Modelling of heterogeneous gas-solid reactions

Papanastassiou, D. A.; Bitsianes, G.

doi:10.1007/bf02648700

Cited by 46 publications

(10 citation statements)

References 13 publications

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“…[19] This model was selected instead of the usual ''shrinking core'' approximation, because it could track the oxidation of magnetite in the individual concentric layers of the pellet. The deficiency of this model compared to the normal shrinking core model is that it is more computationally intensive.…”

Section: B Reactionsmentioning

confidence: 99%

Interactions between Magnetite Oxidation and Flux Calcination during Iron Ore Pellet Induration

Firth

Garden

2008

Metall Mater Trans B

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Many chemical reactions take place simultaneously during the induration of iron ore pellets produced from magnetite concentrates. Two of the most important are magnetite oxidation and calcination of carbonate fluxes. The first reaction consumes oxygen diffusing into the pellet, while the second reaction produces carbon dioxide that must diffuse out of the pellet. A mathematical model combining the two reactions and gaseous diffusion within the pellet has been developed to quantify the interaction between the two reactions. This combined mathematical model showed that current induration plant mathematical models for the mass and energy balance around a pellet furnace are inaccurate in treating magnetite oxidation and flux calcination as separate reactions. Assuming separate reactions can lead to an error of up to 20 pct conversion of magnetite at the end of the preheat stage. This combined mathematical model, confirmed by experiments with single pellets, also demonstrated that calcination of fluxes also tends to follow a ''shrinking core'' model rather than reacting simultaneously across the pellet, as existing whole plant models assume. Modifying induration plant mathematical models in accordance with the findings of this article could lead to further savings in energy costs for pellet plants.

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Section: B Reactionsmentioning

confidence: 99%

Interactions between Magnetite Oxidation and Flux Calcination during Iron Ore Pellet Induration

Firth

Garden

2008

Metall Mater Trans B

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“…The behaviour of heterogeneous gas-solid reactions became a source of challenge for many researchers. Papanastassiou and Bitsianes [22,23] investigated the oxidation of magnetite. Specifically designed experiments were performed to better comprehend magnetite oxidation.…”

Section: Evaporationmentioning

confidence: 99%

Modelling of a Pilot Scale Iron Ore Pellet Induration Furnace

Küçükada¹,

Thibault²,

Hodouin³

et al. 1994

Canadian Metallurgical Quarterly

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In this work, a mathematical model of the pilot scale iron ore pellet induration furnace is presented. The validity of the model has been verified by performing separate experiments of subprocesses: drying, firing and cooling. The experiments were performed in such a way that the phenomena of heat transfer, drying and coke combustion could be studied separately. To do this, the green pellets were first dried, then heated to elevated temperatures at which the coke combustion commences and the pellet strength begins to increase. Finally, the pellets were cooled by passing ambient air across the bed.The pellet induration model is based on the equations describing the phenomena of heat and mass transfer, gas flow, drying and combustion of coke. The experiments and the pellet induration cycle were simulated by solving the differential equations. The pellet bed was divided into differential height elements and the phenomenological equations were solved by numerical methods. This type of model is very useful in many applications such as designing of new plants, evaluating the effectiveness of different process parameters and training the operators and engineers. In addition, it can also serve as a module for on-line control of the moving grate furnace operations. ) pellet or gas humidity (kg m-3 pellet or gas) axial distance or bed height within the pot-grate (m).

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“…Prior studies were done to understand the oxidation phenomenon of magnetite pellet, and various conceptual models were formulated. [8][9][10][11][12][13][14][15] These postulated models are synonymous to the non-catalytic heterogeneous gas-solid reaction models for porous solids, namely, shrinking core model, pore diffusion, and the grain model. Researchers have adopted one of these models and investigated the reaction kinetics of porous solids experimentally, mostly limited to the pellet scale.…”

Section: Introductionmentioning

confidence: 99%

Developing the Oxidation Kinetic Model for Magnetite Pellet

Kumar

Nurni

Ahmed

et al. 2018

Metall Mater Trans B

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Oxidation is a vital phenomenon for magnetite pellets in their excursion through the furnace during induration. One of the prerequisites for magnetite pellets to achieve homogeneously structured good quality pellets is to have complete oxidation before sintering begins. Partially oxidized magnetite pellets, upon sintering, might result in inhomogeneous structured pellets which could be detrimental to pellet quality. It is necessary to understand the mechanisms responsible for magnetite oxidation, and hence, it is intended in this study to investigate experimentally as well as develop a mathematical model based on oxidation kinetics. Oxidation of pellets is largely influenced by the oxidation kinetics of particles and hence should be studied at particle as well as at pellet scale. The principles of the Grain Model have been adopted to develop the Oxidation Model at pellet scale, whereas the particles' oxidation follows the Avrami Kinetic Model. Isothermal oxidation experiments performed Thermogravimetric Analyzer showed that oxidation rate of magnetite at pellet scale contained two peaks. They were complemented well by oxidation rates predicted from the model. Further, the pellet was investigated microstructurally at pellet and particle scale to substantiate the findings from the experiments and the model. The oxidation model developed is used to predict the progression of oxidation in the magnetite pellet with respect to the reaction time at three different temperatures (873 K, 973 K, and 1073 K (600°C, 700°C, and 800°C)) and at four levels of oxygen (0.21, 0.30, 0.60, and 1.00 atm) in the oxidizing gas.

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Modelling of heterogeneous gas-solid reactions

Cited by 46 publications

References 13 publications

Interactions between Magnetite Oxidation and Flux Calcination during Iron Ore Pellet Induration

Interactions between Magnetite Oxidation and Flux Calcination during Iron Ore Pellet Induration

Modelling of a Pilot Scale Iron Ore Pellet Induration Furnace

Developing the Oxidation Kinetic Model for Magnetite Pellet

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