Localized Heating and Reduction of Magnetite Ore with Coal in Composite Pellets Using Microwave Irradiation

Ishizaki, K.; Nagata, Kazuhiro; Hayashi, Tetsuro

doi:10.2355/isijinternational.47.817

Cited by 60 publications

(46 citation statements)

References 14 publications

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“…We have focused on the microwave heating as a new heating source for iron making. [1][2][3][4] Ishizaki et al 2) have produced the highly-pure pig iron from the carbon composite iron ore pellet composed of the mixture of magnetite ore (Romeral) and coal (Robe River) powders by means of a 2.45 GHz microwave furnace. The temperature reached 1 350°C ca.…”

mentioning

confidence: 99%

Complex Permittivity and Permeability of α-Fe2O3 and Fe1−xO Powders in the Microwave Frequency Range between 0.2 and 13.5 GHz

2010

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Nowadays, CO 2 emission reduction and energy conservation are urgent tasks owing to the initiation of Kyoto Protocol adopted for the prevention of global warming. Since large fraction of CO 2 emission is attributed to the blast furnace-type iron making in Japan in spite of the fact that Japanese blast furnace technology has been already advanced, new iron making process should be invented based on innovative theories and mechanisms. We have focused on the microwave heating as a new heating source for iron making. 1-4)Ishizaki et al.2) have produced the highly-pure pig iron from the carbon composite iron ore pellet composed of the mixture of magnetite ore (Romeral) and coal (Robe River) powders by means of a 2.45 GHz microwave furnace. The temperature reached 1 350°C ca. 500 s after the onset of the heating, and subsequently the power was switched off. This study implies that iron making from powder raw materials using microwave heating could yield the low temperature operation and the highly-pure pig iron production: The production of highly-pure pig iron is considered to be relevant to the rapid heating of raw materials. 5)Microwave absorption of materials is caused by Joule loss, dielectric loss and magnetic loss, which are dependent on the electrical conductivity and imaginary parts of permittivity and permeability, respectively. Therefore, it is very important to measure these properties for raw materials and refractories as a function of microwave frequency. In the previous papers, 6) the effects of various factors such as relative density, microwave frequency and particle size of powder SiO 2 and Fe 3 O 4 samples on the complex permittivity and permeability has been investigated by using coaxial transmission line method using a network analyzer. It has been found that the e r Ј values of powder SiO 2 and Fe 3 O 4 samples with the relative density below 1 are smaller than the values estimated using the linear relation between e r Ј and the relative density, and larger than those estimated using the Lichtenecker's logarithm mixed law. It has also been found that the imaginary part of complex permeability of Fe 3 O 4 powder with a particle size of 50 nm-180 mm show the peaks in the frequency range of 706 MHz to 2.99 GHz, depending on the particle size. The imaginary part of complex permittivity of Fe 3 O 4 powder is quite large having a peak around 10 GHz.On the other hand, it is very important to measure the complex permittivity and permeability of a-Fe 2 O 3 because most widely used iron ore contains a-Fe 2 O 3 rather than Fe 3 O 4 . Moreover, it is also of industrial importance to measure the complex permittivity and permeability of wüstite (Fe 1Ϫx O) to evaluate the changes of the microwave absorption characteristics in the course of reduction reaction of raw materials. Fe 1Ϫx O is an nonstoichiometric compound and the value of x ranges from 0.05 to 0.15 depending on the temperature and the oxygen partial pressure. Therefore, it is scientifically interesting to elucidate the x value dependencies of these ...

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Complex Permittivity and Permeability of α-Fe2O3 and Fe1−xO Powders in the Microwave Frequency Range between 0.2 and 13.5 GHz

2010

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“…Na área metalúrgica a literatura reporta muitos experimentos de redução carbotérmica de óxidos metálicos realizados em fornos de micro-ondas de uso doméstico [1][2][3] ou comercial [4][5]. Apesar de sua relevância, esses experimentos geralmente apresentam limitações que decorrem do próprio tipo de forno utilizado, pois utilizam normalmente, fornos domésticos adaptados, com cavidades paralelepipédicas.…”

Section: Introductionunclassified

“…Apesar de ser fácil adaptar uma balança ao forno, podendo acompanhar de maneira contínua a variação da massa da amostra durante o aquecimento, esse recurso é raramente utilizado. As pesquisas com micro-ondas na redução de minério de ferro concentram-se em reduzir o tempo de redução em relação ao consumido em forno elétrico [6]; em reduzir a emissão de CO2 bem como a conservação de energia em um processo de redução carbotérmica comparando-o com alto-forno [7]; nas mudanças das fases do ferro formado variando os níveis de potência irradiada de micro-ondas [5]; do efeito da variação da freqüência de micro-ondas de 2,45 GHz para 30 GHz [8] e da utilização de outras fontes de carbono para substituírem os redutores convencionais [1]. Além disso, devido à diminuição de recursos energéticos e a introdução de leis ambientais mais rigorosas, a busca de novos processos de produção de aço e ferrogusa tornaram-se estratégicos.…”

Section: Introductionunclassified

Equipamento Para Redução Carbotérmica De Minério De Ferro Utilizando Micro-Ondas

Castro¹,

Mourão²,

Jermolovicius³

et al. 2017

Anais Dos Seminários De Redução, Minério De Ferro E Aglomeração

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ResumoO presente trabalho apresenta um forno para a produção de ferro gusa por redução carbotérmica estimulada por micro-ondas de minério de ferro, na forma de pelotas autoredutoras. O forno de redução com potência regulável de até 15 kW de micro-ondas de 2.45 GHz foi especialmente projetado e construído para este processo. A estrutura do forno é em aço inoxidável e utiliza três geradores de micro-ondas focados para o centro de um aplicador cilíndrico. Com esta configuração conseguiu-se produzir um campo eletromagnético de alta densidade energética. As cargas de pelotas auto-redutoras, com massas em torno de 90 g e 30 g foram reduzidas em um cadinho de carbeto de silício. A potência de micro-ondas irradiada foi de 6 kW. A montagem do forno dispõe de uma balança elétrica adaptada para suportar o cadinho de redução. O presente forno dispõe de controle e medida da potência fornecida e refletida, permitindo medir a energia de micro-ondas efetivamente aplicada à carga. Esta característica permite realizar balanços de massa e de energia além de determinar a evolução da taxa de reação através da medida contínua da massa das pelotas sob redução, ao longo do tempo de processamento. Obtiveram-se curvas cinéticas de redução carbotérmica de minério de ferro incentivada por micro-ondas e de seu consumo de energia durante o processo. Palavras-chave: Forno redução carbotérmica; Micro-ondas; Ferro gusa. EQUIPMENT FOR CARBOTHERMAL REDUCTION OF IRON ORE APPLYING MICROWAVE AbstractThis paper presents of furnace for production of pig iron by carbothermic reduction of iron ore in the form of self-reducing pellets enhanced by microwaves. The reduction furnace with adjustable up to 15 kW microwave power of 2.45 GHz has been specially designed and built for this purpose. The furnace structure is made of stainless steel and has three microwave generators focused to the center of a cylindrical applicator. With this setup we were able to produce a high energy density electromagnetic field. The burden of self-reducing pellets with mass around 90 g and 30 g were reduced in a crucible silicon carbide. The power microwave radiated is 6 kW. The oven features an electric balance appropriately adapted to support the crucible reduction. This oven allows the measurement and control of power supplied and reflected establishing the effective energy applied to load. This feature allowed for mass and energy balances and to observe the evolution of reduction rate by continuously measuring of reacting mass during its processing. Curves for carbothermic reduction of iron ore were determined and, also, the energy consumption during the process. This feature allows to perform mass and energy balances and to determine the progress of the reaction rate by continuously measuring the mass of pellets under reducing along the processing time. Curves for carbothermal reduction of iron ore were determined and, also, the energy consumption during the process.

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“…According to the research of Ishizaki et al, 19) in the case of magnetite-coal composite pellets irradiated with microwave, Fe3O4 was reduced to FeO at about 800-1 000°C and then FeO was reduced to Fe at about 1 000-1 250°C. However, the metallic iron contents in Table 4 indicate that the transformation of FeO to Fe happened around 800°C.…”

Section: Characterization Of Productsmentioning

confidence: 99%

Dephosphorization of Iron Ore Bearing High Phosphorous by Carbothermic Reduction Assisted with Microwave and Magnetic Separation

Yin

Bai

et al. 2012

ISIJ Int.

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The integrated process, which combined the carbothermic reduction assisted with microwave irradiation followed by milling and magnetic separation, was investigated as a potential approach for dephosphorization treatment of iron ores bearing high P. Mineralogical Research indicated that the phosphorous in oolitic hematite ores exists in two forms, inter-grew with iron oxide or gather together into a bigger size as gangues. The increase of microwave irradiation time had substantial effect on the reduction of Fe while the influence of carbon dosage was not obvious. As the reduced iron and unreduced P-contained gangues were not efficiently separated, a high iron recovery ratio and a reasonable dephosphorization rate were incompatible under the conditions investigated in this study. This process was successful in the aspect of iron recovery but the dephosphorization rate was unsatisfactory. Microwave-assisted reduction could be a promising pre-reduction process which could be followed by smelting process and dephosphorization treatment.

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Localized Heating and Reduction of Magnetite Ore with Coal in Composite Pellets Using Microwave Irradiation

Cited by 60 publications

References 14 publications

Complex Permittivity and Permeability of α-Fe2O3 and Fe1−xO Powders in the Microwave Frequency Range between 0.2 and 13.5 GHz

Complex Permittivity and Permeability of α-Fe2O3 and Fe1−xO Powders in the Microwave Frequency Range between 0.2 and 13.5 GHz

Equipamento Para Redução Carbotérmica De Minério De Ferro Utilizando Micro-Ondas

Dephosphorization of Iron Ore Bearing High Phosphorous by Carbothermic Reduction Assisted with Microwave and Magnetic Separation

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