Estudo comparativo da formação da microestrutura em aglomerados produzidos com minério hematítico, goethítico e magnetítico

• Ano de defesa: 2016
• Autor(a) principal: Alei Leite Alcantara Domingues
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Materiais e de Minas; Engenharia Metalúrgica; Engenharia metalúrgica; Tecnologia mineral; Minérios de ferro; Microestrutura
• Link de acesso: http://hdl.handle.net/1843/BUBD-AC9GTY

The production of iron ore pellets involves the addition of materials such as limestone and lime, which, among other functions, are sources of CaO for the formation of slag. These gangue phases generated in the microstructure of agglomerates are extremely important not only for chemical quality, but also for their relationship with the physical quality. Thus, a comparative study was performed on the microstructures formed from three ores with different characteristics and origins: a predominantly hematite ore, a goethitic ore and a magnetite concentrate. The ores were blended with three amounts of lime to obtain: natural binary basicity, 1.5 and 3. These mixtures were pressed and the resulting pellets were burnt in a radiant furnace for the formation of the fluid phase at 1280°C temperature. Then the samples were extensively analyzed by reflected light microscopy with image analyzer and scanning electron microscopy to verify the chemical and morphological characteristics of the phases. X-rays diffraction and Mössbauer spectroscopy were used to determine the phases formed. The fired pellets were formed mainly by calciumferrites of the type Ca2Fe22O33 in samples where the main source of iron was hematite (hematitic and goethitic ores), and the type Ca2Fe2O5 calciumferrite for the sample of magnetitic ore. The main silicate formed in all samples was the Ca2SiO4 type. Generally, the porosity increased with increasing basicity, according to the consumption of CaO particles for calciumferrites formation. There was significant porosity formation in the pellet produced with the goethitic ore, generated during dehydroxylation of goethite to hematite. Columnar ferrites were mainly formed in the hematitic and goethitic samples, while in the magnetitic sample acicular ferrites prevailed.