Microporosity of BIF hosted massive hematite ore, Iron Quadrangle, Brazil.

César A.C. Varajao (1) , Ary Bruand (2) , Erick R. Ramanaidou (3) , Robert J. Gilkes (3)

1 DEGEO - Escola de Minas, Universidade Federal de Ouro Preto
2 ISTO - Institut des Sciences de la Terre d'Orléans
3 SOIL SCIENCE AND PLANT NUTRITION - Soil Science and Plant Nutrition The University of Western Australia

Massive hematite ore (MHO) is a special high-grade iron ore, used as lump ore in the process of obtaining direct reduction iron (DRI). The influence of porosity on the reducibility of MHO from the Capitão do Mato Mine (Iron Quadrangle, Brazil) was investigated using optical and scanning electron microscopes on drill core and open pit samples. Hematite is the main component of the samples and occurs as granular crystals (10 mum), microplates (1 mum) and euhedral martite (10 to 30 mum). Quartz, maghemite, kenomagnetite and goethite are minor components. Primary micropores (Å to 1 mum) are associated with microplaty crystals that fill cavities between granular hematite. Secondary micropores (Å to 5 mum) related to euhedral martite crystals, are the most important. The total porosity of weathered samples, measured using nitrogen adsorption and mercury injection, attains values up to 11%, whereas unweathered samples have a porosity less than 2.5%. Reducibility is strongly enhanced by porosity, but inhibited by structure (bedding).

Mots clés: BIF; porosity; massive hematite ore; direct reduction iron; reducibility.; reducibility

Domaines: Interfaces continentales, environnement

César A.C. Varajao, Ary Bruand, Erick R. Ramanaidou, Robert J. Gilkes. Microporosity of BIF hosted massive hematite ore, Iron Quadrangle, Brazil.. Anais da Academia Brasileira de Ciências, 2002, 74, pp.113-126. ⟨10.1590/S0001-37652002000100008⟩. ⟨hal-00022502⟩