydrogen, produced via renewable energies, allows carbon‐free reduction and avoids forming harmful greenhouse gases during the reduction process. The thermodynamic and kinetic behaviors of reduction with hydrogen are summarized and discussed in this review. The effects of influencing parameters, such as temperature, type of iron oxide, grain size, etc. are shown and compared with the reduction behavior of iron oxides with carbon monoxide. Different methods to describe the kinetics of the reduction progress and the role of the apparent activation energy are shown and proofed regarding their plausibility.

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“…In comparison to TGA, the MFBRA features: (1) high rates of heat and mass transfer, (2) capability of online instantaneously pulse feeding and super‐fast heating of powder reactant to bed temperature, (3) negligible external diffusion inhibition, and (4) fast on‐line measurement 19,20 . Until now, it has been successfully applied to study the mechanisms and kinetics of a variety of gas–solid reactions, including pyrolysis, 22–24 gasification, 14,25,26 combustion 27,28 of coal, biomass, oil shale and chars, calcination, 11,20 and reduction 29–32 of various materials as well as catalytic gas–solid reactions, 33,34 etc. These applications have demonstrated that MFBRA is effective, reliable, and adaptable to various gas–solids reactions.…”

Section: Introductionmentioning

confidence: 99%

Acquiring real kinetics of reactions in the inhibitory atmosphere containing product gases using micro fluidized bed

et al. 2021

Self Cite

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This study proposed an isotope‐tagging method to investigate reactions under the atmosphere of product gas. To illustrate this method, the calcination kinetics of calcium carbonate Ca13CO3 in CO2 atmospheres were investigated by monitoring 13CO2 produced using a micro fluidized bed reaction analyzer (MFBRA). The results demonstrated that the presence of CO2 in reaction atmosphere increases the apparent activation energy. The increase in the apparent activation energy is, however, significantly overestimated by the thermogravimetric analyzer (TGA) because of the excessive suppression by stagnated product gas inside the sample crucible. Comparatively, the apparent activation energy increases with CO2 from the MFBRA due primarily to the thermal equilibrium limitation, because the gas diffusion in the MFBRA is essentially eliminated. It is thus concluded that the MFBRA is quite capable of acquiring the real kinetics of reactions in such inhibitory atmospheres.

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Multistep Reduction Kinetics of Fine Iron Ore with Carbon Monoxide in a Micro Fluidized Bed Reaction Analyzer

Cited by 34 publications

References 63 publications

Influence of a Prior Oxidation on the Reduction Behavior of Magnetite Iron Ore Ultra-Fines Using Hydrogen

Influence of a Prior Oxidation on the Reduction Behavior of Magnetite Iron Ore Ultra-Fines Using Hydrogen

Reduction of Iron Oxides with Hydrogen—A Review

Acquiring real kinetics of reactions in the inhibitory atmosphere containing product gases using micro fluidized bed

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