<i>In situ</i>X-ray diffraction analysis of iron ore sinter phases

Scarlett, Nicola V. Y.; Madsen, Ian C.; Pownceby, Mark I.; Christensen, A. Nørlund

doi:10.1107/s002188980400353x

Cited by 69 publications

(67 citation statements)

References 7 publications

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“…Increasing Al2O3 concentration also increased the stability range of SFCA before it melted to form a Fe3O4 + melt phase assemblage. The formation of CFA during heating had not been described in a previous in situ XRD investigation of reaction sequences in the formation of SFCA phases, which was performed under vacuum in the range 298-1 533 K by Scarlett et al 23,24) Eqs. (3) and (4) Based on the absence of Fe3O4 in the study of Scarlett et al 23,24) it was inferred by Webster et al 25) that the oxygen partial pressure was somewhere in the range 0.21 -5 × 10 -3 atm, and it was speculated that pO2 may affect the formation of CFA.…”

Section: Introductionmentioning

confidence: 99%

“…The formation of CFA during heating had not been described in a previous in situ XRD investigation of reaction sequences in the formation of SFCA phases, which was performed under vacuum in the range 298-1 533 K by Scarlett et al 23,24) Eqs. (3) and (4) Based on the absence of Fe3O4 in the study of Scarlett et al 23,24) it was inferred by Webster et al 25) that the oxygen partial pressure was somewhere in the range 0.21 -5 × 10 -3 atm, and it was speculated that pO2 may affect the formation of CFA. Given that CFA was a precursor phase involved in the formation of the SFCA phases in the study of Webster et al, 25) it is also likely that pO2 would exert an influence on the formation mechanisms of SFCA and SFCA-I during heating.…”

Section: Introductionmentioning

confidence: 99%

“…A large number of investigations 2,3,[18][19][20][21][22][23][24][25] have aimed to determine the formation mechanisms of complex Ca-rich ferrite phases. Increased understanding of the mechanisms has the potential to improve the efficiency of the sintering process by a) being able to predict the optimal sintering conditions (temperature, pO2) to produce high quality product based on the chemical and physical composition of the iron ore fines, and b) being able predict the chemical and physical modifications of a particular iron ore fines mixture required to produce high quality product.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Oxygen Partial Pressure on the Formation Mechanisms of Complex Ca-rich Ferrites

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The formation mechanisms of the complex Ca-rich ferrite iron ore sinter bonding phases SFCA and SFCA-I, during heating of a synthetic sinter mixture in the range 298-1 623 K and at pO2 = 0.21, 5 × 10 -3 and 1 × 10 -4 atm, were determined using in situ X-ray diffraction. SFCA and, in particular, SFCA-I are desirable bonding phases in iron ore sinter, and improved understanding of the effect of parameters such as pO2 on their formation may lead to improved ability to maximise their formation in industrial sintering processes. SFCA-I and SFCA were both observed to form at pO2 = 0.21 and 5 × 10 -3 atm, with the formation of SFCA-I preceding SFCA formation in each case, but via distinctly different mechanisms at each pO2. No SFCA-I was observed at pO2 = 1 × 10 -4 atm; instead, a Ca-rich phase designated CFAlSi, formed at 1 420 K. By 1 456 K, CFAlSi had decomposed to form melt and a small amount of SFCA. Such a low pO2 during heating of industrial sinter mixtures is, therefore, undesirable, since it would not result in the formation of an abundance of SFCA and SFCA-I bonding phases. In addition, CFA phase, which was determined by Webster et al. (Metall. Mater. Trans. B, 43(2012), 1344) to be a key precursor phase in the formation of SFCA at pO2 = 5 × 10 -3 atm, was also observed to form at pO2 = 0.21 and 1 × 10 -4 atm, with the amount decreasing with increasing pO2.KEY WORDS: iron ore sinter; complex Ca-rich ferrite sinter bonding phases; SFCA and SFCA-I; in situ X-ray diffraction; oxygen partial pressure; phase formation mechanisms; synchrotron X-ray diffraction.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Oxygen Partial Pressure on the Formation Mechanisms of Complex Ca-rich Ferrites

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“…Furthermore, the sinter mineralogy also has a very complicated nature, and its behaviors are significantly varying and depending on various factors. [1][2][3] In sintering process, since the main source of heat energy is the combustion of coke breeze, the sinter mix is heated in a reducing atmosphere and cooled in an oxidizing atmosphere. 4) As schematically shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Formation of Calcium Ferrites under Controlled Oxygen Potentials at 1273 K

2010

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“…Parâmetros de microestrutura como fases de sustentação da matriz, morfologia das ferritas (aciculares ou colunares), composição química das ferritas, porosidade (total, forma e tamanho), distribuição de elementos químicos na microestrutura (como Al, Ca, Mg e Mn), foram investigados para tipos diferentes de minérios [5][6][7].…”

Section: Análise Microestrutural Em Pastilhas Prensadas Com Diferenteunclassified

Análise Microestrutural Em Pastilhas Prensadas Com Diferentes Tipos De Minérios De Ferro

Domingues¹,

Brandão²

2016

TMM

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ResumoA produção de aglomerados de minério de ferro envolve a adição de materiais como calcário e cal para a formação de escória, que assume função importante na microestrutura do aglomerado envolvendo e sustentando as partículas de minério de ferro. Dessa forma, realizou-se um estudo comparativo das microestruturas formadas a partir de três minérios com características diferentes: hematítico, goethítico e magnetítico. Os minérios foram misturados à cal para obtenção de basicidade binária de 1,5% para todas as amostras. Em seguida, foram prensados e as pastilhas foram submetidas a aquecimento em forno irradiante que atingiu cerca de 1280 °C. As amostras foram então analisadas por microscopia de luz refletida com analisador de imagens e microscopia eletrônica de varredura. Foram observadas diferenças na quantidade de hematita, magnetita, silicatos e ferritas. A porosidade na pastilha hematítica foi menor, enquanto a pastilha magnetítica apresentou os maiores valores de porosidade total. A sustentação da matriz é feita por fases diferentes em cada caso e a composição química das ferritas mostra uma complexa variação composicional. Palavras-chave: Microestrutura; SFCA; Aglomerados; Mineralogia; Minério de ferro. MICROSTRUCTURAL ANALYSIS OF PRESSED SAMPLES WITH DIFFERENT TYPES OF IRON ORES (HEMATITIC, MAGNETITIC AND GOETHITIC) AbstractThe production of iron ore agglomerates involves the addition of materials such as limestone and burnt lime to form slag, which plays an important role in the microstructure involving and sustaining the iron ore particles. Thus, a comparative study of microstructures formed from three ores with different characteristics: hematitic, magnetitic and goethitic, was carried out. The ores were mixed with burnt lime to obtain binary basicity of 1.5% for all samples. Then they were pressed and the samples were subjected to burnt in a rapid heat oven that has reached about 1280 °C. Then the samples were extensively analyzed by reflected light microscopy with digital images analyzer and scanning electron microscopy. Differences were observed in the amount of hematite, magnetite, silicates and ferrites. Porosity in the hematitic sample was lower, while the magnetitic sample had the highest total porosity values. The support matrix is made up by different phases in each case and the chemical composition of ferrites shows a complex compositional variation. Keywords: Microstructure; SFCA; Iron ore agglomerates; Mineralogy; Iron ore. INTRODUÇÃOÉ comum em sinterização o conhecimento de que a formação de fase líquida promove a resistência do aglomerado. Entretanto, excesso de fases líquidas (principalmente SFCA e calcioferritas) podem comprometer sua qualidade química. O que as sinterizações e pelotizações ao redor do mundo fazem, é tentar ajustar a qualidade química dos aglomerados por meio das qualidades dos insumos acrescentados nas misturas.Entretanto, nem sempre com a composição química considerada ideal obtêm-se resultados físicos e desempenho satisfatórios em altos-fornos. Relata-se que a microe...

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In situX-ray diffraction analysis of iron ore sinter phases

Cited by 69 publications

References 7 publications

Effect of Oxygen Partial Pressure on the Formation Mechanisms of Complex Ca-rich Ferrites

Effect of Oxygen Partial Pressure on the Formation Mechanisms of Complex Ca-rich Ferrites

Formation of Calcium Ferrites under Controlled Oxygen Potentials at 1273 K

Análise Microestrutural Em Pastilhas Prensadas Com Diferentes Tipos De Minérios De Ferro

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