Building of a Mathematical Model for the Reduction of Iron Ore in Ore/Coal Composites.

Sun, Shouyi; Lu, W.-K.

doi:10.2355/isijinternational.39.130

Cited by 55 publications

(44 citation statements)

References 5 publications

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“…The emissivity of the sample is high because of its porous nature; literature values for emissivity of similar samples are 0?85 and 1?0. 3,16 If the assumed sample Coetsee and Pistorius Measurement of reduction in packed bed of iron ore and carbon emissivity (0?90) is taken to be correct, the estimated maximum error in the heat transfer calculation due to the other factors is ¡19 kW m…”

Section: Sample Surface Temperature Measurement and Radiation Calculamentioning

confidence: 99%

Measurement of reduction in packed bed of iron ore and carbon under one-dimensional heating

Coetsee¹,

Pistorius

2009

Ironmaking & Steelmaking

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An experimental configuration was developed to quantify the rate of heat transfer into an iron orecarbon mixture during one-dimensional radiative heating. Repeatability and accuracy were evaluated by comparing the results of a radiation network calculation with a mass and energy balance, and by comparing predicted carbon contents after reaction with analysed carbon contents. For a sample consisting of prereduced ore and graphite, heat transfer is limited by both radiation to the sample surface and conduction into the sample; the off-gas analysis indicates that both the gaseous reduction reaction and carbon gasification are significantly away from equilibrium. The configuration is shown to yield reliable results for this complex combination of reaction steps.

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Section: Sample Surface Temperature Measurement and Radiation Calculamentioning

confidence: 99%

Measurement of reduction in packed bed of iron ore and carbon under one-dimensional heating

Coetsee¹,

Pistorius

2009

Ironmaking & Steelmaking

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“…Modelos de devolatilização de carvões para PCI são amplamente divulgados na literatura. (6,7,9,11) Neste trabalho foi adaptado um modelo para representar a volatilização em carvão granular conforme apresentado na Tabela 2. Os modelos da cinética de auto-redução no interior dos aglomerados foram apresentados podem ser encontrados na literatura e foram discutidos em trabalhos anteriores.…”

Section: Modelagem Matemáticaunclassified

Estudo Do Comportamento Da Cuba Do Forno De Auto-Redução Utilizando Carvão Granulado Através Do Modelo Multifasico

Castro¹,

Paco²,

D'Abreu³

2007

TMM

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ResumoA demanda por DRI continua crescente devido à escassez de sucata de alta qualidade para a produção de aço via forno elétrico. Neste contexto, o forno de cuba baseado em processo de auto-redução torna-se uma alternativa para suprir a demanda de metálicos permitindo a reciclagem de rejeitos de finos de indústrias siderúrgicas, metalúrgicas em geral e de mineração. Posto que os aglomerados são usualmente produzidos a partir de uma mistura de finos de minério de ferro ou resíduos e um agente carbonoso, a característica marcante aqui é o "ambiente interno dos aglomerados", que resulta em elevadas taxas de redução (extração do oxigênio do minério) graças às condições cinéticas daí resultantes. O presente trabalho objetiva o desenvolvimento de um modelo matemático capaz de simular as condições ótimas de operação de um forno de cuba operando com briquetes auto-redutores, carvão granulado e injeção secundaria de gás. A técnica para modelar o sistema de duas fases é a de volumes finitos onde se resolve as equações de transporte de momentum, energia e espécies químicas. Resultados de simulação indicaram que aproximadamente 70% de grau de metalização podem ser obtidos neste processo ao passo que o carvão granulado sofre a devolatilização por completo. A produtividade do processo obtida foi de 35 t/m 3 /dia com volume de gás de topo de aproximadamente 2840 Nm 3 /tDRI. Palavras-chave: Aglomerados; Auto-redução; Modelamento matemático; Forno de cuba. INVESTIGATION OF THE BEHAVIOR OF THE SHAFT FURNACE FOR SELF-REDUCING PROCESS USING THE MULTIPHASE MODEL AbstractDRI demand continues increasing due to shortage of high quality scrap iron for the steel production through electric arc furnace. In this context, the shaft furnace based on self-reducing process becomes an alternative route to supply the demand of metallic. It is possible to recycle the fines of iron and steelmaking industries since the self-reducing agglomerate are mixtures of fine ore/residues and reducing agent. The principal characteristic is the "internal environment of the agglomerate", this results in high rates of reduction (extraction of the oxygen from the ore) due to the kinetic conditions. The present paper aims to develop a mathematical model capable of simulating the operating conditions of the shaft furnace with self-reducing agglomerate, lump coal and secondary gas injection. The model used the technique of finite volume to solve the transport equations of momentum, energy and chemical species of both, solid and gas phases considered in this model. The main finds of this paper are: a) the self-reducing furnace can operates with a mixture of self-reducing briquettes and anthracite; b) the productivity of the process can achieve 35.5 t/m 3 /day; and c) the process produces outlet gas with high calorific value. Key words: Self-reducing agglomerates; Mathematical modeling; Shaft furnace. INTRODUÇÃOA demanda por DRI continua crescente devido à escassez de sucata de alta qualidade para a produção de aço via forno elétrico. Neste contexto, o forno de cuba...

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“…The tendency of activation energy against milling time is opposite the present results. Sun et al 10) determined the activation energy of reduction from magnetite to wustite for the mixture of magnetite and carbon powders to be 65.7 kJ/mol and that from wustite to iron to be 69.5 kJ/mol. Murayama et al 12) reduced hematite powder to magnetite by CO-CO 2 gas and obtained the activation energy to be 100 kJ/mol.…”

Section: Mechanisms Of the Reduction Of Iron Oxidesmentioning

confidence: 99%

“…The kinetic studies were also carried out from exhaust gas analysis. 9,10) However, these investigations could not separate the individual reduction reactions of iron oxides. A high temperature X-ray diffraction method is able to detect "in-situ" individual iron oxides and carbon.…”

Section: Introductionmentioning

confidence: 98%

Reduction Kinetics of Hematite Powder Mechanically Milled with Graphite

Seki¹,

Nagata²

2006

ISIJ Int.

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Reduction behavior of iron oxides mixed with graphite has been quantitatively investigated using a high temperature X-ray diffractometer. The mixture was mechanically milled using a vibration mill and heated under He gas flow from room temperature to 1 550 K with the heating rate of 10 to 40 K/min. The diffraction pattern showed the sequential change of products by reduction from hematite to iron through magnetite and wustite. The temperature at which each reduced product sequentially appeared was decreased by several ten degrees with increasing mechanical milling time up to 160 min. The intensity change of diffraction profiles of constituents with temperature was in accordance with the chemical stoichiometry of reduction reactions. The reduction reactions were first order of reaction. The activation energy of reaction decreased and the frequency factor of reaction increased with increasing mechanical milling time. On the other hand, the mixture of milled graphite powder and non-milled hematite powder gave less effect to the activation energy and frequency factor than the milled mixture.KEY WORDS: high temperature X-ray diffraction; milling; iron oxides; graphite; activation energy of reduction.Then, the hematite particles were formed to be spherical with about 54 m m in diameter. Graphite powder was separately milled in dry. The diameter of graphite particles was controlled to be about 30, 25, 17, 12 m m corresponding to the milling time of 10, 30, 60 and 160 min, respectively. After then, the spherical hematite powder and the milled graphite powder were mixed.Type C: The hematite particles prepared by spray-drying method were coated with carbon using a vapor-deposition in vacuum of 1.3 Pa (0.01 Torr). Coating with the coating rate of 0.3 s/coat were 100 times repeated and the position of particles was changed every coating so as to make a uniform carbon layer. The coated hematite particles were mixed with graphite powder milled in dry for 10 min. Analysis of Reduction of Iron Oxides by X-rayDiffraction Sample was set on a shallow flat vessel of alumina with 0.8 mm in depth, 17 mm in length and 9 mm in width. The vessel was horizontally set on the heating plate with Pt resistant heating wire in the center of furnace. The furnace was installed in the sample chamber of a high temperature X-ray diffractometer (RINT2000-TTR, Rigaku Denki Co.), which is explained elsewhere.16) X-ray beam passed through two windows of an outer film of polyimide for sealing up the sample chamber and an inner film of Ni for preventing from heat radiation. The generator of X-ray had the maximum power of 10 kW. The target of X-ray source was Co and Co-Ka line was employed. The optical system was a parallel beam method. The diffraction-scanning rate was 10 degree/min and the diffraction angle was between 46 and 51 degree in 2q . The diffraction angle was calibrated by means of internal standard specimen method using pure silicon particles at room temperature. The temperature of samples was measured by a R-type thermocouple by the side of ...

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Building of a Mathematical Model for the Reduction of Iron Ore in Ore/Coal Composites.

Cited by 55 publications

References 5 publications

Measurement of reduction in packed bed of iron ore and carbon under one-dimensional heating

Measurement of reduction in packed bed of iron ore and carbon under one-dimensional heating

Estudo Do Comportamento Da Cuba Do Forno De Auto-Redução Utilizando Carvão Granulado Através Do Modelo Multifasico

Reduction Kinetics of Hematite Powder Mechanically Milled with Graphite

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